Severe Weather Alerts

Your Weather

To update your location please enter your ZIP code, city, state, airport code or country in the field below. Weather by E-mail: Forecast storm alerts. Weather E-Mail Alert Sign Up »

Next 12 Hours

Forecast data from the National Digital Forecast Database.

5 Day Forecast

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

• Friday
• 
• High: 82 °
• Low: 61 °
• Chance of T-Storms

• Saturday
• 
• High: 86 °
• Low: 61 °
• Chance of T-Storms

• Sunday
• 
• High: 86 °
• Low: 57 °
• Chance of T-Storms

• Monday
• 
• High: 82 °
• Low: 57 °
• Chance of T-Storms

Area forecast discussion 
National Weather Service Blacksburg Virginia 
941 PM EDT Wednesday may 23 2012 


Synopsis... 
an upper level area of low pressure across the region will slowly 
move northeast tonight and be centered over Virginia 
Thursday...then exit the region Friday. High pressure will build 
across the area for the weekend. 


&& 


Near term /through Thursday/... 
as of 935 PM EDT Wednesday... 
broad closed upper low remains anchored across the region tonight 
into Thursday. Kfcx 88d loop showed showers and thunderstorms 
decreasing in intensity and coverage this evening with the loss of 
solar heating. With this trend decreased probability of precipitation for tonight. The 
combination of low level moisture and light winds will result in 
areas of fog overnight. Low temperatures will range from the middle 
50s in the mountains to the lower 60s in the southeast. 


Scattered thunderstorms are expected Thursday across the area. 
Greater instability and better heating will resulted in numerous 
showers and thunderstorms Thursday afternoon into Thursday evening. 
Some of the storms may become severe producing large hail...gusty 
winds and flash flooding. Highs Thursday will range from the middle 70s 
in the mountains to the lower 80s in the southeast. 


As of 615 PM EDT Wednesday... 
upper low over North Carolina moving northeast across the region 
tonight. Scattered showers and thunderstorms developing in the 
unstable air this afternoon into this evening. The best instability 
remain across eastern portions of County Warning Area where convective available potential energy are 1500 to 2000 
j/kg. Adjusted pop grids according to last radar trend this 
evening with some development along southern Blue Ridge and 
convection moving west into northeast portion of County Warning Area. Also modified 
temperatures according to latest observation trend this evening. More 
adjustments as night progresses. 


As of 330 PM EDT Wednesday... 
most convection remains confined to western areas this 
afternoon...espcly northwest where aided by diff heating and across the SW 
close to the Pivot Point of the upper vorticity. Elsewhere showers have been 
quite limited under the cloud canopy to the north of the upper low 
over the Carolinas...and held in place by low level eastern flow. 
Still some time for this to thin through this evening so leaving in 
high probability of precipitation espcly north of hiway 460 and over the west along the I-77 
corridor. Expect a minimum though to persist New River/roa valleys 
per cool wedge with perhaps the southeast getting clipped by convection 
heading NE from NC...but likely no more than chance probability of precipitation there this 
evening. Upper low heads NE to eastern Virginia overnight allowing much of 
the area to work in between pieces of 500 mb energy after midnight. This 
combo with weaker instability from earlier should provide a quicker 
dropoff in convection later this evening...with perhaps most going 
dry for a period after midnight per the rnk WRF which has a good 
handle at this time. Will again see some fog espcly where have seen rainfall 
and espcly valleys if can get more clearing. Thus included fog but 
not quite as much as the last few nights thinking some clouds will 
linger. Lows again mainly 55-63. 


Some drying will try and take shape during Thursday with the departure of 
the main upper cool pool to the east and a little more S/SW flow 
aloft. However most models depict a detached short wave within the broad 
upper low lingering over the County Warning Area during the afternoon. This in 
conjunction with a ribbon of deep moisture on the back of the upper 
low...and the flow turning more southerly should spark renewed 
rain showers/thunderstorms and rain along the Blue Ridge and points north and east closer to 
the colder air aloft. Similar to this afternoon...timing of just how 
quickly the cloud canopy exits Thursday key to coverage but does appear 
that even the cooler NAM breaks things out in the afternoon. 
Therefore running with an axis of likely probability of precipitation along most of the Blue 
Ridge middle afternoon...and chance elsewhere before more drying aloft comes 
in late and likely cuts into the overall coverage. Mav temperatures again 
look too warm based on clouds early and scattered convection later so 
basically went into between the mav/met for now putting most in the 
76-82 range. 


&& 


Short term /Thursday night through Saturday night/... 
as of 330 PM EDT Wednesday... 
shower and thunderstorm activity will continue into the late evening 
hours of Thursday...although coverage is expected to thin out a 
little more quickly than in previous evenings as the upper trough 
pushes out of the area...and an upper level ridge of high pressure 
works its way in from the central Gulf Coast. Upper level ridging 
will control our weather pattern for Friday and Saturday...and while 
we will still see showers and thunderstorms develop across the 
mountains by early afternoon...expect the coverage to be lower than 
what we have seen in the last few days. Regardless of coverage... 
cannot rule isolated strong to severe thunderstorms developing 
during each evening...with large hail and gusty winds as the main 
threats. 


In addition to the lower coverage of shower and thunderstorm 
activity...the upper level ridge will also bring warmer air into the 
area. Increased cloud cover on Friday will help limit temperatures 
to the middle 80s across the piedmonts...and to the upper 70s to low 
80s across the mountains. However...as the upper ridge builds in on 
Saturday...will see highs climb to around 90 degrees east of the 
Blue Ridge...and into the low to middle 80s further west. Overnight 
lows will generally be in the low 60s...with upper 50s expected in 
some of the higher elevations. 


&& 


Long term /Sunday through Wednesday/... 
as of 330 PM EDT Wednesday... 
upper level ridging maintains its control over our weather pattern 
into the early part of next week...and therefore do not foresee any 
major change to the weather pattern. Expect isolated to widely 
scattered showers and thunderstorms to develop with afternoon 
heating...mainly over the mountains. A few storms will become strong 
to severe during the evening. Temperatures will be comparable to 
those found in middle Summer...with highs expected to range from around 
90 across the piedmonts...to the low to middle 80s across the 
mountains. Overnight lows will be mainly in the 60s. 


On Tuesday...the upper ridge will finally weaken. Expect shower and 
thunderstorm activity will increase across the area as another cold 
front approaches from the west. 


&& 


Aviation /02z Thursday through Monday/... 
as of 750 PM EDT Wednesday... 
main concern once again through taf valid period will be 
chance/timing of convection. Broad closed upper low remains anchored 
across the southeast/mid-Atlantic region. Best upward vertical velocity/positive vorticity advection has shifted 
east toward the coastal regions and into the mid-Atlantic. Upper low 
will remain over the area through Friday...then finally lift off to the 
NE in response to a building upper ridge from the 
mid-south/Tennessee Valley. Widespread low clouds/overnight/early 
morning rain left the area relatively convection free this 
afternoon/evening. Still...though with the upper low in the vicinity 
and pockets of heating...isold-sct rain showers/thunderstorms and rain continue across the 
region...mainly the Piedmont. Have confined mention of thunderstorms and rain for this 
evening to areas along-east of a lyh-roa line. With rainfall less 
abundant today than in previous days and widespread broken-overcast middle/high 
clouds overnight...not expecting widespread IFR/LIFR br. The 
exception will be lwb/blf...where heavy rain again late today and 
calm winds along with Mountain/Valley effect will likely lead to 
localized dense fog and LIFR visibility/vertical velocity ceilings. Winds will be near calm 
at most sites overnight. Any wind at all will be generally light southeast. 


For Thursday...expecting a very active afternoon with widespread 
convection as upper low drifts across the region. With better 
heating indicated by afternoon and convective available potential energy near 1000...expect scattered-broken 
coverage of thunderstorms and rain by and after 18z. Have included thunderstorms in the vicinity at all taf sites 
for now in the 18z-19z time frame and beyond. Localized MVFR 
ceilings/IFR visibilities can be expected in thunderstorms and rain. Otherwise...outside the 
early morning hours and thunderstorms and rain...expecting VFR ceilings/visibilities through taf 
valid period. Winds Thursday will generally be southeast to south-southeast 5-7kts...except 
calm/light and variable across WV. 


As of 1240 PM EDT Wednesday... 


MVFR ceilings remain slow to erode this afternoon given deep onshore 
flow and weak upslope along the eastern slopes. Still expecting 
some improvement early on as drier air to the south slides 
northward. However with any breaks will see a quick transition to 
bands of rain showers/thunderstorms and rain that will drift from east to west through early 
this evening. This may produce a period of of rain showers/thunderstorms and rain vicinity of 
all terminals during the afternoon but getting a storm producing 
IFR over any of the airports rather low confidence. Thus will 
maintain a prevailing rain showers/thunderstorms and rain threat with an interval of lower 
ceilings/visibilities but not quite as low as earlier except to init. Still 
expect showers to fade a bit quicker overnight...possibly leading 
to areas of fog again if can get some clearing. May see more 
stratus tonight as ceilings lower early on...then dense fog later 
producing IFR/LIFR most areas excluding kblf and perhaps kdan. 
Fog and low clouds will be again slow to exit early Thursday and 
may take until late morning to reach MVFR levels...then a period 
of VFR by afternoon with slightly less moisture around. More 
scattered nature rain showers/thunderstorms and rain likely Thursday afternoon but likely 
beyond the valid taf period at this time. 


By Friday will see high pressure working in to bring VFR weather...as 
temperatures heat up. However still cant rule out isolated mainly 
mountain induced afternoon/evening convection into Monday despite 
high pressure in place. Otherwise nightly fog in the valleys bcb/lwb a 
good possibility given the moist ground...with little wind. 


&& 


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


&& 


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