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Next 12 Hours

Forecast data from the National Digital Forecast Database.

5 Day Forecast

• Thursday
• 
• High: 79 °
• Low: 59 °
• Chance of a Thunderstorm

• Friday
• 
• High: 82 °
• Low: 59 °
• Rain Showers

• Saturday
• 
• High: 82 °
• Low: 57 °
• Rain Showers

• Sunday
• 
• High: 81 °
• Low: 63 °
• Chance of a Thunderstorm

• Monday
• 
• High: 81 °
• Low: 66 °
• Chance of T-Storms

Area forecast discussion 
National Weather Service Blacksburg Virginia 
406 am EDT Thursday Jun 20 2013 


Synopsis... 
high pressure will shift over the northeast coast today and wedge 
southwest into our region into Friday. Unstable air over the 
mountains will result in isolated to scattered showers and storms 
mainly in the afternoon through Friday. 


&& 


Near term /through tonight/... 
as of 400 am EDT Thursday... 
the southeast flow has kept a few showers locked across the mountains in NC 
early this morning which have now faded. There is some areas of 
fog but the stratocu across the area has kept dense fog isolated. 


This southeast flow will hang around today with best Theta-E ridging across 
the SW. Figuring out where the showers and storms refire is tricky 
but models have been leaning toward the SW Virginia/northwest NC area moreso than 
any other area. However...they have not initialized that well with 
what we are getting this morning as they are overdoing quantitative precipitation forecast too far 
north. 


Out of the model solutions...the 00z CMC seems the best fit for what 
is happening...and will lean toward its solution...again putting 
40ish probability of precipitation over the NC mountains this afternoon with lower chances along 
the Blue Ridge into Virginia and west into WV. Think the Piedmont will 
stay under more influence of high pressure keeping the shower 
chances less than 15 percent. 


Clouds will stay locked in a little longer across the Blue Ridge and 
either side this morning as indicated by the NAM/CMC cloud cover 
product. With the heating of the early Summer sun...still should be 
seeing more breaks. Heights build aloft and humidity stays elevated 
so high temperatures will be similar to yesterday with middle to upper 70s 
mountains...closer to around 80 far SW Virginia with lower 80s east. 


Tonight...the showers should linger into the night over the NC mountains 
with residual outflow and higher Theta-E staying locked in across 
the mountain Empire. Will see showers fade after midnight. 


Lows will be ranging from the upper 50s to lower 60s. 


&& 


Short term /Friday through Saturday night/... 
as of 235 am EDT Thursday... 


Overall onshore flow will be maintained through the period with 
surface high pressure off the middle Atlantic coast ridging SW into the 
region and slowly strengthening as upper heights build. Weak low 
pressure off the Outer Banks should also act to enhance the low 
level easterly fetch...with a drier NE flow out east turning more 
southeast heading west into the western slopes. However latest model 
soundings continue to indicate just enough moisture below 7h to 
perhaps pop a few rain showers/thunderstorms and rain far west...espcly I-77 corridor Friday 
afternoon where the higher 850 mb Theta-E will exist. Thus bumped up 
probability of precipitation a little Friday but no more than low chance at this point... 
with little chance elsewhere given less moisture and cap aloft. Any 
convection should fade with loss of heating per little upper support 
making for a mainly clear Friday overnight. Trend continues Saturday 
with a bit stronger east/southeast flow across the west where moisture will 
be less than Friday as strong ridging aloft will prevail. However 
cant totally rule out isolated rain showers per heating so keeping a 20ish 
pop going mainly far SW/northwest counties...and basically dry elsewhere into 
Sat night. 


Temperatures again should be warming to at or above seasonal levels by Sat given 
slight warming aloft and heating of dry air espcly east...with 
a good diurnal range in rather comfortable highs/lows through Sat night. 


&& 


Long term /Sunday through Wednesday/... 
as of 345 PM EDT Wednesday... 


Gradual uptick of both temperature and dewpoint expected early 
next week. Models are in agreement the subtropical ridge will 
strengthen and retrograde to the west...but differ in handling 
day-to-day details as far as embedded short wave energy. 
As such...confidence is reasonably good for raising temperatures 
during the period...but below average for probability of rainfall. 
Models differ in the handling of the disturbed weather along the 
Carolina coast...the GFS drawing it westward and northward. 
Given that rising heights are anticipated during this period and 
concerns that the convective parametrization of the GFS may be too 
aggressive...the preference is for an European model (ecmwf)-like scenario that 
maintains most of the precipitation along the southeast coast. 
Even siding with the European model (ecmwf)...at some point we warm and moisten 
enough to support daily threat of scattered diurnal deep 
convection over the mountains anyway...so feel scattered afternoon/evening 
rain showers/thunderstorms and rain become warranted for Monday and beyond in spite of the 
model differences. 


&& 


Aviation /08z Thursday through Monday/... 
as of 1233 am EDT Thursday... 


Leftover areas of strato-cumulus continue along the mountains at this time and 
expect ceilings to lower into MVFR levels at times over the next few 
hours. However onset of fog/stratus already ongoing espcly in 
spots that saw heavy rainfall earlier...mainly kroa/kbcb...and 
expect other locations that see less strato-cumulus to fog in by 
daybreak. Thus confidence remains high on sub VFR at most sites. 
MVFR/IFR ceilings with IFR/LIFR visibilities are likely in favored locations 
and at least briefly elsewhere by dawn Thursday. 


For Thursday into the weekend...continued diurnal 
convection...especially along the Appalachians...with locally 
brief MVFR-IFR ceilings/visibilities in thunderstorms and rain. Areas of MVFR-IFR visibilities 
br...locally IFR fog...also possible during the morning hours. Otherwise 
overall VFR during the daytime hours before/after any ridge 
oriented convection develops which looks quite isolated over the 
weekend at this point. 


Due to a problem with the visibility sensor at kdan and apparent 
comms issue in transmitting the observation...will include amend not 
schedule within the kdan taf until these issues are corrected on 
Thursday. 


&& 


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


&& 


$$ 
Synopsis...kk/wp 
near term...wp 
short term...jh 
long term...PM 
aviation...jh/kk/rcs