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fxus61 kakq 070739 
afdakq 


Area forecast discussion 
National Weather Service Wakefield Virginia 
339 am EDT Tuesday Oct 7 2008 


Synopsis... 
strong high pressure builds into the middle Atlantic region from 
eastern Canada today through Wednesday. An area of low pressure 
will develop and move across the southeast states Wednesday night 
through the end of the week. 


&& 


Near term /until 6 PM this evening/... 
latest surface analysis depicts strong high pressure centered over southern 
Ontario...ridging down into the Middle Atlantic States. Infrared imagery 
shows a band of middle level clouds streaming in across central and 
southern Virginia in association with a warm front located back over the 
Ohio Valley. Drier air at the surface/llvls and 5 to 10 knots north/NE winds 
have hindered fog development this am. 


High pressure will continue to build in today...with mostly 
clear/partly cloudy skies expected. High temperatures will be a 
few degrees below climatology today (upr 60s/lower 70s) under continued 
east/NE flow and as 850 mb temperatures drop to between 6 and 9 c. 


&& 


Short term /6 PM this evening through Thursday/... 
excellent radiational cooling conditions again tonight will allow 
low temperatures to drop into the lower 40s to upper 40s (even middle 
30s in the vicinity of sby). By Wednesday the high will move to the S/southeast 
and eventually off of the middle Atlantic coast as a developing area 
of low pressure approaches from the west. High temperatures warm 
slightly on Wednesday as winds weaken and flow becomes S/se...lwr/mid 70s. 


Cloud cover and moisture will increase late Wednesday into Thursday spreading 
from the SW to NE as the low draws closer to our area. Low 
temperatures will be warmer Wednesday night with the increasing 
clouds...lower 50s to lower 60s. GFS/European model (ecmwf) have come into better 
agreement during the Wednesday night/Thursday time period with respect to the position 
and strength of the low. Will continue slight chance probability of precipitation (20%) 
over western half of forecast area beginning Wednesday afternoon...increasing to 40-50% 
for all areas during the day Thursday. High temperatures on Thursday will 
again be in the Lower/Middle 70s under mild/moist southerly flow. 


&& 


Long term /Thursday night through Monday/... 
00z GFS now well aligned with European model (ecmwf) Thursday night into Sat. Both 
models stall and weaken the low off of the southeast US coast Friday 
through early Sat as a reinforcing shot of high pressure builds back 
down from the north. By sun model solutions diverge with the more 
consistent European model (ecmwf) pushing the moisture well to our S...while the 
GFS morphs the low into an open coastal trough with lingering 
moisture remaining over the middle Atlantic. Will continue to follow 
HPC guidance/European model (ecmwf) solution and carry only slight chance of rain on 
Sat...then dry all areas by late sun through Monday. 


Temperatures close to climatology on Friday...then will rise about 3 to 5 degrees 
above normal over the weekend and early next week as clearing and 
drying commences under high pressure. 


&& 


Aviation /07z Tuesday through Saturday/... 
other than a few isolated observation with MVFR ceilings/visibility across southeast 
Virginia...conditions are VFR early this morning...with VFR to prevail 
today. Somewhat breezy through the morning or early afternoon at orf/ecg 
(gusts up to 20 kt). For tonight...light winds/clear skies will allow 
patchy fog to develop into Wednesday morning...particularly for sby. Next 
decent shot for rain and widespread lower ceilings/visibilities still expected 
Thursday into Friday associated west/ low pressure approaching from the 
SW...and redeveloping off the coast. 


&& 


Marine... 
cold surge underway early this morning as high pressure builds in 
from the north later today. Consensus of local WRF/GFS/NAM suggests 
the higher winds will subside from north to south later this morning 
into Erly afternoon. Have dropped the small craft headlines for northern 
coastal waters (shorter fetch west/ north winds will only build seas to 
around 4 ft). Elsewhere have continued the headlines through either 
10 am or 1 PM...except lingering until 4 PM for NC coastal waters 
where stronger gradient remains longer and seas stay up around 5 feet 
through most of the afternoon. High pressure then becomes centered over 
the waters tonight and slides offshore Wednesday afternoon. Lighter winds 
prevail with flow turning southeast and picking up to about 10 kts on Wednesday. 


Still some model differences with respect to next system late in the 
week. With high pressure well off to the north and some troughiness 
to our south would expect seas to increase as flow becomes southeast or 
east later Thursday/Fri/Fri night. Since European model (ecmwf) solution builds the high back 
south into our area by Friday...will not go as strong with winds/seas 
as latest GFS and wavewatch suggest...but will still have 5 feet seas 
back into the forecast by Friday. 


&& 




Akq watches/warnings/advisories... 
Maryland...none. 
NC...none. 
Virginia...none. 
Marine...Small Craft Advisory until 10 am EDT this morning for 
anz630>632. 
Small Craft Advisory until 1 PM EDT this afternoon for anz633- 
654-656. 
Small Craft Advisory until 4 PM EDT this afternoon for anz658. 


&& 


$$ 
Synopsis...jrl 
near term...jrl 
short term...jrl 
long term...jrl 
aviation...lkb 
marine...lkb