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Next 12 Hours

Forecast data from the National Digital Forecast Database.

5 Day Forecast

• Wednesday
• 
• High: 77 °
• Low: 59 °
• T-Storms

• Thursday
• 
• High: 81 °
• Low: 63 °
• T-Storms

• Friday
• 
• High: 84 °
• Low: 63 °
• Chance of T-Storms

• Saturday
• 
• High: 86 °
• Low: 68 °
• Chance of T-Storms

• Sunday
• 
• High: 93 °
• Low: 70 °
• Chance of T-Storms

Area forecast discussion 
National Weather Service Baltimore Maryland/Washington District of Columbia 
955 am EDT Wednesday may 23 2012 


Synopsis... 
low pressure will persist over the middle Atlantic through Thursday. 
High pressure will build into the Middle Atlantic States through the 
Memorial Day weekend...bringing much above normal temperatures. 


&& 


Near term /through tonight/... 
some areas are getting peeks at the sun this morning in the wake 
of yesterday's rain and this morning's fog. Upper level low 
pressure centered near the Carolina coast will lift north today 
and enhance a southeast flow over the region. Surface trough located 
approximately from the District of Columbia area to Fredericksburg will push north 
and west into the Charlottesville area and across perhaps 
Warren...Fauquier and Loudoun counties this afternoon. Bands of 
showers and thunderstorms may again LIFR from south to north 
across the boundary...providing the focus for locally heavy rain. 
The ground is increasingly saturated so we will watch for the 
development of these bands for possible enhanced threat of flash 
flooding. 


Weak deformation axis may set up over the region this 
evening and tonight...continuing steady rainfall. Where the rain 
ends...areas of fog will be possible again tonight. High 
temperatures will range from the upper 60s in the western 
mountains to near 80 in the District of Columbia and Baltimore metropolitan areas. Dew 
points remain in the middle-60s into tonight. 


&& 


Short term /Thursday through Friday night/... 
surface trough currently across the County warning forecast area is prognosticated to dissipate 
later on Thursday...continuing to provide a focus for precipitation. Atmos 
is not prognosticated to change for Thursday...so the potential for 
locally heavy rainfall will continue. 


The trough does look to dissipate by Friday night as an upper 
level low pressure system moves northeast across the County warning forecast area. Models 
do shear out the low pressure center as it approaches. 


With the loss of a focusing mechanism at the surface on 
Friday...the precipitation should become more isolated/scattered in nature. 
Overnight Friday looks dry at this time. 


Took blend for temperatures. 


&& 


Long term /Saturday through Tuesday/... 
no changes to the grids past Friday night. Maximum temperatures low to middle 
90s Saturday through Monday. 


High pressure builds across the middle Atlantic on Saturday and 
remains in place through Monday. Models do have a cold front 
approaching from the north by the end of the weekend. However...zonal 
flow aloft may help impede the southern progression of the 
boundary. The front is expected to stay north of the Mason Dixon 
line at this time. 


High pressure remains across the middle Atlantic on Tuesday...but 
models are hinting at a Lee trough developing across the Blue 
Ridge. 


&& 


Aviation /14z Wednesday through Sunday/... 
IFR bkn010-015 with patchy 3-5sm br will continue through 15z at 
the kbwi...kdca and kiad terminals. VFR expected after 15z. The 
air mass is unstable and scattered to occasional -shra/-ts develop by 18z. VFR 
bkn050 with cumulonimbus tops fl350 and vrb surface winds g25kt likely until 
00z. -Shra may continue through 06z. There is then the potential 
for low stratus and fog development overnight. 


Unsettled weather will continue through Friday. Surface trough 
should begin to dissipate on Thursday. However...an upper level low 
pressure system will move northeast across the middle Atlantic 
through Friday morning. Showers/thunderstorms will focus along the 
surface trough into Thursday. Activity should be more scattered in 
nature on Friday as the upper system pushes off to the NE...but 
atmos will remain moist and unstable. 


High pressure returns for the weekend. 


&& 


Marine... 
with lopres in vicinity...light southeast winds will dominate...though speeds 
toward 15 kts possible this afternoon as low level increases. Num showers/thunderstorms expected this 
aftn/eve...with locally gusty winds. 


No headlines anticipated at this time. Winds remain S/southeast through 
the period. Some channeling up the Bay is possible Thursday 
night...but speeds/gusts should remain at or below 15 knots. 


&& 


Tides/coastal flooding... 
anomalies remain around 0.5 feet above normal...a magnitude that should not 
be sufficient to induce tidal inundation today. 


Water levels are expected to remain slightly above normal through 
the weekend as winds remain S/se. 


&& 


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


&& 


$$ 
Sdg/sk