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Office: JAX

FXUS62 KJAX 181334

Area Forecast Discussion
National Weather Service Jacksonville FL
930 AM EDT Sat Aug 18 2018

Sfc analysis shows near normal position of the high pressure ridge
over north central FL area. Deep 1000-500 mb flow remains southwest
(JAX sounding showing 240 deg at 9 knots) with moisture levels near
or below normal and the driest air noted in GOES imagery over
central FL with min value of about 1.1 inches there, but 1.9 inches
in southeast GA.

At this time, only scattered mid to high levels clouds which are
thin enough in most areas for good heating today with scattered to
broken cu forming by late morning. Highs today forecast in the lower
to mid 90s, perhaps a little warmer than yesterday given latest
sounding temps. With the drier air from central FL lifting slowly
northward, convection chances are diminished from prior days and
will keep inherited 20-30 percent chances for northeast FL, though
southeast GA will have higher POPs around 30-50 percent given PWATs
there closer to normal at 1.7 to 2 inches. There is also some weak
shortwave energy pushing through srn GA later in the day helping to
provide some synoptic lift there. West coast and east coast sea
breeze should be active today with the east coast sea breeze delayed
until around 17z-18z given southwest flow. An isolated strong to
severe pulse storm remains possible today with frequent to excessive
lightning, and given dry air aloft enhances the potential for
downburst winds up to 40-60 mph. For the update, have tweaked max
temps up a deg or so and adjusted POPs toward latest guidance and



VFR conditions prevail. Light southwest flow near 5-10 kt expected
today with wind shift to southeast for coastal TAFs with the east
coast sea breeze. Light winds will become southwest again at all
TAFs by late evening and overnight. Overall, a low chance of showers
or t-storms at the terminals for today so vicinity wording starting
around 18z-19z looks good at this time.



Southwest winds near 5-15 kt will shift to the south and southeast
this afternoon near 10-15 kt. Seas mostly around 2-3 ft with wind
waves about 4 seconds and weak east swells at about 8 seconds. Looks
like coastal waters, except inland waterways, will remain nearly
rain-free today.

Rip Currents: Moderate risk today NE FL coast and lower risk for Low
risk for SE GA today. Surf conditions show 1-2 ft per latest obs and


AMG  91  73  91  73 /  40  30  40  20
SSI  89  76  90  76 /  20  20  20  20
JAX  93  74  93  74 /  30  20  20  10
SGJ  91  75  90  74 /  20  20  20  20
GNV  93  74  93  74 /  30  20  20  10
OCF  94  73  93  73 /  20  10  30  10





Office: EYW
Office: MLB FXUS62 KMLB 181416 AFDMLB Area Forecast Discussion National Weather Service Melbourne FL 1015 AM EDT Sat Aug 18 2018 .DISCUSSION... Latest RAP40 analysis showing the axis of the Bermuda Ridge draped over central FL, resulting in a southerly breeze AOB 10KTS from the sfc thru 10KFT. GOES PWat product showing a pocket of very dry air drifting north acrs central FL, with core values arnd 1.00". Mrng RAOBS map this dry air quite well...PWat values btwn 1.25"-1.50" at KXMR/KTBW, increasing to 1.75"-2.00" at KJAX/KMFL. RAP40 analysis picking up on the dry air as well, H100-H70 mean RH values btwn 50- 60pct north of Cape Canaveral/Lake-K, increasing to 70-80pct over the Treasure Coast/Lake-O region. Thermodynamic instability is modestly steep...H70 temps btwn 9-10C and H50 temps arnd -7C are yielding lapse rates btwn 6.0-6.5C/KM thru the layer. Dynamic support is quite weak, however, as H85-H30 omega and H30-H20 divergence values are negligible. There is a pocket of enhanced H85-H50 vorticity over Polk/Osceola counties associated with a weak ripple in the mid lvl wind fields, but this feature is planted firmly in the center of the dry air, so any PVA that may result will be starved of moisture. The east coast sea breeze has formed from the Cape southward...isold shras dvlpg along its boundary over the Treasure Coast. Given the moisture profile, diurnal precip will be largely confined to areas south of Cape Canaveral and Lake-K. To the north, dry air will smother any large scale PoPs. A few shras/tsras psbl late this aftn along and north of I-4, but will require the east/west coast sea breeze merger to spark them. Dry air and limited cloud cover will allow max temps over the interior from Osceola Co. northward to warm into the M90s. Early formation of the east coast sea breeze will keep coastal max temps in the L90s...Okeechobee Co. in the L90s as well as the prevailing srly flow will place them in the lake shadow. && .AVIATION...Thru 19/12Z. Sfc Winds: Thru 18/15Z...S/SE 4-8KTS. Btwn 18/15Z-18/17Z...coastal sites bcmg E/SE 7-11KTS. Btwn 18/17Z-18/19Z...interior sites bcmg E/SE 6-10KTS. Vsbys/WX/Cigs: Thru 18/16Z...E of KMLB-KOBE isold MVFR shras. Btwn 18/16Z-18/19Z...S of KMLB-KSEF sct MVFR shras/IFR tsras. Btwn 18/19Z- 18/22Z...S of KISM-KTIX sct MVFR shras/IFR tsras. Btwn 18/22Z- 19/02Z...S of KISM-KTIX sct MVFR shras/IFR tsras...N of KISM-KTIX isold MVFR shras/IFR tsras. && .MARINE... Bermuda Ridge axis over central FL will maintain a light to gentle S/SE breeze over the lcl Atlc thru daybreak Sun...bcmg E/SE near the coast this aftn concurrent with the east coast sea breeze. Seas AOB 2FT...up to 3FT in the Gulf Stream north of Sebastian Inlet arnd midnight tonight. Isold shras/tsras, mainly in the Gulf Stream. && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. && $$ Forecast Update......Bragaw Aviation/Impact WX...Volkmer
Office: MOB FXUS64 KMOB 181152 AFDMOB Area Forecast Discussion National Weather Service Mobile AL 652 AM CDT Sat Aug 18 2018 .DISCUSSION...Updated for latest aviation discussion below. && .AVIATION... 12Z issuance...Scattered to numerous SHRA along with a few TSRA will continue to develop across the region through the day today. Localized MVFR to IFR conditions will be possible near heavier convection. VFR conditions should otherwise prevail outside of this activity. Light winds early this morning should become south to southwest 5-10 knots later this morning into this afternoon. && .PREV DISCUSSION... /issued 445 AM CDT Sat Aug 18 2018/ NEAR TERM /Now Through Saturday night/...A mid to upper level trough axis continues to extend southwestward from the Great Lakes/Ohio Valley region to the Lower Mississippi Valley and central Gulf Coast region early this morning. A surface ridge of high pressure meanwhile remains oriented from the western Atlantic to the east central Gulf of Mexico. Abundant deep layer moisture remains entrenched across our forecast area early this morning, with high precipitable water values averaging between 2" and 2.2". So far radar has remained rather quiet, but isolated to scattered rain showers are finally starting to form near the MS coast just west and southwest of our CWA as of 4 A.M. CDT. Somewhat of a challenging forecast today in terms of where the regions of best convective coverage will occur along with the associated timing. Our general expectation is that a trend similar to yesterday will materialize with increasing coverage of showers and a few thunderstorms near coastal portions of southwest AL and across the western FL panhandle early this morning, followed by gradual development of showers and storms farther inland across south central and southwest AL and eventually much of southeast MS late this morning into this afternoon. In terms of POPs, have increased coverage to 60-70% this morning mainly southeast of a Mobile to Andalusia line, with likely POPs then spreading inland across the remainder of the region during the afternoon. Precipitable water values will continue to average between 2" and 2.25" through this afternoon, so the heavier showers and storms will be efficient rainfall producers with potential for localized ponding of water on area roadways and perhaps localized flooding of low lying areas. Short range guidance also indicates a region of surface based CAPE values up to 2000-3000 J/KG across portions of southeast MS and interior southwest and south central AL this afternoon, so a few stronger storms may develop within this region capable of producing localized strong wind gusts over 40 mph along with frequent cloud to ground lightning strikes. Scattered showers and thunderstorms may linger into this evening over interior southeast MS and southwest AL before coverage gradually diminishes. A few showers and storms may then re-develop late tonight into the pre- dawn hours of Sunday, mainly near the coast. Otherwise, temperatures today should be fairly similar to readings recorded Friday with highs in the mid 80s to around 90. Another seasonably warm and muggy night is expected tonight. /21 SHORT TERM /Sunday Through Monday night/...An upper high pressure system off the southeast conus coast will remain in place through the short term, while an upper closed low pressure system over the central Great Plains moves eastward and evolves into an open wave before reaching the Great Lakes. The southern extension of the open wave will reach into eastern Texas by late Monday night. An associated surface low pressure system will form across the central plains by Sunday evening, and then lift east-northeast across the lower midwest. A surface ridge of high pressure extending from the western Atlantic across the Florida peninsula and Gulf of Mexico will remain in place, keeping a light southerly and moist wind flow across the forecast area. Will keep numerous to definite showers and thunderstorms across the area on Sunday, with scattered to numerous showers forecast on Monday. While mainly isolated to rain-free conditions are forecast for much of the overnight periods, there is the potential of scattered showers and thunderstorms affecting much of the forecast area Sunday night after midnight as over-running in the low levels brings the gulf precipitation inland. Additional widespread rainfall amounts through the short term will range from 0.4 to 0.7 inch, with isolated locations affected by the stronger thunderstorms picking up to two inches of rain. /22 LONG TERM /Tuesday Through Friday/...The southern extension of the upper level trough to our west will approach and pass over the region through midweek, followed by upper high pressure building in from the north. As a result, kept scattered to numerous daytime showers and thunderstorms in the forecast through midweek. The best chance of overnight precipitation should occur Tuesday night as a weak frontal boundary associated with the lifting center of low pressure enters into the forecast area and possibly moves south of the coast. Drier conditions are set for Thursday and Friday. /22 MARINE...A surface ridge of high pressure will continue to extend from the western Atlantic through the central Gulf of Mexico through early next week. This feature will maintain a light to occasionally moderate south to southwest flow over the marine area through Tuesday. There is some potential for a weak front to bring offshore flow by next Wednesday, but this is still several days out. Seas remain around 2 feet over the next few days. Winds, waves and seas will be locally higher near showers and thunderstorms. /21 && .MOB WATCHES/WARNINGS/ADVISORIES... AL...None. FL...None. MS...None. GM...None. && $$ This product is also available on the web at:
Office: TBW FXUS62 KTBW 181319 AFDTBW Area Forecast Discussion National Weather Service Tampa Bay Ruskin FL 919 AM EDT Sat Aug 18 2018 .UPDATE... Mid/upper-level ridging remains over the state this morning with a band of drier air clearly noted on water vapor imagery. This drier air is lingering right over the central part of the peninsula and is forecast to persist through much of the day. At the surface, the subtropical ridge axis is stretched across the north-central peninsula, with a light southeast low-level flow in place across the forecast area. These winds will turn onshore in the afternoon as the sea breeze circulation gets going, but the dry air will keep rain chances low for most areas. The exception is over the southwest Florida region, where the air is not as dry. The overall forecast is on track with just a few minor tweaks made this morning. && .AVIATION... VFR conditions are expected outside of any thunderstorm activity this afternoon. Best chances are for KLAL as well as KPGD, KFMY, and KRSW. Chances are too low to mention for the other sites. Light and variable winds this morning will become more southwest to west along the coast this afternoon with the sea breeze. && .MARINE... High pressure will remain over the region for the next several days. Winds and seas will be briefly higher in or near thunderstorms, but otherwise no headlines are expected. && .Preliminary Point Temps/PoPs... TPA 92 78 91 78 / 10 10 20 20 FMY 91 76 91 76 / 50 10 30 20 GIF 95 75 92 75 / 30 20 50 30 SRQ 89 77 89 77 / 10 10 10 20 BKV 93 73 92 75 / 10 10 30 20 SPG 92 79 90 78 / 10 10 10 20 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...Beach Hazards Statement through this evening for Coastal Manatee. Beach Hazards Statement through Monday evening for Coastal Charlotte-Coastal Lee-Coastal Sarasota. Gulf waters...None. && $$ DISCUSSION...05/Carlisle
Office: TAE FXUS62 KTAE 181331 AFDTAE Area Forecast Discussion National Weather Service Tallahassee FL 931 AM EDT Sat Aug 18 2018 .UPDATE... Precipitation coverage continues to increase across the western FL Panhandle and will expand northeast this afternoon. Forecast is on track with no major changes. && .PREV DISCUSSION [644 AM EDT]... .NEAR TERM [Through Today]... An upper level trough will persist over the area between a ridge trying to build in from the west and the Bermuda ridge to our east. Global models show a southwest to northeast oriented deep plume of moisture cutting through all but the southeast Big Bend of our CWA. Forecast PW at Tallahassee this afternoon is 2.2" compared to 1.7" at Cross City. This moisture combined with daytime heating and sea breeze interaction will result in scattered to numerous showers and thunderstorms. PoPs today will be tapered highest(70%) west to lowest (20-30%) across the southeast Big Bend. .SHORT TERM [Tonight Through Monday]... The general upper-level northern stream pattern will be driven by a couple of shortwaves through early next week. The first will move through the Ohio Valley and Mid-Atlantic Sunday through Sunday night, with a brief period of ridging building in ahead of the second wave forecast to be in the Middle Mississippi Valley towards the end of the period. At the same time, a TUTT is forecast to move over the Florida Straits and across the extreme southern GOMEX. Favorable upper-level forcing on the NW quadrant of the TUTT, combined with deep layer southwesterly flow will result in an early start to shower and thunderstorm activity, becoming more widespread through the day. The most favorable region for widespread and potentially heavy rain will be along and northwest of a line from Apalachicola through Tifton. On Monday, drier air will move in aloft, with deep layer ridging taking hold in the wake of the northern stream trough and TUTT. Expect a more typical scattering of summertime seabreeze convection Monday. .LONG TERM [Monday Night Through Saturday]... The shortwave in the Middle Mississippi Valley will start the anomalous amplification of the northern stream longwave trough, with a couple more shortwaves superpositioning over the eastern CONUS through the week. Tuesday's convection will likely still be seabreeze driven, though mid to late week storms should be more widespread associated with the northern stream trough and associated cold front. It's unlikely we'll get a 'clean' frontal passage, so wet conditions should be expected as the front will likely stall and dissipate over the Southeast. .AVIATION [Through 12Z Sunday]... Brief period of MVFR cigs/vsbys at DHN and VLD this morning. Otherwise, showers and thunderstorms currently developing along the panhandle coast and inland near ECP this morning will gradually spread north and east through the day. Expect at least brief impacts from storms with gusty winds and possible MVFR vsbys/cigs. .MARINE... Seasonably low winds and seas are expected over the next several days, but could increase as we near mid-week as a cold front approaches. .FIRE WEATHER... Outside of possible low dispersions across portions of the Florida panhandle Sunday afternoon, hazardous fire weather conditions are not expected. .HYDROLOGY... In general, 1-2" of rain is forecast along and west of the Apalachicola and Chattahoochee rivers over the next couple of days and around 1" to the east. Isolated higher amounts are possible especially through the weekend. Ensemble guidance for area rivers suggests the potential for action stage along the most reactive basins west of the aforementioned delineation. Scattered 'nuisance' urban and rural flooding will also be possible through the next week. .SPOTTER INFORMATION STATEMENT... Spotter activation is not requested. However, spotters are always encouraged to safely report significant weather conditions when they occur by calling the office or tweeting us @NWSTallahassee. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 90 74 89 73 90 / 50 20 40 10 40 Panama City 88 78 86 77 88 / 70 40 60 40 40 Dothan 87 73 86 73 88 / 70 30 60 30 40 Albany 88 73 88 73 90 / 60 30 60 20 30 Valdosta 90 73 89 72 91 / 40 20 40 10 30 Cross City 91 75 90 74 91 / 30 20 20 20 30 Apalachicola 88 78 87 77 87 / 40 30 50 20 30 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AL...None. GM...None. && $$ UPDATE...LF NEAR TERM...Barry SHORT TERM...Harrigan LONG TERM...Harrigan AVIATION...Barry MARINE...Harrigan FIRE WEATHER...Barry HYDROLOGY...Harrigan
Office: MFL FXUS62 KMFL 181354 AFDMFL Area Forecast Discussion National Weather Service Miami FL 954 AM EDT Sat Aug 18 2018 .UPDATE... Isolated Atlantic showers are spreading toward the coast and will increase in coverage this afternoon as sea breeze spreads inland. Guidance is not overly enthused with convection anywhere but western interior, and 12z RAOB analysis doesn't appear to reveal air mass too favorable for intense convection. Thus, considering that Gulf/Atlantic sea breezes in easterly flow regime should collide over western interior, have maintained high POPs and potential for strong downburst winds in this area. Otherwise, expect near normal temperatures reaching around 90 degrees for maxima. && .CLIMATE... Fort Lauderdale's low temperature yesterday /August 17/ was only 83 degrees, which tied the daily record warm minimum, last set in 2013. Rainfall this morning cooled Fort Lauderdale such that no records were threatened today. && .PREV DISCUSSION... /issued 831 AM EDT Sat Aug 18 2018/ AVIATION... Guidance suggests most activity will develop over or just inland of east coast terminals midday and then spread westward, thus will maintain only VCSH this afternoon, not VCTS. Better chance will occur at KAPF where Gulf sea-breeze intrusion will be impeded by easterly flow. Expect ESE flow 10 KT during the day and light/calm overnight. BEACH FORECAST... East/southeast onshore flow will create a moderate risk of rip currents on Atlantic beaches today. PREV DISCUSSION... /issued 421 AM EDT Sat Aug 18 2018/ DISCUSSION... Latest water vapor imagery loop indicates an area of dry air in the mid and upper levels stretching from Central Florida eastward towards Bermuda. This dry/sinking air is associated with a rather strong 594 mb high pressure cell. Clockwise motion around this feature has allowed for persistent easterly flow to southern Florida overnight. A distinct tongue of moisture can be observed on satellite derived PWAT stretching from the northern Keys eastward toward the Bahamas with values greater than 2.0". As this area of enhanced moisture slowly edges towards our CWA, the threat of precipitation will steadily increase. The GFS progs a rather compact vort max to develop this afternoon near the Straights and move over the Everglades. As this feature approaches, 500 mb temps drop to -8 or -9 C. Deeper moisture and greater instability, compared to the last several days, should bring a greater coverage of mainly afternoon and evening thunderstorms. Some of the storms could become strong, producing downdraft winds in excess of 45 mph. Small hail will also be possible due to the colder than normal air aloft, especially over the western interior and southern portions of Miami-Dade County. Maximum temperatures are forecast in the upper 80s to near 90 along the coasts with low 90s forecast elsewhere. These values are a degree or two below normal for this time of year. Late this weekend through mid next week the synoptic pattern does not budge much. High pressure over the western Atlantic will continue to bring easterly or southeasterly flow into South Florida, driving deep moisture and instability over the area. Similar to previous days, there will be an elevated threat of mainly afternoon/evening convection over the interior and Gulf Coast. Showers and thunderstorms will also be possible along the east coast metro region, but definitely more isolated. Temperatures each afternoon should reach near 90 degrees along the coast and low 90s for the interior. MARINE... High pressure across the western Atlantic will prevail through early next week. Moderate east to southeasterly flow will continue across the local waters with favorable boating conditions. Scattered showers and thunderstorms are possible each day. Winds and waves could be higher in and around any shower or thunderstorm. AVIATION... Convection continues pushing ashore from the Atlantic this morning. Expect mostly VFR with brief bouts of sub-VFR. Additional convection possible through the morning into the afternoon with the highest storm coverage expected to the interior of the terminals. APF should see a diurnal sea breeze pattern with the threat of storms again as well. Short-fused amendments will likely be necessary. && .PRELIMINARY POINT TEMPS/POPS... West Palm Beach 89 78 89 78 / 30 30 40 20 Fort Lauderdale 89 80 89 81 / 20 30 40 20 Miami 89 78 89 79 / 20 30 40 30 Naples 90 76 90 77 / 50 20 30 10 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. GM...None. && UPDATE...23/SK DISCUSSION...27/JT MARINE...27/JT AVIATION...23/SK BEACH FORECAST...23/SK CLIMATE...23/SK