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Area forecast discussion 
National Weather Service Tallahassee Florida 
308 am EDT Thursday Jul 24 2008 


Synopsis...03 UTC surface analysis shows a cold front across the 
lower Tennessee Valley. The gradient with this front is rather 
pronounced for this time of year...dewpoint difference across the 
front between Nashville and Huntsville was 16 degrees. This boundary 
will continue to move slowly southward toward our region today. The 
upper air analysis shows the upper trough more amplified than 24 hours 
ago. The ridge over the southwest has shifted its center eastward 
into the southern High Plains. Drier air is noted surging southward 
on the vapor imagery this morning and this will have a direct impact 
on thunderstorm development for the next couple of days. 


&& 


Short term...today through Saturday. 
It is nice to see some general agreement between the NAM and GFS 
this morning. In fact...it is the GFS solution this cycle that has 
come around more to the NAM solution. Vapor imagery this morning 
confirms that middle and upper level dry air is surging southward as 
the upper trough amplifies over the northeast and Middle Atlantic States. 
This surge of drier middle/upper level air will help to suppress 
afternoon convection...especially across our northern zones. 
Moreover...model soundings indicate that temperatures in the 700 to 
400 mb layer will be around 2 degrees c warmer today than yesterday. 
The surface boundary should remain far enough north throughout today 
to limit drier surface air from reaching our counties. With a type 
8/9 sea breeze regime today (1000-700 mb flow northwest around 10 
knots)...the sea breeze fronts will be pinned near the coast...but 
with the best deep layer moisture available in these areas...higher 
probability of precipitation are indicated closer to the coast. Will go for slight chance 
probability of precipitation far northern areas where moisture and instability will be 
lowest. Modified parcels in the north (93/67...which may be generous 
for the dewpoint) yields about 1500 j/kg of SBCAPE...but a precipitable water 
around 1.5 inches. This is easily 1 Standard deviation below the 
mean for this regime. Further south...a modified parcel of 91/69 was 
used which produced around 2000 j/kg of SBCAPE...but the precipitable water was 
around 1.8 inches. These values are closer to the mean for this 
regime. Temperatures will be noticeably warmer today across the 
north as less cloud cover and thunderstorm activity will allow 
temperatures to reach the middle 90s. 


Friday...a middle level ridge will build eastward over the western 
parts of our region...helping to suppress afternoon convection. The 
presence of the dry air will make it difficult for storms to develop 
in the north as well. The only positive for decent convection will 
be the decaying frontal boundary across our County Warning Area. This...along with 
the sea breeze fronts will serve as a focus for storms...but mainly 
along and south of the I-10 corridor. Temperatures will be quite 
warm...in the upper 90s or better across our northern tier counties 
where near full insolation under the July sun will make for a hot 
day. 


Saturday...moisture gradually increases as low level flow turns 
southerly. The middle level ridge should serve to limit the overall 
coverage of storms...but with increasing deep layer moisture...probability of precipitation 
increasing into the 30 to 40 percent range...even in the northern 
zones seems appropriate. Will scale temperatures back a little from 
the high values on Friday...but will still be a warm day with most 
inland areas hitting the middle 90s. 


Long term...Sunday through Thursday. 
Large scale pattern to remain relatively unchanged through the next 
seven days. Upper flow will be dominated by a persistent eastern 
Continental U.S. Trough flanked by ridges over the western Atlantic and 
Southern Plains. At the surface...trough will persist north of the County Warning Area 
with ridge axis over the Gulf south of the coastal waters. This will 
keep a general west to southwest flow in place through the forecast 
period. Overall...expect near climatology conditions through period with 
scattered afternoon and evening convection and near normal 
temperatures. 


&& 


Marine...wave periods at the buoys are gradually coming 
down...indicating that the swell from Dolly is diminishing. 
However...there still is likely some lingering secondary swell 
coming in today that will keep sea heights elevated...so will 
continue ongoing forecast of 2 to 4 feet...but show a decreasing 
trend tonight. Winds and seas Friday and beyond will remain low. 


&& 


Aviation...predominantly VFR conditions through the remainder of 
the overnight hours with copious amounts of middle and upper 
cloudiness. Will see some MVFR conditions develop by daybreak for 
inland terminals with 3-5sm visibility. Typical summertime day for the 
area Thursday with scattered thunderstorms and rain in the afternoon. Have tempos at 
all terminals...coming to an end in the early evening. 


&& 


Fire weather...low level flow will become more northerly today and 
Friday with slightly drier air mass filtering into the area. 
However...relative humidity values are expected to remain well above 
red flag criteria. No headlines needed. 


&& 


Preliminary point temps/pops... 
Tallahassee 92 72 95 71 93 / 50 30 30 20 40 
Panama City 90 74 91 77 90 / 50 30 40 20 40 
Dothan 92 71 95 73 93 / 40 20 20 10 40 
Albany 94 70 97 73 95 / 20 10 20 10 30 
Valdosta 92 71 95 70 95 / 40 20 20 10 30 
Cross City 91 72 93 71 93 / 40 30 40 20 40 


&& 


Tae watches/warnings/advisories... 
Alabama...none. 
Georgia...none. 
Florida...none. 
GM...none. 


&& 


$$ 


Aviation/long term/fire weather...Camp 
rest of discussion...Godsey