NATIONAL WEATHER SERVICE TALLAHASSEE FL
315 AM EST Fri Dec 6 2013
NEAR TERM [Through Today]...
Early morning subjective analysis places a sharp cold front from near Chattanooga, to Tuscaloosa, to Jackson MS.
We appear to be far enough removed from the front that rain chances over the next 6-12 hours should remain fairly low.
EOX radar did show some very small, light showers just west of our area in Covington County, AL 05-07z. A small area of 15-20% PoPs was included in the western row of counties to account for this through 18z.
Thus far, fog has not been much of an issue with only a few stations reporting any visibility restrictions and none below 1 mile. We scaled back the areal coverage of fog in the grids to fit with the latest probabilistic guidance from our local CAM ensemble and SREF.
We can`t rule out some isolated dense fog, but it doesn`t appear like it will be a widespread issue this morning.
Highs yesterday exceeded model expectations, and an examination
of the past three days worth of 00z soundings from TAE show
consistent warming trend below 700mb.
Given that the low-level temperature profile should be no cooler today, we opted for a persistence forecast in large part, with highs very close to yesterday`s low 80s - which produced some records.
Late in the day the cold front to the NW should have moved close enough that NW parts of our forecast area should experience a greater degree of low-level forcing.
This should be sufficient for some scattered showers, particularly in southeast Alabama.
Average forecast sounding from NAM, RAP, and GFS at DHN shows some convective instability with a tall, skinny CAPE profile. This could be sufficient for some isolated thunderstorms too.
SHORT TERM [Tonight Through Sunday]...
A shortwave, exiting the mean western trough, will weaken the
periphery of the strong upper ridge overnight.
This will allow the cold front to advance southeastward into the local forecast area.
Scattered showers will be possible along and behind the front
tonight. While PoPs will be relatively high over the northwestern
zones, rainfall amounts are expected to be very light given the
lack of synoptic forcing.
A substantially colder airmass will slide in behind the front on
This will make the max temperature forecast highly dependent on exactly how far into the area the front gets before stalling.
Current thinking is that the front will make it very close to Tallahassee during the afternoon before stalling.
To the northwest, temperatures will fall behind the front, with max
temperatures in SE Alabama likely occurring close to sunrise.
Southeast of the front, the unseasonably warm weather will continue with highs in the upper 70s to around 80.
As the aforementioned shortwave moves into New England and the
western trough reloads late on Saturday, the upper ridge will flex back to the northwest, with the frontal boundary retreating rapidly to the north.
This will result in the warm airmass spreading back across the entire forecast area for Sunday, with highs back in the mid 70s to near 80 for the entire region.
LONG TERM [Sunday Night through Thursday]...
One more warm day will occur on Monday before a stronger cold front crosses the entire forecast area from Monday night into Tuesday.
We could see some isolated thunderstorms out ahead of the front Monday afternoon.
Once again PoPs will be in the chance category.
Much cooler air will arrive behind this front with daytime highs ranging from the mid 50s in Coffee County AL to around 70 in Dixie County FL.
Wednesday will be the coolest day with highs in the 50s northwest of a TLH-VLD line.
At this point, it does not appear that a freeze will occur, although lows will drop into the mid 30s across our extreme northwestern zones by
sunrise Wednesday. TLH should get no lower than 40 degrees.
AVIATION [through 06 UTC Saturday]...
Probabilistic guidance is very consistent in showing the best chance
for IFR-LIFR CIGS (FOG) late tonight and early in the morning over the
western parts of our area: affecting ECP and DHN. This is where we included more persistent low CIGS.
At TLH and VLD there is still a chance for some periods of dense fog, but confidence is lower there.
At ABY, guidance suggests the chances of IFR CIGS or VIS is low.
Models then indicate that an MVFR ceiling may linger in the west
through the day (ECP + DHN), with VFR elsewhere.
Southerly flow will continue across the waters today ahead of an
approaching the cold front.
Winds over the western waters will become offshore late tonight into Saturday, before becoming southeasterly again on Sunday.
Winds and seas are currently forecast to remain below headline criteria through the forecast period.
Relative humidity values will remain above critical thresholds through the forecast period; therefore no red flag conditions are expected.
Fog is expected the next several nights and mornings.
Total rainfall amounts over the next 5 days should range from roughly an inch northwest of Dothan to less a quarter inch over the southeastern half of the HSA.
This will have only minimal impacts on area rivers and streams.
PRELIMINARY POINT TEMPS/POPS...
Tallahassee 82 65 74 57 77 / 10 30 30 20 10
Panama City 77 64 67 56 75 / 20 40 40 20 10
Dothan 81 55 60 51 75 / 30 60 40 20 20
Albany 81 63 68 54 74 / 10 40 50 30 20
Valdosta 85 63 76 58 78 / 10 20 30 20 10
Cross City 82 60 80 56 79 / 10 10 20 10 10
Apalachicola 75 67 72 59 72 / 10 30 30 20 10