607 
fxus61 klwx 281901 
afdlwx 


Area forecast discussion 
National Weather Service Baltimore Maryland/Washington District of Columbia 
301 PM EDT Thursday Aug 28 2008 


Synopsis... 
low pressure over southwest Virginia associated with former 
Tropical Storm Fay will lift slowly to the northeast through 
Friday a cold front will move across the area Saturday...then high 
pressure will build in behind this front for early next week. 


&& 


Near term /until 6 am Friday morning/... 
radar imagery over the past hour or so has shown signs of the rain 
dwindling across the County Warning Area. This is in tandem with the exit of a low 
level jet. Will play evening probability of precipitation accordingly...and believe the 
overnight will be characterized more by a stratus deck with areas of 
drizzle and fog. Fog could be locally dense toward the Shenandoah 
Valley/Charlottesville area and will include mention of the severe weather potential statement. 


&& 


Short term /6 am Friday morning through 6 PM Friday/... 
Friday may start how tonight ends...with a stratus deck with areas 
of drizzle and fog. Models hint at ceilings rising in the 
afternoon...but clouds will likely linger through the day. Isolated 
to scattered showers will be possible toward afternoon. 


&& 


Long term /Friday night through Thursday/... 
the remnants of Fay will continue to weaken Friday night as it moves 
off the coast. However...an onshore flow around high pressure just 
off the coast will continue to bring plenty of low-level moisture 
across the region allowing for more low clouds along with areas of 
fog and drizzle. Will continue with isolated probability of precipitation for showers Friday 
night...but any rainfall amounts should be light due to a lack of 
any forcing mechanisms. A cold front will slowly pass through the 
region Saturday into Saturday evening bringing a chance for 
showers/T-storms. Both NAM/GFS BUFKIT along with sref guidance do 
indicate over 1000 j/kg of MLCAPE developing by the afternoon. This 
may be enough instability for any thunderstorms to produce gusty 
winds and hail. However...will leave wording out of the forecasts 
and severe weather potential statement for now. Uncertainty still exists as to how fast low clouds 
and fog will burn off during the morning...and most of the dynamics 
with the front will be well to our north. 


High pressure will build in behind the cold front early next week 
bringing a return of dry and seasonable conditions. Surface high 
will remain in control for the middle of the week...but temperatures 
will be a bit above climatology as a ridge of high pressure builds aloft. 


&& 


Aviation /19z Thursday through Tuesday/... 
kcho is in IFR...and will likely remain so through the valid taf 
period. Other terminals have exhibited some improvement this 
afternoon...but will deteriorate to MVFR then perhaps IFR tonight 
/especially for cigs/. 


An onshore flow will bring a good chance for IFR/subifr visibilities and 
ceilings Friday night into Saturday morning. A cold front will bring the 
chance for showers/T-storms Saturday afternoon and evening. High 
pressure will bring a return of VFR conditions Sunday into next 
week. 


&& 


Marine... 
will drop the Small Craft Advisory for the northern 2 Bay zones and top Potomac zone 
where winds have dropped at or below 15 knots. Across the rest of the marine 
area...gusts to 20 knots continue and will likely for a few more hours. 
So will have Small Craft Advisory out through this evening. Models keep winds 
below Small Craft Advisory criteria on Friday. 


A southeast flow is expected Friday night and Saturday...but wind 
speeds should remain below Small Craft Advisory criteria. 


Small Craft Advisory conditions are possible behind a cold front 
late Saturday night into Sunday as wind gusts approach 20 knots from 
the north. No flags are anticipated for later Sunday through 
Tuesday. 


Showers and thunderstorms are possible Saturday across the 
waters...mainly during the afternoon and evening hours. 


&& 


Tides/coastal flooding... 
water levels within the tidal Potomac River and Maryland 
Chesapeake Bay were running up to a foot above astronomical 
predictions. This could increase a little more tonight. There is a 
high tide later tonight into early Friday that needs to be 
watched...where one water level models brings the Annapolis level 
just under 2.5 feet. 


&& 


Lwx watches/warnings/advisories... 
District of Columbia...none. 
Maryland...none. 
Virginia...none. 
WV...none. 
Marine...Small Craft Advisory until 10 PM EDT this evening for 
anz532>537. 


&& 


$$ 
Synopsis...peloquin 
near term...peloquin 
short term...peloquin 
long term...bjl/sar 
aviation...bjl/peloquin 
marine...bjl/peloquin 
tides/coastal flooding...peloquin