AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 900 PM EST Wed Feb 22 2012 SYNOPSIS... AT UPPER LEVELS... The large scale longwave pattern is highlighted by a LOW-AMPLITUDE TROUGH/CUTOFF low over Baja CA and and the northeast portion of the country, with a similarly low-amplitude RIDGE over PAC NW and Rockies. This Baja low is expected to MEANDER slowly EWD over northern Mexico through Friday. Another SHORTWAVE over PAC nw will amplify AS it continues to dig east-southeast, reaching the Ohio River Valley by early Friday. AT LOWER LEVELS... A broad diffuse HIGH PRESSURE ridge extended north of the Bahamas through the southern Florida peninsula. Generally lower pressure was found to the northwest OF CWA. In between, warm FRONT near the coast. This combination has SET up broad southerly low-level FLOW over much of the Southeast. On Thurs, an H5 Trough lingers over N FL with WSW flow and 40kt JET over area. warm front should lift new during days enhanced by jet. This should lead to BREEZY to WINDY conditions approaching WIND ADVISORY criteria, particularly over the northern third of our forecast area. As the above upper level shortwave digs and amplifies, surface CYCLOGENESIS should commence from the Dakotas tonight into the eastern Great Lakes by Friday. An accompanying cold front trailing to the southwest will also SURGE southeastward across much of the central and eastern US, reaching the eastern Gulf Coast on Friday and will LIKELY be our next STORM system. Until that cold front passage occurs, there will be periodic chances of RAIN and storms with breezy south to southwest winds. There is better model consensus today on the timing of the cold front, reaching roughly the I-65 corridor just northwest of our area shortly after SUNRISE, and pushing into the southeast part of our area (near Dixie County) by 00z Saturday. This places the arrival of the front squarely in the DIURNAL timeframe, and that`s when the highest (approx 60%) POPS were concentrated. as the upper level trough and cold front move SEWD and phase with lingering H5 Trough over local area. The main concern then is related to potential severe weather which remains a possibility and will dealt with in more details on next AFD. && .SHORT TERM [REST OF TONIGHT THRU EARLY THURSDAY]... Analysis during wed AFTN/early EVE was due to upper shortwave moving ewd across NB most Apalachee Bay. At surface weak warm front from SRN la ESE thru the warm gulf CURRENT to our west and then across and shelf waters of Gulf of MEX. This combination provided enough lift for ample rain and SCT thunderstorms especially over SE Big Bend and Apalachee Bay. However, activity waned last FEW hours as initial shortwave moved ewd reaching E coast by 9PM with some drying in its WAKE. Also, earlier large scale warm and MOISTURE ADVECTION shifted NWD. However, AT 9PM another albeit weaker shortwave was moving ENE across Apalachicola Bay generated showers across se Big Bend and adjacent waters. Have updated ZFP to lower pops thru 06z with MAX 60% over water down to less than 20 PCT NRN tier counties. (ALTHO some light DRIZZLE a good bet over CWA). satellite PIX implies a few more impulses may move in from waters later tonight so cant drop pops too much. For 06z-12z, 0-40% NW-SE GRADIENT with ISOLD tstms across mainly coastal counties and waters. Aside from rain chances overnight, tonight will be the first of a couple of MUGGY nights out ahead of the main system expected to arrive on Friday. Strengthening surface winds and CLOUD cover and passing impulses will likely limit dense FOG development across the region, however, the potential for low STRATUS will be high. Best CHANCE of fog will be near the coast and e/se of a line from Tallahassee thru Valdosta and Cross City and adjusted GRIDS accordingly. && .AVIATION..(thru 00Z Thursday) Ongoing moist AIR advection from the gulf will keep ceilings in the IFR/LIFR RANGE for most of the area overnight. Expecting fog to impact all terminals starting at 3z near the coast and near 5z further inland, with significantly reduced VIS between 1 to 2SM at TLH,VLD,and ECP. 40kt winds near 2000ft will keep wind SHEAR wording in the TAFs from 3z to 14z. Winds will pick up to around 20 KTS gusting to 30kts region wide tomorrow afternoon and MVFR ceilings will linger into the afternoon as well. && .MARINE...MID eve buoys showing 10-15kts. winds expected to increase from w-e overnight with se winds 15-20kt likely with SEAS building to 4-5 feet offshore. thus will keep SCEC headlines.