AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 249 PM EST Wed Feb 1 2012 .SYNOPSIS... The 16 UTC regional surface analysis showed a very weak, 1022 MB spot LOW along the southeast LA coast and a slow-moving frontal system from the IN-KY border to north TX. Vapor imagery and upper AIR data showed a TROUGH propagating east out of the the Central Plains, with moist southwest FLOW (and areas of RAIN) ahead of it. && .SHORT TERM... (Tonight through Saturday) Recent RADAR/satellite trends indicated that rain (briefly heavier) was moving into southeast AL and the eastern FL Panhandle from the west. This rain will slowly spread eastward tonight, but the forcing for it will be weakening so we also expect the rain coverage and intensity to be diminishing. Our QPF for this afternoon through Thursday morning ranges from half an inch (west of the Apalachicola/Chattahoochee Rivers) to a quarter of an inch or less east. There may be enough INSTABILITY and lift for a FEW thunderstorms through this evening, but thunderstorms will become much less LIKELY later tonight. Although the 0-6 km vertical WIND SHEAR magnitudes would support some STORM organization/UPDRAFT ROTATION, the poor instability and weakening lift make severe storms unlikely. Most of the rain will end Thursday morning, but the proximity of a QUASI-STATIONARY FRONT (which will become a warm front lifting northward Friday NIGHT) warrant a small CHANCE of rain for Thursday afternoon. Rain chances will increase modestly again by Friday afternoon, mainly over our north and western zones (around Dothan and Albany). Temperatures will remain well above average. .LONG TERM... (Saturday night through next Wednesday) It looks like the pattern will have fairly low predictability during the long RANGE period. Both the 01/00z GFS and 01/00z Euro develop a rex block over the central U.S. with a large 500 mb closed low south of an upper level RIDGE. The closed low eventually opens up into a trough and moves eastward, but the models differ on the details of when this occurs. At the surface, broad southeast to south low level flow ahead of the eventual approach of a cold front may keep a low end chance of showers in the area through the weekend. Forcing and instability for thunderstorms looks fairly weak, although an ISOLATED THUNDERSTORM is possible, mainly during the daylight hours. The timing of the frontal passage is quite unclear at the moment with the 01/00z GFS favoring a Sunday afternoon passage and the 01/00z Euro favoring more of a Tuesday passage. AS a result, a 20-30 POP was kept in the forecast through Tuesday morning over most of the area to account for the timing uncertainty. Unfortunately, the TEMPERATURE forecast also becomes more uncertain for late in the weekend and early next week due to the timing differences. The raw GFS is about 10-15 degrees cooler than the raw Euro on the highs for Monday and Tuesday due to the GFS`s earlier frontal passage. Curiously though, the GFS MOS HIGH temperature output lines up quite nicely with the raw Euro (perhaps due to its trend towards CLIMATOLOGY at this time range), and as a result we were able to use the GFS MOS temperatures in the official forecast. && .AVIATION... Conditions at the terminals will slowly deteriorate throughout the evening hours as showers spread eastward. Expect MVFR conditions to arrive at DHN before SUNSET and then ECP shortly thereafter. Expect WIDESPREAD MVFR conditions at all sites by midnight with a potentially larger area of IFR conditions at DHN/ABY before SUNRISE on Thursday. Expect conditions to improve by 15z, but MVFR conditions should linger through the end of the TAF cycle. && .MARINE... Winds and SEAS will decline quickly this evening, followed by a period of low winds and seas until Thursday night and Friday, when winds and seas may increase to ADVISORY levels. && .FIRE WEATHER... No concerns as low level MOISTURE will be plentiful throughout the period.