AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE TALLAHASSEE FL 1017 PM EST Mon Jan 23 2012 .UPDATE...The thin band of RAIN and thunderstorms has been pushing gradually into our forecast area this evening from west to east, reaching a EZM-ABY-MAI-ECP line by around 0230z. This activity has advanced ahead of the main cold FRONT, which extended from just NW of Atlanta to far southern Mississippi. A much drier AIR mass was noted behind the front, with dewpoints 35-45F on most surface OBS. HIGH-resolution model guidance, including all flavors of the 4km WRF AS well as the HRRR, dminishes this activity to just ISOLATED showers around 06z. This seems to match recent RADAR and LIGHTNING trends, and makes sense with a lack of strong LOW-level forcing. We used a 3-HR POP trend with hourly weather GRIDS to time the PRECIPITATION trends in the very near term (0-6hr). The other concern tonight is FOG potential. One area of fog was already developing in the WAKE of the precipitation across SE Alabama and the far western Florida Panhandle. KTOI and KCEW (both just outside our forecast area) have reported visibilities as low as 1/4SM in the past hour or so. Therefore, as the rain moves out of our northwestern areas we will probably see some fog develop. This may be abbreviated somewhat by the arrival of the main front later tonight and therefore some drier air. As such, confidence was not high enough in true dense fog (1/4SM or less) developing to issue any ADVISORY in our AL zones and adjacent FL/GA zones. Meanwhile, some of the high-resolution guidance and VSREF probabilities indicate some potential for dense fog over Apalachee Bay and into our eastern Big Bend counties as well, particularly after 06z. There is uncertainty in those locations related to the dense MID level CLOUD cover BLOWING off the CONVECTION to the west. Also, no observations in that area have any restricted VISIBILITY at this time. It isn`t inconceivable that a Dense Fog Advisory may be needed later tonight, but confidence is not high enough at this juncture to accurately place one. Some minor tweaks were made to the weather and POPS into tomorrow afternoon as well. Our 18z local 4km WRF-ARW, and to a lesser extent the 12z SPC WRF-NMM, indicate some more focused afternoon THUNDERSTORM activity around the rim of Apalachee Bay, from near Apalachicola up towards Tallahassee and Madison. This seems to be related to some enhanced onshore FLOW off the cooler waters as the land areas heat up. PoPs were nudged up 5-10% in aforementioned corridor. WRF forecast soundings show about 1000 j/kg of MLCAPE in the afternoon, so THUNDER seems like a good bet south of wherever the stalled cold front sets up. && .AVIATION [through 00z Wednesday]...Tricky TAF package for the overnight hours into Tuesday. Approaching cold front is forecast to stall along the I-10 corridor all day Tuesday, creating impacts for KTLH, KECP, and KVLD. SCATTERED showers and will impact KDHN, KABY, and KECP for the next several hours before the activity weakens. MVFR conditions expected at these sites through the NIGHT. Conditions will improve through the day for the northern terminals, which will be well north of the front. Farther south, after patchy fog and low cigs overnight, conditions will LIKELY only improve to near Alt. Arpt. thresholds during the day. Isolated thunderstorms are possible during the afternoon. && .MARINE...Considered a Marine Dense Fog Advisory for nearshore waters from Apalachicola to the mouth of the Suwannee River. However, despite a 63 degree dewpoint, Keaton Beach was holding steady with a 2F dewpoint DEPRESSION, and there was no evidence of any fog having developed yet at any coastal observations. This will need to be monitored closely during the overnight. Subdued SEAS and winds will continue through Wednesday when there should be a gradual increase in southeasterly winds as a low develops along the Texas Gulf coast. A front still looks to arrive late Thursday Night, and advisory level winds and seas will be possible just before and after the front. The front also looks to be accompanied by some thunderstorms.