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Area forecast discussion...updated 
National Weather Service Baltimore Maryland/Washington District of Columbia 
943 PM EDT Thursday Jul 24 2008 


Synopsis... 
high pressure will build across the middle Atlantic through the end of 
the work week. A cold front will cross the area on Sunday. High 
pressure return over the region next week. 


&& 


Near term /through Friday/... 


Center of high pressure over western WV will move eastward overnight and be 
centered over the eastern ww Panhandle by sunrise. Clear skies and 
cool tonight west of I-95. Lowered temperatures in the west due to low 
dewpoints running in the upper 30s. Expect lows to bottom out near 
40 in the usual cold spots in the west with middle 50s across northern Virginia 
to low 60s along and east of I-95. Middle 60s in city centers. 


&& 


Short term / Friday through 6 am Friday/... 
high pressure will reside over the middle Atlantic on 
Friday...providing plentiful sunshine with only a scant few cumulus. 
Dry air will warm quickly...with high temperatures easily rising 
into the upper 80s. 


&& 


Long term /Friday through Thursday/... 
there remains a great deal of uncertainty with the medium range. 
Inconsistencies remain when it comes to the strength and timing of 
the upper trough. The GFS is stronger and more progressive with a 
cold front moving through on Sunday. The NAM has energy remaining 
well to the north and little if anything happening over the area 
this weekend. Went with HPC guidance as a starting point..but more 
optimistic through most of the long term given uncertainty. 


A pre frontal trough will develop Saturday afternoon and evening. 
Combined with some instability...expect showers and thunderstorms 
during the afternoon and into the overnight. Main frontal boundary 
will move through on Sunday...triggering more showers and 
thunderstorms. The front will be off the coast by late Sunday 
evening. Due to inconsistencies in timing...will need to keep chance 
probability of precipitation in Saturday afternoon through late Sunday night. There will 
probably be a dry period sometime late Saturday night into Sunday 
morning...but confidence not high enough at this time. 


GFS brings a couple waves across the southeast and middle Atlantic 
through the remainder of the forecast period with an upper low and 
trough stuck over the eastern US. The next cold front across the 
area will be late next week. 


&& 


Aviation /02z Friday through Tuesday/... 
VFR cumulus will dissipate this evening. Dry air will squelch fog 
development overnight as high pressure remains in control through 
Friday. 


Showers and thunderstorms are expected Saturday afternoon through 
Sunday night as a cold front moves through the region. High pressure 
will then return briefly early next week. 


&& 


Marine... 
light and variable winds overnight and Friday 


Showers and thunderstorms are expected Saturday afternoon through 
Sunday night as a cold front moves through the region. Southerly 
winds ahead of the front may approach Small Craft Advisory criteria 
late Saturday. High pressure will then return briefly early next 
week. 


&& 


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


&& 


$$ 
Update...Rosa 
products...peloquin/sar