AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 315 PM EST Mon Jan 16 2012 SHORT TERM [Tuesday through Wednesday NIGHT]...The short term period will be encompassed by a frontal passage. The cold FRONT in question currently stretches from eastern Ontario to northern Missouri, and then arcs westward through southern Kansas. A frontal wave developing along the front in the central Plains is expected to grow into a surface low as a low amplitude upper level TROUGH ejects into the Plains. The rapid CYCLOGENESIS in the Great Lakes and up the ST. Lawrence Seaway, along with the progressive zonal flow aloft, should help drive a cold front into the Gulf Coast region late Tuesday Night and early Wednesday. Tuesday: Despite some gradually increasing CLOUD cover, especially above 10,000 feet, it still looks like a pretty warm day. There is good agreement amongst the NAM, GFS, and GEM that 850mb TEMPS will SURGE up into the +13C to +14C RANGE. Even if the TEMPERATURE profile in the low-levels ends up being closer to the moist ADIABATIC lapse rate, it would still LIKELY result in highs in the low-to-mid 70s. The southeastward progression of POPS was delayed relative to previous forecasts, and it wouldn`t be entirely surprising to see most of the area staying dry prior to 00z Wed. There may be a FEW showers in the THETAE ADVECTION MAX near the coast, as is hinted at by our local 4km WRF-ARW, but confidence is not high enough to portray that scenario yet. Tuesday Night: The cold front finally pushes into our area. Timing differences on the 16.12z SET of models are much less than in previous model runs. For this forecast package, we used ENSEMBLE approach. SREF and GFS Ensemble means have roughly the SAME timing with the front entering our Alabama zones (NW corner of our area) around 06z Wednesday, and reaching a TMA-TLH-AAF line by 12z. Likely PoPs were included behind the front on Tuesday Night, where the bulk of the PRECIPITATION will occur. ISOLATED THUNDER was included as well, with MUCAPE 200-400 j/kg and equilibrium level around -25 to -30C. For temperatures, we used a non-DIURNAL trend as they will likely be almost steady ahead of the cold front for much of the night. Wednesday: As the front quickly exits the area, precipitation should come to an end. It will be a cooler day with highs closer to seasonal normals (low-to-mid 60s). Light FREEZE possible for Wednesday Night. && .LONG TERM [Thursday through next Monday]...Extended forecast period will begin Thursday with a rather unamplified upper level pattern across the CONUS, consisting of broad riding over the inter-mountain west and broad troughing over the eastern half of the nation. Wednesday`s cold front will be well to our south by Thursday morning with high pressure building in from the north in its WAKE. Some slight disagreement among the global guidance suite as to the position of the surface high, with the GFS building the CENTER overhead, and the the ECMWF/Canadian showing the high center up over the Carolinas. The GFS would be a colder solution Wednesday night, as the high position would favor a better radiational cooling setup. Will not deviate much from the MEX numbers for now which bring the normally colder inland spots down into the lower 30s. A solution closer to the EC/Canadian will lower the potential for significant coverage of subfreezing temps. Overall pattern becomes quite zonal in nature for Friday with just a weak shortwave riding the flow across the central portions of the country. Influence of this energy will hold off until Saturday providing a dry and warm final day of the workweek. Friday should see highs well into the 60s to around 70 degrees away from the immediate coast, where onshore flow off the cooler shelf waters will hold temps in the lower/mid 60s. GFS/ECMWF do not agree on the evolution of shortwave energy by the time it arrives here in the SE part of the CONUS. GFS is very progressive, passing the energy over us, and off the SE coast by Saturday evening. The GFS solution has very little, if any, surface REFLECTION associated with this energy, and only a CHANCE of a few showers. ECMWF is slower and stronger with its shortwave. This solution does show a surface reflection/front moving into our northern areas Saturday night. For now did not choose to follow this solution which would keep SHOWER chances in the forecast Saturday night. In fact, will continue to follow the GFS pattern through the early portion of next week, as the ECMWF becomes somewhat questionable. GFS keeps our area with a general southerly low level flow underneath a zonal to ridged upper level pattern. This would suggest above NORMAL temperatures for Sunday and Monday. Can not rule out a few isolated showers embedded with the southerly flow, however a generally dry forecast will also be shown. && .MARINE...The descending ASCAT pass at 1914z showed much of the coastal waters (except the two eastern nearshore segments) with 15-20 KNOT winds. In fact, there were some values around 20kt in our western offshore zone. Both of the buoys just outside our marine zones were reporting 17-19kt winds, so the scatterometer data is probably pretty accurate. Thus, winds have been slower to decrease than models have indicated. The "Small Craft Exercise Caution" headline will be continued into Tuesday morning for all but the two eastern nearshore segments. Although the central segments may see winds decrease briefly in the evening, they are expected to increase once again after midnight. After a brief lull, there are likely to be SCEC conditions again late Tuesday Night and early Wednesday as the cold front comes through. With respect to sensible weather, we added patchy FOG to the nearshore zones from 18z Tuesday to 18z Wednesday where RH was above 85% in the forecast GRIDS. This timeframe encompasses a surge of higher dewpoints in the 60-62F range (compared with observed water temps of 58F and 56F at Panama City and Apalachicola respectively). && .AVIATION [through 18z Tuesday]...Mid and upper clouds will continue to impact area terminals into Tuesday. However, prevailing conditions are expected to remain VFR. There is some possibility of brief MVFR conditions at KECP and KDHN after 12z Tuesday. && .FIRE WEATHER...Relatively moist onshore flow will continue into Wednesday ahead of an approaching cold front. This will keep HUMIDITY values well above critical levels, as well as provide some RAINFALL late Tuesday into Wednesday. Much drier AIR will push in behind the front for Thursday with humidity values dropping into the 20s for much of the region.