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fxus62 kjax 071406 
afdjax 


Area forecast discussion 
National Weather Service Jacksonville Florida 
1002 am EDT Thursday Aug 7 2008 


..one more hot day with strong to severe thunderstorms possible... 


Public update...today is shaping up to be an active weather day. 
Upper level ridge has been suppressed further south...with low 
level presence expected to weaken as day progresses. Surface 
trough is positioned near the Altamaha river. As the day unfolds...an 
upper level disturbance/shortwave trough/ is forecast to approach 
from the northwest. This feature coupled with aforementioned surface 
trough...weakening cap in the lower levels...precipitable waters  above 2 inches and 
strong thermodynamics with forecast highs in the 90s will set the 
stage for strong to severe thunderstorms across jax County Warning Area. Storm Prediction Center day 1 
outlook includes portions of southeast Georgia under slight risk and this 
certainly looks reasonable given ingredients above. 12z kjax and ktae 
soundings indicate the atmosphere is very unstable. After modifying 
kjax sounding using T/dew Point of 95/72...surface-based cape of 3500 j/kg 
and Li of -10 were derived. Thus...concerns of strong to severe 
thunderstorms with damaging winds...small hail and frequent cloud 
to ground lightning. Given precipitable waters  around 2 inches and slow storm 
motion...localized heavy rainfall is anticipated as well. Have 
beefed up probability of precipitation and wording in zone forecast product. 


&& 


Aviation...looking at another predominately VFR forecast in store 
for today. Upper trough will be approaching the area late today 
which should enhance the thunderstorms and rain potential over previous days. 
Current terminals include thunderstorms in the vicinity wording for this afternoon....but 
may need to include tempo groups as atmosphere is quite moist and 
unstable. Will defer inclusion of tempo groups until 18z package. 


&& 


Marine...southwest flow will be increasing over the next 36 to 48 
hours as surface trough approaches from the north. Still looks as 
though values will be largely below scec criteria although cannot 
rule out a brief period over the offshore portion Thursday night into 
Friday morning. Otherwise...winds will ease as trough slides 
through the waters by the latter half of the weekend. 


&& 


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


&& 


Previous public..upper high pressure ridge continues to extend from 
The Rockies to the jax County Warning Area. Trough has begun to 
suppress the ridge along the east Seaboard. Dry air aloft continues over 
the area. Cold front extends from Virginia to S Kansas. Skies are mostly clear 
across NE Florida and southeast Georgia with temperatures still in the upper 70s to lower 
80s. 


Short term...east US upper trough will continue to dig over the next 
48 hours. One more hot day is on tap for today. However...maximum temperatures 
will be a couple of degrees lower than on Wednesday due to slowly 
falling heights. Atmospheric moisture and rain chances will 
be on the increase. Thunderstorm development should be enhanced by pre- 
frontal trough and seabreezes...with the best coverage over our west 
zones. Increasing SW flow may allow convection that does develop 
to spread toward the East Coast during the evening hours. 


As upper trough continues to dig...surface cold front will continue to 
sag S into the area on Friday. Continued moisture increase...coupled 
with low-level convergence and destabilization...will lead to 
numerous thunderstorms across the area. Temperatures will continue their decline 
with maximum values near 90. 


Long term...cold front will stall across central Florida and become 
diffuse. Enough dry air will trail the front to lead to an overall 
decrease in probability of precipitation from sun to Tuesday...with best chances over our 
extreme S zones. Probability of precipitation will increase by Wednesday of next week as 
moisture returns and another frontal boundary approaches the area. 
Temperatures will average near climatology normals through the extended period. 


&& 


$$ 


Ecz