469 
fxus62 kjax 281803 
afdjax 


Area forecast discussion 
National Weather Service Jacksonville Florida 
203 PM EDT Thursday Aug 28 2008 


Short term...a mean layer trough extends from the Ohio Valley into 
the NE Gulf of Mexico while a ridge is south of the area. This 
pattern begins to weaken Friday as a ridge builds in from the 
western Atlantic late in the day. Drier and more stable air mass 
will move into the region from the northwest Friday and will keep a north-S 
pop distribution with best chances over inland NE Florida from 
seabreeze collisions. The NAM is even drier on Saturday with precipitable waters  
dropping to 1.5 inches...but the GFS keeps precipitable waters  around 1.8 inches 
and that seems more reasonable. The synoptic flow will shift to 
southeasterly Friday then easterly over the weekend as the ridge 
drifts northward. With the onshore flow the best chances for 
precipitation Sat-sun will be along the I-75 corridor...but still only a 
20-30% chance for Saturday. Deep moisture will filter into the 
area from the south Sunday and probability of precipitation will increase to at least 40% 
and may be raised depending on how close Gustav is to the state. 


Long term (sun-thu)...forecast is predicated on the path Gustav 
takes over the Gulf of Mexico and Hanna in the Atlantic. High 
pressure will build over the Great Lakes and push southward along 
the eastern Seaboard resulting in an onshore flow during the week. 
Drier air and lower than normal probability of precipitation are expected as the middle/upper 
high drifts builds over the middle Atlantic Tue-Thu. Also...a 
tightening pressure gradient could result in breezy conditions 
near the East Coast by middle week. 


&& 


Aviation...model guidance in agreement in showing a late 
developing seabreeze along the East Coast which should create 
enough of a convergence boundary to produce low end scattered 
coverage of shra/tsra. Coverage still looks limited enough to 
warrant continued thunderstorms in the vicinity advertisement with the 18z package. Most 
sites saw some MVFR fog last night and similar conditions should 
yield similar results tonight. 


&& 


Marine...rather tranquil conditions expected for the next several 
days as light westerly flow will transition to easterly with the 
passage of the seabreeze on Friday. Ridge builds in to the north 
as Gustav passes well to the southwest...increasing the easterly 
flow across the area. Conditions will remain below any flag 
criteria. Swells could increase to 4 to 6 feet by the end of the 
period depending on the fate of Hanna. 


&& 


Preliminary point temps/pops... 
amg 69 93 69 94 / 10 30 20 30 
ssi 74 89 75 88 / 20 20 10 20 
jax 72 91 73 92 / 20 30 10 30 
sgj 74 89 75 88 / 30 30 10 20 
gnv 71 92 71 92 / 20 40 20 30 
ocf 71 92 72 93 / 20 40 20 30 


&& 


Jax watches/warnings/advisories... 
Florida...none. 
Georgia...none. 
Am...none. 
&& 


$$ 


Mkt/jd/acs/mm