703 
fxus61 klwx 070719 
afdlwx 


Area forecast discussion 
National Weather Service Baltimore Maryland/Washington District of Columbia 
319 am EDT Tuesday Oct 7 2008 


Synopsis... 
high pressure will remain over the region today. This high will 
move off the middle-Atlantic coast Wednesday allowing the next storm 
system to approach the region Wednesday night and Thursday 
bringing unsettled conditions. This system may hang around into 
the weekend before high pressure builds over the region early next 
week. 


&& 


Near term /until 6 PM this evening/... 
high pressure has settled over the middle Atlantic region. 


Some patchy cirrus is noted over the southwest County warning forecast area. Winds have 
mostly de-coupled...except in the northeast quadrant of the County warning forecast area. 
Temperatures are currently around five degrees cooler than this time 
last night at most locales. Expect the coldest temperatures this 
morning right along the Mason-Dixon line and in the sheltered 
valleys out west where the best radiational cooling will occur. Some 
patchy frost is possible early this morning where temperatures 
settle in the middle 30s. 


Mostly sunny skies are expected today with temperatures running 
slightly below normal. 


&& 


Short term /6 PM this evening through Wednesday night/... 
the surface high pressure will begin to move offshore tonight. 
Temperatures are expected to be a few degrees over this mornings 
readings as the surface flow turns more towards the south. 


&& 


Long term /Thursday through Monday/... 
high pressure both at the surface and aloft will move off the coast 
Wednesday allowing for a return flow to set up. The next storm 
system will approach the region from the Midwest. Increasing high 
and middle-level clouds are expected ahead of this system...but it 
should remain dry during the day. The northern branch of the system 
will pass through Wednesday night while a cut off upper-level low 
develops with the southern branch of this system across the 
southeastern Continental U.S.. while most of the dynamics will remain with the 
southern piece there will be enough deep layer moisture from the 
Gulf and Atlantic for scattered showers. Have allowed for chance 
probability of precipitation covering the region from west to east Wednesday night. 


Model guidance for the latter part of the week into the weekend 
remain uncertain. The cut off upper-level low will likely remain 
somewhere over the southeastern Continental U.S. Or middle-Atlantic into the 
weekend before high pressure aloft pushes this system off to the 
southwest early next week. Where exactly this storm system is will 
have significant impact on our weather. The 12z European model (ecmwf) keeps it over 
the southeastern Continental U.S. Which would allow high pressure to bring 
dry conditions along with sunshine. The 00z GFS and CMC keep it 
just off the middle-Atlantic coast which would provide an easterly 
flow off the Atlantic bringing more clouds and the chance for 
showers. Will continue to lean forecast towards the GFS/CMC which 
is closer in line with continuity and HPC. 


&& 


Aviation /07z Tuesday through Saturday/... 
some patchy MVFR fog is possible mainly near kcho before sunrise. 
Otherwise...VFR conditions are expected through the period. 


VFR conditions expected Wednesday with increasing high/mid-level 
clouds. A storm system will bring the chance for showers Wednesday 
night into Thursday bringing subvfr cigs/vbys. This system may 
hang around into the weekend. 


&& 


Marine... 
gradient will continue to lessen through the morning hours. NE winds 
around 15 knots will drop off to around 5 to 10 knots for the afternoon. 
Gusts to 20 knots will be possible early this morning. 
Overnight...winds will switch around to the southeast/S but will remain 
below 10 knots. 


High pressure will move off the middle-Atlantic coast Wednesday. A 
storm system may allow for wind speeds to approach Small Craft Advisory criteria late 
in the week into the weekend. Will keep speeds below Small Craft Advisory criteria 
for now given the uncertainty in the exact location of the storm 
system. 




&& 


Lwx watches/warnings/advisories... 
District of Columbia...none. 
Maryland...none. 
Virginia...none. 
WV...none. 
Marine...Small Craft Advisory until 8 am EDT early this morning 
for anz530>534-537. 


&& 


$$ 
Listemaa/lasorsa