Area Forecast Discussion
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450 FXUS62 KTAE 221805 AFDTAE AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 205 PM EDT Tue Apr 22 2014 .Near Term [Through Tonight]...
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The local pattern shows that mid/upper low amplitude shortwave trough over local area this eve moves SEWD and offshore overnight to be replaced by upstream shortwave ridging thru overnight hours. At the surface...this will push cold front to S/Cntrl AL/GA by sundown with assocd shwrs and thunderstorms ahead of front reaching our Nrn tier counties and increasing west winds. With mid/upper trough and support exiting...The front and assocd precip will continue to weaken and likely stall across extreme N FL and become oriented east to west. The deepest moisture and best lift with this system will stay well to our north. Locally...poor mid level lapse rates...meager CAPE and loss of sun translates to marginal instability and deep layer shear so chance for strong storms not high. Still...evening guidance shows vorticity axis from SC across FL Panhandle into NW Gulf. H5 temps will be cool enough i.e. -14C combined with aftn temps in the low 80s and dew points approaching 60 degrees...enough ingredients lingering into eve for isold Tstms. Our local CAM forecasts best chances of preccip will be closest to upper support...NE tier GA counties with increasingly limited POPs NE-SW. All of the MOS and dynamical guidance forecast a strong weakening/drying trend after midnight so divided POPs into 3hr GRIDS. Sharp 50-0% NW-SE evening POP gradient. With loss of sun and dynamics....NIL POPs after midnight. Good chance for low stratus and at least patchy fog ahead of front. .Short Term [Wednesday Through Thursday Night]... The mid/upper level local pattern begins with shortwave trough well into Atlc replaced by amplified ridging...rising heights and subsidence. At surface...remnants of Tuesday`s cold front limps into our SE Big Bend Swwd into our Nrn marine area. In its wake...area model soundings show flow sfc-upper levels NWLY however with proximity of front...PWATS remain around 1 inch. During the rest of the period...local ridge amplifies into Thurs ahead of upstream trough/low developing over Wrn states. By aftn... this low pivots Newd resulting in Ern ridge flattening yielding near zonal flow. At surface...increasingly diffuse front lingers in place before likely lifting Nwd late Wed into Thurs as high develops over NE Gulf and...along with ridge across Nrn Gulf Coast...remains established into Thurs night. The combination of strong mid/upper subsidence and weakening front south will yield partly to mostly sunny skies. The lifting front will shift local winds to onshore on Thurs with rising humidity as reflected in model PWATS which remain around 1 inch. So it will feel muggy. With very dry mid/upper levels...at best isold POPs near the front. Temperatures will be near climatology through the period, with lows in the 50s and highs in the lower to mid 80s. .Long Term [Friday Through Tuesday]... On Friday, a weak surface trough will extend down from the Great Lakes. This trough will become oriented SW to NE as the parent low moves off to the northeast and the trough weakens. Southerly flow off the Gulf and weak forcing will cause a slight chance of thunderstorms over the the northern half of our area Friday through Saturday. Ridging will settle in on Sunday with southerly surface flow which will bring highs in the mid to upper 80s during the day. At the end of the period both the GFS and EURO show a very amplified pattern emerging with a deep upper-level trough digging down over the southern Plains. While these models differ some in timing and structure, they both show a blocking pattern emerging with a strong upper ridge in the west and an amplified deep trough in the east. This system should be our best chance of seeing showers and thunderstorms in the extended period.
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&& .Aviation...
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[Through 18Z Wednesday] VFR cigs and vsbys will prevail today before another round of fog tomorrow morning. Around 20Z, thunderstorms will move in to the northern terminals (DHN, ABY) from west to east, exiting the area by around 03Z. Around 09Z, area BR and FG will set in again across the area. The lowest cigs/vsbys will be at TLH and VLD with LIFR conditions possible. Guidance hinted at low vsbys along with low cigs at ECP, but left out since winds are expected to remain around 5 kts overnight.
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&& .Marine...
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Despite the front approaching from the north into tonight, then stalling across extreme North FL through Thursday, winds and seas on the whole will remain quite low. The exception will be a moderate increase in onshore winds and chop near the coast each afternoon because of the daily sea breeze.
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&& .Fire Weather...
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Red Flag conditions are not expected through the remainder of the week.
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&& .Hydrology...
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Most of our area rivers are above normal stage with many in flood stage. The Choctawhatchee at Bruce is at major flood stage, several others are in moderate. Most area rivers will crest soon or have already crested. The exception is the Suwannee River chich will rise slowly for the remainder of the week. Rainfall amounts are expected to be less than 0.25 inch and will have little impact on area river levels. The most up-to-date river forecast information can always be found on our AHPS page (below). http:/water.weather.gov/ahps2/index.php?wfo=tae.
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&& .Preliminary Point Temps/PoPs...
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Tallahassee 62 82 58 82 62 / 10 0 0 10 0 Panama City 65 77 63 75 65 / 10 0 0 10 0 Dothan 61 82 57 83 62 / 30 0 0 10 10 Albany 60 82 56 83 61 / 40 0 0 20 10 Valdosta 61 83 59 83 61 / 20 10 10 20 0 Cross City 61 82 59 82 60 / 10 10 10 20 0 Apalachicola 63 75 63 74 64 / 10 0 0 10 0
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&& .TAE Watches/Warnings/Advisories... FL...None. GA...None. AL...None. GM...None. && $$ NEAR TERM...BLOCK SHORT TERM...BLOCK LONG TERM...BLOCK AVIATION...MOORE MARINE...BLOCK FIRE WEATHER...MOORE HYDROLOGY...BOLDEN

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