070 
fxus61 kakq 220010 
afdakq 


Area forecast discussion 
National Weather Service Wakefield Virginia 
710 PM EST Friday Nov 21 2008 


Synopsis... 
low pressure will intensify as it tracks northeast toward the 
Canadian Maritimes tonight and Saturday. High pressure will build 
in from the west for Saturday into Monday. A cold front approaches 
from the west Monday afternoon...then moves across the area Monday 
night into early Tuesday morning. Low pressure aloft prevails over 
New England Tuesday through Thursday as high pressure ridges into 
the middle Atlantic region from the Mississippi Valley. 


&& 


Near term /until 6 am Saturday morning/... 
widely scattered snow showers across Virginia/NE NC portions of County Warning Area this 
afternoon in unstable northwest flow aloft behind surface cold fnt. Expect this 
cloudiness to gradually dissipate after sunset...leaving skies clear/partly 
cloudy overnight. More widespread snow showers occurring over the 
lower Maryland Eastern Shore. These snow showers expected to persist 
into this evening ad weak shortwave and Bay enhancement combine to 
maintain precipitation. In general...snow showers are light and no 
accumulation expected most areas. Could be a half inch or so on 
grassy areas...but few if any roads problems expected since temperatures 
still above freezing. 


Expect a cold night tonight all areas...although clouds and wind are 
expected to keep temperatures from getting too cold. If winds 
decouple...which did not happen with cold surge earlier this 
week...then widespread temperatures in the upper teens would be possible 
over the Piedmont...and Route 460 corridor. Have gone close to or 
a couple degrees above previous forecast for mins tonight. 


&& 


Short term /6 am Saturday morning through Monday night/... 
Sat/sun look quiet as surface high pressure builds over the region from 
the west. Highs in the low to middle 40s Sat then slightly warmer upper 
40s to lower 50s sun...with lows mostly in the 20s Sat night. Have 
gone above guidance for mins most areas Sat night as models forecast 
shortwave and associated cloudiness to prevail across the southern 2/3rds 
of County Warning Area. This should temper amount of cooling Saturday night. 
Although low level flow becomes southerly/southwesterly Sunday night...it is 
expected to be weak. Thus...with clear skies...widespread upper 20s 
to low 30s expected Sun night. Lowest temperatures Sun night expected in 
the sby area...were temperatures could be in the lower 20s again. 


Next cold front approaches/moves through region Monday/Monday night. Expected 
strong warming ahead of fnt...with most areas getting at least to 
the 55-60 degree range for maximum temperatures. Showers likely to develop by 
early afternoon in the Piedmont...and move steadily east to eh CST 
by early evening. Have not added thunderstorms to forecast...although 
intensity of fnt and associated upper support would suggest it cannot be 
ruled out. Latest GFS more bullish on precipitation with 
fnt...which looks reasonable. Have thus upped probability of precipitation to 50 percent Monday 
afternoon/evening. 


&& 


Long term /Tuesday through Friday/... 
extended period will be dominated by strong low pressure slow to exit NE 
Continental U.S....providing deep layered west-northwesterly flow. Xpctg at least periods of broken cloudiness 
midweek b4 low pressure begins to mv east-northeast and away from region. Surface hi pressure 
gradually returns Thursday into Friday. Temperatures will continue to average several degrees f below 
normal through the period...probability of precipitation at or below 10% for now. 


&& 


Aviation /00z Saturday through Wednesday/... 
scattered snow showers continue on the Eastern Shore which will 
affect sby for the next few hours. Any deviations from VFR should 
be short lived. Dew points have lowered to the single digits and 
teens at the other taf sites and skies are clearing from the west. 
Northwest winds will diminish overnight and increase again Sat as high 
pressure remains to the west of the area. Looking at NAM bufr 
soundings...it appears that only sby should have a ceiling of 
daytime stratocu. 


Hi pressure settles over the area on sun. VFR conds will prevail into 
early Monday. The next front will approach from the west and bring 
rain showers to the area Monday afternoon and night. The main low pressure 
system associated with the cold front will remain to the north and 
widespread IFR conditions are not expected. As high pressure 
builds back into the area...VFR is expected Tuesday and Wednesday. 


&& 


Marine... 
glw up for all waters. Continued colder than normal air on moderate/strong northwest 
through much Sat. Gusts to 35/40kt...especially near mouth of Bay/on ocn 
waters into early Sat morning. After that...scas will be the rule into Sat 
night. Brief break on sun as center of surface hi pressure passes over the waters. 
Low level flow turns south-southwest and incrss lt Sun night through Monday ahead of next 
approaching cold front. That fnt to crs the waters lt Monday night...followed 
by another period of moderate/strong low level cold air advection and incrsd northwest wind spds Tuesday 
(lasting at least a 24-36 hour period for scas). 


&& 


Akq watches/warnings/advisories... 
Maryland...none. 
NC...none. 
Virginia...none. 
Marine...Gale Warning until 6 am EST Saturday for anz630>633-650-652- 
654-656-658. 


&& 


$$ 
Synopsis...worse 
near term...worse 
short term...worse 
long term...alb 
aviation...lsa 
marine...alb