038 
fxus62 kjax 181903 
afdjax 


Area forecast discussion 
National Weather Service Jacksonville Florida 
303 PM EDT Friday Jul 18 2008 


Synopsis...visible and water vapor imagery loops give a good sense of 
the current features. Tropical low is off the Georgia the coast at about 
1011 mb about 60-70 nm east-northeast of Brunswick Georgia. There may be more than one 
center based on visible images this morning. The water vapor imagery 
shows drier air filtering into SC and Georgia and some of this drier air 
is moving into our Georgia zones. Radar imagery continues to show good 
coverage of mostly showers over the eastern zones with most of it in southeast 
Georgia at this time but shifting southward at 10-15 miles per hour. Latest laps analysis 
shows SBCAPE of around 1500 j over the southern zones and lower further 
north. Best low level forcing is over southeast Georgia and inland NE Florida. 
Temperatures are reaching the middle and upper 80s at this time. 


Short term... 
tonight...latest RUC shows best moisture will be over the eastern zones 
and 700 mb Omega maximum over NE Florida. Thus will go with at least scattered 
probability of precipitation for showers and possible thunderstorms this evening as the 
activity slides S to southeast. NAM and GFS lift the low further NE tonight 
with middle level lift and precipitation gradually ending. Will take down probability of precipitation 
to about 20% after midnight. Saturday...left over SW-NE surface trough 
will be across the County Warning Area with the low center somewhere near the SC 
coast. Still moist airmass with precipitable waters  up to near 1.7-1.9 inches with 
some drier middle and upper level air over southeast Georgia. Current forecast 
looks on track with about 30% probability of precipitation over NE Florida and 20-30% over southeast Georgia. 
May be slightly better chances where the low level trough sets up in 
the afternoon. Warmer temperatures and higher instability should result in 
more thunderstorm activity as well. Saturday night and 
Sunday...isolated evening showers and thunderstorms Saturday night 
mainly southeastern zones as mean 1000-700 mb flow will be west to northwest. 
Sunday...heights continue to rise in the wake of the low pressure 
system and so warming trend continues. Highs in the middle and upper 
90s are anticipated. Will advertise 20% probability of precipitation but show a bit higher 
chances toward the East Coast and southeast zones. Mean low level flow becomes more 
west and SW. Moisture levels drop a bit but still warrants the low end 
rain chances with precipitable waters  of about 1.7 inches. Sunday night...middle and 
upper level flow continues to dry out but the flow becomes northwesterly with 
a shortwave trough possibly moving into/affecting the forecast area 
late Sunday night. Monday...low and middle level ridge continues over 
central Florida and shortwave trough will move through the forecast area. 
However...relative humidity levels continue to decrease which should make it harder 
to generate convection. Current guidance and previous forecast shows 
20-30% probability of precipitation which still is reasonable. Maximum temperatures continue into the 
lower to middle 90s. 


Long term...Tuesday-Friday. Surface-850 mb ridge located S of the area 
Tuesday will gradually shift northward during the week. Weak troughing 
initially is located over Georgia to NC Tuesday but weakens by Wednesday and Thursday. 
Temperatures near normal expected in the lower 90s and mins in the lower 
70s. Average rain chances of 30-40% are forecast for this period as 
well. 


&& 


Aviation... 
rain showers will produce temporary MVFR conditions for the 
remainder of the afternoon. Shower activity will mostly affect ssi 
and the Jacksonville terminals. VFR conditions will otherwise rule 
through the night with much improved conditions expected on 
Saturday as low pressure offshore pulls north. 


&& 


Marine... 
low pressure continues to spin over the southern Georgia waters 
with little movement observed today. Movement and intensity 
forecast uncertainties are making it difficult to pin down the 
wind forecast over the next 24 hours. The latest data suggests a 
slow northward drift overnight and the forecast will reflect this 
thinking. The flow should remain predominately out of the 
southwest at around 10 to 15 knots with seas 2 to 4 feet...thus no 
headlines are expected though it bears mentioning that the system 
could strengthen prior to exiting north...thus marine interests 
should stay updated on the latest information regarding this 
system. Numerous showers and thunderstorms will continue offshore 
overnight with much improved conditions expected on Saturday. 
Thereafter...high pressure to the south will keep the area in a 
southwest flow and below headline criteria. 


&& 


Preliminary point temps/pops... 
amg 69 96 70 97 / 20 10 10 20 
ssi 73 92 75 93 / 30 20 10 20 
jax 73 94 72 96 / 30 30 20 20 
sgj 73 90 73 92 / 30 30 20 20 
gnv 71 93 71 95 / 20 30 10 20 
ocf 72 93 71 94 / 20 30 10 20 


&& 


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


$$ 


Shashy/Shuler/