352 
fxus61 krnk 200526 
afdrnk 


Area forecast discussion 
National Weather Service Blacksburg Virginia 
126 am EDT Sat Mar 20 2010 


Synopsis... 
high pressure shifts east across the Gulf Coast states off the 
southeast coast Saturday afternoon. A storm system will track 
eastward from the plains and across our region by Monday. 


&& 


Near term /until 6 am this morning/... 
tranquil weather continued across the region. Kept overnight low 
temperatures warmer on the ridges and colder in the sheltered 
valleys that have already decoupled. 


&& 


Short term /6 am this morning through Monday night/... 
an upper level low over Texas will approach the region Saturday 
night. This will result in increasing clouds over the area. Warm air 
will advect in out ahead of this system in a southwesterly flow. Low 
temperatures will not be as low as tonight due to the cloud coverage 
and warm air advection. This will also aid in rising relative 
humidities across the forecast area through late weekend. 


The upper low is forecast to enter the Tennessee Valley Sunday and then 
slowly drift east across the southern Appalachians Sunday 
night...crossing the Carolinas Monday. Deepest moisture...with 
a southerly wind component and highest precipitable waters  will be over our 
forecast area Sunday night and Monday...with wrap around moisture...but 
lowering precipitable waters  Monday night. Quantitative precipitation forecast with this system looks 
respectable with upwards of an inch possible with the southeast 
upslope flow Sunday night. Not out of the question to hear a 
rumble of thunder during this time frame...but the greatest 
instability for thunderstorms should occur well south of the 
forecast area. Wrap around moisture will be most significant on the 
western slopes Monday night...but some of this likely to penetrate 
east of the mountains too per upper diffluence from slow moving 
upper level low. 


Prior to the arrival of the heavier precipitation Sunday night...S-se 
850 mb jet around 40-45knots...suggests the higher elevations of 
northwest North Carolina and far southwestern Virginia could see 
gusty winds Sunday evening into Sunday night. These winds should 
tame as the low moves east of the mountains Monday. 


Sundays temperatures look mild...but Monday highs are a challenge as low 
tracks across NC...leaving US with abundant cloud cover... 
precipitation...and lowering thicknesses. 


&& 


Long term /Tuesday through Friday/... 
the cold air behind this upper level low is not as strong as 
originally forecast...due to the fact that the low cuts off from 
the northern stream and the cold air. However it could still be 
cold enough for some upslope snow showers or mixed rain and snow 
in the mountains Tuesday morning. An 850mb jet of 45 kts and 
decent pressure rises behind the low should bring a period of 
gusty winds Tuesday. 


Warmer air quickly moves back into the area behind this system for 
Wednesday and Thursday with a return to mostly clear skies and 
dry weather. Another upper level low...and track similar to the 
one Sunday and Monday is expected by the end of the week. 


&& 


Aviation /06z Saturday through Wednesday/... 
above average confidence for VFR conditions through the taf period as 
dry airmass in place under high pressure. Middle-level moisture will 
be pushing into the area late Saturday afternoon from a 
southwesterly flow. 


A storm system will approach the region on Sunday into Monday 
with MVFR conditions likely in any precipitation that accompanies 
the front. 


Low ceilings...sub VFR on the backside of this system is expected into 
Tuesday...especially in blf/lwb on northwest flow...along with potential 
for rain or snow showers. 


&& 


Fire weather... 
very dry airmass over the area will persist through this afternoon. 
Expect poor humidity recovery tonight...especially in the higher 
elevations. Mountain valleys should recover to about 70 or 80 
percent after midnight...but the mountain ridges...especially the 
eastern and southern slopes may not recover above 40 percent tonight. 


Another dry day is forecast for Saturday...but with light 
winds...fire weather conditions not expected to reach extreme. 
Dewpoints should be up a few degrees on Saturday compared to 
Friday...so instead of minimum humidities dipping into the 
teens and lower 20s...they should be in the 25 to 32 percent range. 


&& 


Rnk watches/warnings/advisories... 
Virginia...none. 
NC...none. 
WV...none. 


&& 


$$ 
Synopsis...reb 
near term...air mass 
short term...PM/reb 
long term...PM 
aviation...km/wp 
fire weather...PM