AFDTAE AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 805 PM EST Sat Feb 4 2012 .UPDATE...Upstream radars show the line of showers and isolated thunderstorms rapidly diminishing in intensity and coverage as it moves eastward across southern Alabama. At it`s current pace of 20 to 25 mph it would be around midnight EST before any of this activity would make it to our westernmost zones. By that time we may just be looking at a few showers or patchy light rain. For tonight will keep PoPs tapered from low end chance northwest to silent 10% southeast. No changes to grids or zone updates anticipated. && .AVIATION...Advancing area of showers and thunderstorms across Southern Miss is expected to diminish before significantly impacting any of our terminals. The moist low level airmass in place is expected to be supportive of both fog and stratus development overnight, especially at the DHN and ECP terminals. Based on the bulk of the hi-res guidance and statistical guidance indicating higher likelihood of restrictions at our western sites, will include prevailing IFR/LIFR conditions overnight at DHN/ECP with less pessimistic MVFR/IFR blends at TLH/ABY/VLD. Expect morning ceilings to only slowly lift throughout the day with VFR cigs finally returning around 18z. Rain chances look spotty at best, so will only mention VCSH groups at ABY/DHN in the afternoon where chances are best. .PREVIOUS DISCUSSION (241 PM EST Sat Feb 4 2012) .NEAR TERM (through Tonight)...In the very near term we are watching to see if any isolated showers or thunderstorms will crop up in the western parts of our area. This is a scenario hinted at by some of the convection-allowing models, most notably 4km WRF runs with an NMM core. With this possibility remaining, a small PoP was kept in the forecast through 00z in these areas. Overnight, the 0-1km mean flow turns initially to the south, and eventually veers southwest late, allowing for some weak but positive thetae advection. The maintenance of the higher boundary layer dewpoints should allow for some fog and low clouds to develop, and patchy fog was inserted into the grids to coincide with RH at or above 95%. The timing of PoPs was slowed down a bit from the previous forecast, as models seem reluctant to bring much rainfall in prior to even 12z Sunday. A linear extrapolation of the squall line to the west would bring it to our western CWA border around 06z, but lightning activity is on the decrease and the overall trend should be for this to weaken and become more scattered with time. .SHORT TERM (Sunday through Monday Night)...Piece of upper level energy over Missouri Sunday morning, is forecast to reach the mid- Atlantic region by late Monday or early Tuesday. The associated surface front will move into the forecast area on Sunday, bringing with it a chance of rain. Upper support and low-level convergence is expected to be minimal. However, with the above normal temperatures, there will be just enough instability to generate isolated to scattered showers and thunderstorms across the area. Models differ on how quickly the upper energy will move east to the Atlantic coast, with the ECMWF being the slowest and the GFS being the quickest. This impacts the potential for any lingering precip over the eastern portion of the forecast area for Monday. Have hedged a bit towards the slower solution, with some slight chance PoPs for the eastern zones on Monday. Otherwise, slightly cooler air will be filtering into the region for Monday, with highs 8 to 10 degrees lower than Sunday. .LONG TERM (Tuesday through next Saturday)...The long term forecast is still low confidence with model disagreements continuing. The 03/12z Euro made a change from its 02/00z run and trended wetter across the area on Wednesday into Wednesday night with a decent upper level shortwave moving north of the area. This would have brought rain into the area a full day faster than the GFS. However, the new 04/00z Euro has a weaker shortwave now and is back to dry conditions all the way until next Saturday. The developing pattern is a tough one for the models to handle with both northern and southern stream disturbances and their interactions with each other to consider. The 04/00z GFS has remained fairly consistent with its handling of the southern stream and continues to show a Gulf low affecting the area on Thursday with deep moisture and widespread rainfall. Previous Euro runs left a cutoff upper level low west of the Baja whereas the GFS has been more progressive moving it eastward and spawning the Gulf low. The new 04/00z Euro actually trended towards the GFS with its 500 mb depiction, but it does not show any surface reflection in the Gulf until Saturday. The GFS has some support from the Canadian model in showing increasing rain chances on Thursday. The 04/00z GFS ensemble mean 500 mb pattern also continues to agree with the GFS. It does seem probable that it will rain sometime between Thursday and Saturday, but given the discrepancies in timing, PoPs were kept in the low chance range until the timing of these systems can be better defined. && .MARINE...Seas remain a bit elevated over the offshore western legs due to some ongoing swell, as indicated by the 7 to 8 second period at area buoys. Guidance appears to diminish the swell a bit too quickly, so have bumped up seas a little above guidance for the overnight hours. Thereafter, winds will diminish for Sunday into Sunday night with high pressure overhead. Offshore flow will increase modestly on Monday in the wake of a cold front. Light to moderate north to northeast flow will then continue through much of the coming week. && .FIRE WEATHER...no major fire weather concerns in the upcoming forecast. Minimum RH will start bottoming out closer to 35% in the upcoming work week, but for now things seem too marginal to hit the red flag criteria. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 56 77 52 70 43 / 10 40 30 20 10 Panama City 61 73 54 67 48 / 20 30 20 20 10 Dothan 60 74 48 66 42 / 30 40 20 10 10 Albany 58 76 48 67 41 / 20 30 20 10 10 Valdosta 55 77 51 70 43 / 10 40 30 20 10 Cross City 55 77 55 74 45 / 10 40 30 20 10 Apalachicola 59 72 54 66 48 / 10 20 20 20 10 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...None. GA...None. FL...None. GM...None. && $$