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Office: BOU

FXUS65 KBOU 190347

Area Forecast Discussion
National Weather Service Denver/Boulder CO
847 PM MST Sun Nov 18 2018

Issued at 847 PM MST Sun Nov 18 2018

No changes to the forecast package necessary this evening as skies
will remain mostly clear for a few more hours, before some high
clouds move in from the north after midnight. The mostly clear
skies have allowed evening temperatures to cool off rapidly, but
after midnight the cooling should moderate as increasing cloud
cover cuts off the radiational cooling of the dry airmass.
Moderate northwesterly flow aloft continues over the state which
is causing windy locations up along the Continental Divide to have
gusty winds, but these are not expected to extend down to any
lower elevations. Tomorrow should be a mix of some high clouds and
mostly sunny conditions with temperatures around seasonal normals.


.SHORT TERM...(This evening through Monday)
Issued at 230 PM MST Sun Nov 18 2018

Dry, subsident north-northwest mid-level flow on backside of the
departing trough will help warm overnight temperatures. There will
also be a gradual increase in high-level cloud cover overnight with
warming aloft. Lows tonight are expected to run near to slightly
below average, with the colder readings in the mtn valleys and
river bottoms, such as along the South Platte River. On Monday,
models show the inbound moisture lowering through the morning as
jet maxima passes to our northeast. Cross sections show cloud
ceilings lowering to around 4000 ft agl over the northeast corner
before noon, where it's conceivable we could see a few snow
flurries with gusty northwest sfc winds. Also on Monday, should
see an increase in mountain top winds with strengthening
northwest flow aloft. Gusts in the 30-40 mph range a possibility
on Front Range ridge tops and upper east slopes by afternoon.
Otherwise a dry 24 hours with temperatures on the plains similar
to those today. If it wasn't for the cloud cover tomorrow,
temperatures on the plains could potentially be several degrees

.LONG TERM...(Monday night through Sunday)
Issued at 230 PM MST Sun Nov 18 2018

No big surprises in the long term forecast at least until Friday
as models have been relatively consistent with the pattern this
week. Overall, dry and mild on the plains with temperatures
becoming above normal with readings in the 50s/lower 60s. Over the
mountains, dry except mountain snows on Thursday and Friday.

From late Monday through Wednesday, High amplitude ridge of high
pressure will dominate the regional weather as the high moves
from the west coast to Colorado by Wednesday. The flow aloft will
remain from the northwest with dry conditions along with a
warming trend.

Next Pacific storm system will traverse across Colorado as a
progressive open wave which will bring a period of snowfall to
the mountains for Thursday afternoon through Friday morning. The
plains will be dry with this system due to the stronger northwest
downslope flow. As this trof passes through, there is strong
subsidence behind it while cross sections show strong 40-50kt
cross barrier flow over the foothills. Certainly a windy period a
good bet for Thursday night and early Friday.

More uncertainty comes into play during the weekend as long range
models are showing quite varied solutions. The GFS and Canadian
solutions remain more progressive with the next trof as an open
wave across Colorado on the weekend, while the European solutions
has been consistently showing a closed low over near the 4 corners
by late Saturday. If the European is right, then much colder and
higher snow potential for much of northern Colorado. In contrast,
the more progressive solutions would offer snow to the mountains
but more limited chances of snowfall on the plains. For now,
ongoing forecast has a chance of precipitation and cooler
temperatures for the area this weekend and will hold tight for
now. Certainly some potential to keep an eye on.


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 847 PM MST Sun Nov 18 2018

No aviation impacts tonight or tomorrow. Surface pressure
gradients will be weak and therefore winds will be light,
generally following diurnal patterns.




LONG TERM...Entrekin

Office: PUB FXUS65 KPUB 190528 AFDPUB Area Forecast Discussion National Weather Service Pueblo CO 1028 PM MST Sun Nov 18 2018 .UPDATE... Issued at 856 PM MST Sun Nov 18 2018 Updated to add patchy fog and low stratus for Fremont and Pueblo Counties through the 1 AM hour as nighttime satellite imagery indicates this isolated area. As mid and upper level clouds move in from the north this area should dissipate. Area webcams show fog in Canon City, east to Penrose, with possible slick roads at the Highway 50 and CO 115 interchange. In addition, adjusted overnight lows across much of the Plains as a few areas are already below the minimums. Mozley && .SHORT TERM...(This evening through Monday) Issued at 304 PM MST Sun Nov 18 2018 Currently: Clouds have been hanging tough over locations such as Pueblo and Baca county into early this afternoon, however latest satellite trends and real time data indicate that a clearing trend is developing over these locations. Tonight: A chilly and dry night is anticipated tonight, with minimum temperatures projected to drop into the upper teens to lower 20s over the Interstate 25 corridor and southeastern Colorado Plains and into the positive single digits over the San Luis Valley. For Monday: A dry northwesterly upper flow in the wake of departing storm system will allow dry conditions in combination with a gradual warming trend to develop over southern Colorado Monday with maximum temperatures expected to climb into the 40s over the Interstate 25 corridor and San Luis Valley and even into the lower 50s over the southeastern Colorado Plains. In addition, generally low-grade gradient winds are anticipated over the majority of the CWA Monday. .LONG TERM...(Monday night through Sunday) Issued at 304 PM MST Sun Nov 18 2018 An upper ridge centered over the Great Basin Monday night into Tuesday gradually moves eastward over the central and northern Rockies into Wednesday. A shortwave trof moves through the southwestern U.S. Wednesday and Wednesday night, but remains well to the south of the area and forecast area will remain dry and mild through Wednesday. On Thursday, a progressive trof moves through the region. Expect to see snow spread across the high country Thursday, but the plains will remain dry with limited amounts of moisture in the atmosphere and west to northwest downslope winds at the surface. Expect gusty surface winds behind the departing trof Thursday night into early Friday. Still temperatures on Thanksgiving will remain mild with highs in the 50s and lower 60s on the plains. Major model differences crop up for the weekend leading to considerable uncertainty in the forecast. GFS continues to be progressive moving an open trof through Colorado Saturday. GFS solution would bring a period of snow to the mountains, but dry conditions on the plains. Meanwhile, the ECMWF has been consistent with its solution of developing a closed 500mb low over the four corners region Saturday into Sunday. If the ECMWF solution pans out, it would mean a colder, snowier forecast for southeast Colorado. The ECMWF solution may also impact travel the weekend after Thanksgiving, so later forecasts should be monitored as models converge on a solution in the upcoming days. Included low scattered pops in the forecast for the southeast plains Saturday. Stark && .AVIATION...(For the 06Z TAFS through 06Z Monday night) Issued at 1024 PM MST Sun Nov 18 2018 Patchy IFR stratus along the Arkansas River extends from Canon City to KPUB will persist through 10-11z. Will keep IFR conditions in through this period, with VFR conditions returning Monday morning. KCOS and KALS will remain VFR with light winds under 12 kts over the next 24 hours. -KT && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...MOZLEY SHORT TERM...77 LONG TERM...STARK AVIATION...KT
Office: GJT FXUS65 KGJT 190534 AFDGJT Area Forecast Discussion National Weather Service Grand Junction CO 1034 PM MST Sun Nov 18 2018 .SHORT TERM...(Tonight through Monday night) Issued at 1256 PM MST Sun Nov 18 2018 The stratus that blanketed many of the valleys this morning has mixed out into a few patches of cumulus clouds, which has allowed temperatures to warm into the 30s and 40s. In the wake of the midlevel trough pushing southward high pressure is building in from the northwest. Tonight light winds and clear skies should favor radiational cooling with low temperatures dropping into the teens and single digits. The only exception would be southeast Utah where lows only reach the 20s. Those locations in the clouds this morning should be cooler tomorrow morning so tended towards the coldest guidance. A few mid-high level clouds could move into northern Colorado and Utah tonight, which might offset some of the radiational cooling. Tomorrow the high pressure remains over the region so expect mostly sunny skies and highs in the 30s and 40s. .LONG TERM...(Tuesday through Sunday) Issued at 1256 PM MST Sun Nov 18 2018 Into early week the upper ridge gradually shifts eastward along with a low pressure that passes south of the forecast area along the US/Mexico border. The models are fairly consistent keeping the precipitation associated with that low pressure across southern New Mexico on Wedensday. By mid week several shortwave troughs work towards the west coast. One of these troughs is forecasted to track over the area on Thursday bringing valley rain and mountain snow with the western slopes being favored for orographic lift. The 700 mb temperatures will start around -5 to -3 C as the trough arrives during the day Thursday. As a result snow levels should range from around 5000 feet across northeast Utah to around 7000 feet in southern Colorado as the precipitation develops. As cold air continues to filter in the snow levels will lower overnight. The modest QG forcing passing over the region will be progressive so enhanced precipitation rates will be brief. Despite that there could be enough snow for travel impacts Thursday evening into Friday. One big concern is the potential for moist upslope flow to persist through Saturday. Into the weekend a more amplified shortwave begins to drop southeastward from the Pacific Northwest. This increased forcing within the northwest flow will arrive on Saturday. The models begin to diverge on the evolution of this wave with the ECMWF showing the system closing off over the Four Corners, while the GFS shows a more open wave. This time frame will need to be closely monitored with the potential for more widespread impacts. && .AVIATION...(For the 06Z TAFS through 06Z Monday night) Issued at 1032 PM MST Sun Nov 18 2018 Minimal impacts to flight operations are expected over the next 24 hours with light winds in place and thin high cloudiness drifting overhead. VFR will prevail. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...KJS LONG TERM...KJS AVIATION...TGJT