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Office: AMA

FXUS64 KAMA 162024
AFDAMA

Area Forecast Discussion
National Weather Service Amarillo TX
224 PM CST Sat Dec 16 2017

.DISCUSSION...Upper level low over southeastern New Mexico this
afternoon is lifting northeast across west Texas bringing with it
high clouds across the eastern Texas Panhandle. At the surface,
lee side cyclogenesis is occurring with noticeable pressure falls
in northeast New Mexico. Associated pressure falls along with lee
side troughing has increased pressure gradients across the area,
bringing with it downsloping southwesterly winds. Fire weather
concerns exists, which are detailed in the fire weather section
below. As the surface low continues to strengthen, it will join
with an approaching cold front and help push it across the
Panhandles late this evening. Winds in association with this cold
front will be northwesterly around 10 to 20 MPH, with high
temperatures being near to slightly cooler tomorrow.

The long awaited pattern shift has started to show signs of
occurring as a longwave trough is currently moving across the
Great Basin of the western United States, which is causing the
prevalent ridge to break down and push west. Model guidance has
indicated that a vort max will pinch off the bottom of this
trough, and become a closed low over the desert southwest. Details
have come into better focus that as this system moves south
across the region Tuesday afternoon and early Wednesday morning,
moisture will remain to the south and east of the area. A brief
reprieve will follow with a shortwave ridge passing over, with
another system potentially moving across the region late Thursday
into Friday. Model guidance difference is sufficient enough to
preclude precip chances, as the ECMWF sends the system through the
area as an open wave while the GFS cuts it off over Arizona.

It is as a result of the above mentioned model difference that
will play a major role in how the forecast evolves for the weekend
before Christmas. Both the ECMWF and GFS show an arctic frontal
boundary moving across the combined Panhandles. The uncertainty
remains whether the GFS is correct with the cutoff upper low
Saturday and Sunday, as that could potentially present with winter
weather concerns. If the ECMWF is correct, then any winter weather
precipitation that may fall would be brief. We will continue to
monitor the evolution of the weather pattern for next weekend due
to these concerns.

Bieda

&&

.AVIATION...Previous Discussion...18Z TAFs..
VFR conditions to prevail throughout the 18Z TAF issuance.
Southerly winds have already begun to pick up into the 15 to 20kt
range and are expected to remain in this range through the
afternoon. Winds will decrease around sunset and remain light
until a cold front switches them out of the north overnight
tonight. Given the orientation of the front, KDHT will see this
wind shift first then followed by KGUY and KAMA. There is some
indication that a low stratus could develop post-front at KGUY but
confidence isn't high enough to mention in prevailing.

14

&&

.FIRE WEATHER...Fire Danger Statement continues until 5 PM CST due
to elevated fire weather conditions. South to southwest winds of
15 to 25 MPH with gusts to 35 MPH, and relative humidity values
around 15 to 20 percent, are being observed. Winds should decrease
around sunset, with relative humidities beginning to recover.
Beyond today, no fire weather conditions of significance are being
forecasted at this time through next Friday.

Bieda

&&

.PRELIMINARY POINT TEMPS/POPS...
Amarillo TX                27  52  28  61  33 /   0   0   0   5   0
Beaver OK                  22  47  21  63  27 /   5   0   0   0   0
Boise City OK              23  45  25  60  28 /   0   0   0   0   0
Borger TX                  29  51  30  63  36 /   0   0   0   5   0
Boys Ranch TX              24  53  24  63  27 /   0   0   0   5   0
Canyon TX                  25  53  26  61  30 /   0   0   0   5   0
Clarendon TX               28  54  29  60  35 /   5   0   0   5   0
Dalhart TX                 25  49  26  61  28 /   0   0   0   5   0
Guymon OK                  25  46  25  62  30 /   0   0   0   0   0
Hereford TX                23  55  26  62  30 /   0   0  10   5   0
Lipscomb TX                29  50  27  63  33 /   5   0   0   0   0
Pampa TX                   28  51  28  62  34 /   0   0   0   5   0
Shamrock TX                31  53  28  60  34 /  10   0   0   5   0
Wellington TX              31  55  29  61  36 /  10   0   0   5   0

&&

.AMA Watches/Warnings/Advisories...
TX...None.
OK...None.

&&

$$

14/98



Office: EWX FXUS64 KEWX 162051 AFDEWX Area Forecast Discussion National Weather Service Austin/San Antonio TX 251 PM CST Sat Dec 16 2017 .SHORT TERM (Tonight through Sunday Night)... Water vapor satellite images show an upper level low pressure system moving over west Texas and to the northeast. All HiRes and medium- range models agreed on continuing to bring this system to the northeast and into the Southern Plains this evening as it opens into an upper level short-wave. As the upper level system moves to the northeast for the rest of this afternoon and evening, light to moderate rain is expected across the eastern two-thirds of South Central Texas. There will be a window late this afternoon and early evening for isolated thunderstorms mainly along and east of Interstate 35 as an upper level wind speed maxima moves across the area. Also, it could enhance any activity for the period and result in periods of heavy rain. Overall, rainfall amounts should stay in the half to one inch range especially along and east of I35 with the potential for up to two inches of rainfall along and east of Highway 77. The rain chances come to an end from west to east this evening with rain-free weather over all areas overnight tonight. Due to a warm night and wet surfaces, expect patchy fog to develop late tonight across much of South Central Texas. Sunday should be dry with clouds lingering all day across the eastern counties and highs in the 60s. && .LONG TERM (Monday through Saturday)... Another upper level low pressure system is forecast to slowly move across the four corners region on Monday and brings showers and thunderstorms across the area for the first part of next week. A cold front passage will enhance the chances for rain on Tuesday. The cold front and upper level energy will move to the east and southeast with dry weather expect for Wednesday and Thursday. Yet, another upper level disturbance and a much strong cold front is expected on Friday. A cold airmass will spread across the area for next weekend with lows in the 30s and highs only in the 40s. There is still a lot of uncertainty for the extended forecast period as far as the type of precipitation we will get if moisture is around. We will be closely monitoring model guidance and adjusting the forecast as you plan for the Christmas holiday weekend. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 43 65 52 64 57 / 100 0 10 30 50 Austin Bergstrom Intl Airport 42 64 51 64 58 / 100 0 10 30 50 New Braunfels Muni Airport 42 64 52 66 59 / 90 0 10 30 50 Burnet Muni Airport 41 64 48 62 55 / 80 0 - 30 40 Del Rio Intl Airport 41 59 47 64 53 / - 0 - 10 30 Georgetown Muni Airport 42 64 49 62 55 / 100 0 10 30 50 Hondo Muni Airport 41 62 51 65 58 / 40 0 10 30 40 San Marcos Muni Airport 42 64 51 65 59 / 100 0 10 30 50 La Grange - Fayette Regional 43 65 53 67 61 / 100 0 20 40 50 San Antonio Intl Airport 44 64 53 66 60 / 80 0 10 30 40 Stinson Muni Airport 43 63 54 66 60 / 80 0 20 30 40 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Mesoscale/Aviation...Hampshire Synoptic/Grids...17 Public Service/Data Collection...30
Office: BRO FXUS64 KBRO 162127 AFDBRO Area Forecast Discussion National Weather Service Brownsville TX 327 PM CST Sat Dec 16 2017 ...Chilly Damp Weather Slow to Depart This Weekend... .SHORT TERM (Tonight through Sunday Night): Dreary and damp conditions continue this afternoon, with 500 mb low ejecting quickly through west Texas this afternoon and into Oklahoma overnight while dampening out. Southwesterly flow continues aloft, however, as another southwest U.S./Northwest Mexico trough crosses along the international border between Arizona/New Mexico by Sunday night as the subtropical ridge keeping South Florida nice and mild today spreads into the western Gulf. Deep South Texas, being caught in the "squeeze" between these two systems aloft - and sitting in a classic "cold air damming" situation from the current chilly air mass which is keeping low to very low clouds locked in place east of the Sierra Madre, will see very slow moderation on Sunday based on analog cases at this time of year when the sun is near its nadir for our part of the world. Bottom line? Even after the quick and final shot of rain ends quickly this afternoon, low clouds and fog/mist will be difficult if not impossible to scour out Sunday. With another stripe of mid level moisture arriving Sunday, that will also prevent sunshine from breaking through - ensuring a still cool-ish day. The NAM-12, which has been one of the best models in these situations, was followed closely through the short term. For the sensible weather: Light to moderate rain will continue to prevail across the ranchlands/upper Valley through 4 or 5 PM before quickly exiting stage northeast and eventually providing more helpful rain to parts of the upper Texas coast tonight into early Sunday - areas that have seen dryness return. The 2.5 day rain event for places like Jim Hogg and Brooks County looks to add up to 2+ more inches in some areas, eradicating what's left of the drought/dry conditions there and a nice surprise for a December that at one point looked to end at or below average. No longer the case, when including some more rain by late next week/weekend. Farther east, more occasional rain will end as forcing exits quickly, leaving low clouds, fog, and light west/northwest winds for the overnight. Current temperatures in the mid 40s to lower 50s may nudge down a degree or so overnight but that's about it. Guidance shows already low cloud bases (500 to 900 feet) to fall further and perhaps dip below 200 feet, which would end up a de facto fog event just about anywhere. Even though chilly temperatures are not necessarily conducive, the crashing ceilings should aid in perceptible fog of 1-3 mile visibility so added to the entire land mass. Sunday will begin with dreary overcast and fog with some drizzle just about everywhere, and it won't necessarily be gone by noon as would be typical in late winter and spring. Therefore, have maintained mention through noon with a very slow rise in temperatures. With light north winds more likely to prevail the entire day as the low clouds only lift a few hundred to a thousand feet, it would not surprise if 60 is not achieved in many areas. The NAM covers this well, keeping the ranchlands locked into the 50s with readings creeping over 60 in the Lower Valley. As mentioned above, elected to lean strongly this way and disregard the warmer blends as even the GFS has been trending toward no discernable wind shift to the east or southeast Sunday afternoon. This is a far cry to earlier optimistic Sunday forecasts, but follows the trend and the climatology of the pattern. For Sunday night, the chilly air continues to gradually erode. This is when it gets interesting, with low temperatures at or just below Sunday's highs, as dewpoints remain or rise to meet them. Upper 50s is often a "sweet spot" for winter fog as warm advection above the cold dome develops, and guidance signals are very much in line with a potential dense fog episode late Sunday night through the Monday morning commute. Did not add "dense" to the forecast just yet but will highlight in the hazardous weather outlook. As for precipitation? The GFS shows a stripe of deeper moisture but forcing is weak; still, elected to keep a mention of slight chances across the eastern half of the area, mainly east of US 281/IH 69C, Sunday night. .LONG TERM (Monday through Saturday): The synoptic pattern at the beginning of the work week will include another Baja California mid-level trough/low pressure system and a strong high over the eastern Gulf of Mexico. In between, southwest flow aloft and weak surface troughing will continue across Deep South Texas and along the coast. High moisture in the column will keep a good amount of cloud cover across us through the first half of the week. Models are somewhat in disagreement with how long the overcast, cool conditions will persist into Monday. The NAM wants to keep a more notable coastal low with northerly flow and much cooler temperatures, whereas the ECMWF and GFS bring temperatures back into the upper 70s and low 80s. Decided to stick somewhere on the higher side of a blend of the three with temperatures in the mid 70s and lower (isolated) rain chances. Also added fog through early Monday morning with high surface and soil moisture and light winds. On Tuesday, confidence is higher that temperatures will warm up with stronger S/SSW flow returning. A cold front is expected to move through late in the day after peak heating with northwest flow very briefly returning. The surface high will move quickly to the east, bringing southeast flow and a better moisture return by the end of the week. Confidence is modest right now with our next cold front by the end of the week, with the latest 12Z model guidance. The ECMWF brings a very weak trough through Central Texas with very low rain chances and the GFS continues to dig another deep low over the Desert Southwest with much cooler and wetter conditions for the weekend. Until models come into better agreement, decided to lean on the wetter, cooler GFS side due to pattern persistence. && .MARINE: Now through Sunday night: Surface low/trough splitting the nearshore and offshore waters (beyond 20 nm) with caution conditions (15 to 20 knots and gusty from the southeast) hanging on a little while longer before back side northwest winds overtake the situation. Current forecast covers this well, and will maintain the current trends through this evening. Seas have likely risen toward 6 feet, as buoy 19 (in better gradient, but developing a northeast swell) well east of Matagorda carried 6.2 foot seas and, as prior discussion mentioned, these should briefly carry into the 20 to 60 nm leg through early to mid evening. Thereafter, northwest winds fade to north/variable overnight into Sunday, then turn northeast or east beyond 20 nm out Sunday afternoon while remaining light north close to shore in the cooler waters and especially on Laguna Madre. Light/variable winds will continue Sunday night near shore and Laguna Madre, with a slight uptick in southerly flow over the warmer waters farther east where air mass recovery gets going in earnest. Monday through Friday night: Light to moderate winds will continue over the coastal waters with scattered showers and possibly a few thunderstorms through Tuesday. A weak front will move through late Tuesday with brief northwest winds returning and higher seas to 3 to 5 feet. The next cold front on Friday could be strong with Small Craft Advisory conditions possible. && .BRO WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ This product is also available on the web at: HTTP://WEATHER.GOV/RGV Short term...52/BSG Long term...65/CB Marine...52/65
Office: CRP FXUS64 KCRP 162155 AFDCRP Area Forecast Discussion National Weather Service Corpus Christi TX 355 PM CST Sat Dec 16 2017 .SHORT TERM (Tonight through Sunday Night)... Areas of rain continue across western areas with showers developing offshore and along the coast in vicinity of developing boundary/surface low. All of this being driven by potent upper level disturbance currently over far West Texas as well as moisture stream from the Pacific. Surface low/boundary could clip far northeast CWA this afternoon. Think any chance for thunderstorms will be limited to immediate coastal areas in vicinity of the boundary. Models have pretty good handle on positioning of upper disturbance, increasing confidence in timing of end of precip shield...expected to be out of the forecast area by around midnight. Could linger just a bit longer far northeast. Despite the upper disturbance getting out of the area, will keep a very thick/low cloud cover over most of the area tonight. Some vis reductions are possible with this low ceiling/fog. Some guidance suggests some clearing of mid level clouds far west, which could enhance fog potential in that area. Should see an increase in cloud deck by mid-day Sunday, though generally overcast conditions will continue. Another coastal trough may develop by late Sunday to providing another low chance for showers. Fog looks like a good potential for Sunday night as lingering ground moisture from today's rain will have nowhere to go with cool temps and persistent cloud cover. Min temps tonight drop mainly into the 40s, but expect warmer temps Sunday night with a general onshore flow. Highs will warm only into the lower 60s on Sunday. && .LONG TERM (Monday through Saturday)... Anticipate convection across the CWA/MSA Monday/Tuesday as an upper level disturbance moves across the region (confident in deterministic NWP output.) Drier Tuesday night/Wednesday as the upper system moves east. Deterministic GFS/ECMWF predict a strong disturbance to enter the NW CONUS Wednesday then move SE across the Rockies. Yet, the GFS/ECWMF diverge with respect to this system, with the ECMWF becoming progressive and the GFS cuts it off over the SWRN CONUS. Will follow the GFS ensemble mean, which maintains the upper trough axis west of TX Friday/Saturday. The ECMWF predict the development of a surface ridge over Western Canada and coincident with a polar air mass Tuesday, which is a precursor pattern to cold air outbreak (CAO) events east of the Rockies. Further, the MSLP center/polar air mass begins to move SWD into the CONUS as the foregoing upper system predicted to move SE across the Rockies Wednesday, which is a large scale meteorological pattern that occurs during CAO events. Thus, confident that the polar air will enter the CWA Friday as predicted by deterministic output. If the upper trough axis remains west of the CWA/MSA Friday/Saturday, a wintry precipitation scenario could occur as early as Saturday. Yet, will maintain sfc temperatures above freezing over the CWA Saturday consistent with the SuperBlend. Further, applying the top down approach to select GFS deterministic soundings suggest rain over the CWA. && .PRELIMINARY POINT TEMPS/POPS... Corpus Christi 47 63 59 72 64 / 70 10 30 30 40 Victoria 45 66 57 71 61 / 90 10 20 50 50 Laredo 44 61 55 68 61 / 20 10 10 20 30 Alice 46 63 58 73 63 / 60 10 20 30 40 Rockport 49 63 60 71 64 / 80 10 30 40 50 Cotulla 42 60 54 67 58 / 30 10 10 20 40 Kingsville 46 63 59 74 64 / 60 10 20 30 40 Navy Corpus 51 63 62 72 66 / 70 10 30 40 40 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...None. GM...Small Craft Advisory until 8 PM CST this evening For the following zones: Coastal waters from Port Aransas to Matagorda Ship Channel out 20 NM...Waters from Baffin Bay to Port Aransas from 20 to 60 NM...Waters from Port Aransas to Matagorda Ship Channel from 20 to 60 NM. && $$ PZ/83...SHORT TERM WC/87...LONG TERM
Office: EPZ FXUS64 KEPZ 162238 AFDEPZ Area Forecast Discussion National Weather Service El Paso Tx/Santa Teresa NM 338 PM MST Sat Dec 16 2017 .SYNOPSIS... An upper level storm system will bring increasing clouds to the area overnight, which will help keep temperatures a little warmer than the past few nights. The approaching storm system will bring widespread lowland rain and high elevation snow showers to the area Sunday, with several inches of snow expected in higher elevations above 7,500 feet, and lesser amounts down to around the 6,000 foot level. A few showers will linger around into Monday, with dry weather persisting for most of the week ahead. A cooler airmass will approach the area towards the weekend, along with more unsettled weather. && .DISCUSSION... Water vapor satellite imagery shows twin upper lows -- one ejecting out and moving NE over the Trans-Pecos, soon to be out of sight/out of mind...and another embedded in a high amplitude trough digging into northern Baja. Models have come into better agreement on the track of this low at least until Monday morning when the low should be over SE Arizona. After that, things become a little less clear with the low possibly stalling out and drifting south into Sonora. In the meantime, it looks like most of the precip should hold off until around dawn Sunday, after which a strong vortmax moving into NE Sonora will bring a rapid increase in PVA and larger-scale lift over SW New Mexico. Mid-level SSW winds will also increase, with orographic lift helping develop/enhance precip over the Gila. Precip will spread east towards Las Cruces and El Paso towards noon or a little after. Precip might be a little more delayed over Otero county, but still expect orographic lift to lend a hand over the Sacramento Mountains, with precipitation starting in the early afternoon. Snow levels still look to be well-behaved thanks the lack of a backdoor front and attendant low level cold air mass, and deep southerly flow aloft. Although precip will hold off most of the night and winds will remain light, thickening high clouds will help keep temperatures from bottoming-out over the Gila like they are apt to do under clear skies. Still, any early-morning precip could start out as a mix of rain/snow or even snow pellets down to around 5,000 feet, but snow levels will quickly increase after sunrise and generally hover between 6500 and 7500 feet throughout the day both in the Gila Region and the Sacramentos. Some weak instability and steepening lapse rates ahead of the low may result in some isolated thunderstorms with the initial round of precipitation Sunday, mainly in the lowlands in SW New Mexico. Snowfall amounts...in the Gila: generally looks like 3 to 6 inches above 7500 feet, with localized areas up to 8 inches (mainly along the crest of the Black Range and perhaps the Pinos Altos Range). Between 6000 and 7500 feet...expect 1 to 3 inches of snow, and it'll be pretty sloppy below 6500 feet. Silver City (which varies between 5800 and 6200 feet) will be on the lower end of the scale, with their hopes mostly dependent on keeping precip around into Sunday night. The heaviest snow will be in unpopulated areas, with the worst impacts on higher mountain passes. This includes NM-15 in two spots -- crossing the Pinos Altos Range, and again near the Copperas Ridge just south of Gila Hot Springs. Also NM-152 through Emory Pass. Some of these areas will flirt with Winter Storm Warning criteria (6 inches in 12 hours or 9 inches in 24 hours), but given the relatively limited impacts (especially in Silver City), we decided to go with a Winter Weather Advisory for Zone 402 (which covers the southern Gila region above 6,000 feet). Snowfall...for the Sacramentos: generally 3 to 5 inches above 7500 feet, with 1 to 3 inches down to 6,000 feet. A little less confident in this given the tendency of some models and ensemble members to slow the system down, including the ECMWF which is very shy about spreading QPF into the Sacramentos. Went with an Advisory for all 3 Sacramento Mountain zones, starting it a little later in the day Sunday (18z). Elsewhere...could be a sloppy inch or so in some of the higher terrain in the Bootheel. Some rain/snow mix is possible in a few lowland areas late Sunday night or Monday morning, but with little to no accumulation. The best chance of this will be north and west of Las Cruces. For El Paso, expect a healthy rainfall of 0.20 to 0.50 inches. For Monday, we could see some lingering snow showers in the higher terrain, especially if the low stalls out, but the amounts will generally be low since we will dry-slot early Monday, and then the low rapidly weakens. Dry conditions with a low warm-up are expected Tuesday into Thursday. On Friday, a fast-moving shortwave trough may sweep through, but it looks dry. Then things get very unclear. There is good agreement on a very high-amplitude ridge setting up along the West Coast northward towards the Yukon. This is an ideal pattern for sending an arctic airmass southwards into the U.S.. The question is with the strength, orientation, and amplitude of the trough that sets up to the east of the ridge. The ECMWF continues to favor the less- amplified solution, with the Arctic air mass mostly deflecting into the Great Lakes. The 12z GFS pushes the colder air further south and backs it up into the Rockies, and keeps it around through next weekend. However, the 12Z GFS Ensembles show there is a large amount of variation Friday onwards, with most members preferring a warmer solution. FWIW, the 18Z deterministic GFS has flopped back to a warm solution. So, there is some increasing confidence in precip being around the area Christmas Eve/Christmas (Sun/Mon), but it's not a slam dunk (20-30 PoPs seem OK), and precip type remains completely up in the air. && .AVIATION... Valid 17/00Z-18/00Z... VFR conds thru most part of the period. A closed low approaching the region will start deteriorating conds after 12Z. Widespread lowland rain showers are possible along with mountain snow showers above 7000 feet. However, some wintry mix and light snow showers could be possible in lower elevations. Areas near rain and snow showers could observe lower CIG and VIS, taking flight categories into the MVFR or even IFR. Winds will start from the SW && .FIRE WEATHER... A closed low pressure system is going to be moving through the region tonight and tomorrow. This system brings lowland rain showers and mountain snow showers. The effects of this system will be felt until Tuesday morning. Dry and warmer air makes a short come back between Tuesday and Thursday, before the next system comes to the Borderland. Temperatures will be around or slightly above normal in those days and winds will be between 5 to 15 mph. Minimum relative humidities will be higher than in previous days with peak values tomorrow between the 50´s and 60´s, then decreasing into the lower 30´s for the rest of the week. && .PRELIMINARY POINT TEMPS/POPS... El Paso 39 54 36 54 / 0 40 60 20 Sierra Blanca 40 60 41 55 / 0 20 30 10 Las Cruces 35 48 34 52 / 0 60 50 20 Alamogordo 34 50 34 51 / 0 50 50 20 Cloudcroft 26 33 24 35 / 0 70 70 20 Truth or Consequences 34 47 33 49 / 0 70 50 30 Silver City 34 42 31 45 / 10 80 60 20 Deming 34 49 36 52 / 10 70 50 20 Lordsburg 39 50 34 52 / 30 80 50 20 West El Paso Metro 41 52 38 53 / 0 50 60 20 Dell City 32 61 39 58 / 0 20 40 20 Fort Hancock 37 62 42 57 / 0 20 30 20 Loma Linda 38 54 35 50 / 0 30 60 20 Fabens 33 58 36 55 / 0 30 60 20 Santa Teresa 38 50 34 52 / 0 60 60 20 White Sands HQ 38 51 35 52 / 0 60 60 20 Jornada Range 26 51 31 52 / 0 70 50 20 Hatch 33 48 35 53 / 0 70 50 20 Columbus 37 50 35 53 / 10 70 50 20 Orogrande 35 54 35 53 / 0 40 60 20 Mayhill 32 43 26 42 / 0 60 60 20 Mescalero 27 42 23 42 / 0 60 70 20 Timberon 26 41 27 42 / 0 50 60 20 Winston 27 40 21 42 / 0 80 60 30 Hillsboro 32 44 31 49 / 0 80 60 30 Spaceport 28 49 31 50 / 0 70 50 20 Lake Roberts 24 38 23 43 / 10 80 60 30 Hurley 31 44 31 48 / 10 80 60 20 Cliff 31 48 27 50 / 20 80 50 20 Mule Creek 31 47 30 48 / 20 80 50 20 Faywood 33 45 30 49 / 10 80 60 30 Animas 40 51 36 52 / 30 80 50 20 Hachita 37 50 36 51 / 20 80 50 20 Antelope Wells 38 48 36 51 / 30 80 50 20 Cloverdale 39 46 36 49 / 30 80 60 20 && .EPZ WATCHES/WARNINGS/ADVISORIES... NM...Winter Weather Advisory from 5 AM Sunday to 11 AM MST Monday for NMZ402. Winter Weather Advisory from 11 AM Sunday to 11 AM MST Monday for NMZ414>416. TX...None. && $$ 25-Hardiman/29-Crespo
Office: HGX FXUS64 KHGX 162201 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 401 PM CST Sat Dec 16 2017 .DISCUSSION... A complicated forecast continues to unfold for Southeast Texas as a series of upper level disturbances cross Texas over the next week. The first disturbance is noted on afternoon water vapor imagery lifting across Southwest Texas from Mexico, with a coastal low having developed in response near the Texas Coastal Bend. Little has changed in the forecast thinking through tonight regarding the evolution of this feature, with the surface low lifting up the coast towards Matagorda Bay and then into the Sabine Pass tonight. Light to moderate rain across the northern counties this afternoon will spread south towards the coast in response to enhanced convergence from the low this evening, with a line of showers and thunderstorms sweeping across the region from west to east as the parent storm system ejects towards the Midwest. VAD wind profilers from Corpus Christi show southeast to south winds above 2000 feet and expect more of a northerly movement to the surface low within the next few hours. This would begin to shunt some of the moisture near the low into the Upper Texas coast (dew points in the 64-68 degree range) and increase the potential for a few surface-based thunderstorms. SPC Mesoanalysis shows 0-1 km shear values in the vicinity of this surface low have already increased into the 20-30 knot range (more than sufficient low level rotation to support tornado or waterspout development) and expect an isolated tornado/waterspout potential to increase for the coastal waters and immediate coastal areas within the next few hours. The speed of the overall system should limit any widespread flooding threat with this rainfall, but widespread rain amounts of 1-2 inches will be possible. Expect the line of thunderstorms to clear the region 1-2 AM with the potential for some patchy fog development across the western counties behind the line as the surface pressure gradient slackens. The next system to impact the region is currently in the process of closing off near Baja California this afternoon and will ensure that the region maintains southwest flow aloft in the wake of tonight's system. Moisture behind tonight's storm system is never fully scoured out of the northwest Gulf and east to southeast winds becoming reestablished on Sunday will draw this moisture back into the region. This will mean that smaller disturbances moving across the region in the flow aloft will result in periods of showers and thunderstorms spreading into the region from the Gulf beginning Sunday night. Rain chances continue through late Tuesday into Wednesday as the Baja closed low translates eastward and crosses Texas. This looks to drag another cold front across the region and end rain chances for a brief period of time during the mid-week period. A second, stronger cold front is expected to enter the state late Thursday into Friday. Warm air advection ahead of this front may result in light rain spreading inland from the Gulf on Thursday, with a combination of isentropic upglide and mid/upper level forcing from another disturbance west of the region resulting in periods of rain continuing into the upcoming weekend. Much colder air is expected to move into the region behind this cold front, with high temperatures on Friday almost 20 degrees cooler than Thursday. Huffman && .EXTENDED DISCUSSION /THE WEEKEND BEFORE CHRISTMAS/... Speculation continues about the forecast for the weekend before Christmas. CIPS Extended Analogs have shown a consistent signal for sub-freezing temperatures to reach at least parts of Southeast Texas sometime during the December 24 through December 26 timeframe... and this increases confidence that the region will see a spell of much below normal temperatures around Christmas. What remains more uncertain though is when this cold air will actually reach the region. This airmass looks to originate over western/northwestern Canada before being dislodged southward towards the Great Plains as a disturbance now near the Bering Strait also dives south. These polar airmasses tend to be very shallow by the time they reach Texas, which means that model guidance can struggle with when the coldest temperatures arrive behind the initial cold front. This is because the airmass behind the front moves moreso from propagation due to density differences at the surface than forcing from higher up in the atmosphere. The medium range guidance that was inspected today continues to shows signs of that struggle with the deterministic GFS/European not bringing in sub-freezing surface temperatures until Christmas and the Canadian, well, doesn't bring them into the region at all. This is further compounded by the signal that at least a weak over-running regime sets up across the region behind the front. This over-running, where more warm, moist air is lifted over the colder, shallow post-frontal air, looks to produce periods of light to moderate precipitation across the region over the weekend before Christmas and into Christmas week. Not only is the timing for arrival of colder temperatures in question, but whether or not the atmosphere will be precipitating when they arrive is too. So what do we know? - It will be colder than normal the weekend before Christmas into the beginning of next week. - Winter weather could certainly be possible... but several things have to come together for that to be the case. - It is too early to determine impacts, if any. - Model guidance is still in poor agreement on what will actually happen in that portion of the forecast. This makes forecast confidence low. - Forecast confidence probably won't begin to increase until the middle of next week when the disturbance near Alaska begins to dislodge our next round of colder air. Huffman && .MARINE... A Small Craft Advisory is currently in effect across the coastal waters and Matagorda Bay, with easterly winds sitting around 20 kts. A SCEC is in effect for Galveston Bay until 00Z this evening, as winds hover between 15 to 20 kts. As the coastal trough continues to slide up the northern Texas coastline, winds in Galveston Bay will also increase in speed, and a Small Craft Advisory will be in effect beginning at 00Z Sunday. Wave heights will also rise and 4 to 7 feet with this system, as it moves through the coastal waters during the overnight hours. Scattered to numerous showers and thunderstorms will fill in across the waters later this afternoon into the early evening hours as the coastal low slides north/northeast. This activity should continue until shortly after midnight when this system shifts eastward. Embedded in these showers and thunderstorms will be the potential for gusty winds and isolated waterspouts through early Sunday morning. Wave heights will begin to lower Sunday afternoon to between 2 to 4 feet, and onshore flow will return. With winds out of the east/southeast, warm moist air will flow over cooler shelf waters and periods of sea fog will be possible out ahead of the next cold front expected to push through the region early Wednesday. Light to moderate offshore winds will prevail behind this front. This offshore flow will not last for long though, as moderate onshore winds will return Thursday. Towards the end of the week, the next frontal passage is expected to reach our bays and coastal waters on Friday afternoon. Moderate to strong offshore flow is anticipated behind this front, resulting in elevated wave heights between 3 to 5 feet. Hathaway && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 45 63 52 64 60 / 90 10 10 50 70 Houston (IAH) 48 67 57 69 63 / 90 10 30 60 60 Galveston (GLS) 56 63 60 67 64 / 80 20 40 70 40 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...Small Craft Advisory until 8 PM CST this evening for the following zones: Matagorda Bay. Small Craft Advisory until 10 PM CST this evening for the following zones: Galveston Bay. SMALL CRAFT SHOULD EXERCISE CAUTION until 6 PM CST this evening for the following zones: Galveston Bay. Small Craft Advisory until midnight CST tonight for the following zones: Coastal waters from Freeport to the Matagorda Ship Channel out 20 NM...Coastal waters from High Island to Freeport out 20 NM...Waters from Freeport to the Matagorda Ship Channel from 20 to 60 NM...Waters from High Island to Freeport from 20 to 60 NM. && $$ Discussion...14 Aviation/Marine...08
Office: LUB FXUS64 KLUB 162030 AFDLUB Area Forecast Discussion National Weather Service Lubbock TX 230 PM CST Sat Dec 16 2017 .DISCUSSION... A couple of short waves are still on track to affect the region over the next several days followed by a significant pattern change at the end of next week. The first short wave was currently extending as far south as northwestern Mexico and will continue to lift out to the northeast this evening. Strong jet level winds on the east side of the short wave will bring large scale lift mostly east of the forecast area for the rest of today. There is abundant mid and upper level moisture with this system evidenced on GOES-16 water vapor imagery but low levels remain fairly dry. This short wave will quickly move east of the area tonight followed by a weak surface cold front during the day on Sunday. Models are still inconsistent in the handling of the second short wave after it becomes cut off from the northern stream. This short wave was currently moving into Baja California and will move very slowly over the next few days. The main difference in model guidance is on the timing of the ejection of this system but lift will favor the Rolling Plains on Tuesday. Mid level moisture will be available for this lift but lower levels of the atmosphere will again be lacking. Much better low level moisture will exist to the south and east of the region which is usually the case. The pattern change coming at the end of next week will bring a large atmospheric dump of arctic air into West Texas. A reinforcing shot of cold air may enter late next weekend before Christmas with both the GFS and ECMWF depicting a 1056mb surface ridge moving into the north-central CONUS. Colder temperatures are the most certain part of the forecast following the initial cold front during the day on Thursday. However, anything else in the forecast remains murky. The latest ECMWF continues to be dry while the GFS is in sharp contrast bringing wintry precipitation to the area. && .LUB WATCHES/WARNINGS/ADVISORIES... None. && $$ 01
Office: MAF FXUS64 KMAF 162044 AFDMAF Area Forecast Discussion National Weather Service Midland/Odessa TX 244 PM CST Sat Dec 16 2017 .DISCUSSION... An upper trough is over West Texas and southeast New Mexico with another upper trough over the western CONUS. Temperatures today are expected to be similar to yesterday with highs mostly in the 50s. Upper lift will be enhanced over the area today with moisture increasing so there is a chance of showers from the Western Low Rolling Plains south to the Big Bend area this afternoon and evening. The upper trough to the west deepens and approaches the area on Sunday. Temperatures are expected to increase into the 60s across most of the area on Sunday. The increase in upper lift will allow for a chance of precipitation across southeast New Mexico south to the Van Horn area Sunday into Monday. This second upper trough will move over the area on Monday night/Tuesday allowing for increased rain chances across much of the CWA. Zonal flow takes shape over the region on Wednesday as the previously mentioned upper trough passes to the east and another upper trough develops and digs southeast over the western CONUS. This upper trough moves closer to the region on Thursday with the northern portion of it moving over the Northern Plains. As a result, a cold front approaches and begins to move into the area late Thursday afternoon into Thursday night. Much colder air will be in place for Friday with highs possibly only reaching the 30s and 40s across all but along the Rio Grande. The models greatly diverge on precip output/timing and positioning of the upper trough with the ECMWF warmer and dry and GFS colder and wet; although, the ECMWF brings in a secondary cold front Saturday night. There are indications of possible wintry precipitation across the area beginning Friday but will have better confidence in this as time gets closer. The models really diverge on temperatures on Saturday so do not have much confidence at all for temperatures or precipitation next weekend. && .PRELIMINARY POINT TEMPS/POPS... Big Spring 39 64 38 60 / 10 10 10 10 Carlsbad 37 63 36 60 / 0 20 30 10 Dryden 39 63 44 62 / 10 10 10 10 Fort Stockton 42 68 40 64 / 10 10 10 0 Guadalupe Pass 39 56 40 52 / 0 30 30 10 Hobbs 32 60 33 57 / 0 10 20 10 Marfa 28 62 33 62 / 0 10 10 10 Midland Intl Airport 39 65 39 61 / 10 10 10 10 Odessa 39 65 39 61 / 10 10 10 10 Wink 35 66 37 61 / 0 10 10 0 && .MAF WATCHES/WARNINGS/ADVISORIES... NM...None. TX...None. && $$ 49/80
Office: SJT FXUS64 KSJT 162121 AFDSJT Area Forecast Discussion National Weather Service San Angelo TX 321 PM CST Sat Dec 16 2017 .SHORT TERM... (Tonight and Sunday) Patchy rain is occurring this afternoon across our area along with widespread cloud cover, in association with an upper low and trough moving across the Big Bend region. The upper trough will lift out to the northeast across our area early tonight, as an upstream low and trough dive southeast into the northern Baja region. Rain chances will shut off as the aforementioned trough axis swings through. Low cloud cover should linger until late tonight/early Sunday morning, when boundary layer flow starts to veer to the southwest. Not that much of a temperature dropoff is anticipated tonight, with overnight lows expected to range from the upper 30s across our western and southern counties, to the lower 40s in the eastern Big Country and Heartland areas. Mostly sunny skies and pleasant conditions are expected on Sunday with southwest and south winds remaining generally under 10 mph. A weak cold frontal boundary should sag south into our far northern counties by late afternoon or early evening. Afternoon highs Sunday are expected to be in the mid 60s to around 70. .LONG TERM... (Sunday night through Saturday) ...Sharply colder by Christmas Weekend... Another upper level low will approach the area from the Desert Southwest on Monday and will bring another chance of precipitation to the area Monday night and especially Tuesday. Most of the area should see some rain with this system but southeast sections will have the best chance and will have highest POPs across this area on Tuesday. Temperatures will be warm through midweek, with highs mainly in the 60s and overnight lows in the 40s. Significant changes are anticipated towards the end of the week and into Christmas weekend as the medium range models continue to show a very strong cold front moving across the area Thursday night, with an arctic airmass becoming entrenched across the area through Christmas day. Forecast highs are only expected to be in the 30s Friday through Sunday, with lows in the 20s. However, there is considerable model uncertainty concerning precipitation chances and amounts for next weekend. The GFS continues to be the wetter model as it closes off an upper low over the Desert Southwest by Friday and then slowly moves it east across the area through Christmas Day. The ECMWF shows a much more progressive trough, with little if any precipitation affecting the area. For now, will side closer to the wetter GFS solution and have POPs across the area Friday through Sunday. Temperatures will be cold enough for winter precipitation, starting off as rain on Friday and transitioning to a mix of rain, sleet and snow by Friday night and Saturday. Temperatures look cold enough for a transition to all snow by late Saturday night into Christmas eve. We would like to stress that confidence regarding winter precipitation and amounts remains low at this time due to the model discrepancies with the upper pattern but is high concerning the arrival of much colder air by next weekend into Christmas Day. && .PRELIMINARY POINT TEMPS/POPS... Abilene 40 67 41 62 / 30 0 5 5 San Angelo 39 69 42 65 / 30 0 5 10 Junction 39 69 44 66 / 30 0 10 20 Brownwood 40 67 43 64 / 50 0 5 10 Sweetwater 39 65 40 61 / 20 5 5 5 Ozona 37 67 41 63 / 20 0 5 5 && .SJT WATCHES/WARNINGS/ADVISORIES... None. && $$ 19/24
Office: FWD FXUS64 KFWD 162141 AFDFWD Area Forecast Discussion National Weather Service Fort Worth TX 341 PM CST Sat Dec 16 2017 .SHORT TERM... /Tonight/ Extensive cloud cover has shrouded most of North and Central Texas now, and rain has begun to fall across portions of Central Texas. The continued influx of moisture across the region, combined with appreciable lift from the main upper level low across West Texas will allow for an expanding area of rain for most of the region this evening into tonight. No severe weather is expected overnight, but can't rule out a rumble of thunder with any thunderstorm that manages to take advantage of the meager elevated instability south of I-20 and east of I-35. Rain amounts should remain below half an inch across most of the region, with the exception of areas southeast of an Athens to Groesbeck line where strong frontogenetic forcing may lead to a beneficial rainfall between 1-1.5 inches. A strong push of dry mid to upper level air will move in behind the system as it continues its northeasterly trek overnight, leading to an end in precipitation from west to east early Sunday morning. Although the mid and upper levels will begin to dry out, a decent amount of moisture will remain at the low levels. This moisture will need to be monitored overnight given it could lead to either a low stratus deck, or patchy fog. Current thinking is that winds between the surface and 925mb should stay strong enough the allow enough mixing and keep fog from developing. This, however, will need to be monitored this evening in case new model guidance output depicts weaker low-level wind speeds. Hernandez && .LONG TERM... /Sunday Through Friday Night/ The weekend shortwave disturbance will be quickly exiting the northeast, away from the area with shortwave ridging in it's wake on Sunday. Modest southerly winds near 10 mph will return at the surface, while mid levels dry out in response to subsidence occurring in this system's wake. However, a shallow layer of stratus, along with a lingering cirrus canopy will remain through much of the day. Had worried about patchy dense fog developing Sunday morning with wet soils and light winds, but it appears the sub-boundary moisture remaining will be relatively deep with winds speeds in the boundary layer high enough to keep hydro-lapse rates steady with no fog mentioned in the forecast. Despite modest low level warm advection later on Sunday, temperatures will only warm into the 60s, as insolation is minimized with any lingering cloud cover and soils remain moist from the first round of rain we received Saturday night. In a fujiwara fashion, a second shortwave will arrive Monday into Tuesday and induce low level warm advection and isentropic ascent once again across particularly our southwest counties by Monday morning. As this system approaches later Monday and Monday night, rainfall will spread east-northeastward across mainly our Central Texas counties and those south of I-30 in the east. Moistening mid levels and slightly cooler 500mb temperatures will steepen lapse rates to between 6-7 deg C/km later Monday afternoon into Monday night. Skinny MUCAPE 500 J/kg or greater is forecast above an elevated subsidence inversion anchored around 800mb. This elevated instability may be enough to allow charge distribution to occur aloft with isolated elevated tstorms expected with the increasing band of showers or rain activity. I did raise POPs across the southeast half of the region where low level warm advection and isentropic ascent will be maximized with this second shortwave. No severe weather is expected, but don't be surprised to hear a random crackle of thunder, especially as we move into Monday night and Tuesday. These first two shortwave disturbances will likely give some drought relief. The rainfall will be more of an off/on, gradual soaking rainfall, especially across Central Texas where 1-3 inch totals are possible. This second shortwave disturbance will lift out after midnight Wednesday morning. Otherwise, the light winds, cloud cover, periods of rain/isolated tstorms will keep diurnal temperature trends small with mild conditions for late December expected. Highs in the 60s and lows in the mid 40s-mid 50s will be the rule across the area. Medium range models continue to show good consistency with a cold front arriving Thursday night and early Friday morning. Ahead of the cold front on Thursday, partial sunshine combined with veering, warm, low level flow will likely assist highs back into the lower 70s, except possibly the immediate Red River area. Scattered showers may occur within the better moisture across Central Texas and areas mainly east of I-35 late Thursday night and Friday with the well-advertised, shallow but strong arctic cold front moving through. With the arctic cold front well east of the better upper support and with the shallow nature of a very dense and chilly airmass, we do not expect much in the way of any tstorms at all. Now for the Friday period and into the holiday weekend, which everyone is curious about. Model run-to-run consistency both amongst the deterministic ECMWF/GFS/and Canadian models continues to remain very high and differing quite a bit from their ensemble means. Will we have very shallow cold air in place?? The resounding answer is YES! However, these models and their ensembles are struggling with position, strength, and track (to an extent) of the Western U.S. upper trough. These parameters can make all the difference in the world on whether we get all rain, a wintry mix, ice, or nothing at all, especially areas west of I-35/35W and north of Highway 380 to the Red River where colder surface temperatures are expected to arise. After all that verbiage, the conclusion is...we just DO NOT have enough agreement and consistency with ANY of the medium range models to say which scenario pans out with a very low confidence on evolution. My gut feeling is somewhere winter impacts may occur Friday into next weekend. However, I just do not have the confidence to say to what extent north-south or east-west across the area at this time with so much variability with the deep, mid level longwave trough. As such, persistence was carried through on the forecast with this period now entering into the end of our 7-day extended forecast. Be sure to stay informed from trusted weather sources through the week and beware of what you read on social media forums. We should see models coming more in line on this system as we push through this week and the system becomes better sampled by our upper-air network. && .AVIATION... /Issued 1215 PM CST Sat Dec 16 2017/ The upper level low across the Trans-Pecos Valley is leading to a deep layer of moisture surging northward into North and Central Texas through the day today. The effects of the low can already be seen with the increase in cloud cover across the region. A 120+ kt jet streak in the vicinity of KDRT to KABI is leading to an increase in turbulence between FL250 to FL300. The jet streak is expected to continue moving east/northeast through the afternoon, and would not be surprised if turbulence reports pick up across North and Central Texas. The atmosphere will continue to saturate from the top to bottom, leading to MVFR cigs for Waco around 22Z and the Dallas/Fort Worth airports by 00Z. As lift and moisture increase, rain will overspread the region this afternoon into the evening. Light rain showers have already developed south of Waco, and further development is expected as large scale ascent approaches the region. The heaviest of the precipitation will begin at Waco around 00Z Sunday, and continue northward into the Dallas/Fort Worth by 03Z, with IFR likely during the heaviest of the precipitation. Although mid and upper level moisture will scour out after midnight, the low levels will remain saturated, leading to an extended period of IFR across the region through the early morning hours. Low levels will dry out by Sunday afternoon as the influence of the upper level low decreases. Winds will remain southerly throughout this forecast cycle across all TAF cites. Winds will slowly diminish to around 5-7 kts tonight, and continue through the tomorrow afternoon. Hernandez && .PRELIMINARY POINT TEMPS/POPS... Dallas-Ft. Worth 45 64 47 65 52 / 80 0 5 20 30 Waco 43 65 49 64 55 / 90 0 10 30 50 Paris 44 59 44 64 52 / 90 5 5 10 30 Denton 43 63 43 66 50 / 80 0 5 10 20 McKinney 43 61 44 65 51 / 90 0 5 10 30 Dallas 45 63 47 65 53 / 90 0 5 20 30 Terrell 45 63 45 66 52 / 90 5 5 20 30 Corsicana 45 63 47 65 54 / 100 0 10 30 50 Temple 43 65 49 63 55 / 90 0 10 30 50 Mineral Wells 43 67 42 66 49 / 60 0 5 20 20 && .FWD WATCHES/WARNINGS/ADVISORIES... None. && $$ 05/08