703 
fxus61 klwx 110732 
afdlwx 


Area forecast discussion 
National Weather Service Baltimore Maryland/Washington District of Columbia 
332 am EDT Sat Oct 11 2008 


Synopsis... 
high pressure will build into the area today and it will continue to 
control our weather pattern through the Holiday weekend. A weak 
front may approach the area towards the middle of next week. A 
stronger cold front may reach the area next Friday. 
&& 


Near term /until 6 PM this evening/... 
rgnl surface analy features large surface hipres ridging southward from eastern Great Lakes/southern 
ont and a weak lopres circulation off the southeast Continental U.S. CST. The latter 
responsible for tossing a shield of cirrus northward toward County warning forecast area...touching 
cho-nyg-cge. Elsewhere...clr/calm conds favorable for fog development...and a few 
mtr sites reflect that. Will be adding patchy Ely morning fog to weather grids 
for climatology prone valley locations. 


Ovrall theme for the day will be for hipres to build down CST...W/ none 
moisture evident west/in column. A pinch of cold air advection should lead to slightly cooler 
maxt...but will be making the most of practically full sunshn. Thus... 
went on higher end of guidance...and in some cases went above guidance outright. 
Think building ridge /sfc through 500 mb/ will effectively shunt clouds away from 
County warning forecast area...so lw be going west/ sunny skies through the day. 
&& 


Short term /6 PM this evening through 6 am Sunday/... 
hipres ridge will continue to build surface and aloft tonight. West/ that...lower derpt 
air will filter southward...and thus undercut prvs min-T forecast by several 
degree....in line west/ 00z MOS cycle. Dewpoints will bttm out inthe 40s xcpt 
upper 30s in the mountains...so dont think frost will be an issue. May get 
patchy fog once again...but dayshift can address that taftn. 
&& 


Long term /Sunday through Friday/... 
high pressure will remain in control through the weekend...bringing 
gradually warming temperatures through Tuesday. The ridge will break 
down Tuesday night into Wednesday as a weak front approaches the 
region from the west. The front and any associated precipitation 
looks to break down over the region...so only silent slight chance 
probability of precipitation late Tuesday night. High pressure briefly rebuilds for 
Wednesday and Thursday. The next cold front is expected to bring 
more moisture and rain chances for the end of the week. 
&& 


Aviation /08z Saturday through Wednesday/... 
cho has been the only problematic taf site...as fog has developed 
dropping visibilities to IFR. Cannot rule out a few dips into LIFR through 
sunrise. Elsewhere...VFR conds prevail. Mrb next on the list for climatology 
fvrd areas. No signs of fog developing yet...but will be going prevailing 
MVFR tempo IFR based largely on climatology. Tempo MVFR possible in District of Columbia/balt 
terminals...but will attempt to go west/o at this time. 


Any fog will dspt soon aftr sunrise...W/ ceiling and visibility unlimited conds prevailing through 
day into evening. There may be a rtn of fog tonight...which will be 
addressed west/ 12z pkg. 


High pressure remains in control through the weekend into early next 
week. Other than morning fog...VFR conditions to prevail. 
&& 


Marine... 
no flags next 24 hours. Hrly soundings pick up a layer of winds in the middle 
teens 1000-3000 feet aloft. Will mix a portion of that down...leading to 
10-15 knots winds despite building hipres. Winds should subside below 10 knots tonight. 


High pressure remains in control through the weekend into early next 
week. A weak cold front is expected to cross the region Wednesday 
with another stronger front towards the end of the week. 
&& 


Lwx watches/warnings/advisories... 
District of Columbia...none. 
Maryland...none. 
Virginia...none. 
WV...none. 
Marine...none. 


&& 


$$ 
Synopsis...Woody! 
Near term...heights 
short term...heights 
long term...sar 
aviation...hts/sar 
marine...hts/sar