479 
fxus61 kakq 290015 
afdakq 


Area forecast discussion 
National Weather Service Wakefield Virginia 
815 PM EDT Thursday Aug 28 2008 


Synopsis... 
the remnants of Fay will continue to slowly move to the northeast 
across the area through Friday. A weak cold front will move through 
the region from the northwest this weekend. High pressure will 
then build in and hold in place over the middle Atlantic next week. 


&& 


Near term /until 6 am Friday morning/... 
weak area of low pressure centered near avc very slow to move this evening. 
Showers/tstrms continue along moisture/wind convergence zones over most of central 
& S central Virginia at this time. However...radar trends past hour or so have shown 
a decrease in echo intensity. With plnty of moisture to tap to the S... 
have adjusted zones/grids to reflect these cndtns. Basically extended 
the thunder chance through midnight across southern forecast area...with activity expeceted 
to become lghtr with more drizzle aftr midnight as moist flow off 
the water continues. Temperatures should only fall a few degrees from current 
values as airmass becomes saturated. Patchy fog also possible away 
from the water. 


&& 


Short term /6 am Friday morning through Saturday/... 
another vorticity maximum moves over the region on Friday. Breaks in the clouds 
will give way for the chances of rain showers/thunderstorms and rain to redvlp...mainly afternoon/evening 
activity (but not confined to). Tmrw night some clearing will develop 
and look for variable to light winds over inland areas. With all the 
rainfall some areas got the potential looks to be favorable for 
patchy/areas of fog to develop. 


Frontal boundary moves twrds the region on Sat although seems to have 
a weakening trend. The NAM/GFS differing on temperatures and instability 
to develop ahead of this feature. For now will continue with chances for 
scattered rain showers/thunderstorms and rain showers to develop ahead of it. 


&& 


Long term /Saturday night through Thursday/... 
GFS and European model (ecmwf) remain in sync with the main features to affect the 
middle Atlantic region during this period. Cold front gradually pushes S 
through southern Virginia and northestern NC Sat night...therefore have maintained 
low (30%) rain chances across these areas after midnight. On sun... 
front continues a slow progression southward. Given the trends... 
close proximity to the front (llvl moisture convergence zone) would 
justify minimal probability of precipitation (20-30% chances) across far southern Virginia and northestern 
NC on sun as well. 


After that...Sun night through the remainder of next week...the 
consensus among the medium range ensembles continue to indicate a 
dry pattern re-establishing across the middle Atlantic region...as deep 
ridge axis remains parked over the eastern Seaboard. Obviously this 
large blocking ridge will have great deal of influence as to the 
eventual track of Gustav and it's remnants next week...and likely 
with Hanna as well toward next weekend. It certainly would appear 
our next best chance for any appreciable rainfall would be from 
one of these tropical systems...however given the model consensus 
with the ridge over the eastern Continental U.S....for now it would appear the 
moisture from Gustav and possibly Hanna will be pooled well west of 
the middle Atlantic region. 


&& 


Aviation /00z Friday through Tuesday/... 
east to southeast flow of very moist air ahead of the remnants of Fay was 
producing scattered showers and a few thunderstorms to the taf 
sites this afternoon. Put cumulonimbus remarks at phf and ecg where ts are 
most likely. Precipitation tapers off this evening but GFS and Eta model MOS 
indicates MVFR/IFR stratus by early Friday morning which looks 
reasonable with plenty of surface moisture in place. 


Chances of rain will continue through Saturday although ceilings should 
improve on Saturday compared to today and tomorrow. High pressure 
builds in late in the weekend and should finally clear things out. 


&& 


Marine... 
high pressure to our north and low pressure to our SW still creating 
a tighter pressure gradient over our area today...leading to 
marginal Small Craft Advisory conds over most of our waters (4-5 ft). Winds will 
likely stay in the 15-20kt range over the Bay today so Small Craft Advisory will be 
continued through late tonight. Seas over our northern waters 
however have stayed right around 3-4ft so far...and with winds 
expected to remain slightly lower up there today have chosen to 
drop Small Craft Advisory just for our northern two coastal sections. Seas over our 
southern waters will be closer to 5ft however with winds in the 
15-20kt range. 


As the high shifts further north tonight...winds should diminish to 
just under Small Craft Advisory criteria. Easterly flow will continue through 
Saturday...before shifting more to the south ahead of the next front 
that will move through on Sunday. 


&& 


Akq watches/warnings/advisories... 
Maryland...none. 
NC...none. 
Virginia...none. 
Marine...Small Craft Advisory until midnight EDT tonight for anz630>633. 
Small Craft Advisory until 6 am EDT Friday for anz652-654-656- 
658. 


&& 


$$ 
Synopsis...ccw 
near term...mpr 
short term...ccw 
long term...bkh 
aviation...lsa 
marine...bkh/jym