Severe Thunderstorm Warning 46, NWS Blacksburg, VA

Area Forecast Discussion
National Weather Service Blacksburg VA
Issued by National Weather Service Raleigh NC
355 PM EDT Tue May 13 2025

.SYNOPSIS...
A large mid and upper level low pressure system will drift northeast
from the Ohio Valley into the mid-Atlantic on Wednesday resulting in
unsettled conditions. The storm system will shift away from the
region late in the work week. A cold front will move through our
region on Saturday and should shift southeast of the area on Sunday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 135 PM EDT Tuesday...

Key Messages:

1) Flood Watch remains in effect along/east of Blue Ridge through
this evening.

2) A risk of mostly scattered showers and a few storms will continue
through tonight.

Unsettled weather will persist through tonight, albeit with a
gradual waning of rain coverage and storm intensity overnight. The
mid level low over N-central TN will drift NE into E KY through
tonight, while the corresponding surface trough/confluence zone
stretching from the Ohio Valley E and ESE through the forecast area
pivots slowly northward, in tandem with a shortwave trough aloft
swinging around the low. PW is down slightly from last night as the
most anomalous values are shifting N and NE of the forecast area,
however the PW remains above normal with a somewhat deep warm cloud
layer (~10kft) and S/SE low level flow yielding slow cell movement
and a localized heavy rain threat. One such storm cluster lifting
into WV just WSW of Greenbrier has produced rain rates up to 1" in
15 min, and another broken band of showers and strong storms with
heavy rain stretching from SW VA through the W Piedmont of NC will
likely bring another round of flood potential into the CWA from the
SW through the afternoon, as noted by the latest CAMs. These show
additional convection rotating from E TN NNE into the W forecast
area this evening, potentially spawning additional storms through
the overnight hours. SBCAPE is expected to remain moderate (1500-
2000 J/kg) into early evening, favoring a continued chance of a few
strong storms, although bulk shear will continue to decrease as the
mid level low draws closer to the NW CWA, and by the overnight
hours, SBCAPE should have dipping to around 500 J/kg. All told, will
maintain high pops through the evening, with a slow decrease
overnight, but the still-high PW and lingering marginal CAPE will
necessitate keeping pops in through the night. Expect lows in the
50s to lower 60s, with areas of stratus and pockets of fog expected
to form late.

&&

.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
As of 335 PM EDT Tuesday...

Key Messages:

1) Marginal Risk of excessive rainfall continues for Wednesday.

Thick clouds, areas of fog, and patchy showers will dominate through
mid morning, then showers and storms should become widespread in the
afternoon, as the mid level low tracks into WV with a potent,
negatively tilted trailing shortwave trough swinging NE through the
CWA. Mid level flow will continue to steadily weaken, so while
SBCAPE is projected to peak at 1000-2000 J/kg Wed afternoon, the
deep layer bulk shear will be subdued at around 20 kts, thus
somewhat limiting the threat of strong to severe storms as the
better mid level flow is pushed E of the CWA. PW will hold just
above normal, and with the DPVA and shot of decent upper divergence
to augment thermodynamic lift, we should see high coverage of
showers and storms in the afternoon through early evening, until the
trough axis shifts to our NE, with mid level flow veering to WNW and
lowering CAPE with loss of heating. Expect highs mostly in the 70s
except 60s higher terrain, followed by lows in the 50s to around 60s
with a decreasing sky cover trend to partly cloudy.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
As of 355 PM EDT Tuesday...

Key Messages:

1) Daily chances for scattered showers and storms, highest coverage
late Fri through Sat.

2) Hot weather expected Thu through the weekend, with perhaps some
relief by Mon/Tue.

As the shortwave trough pushes well to our ENE and off the East
Coast, we'll see mid level ridging building from the Gulf NE through
the CWA, with low level thicknesses rising well above normal, with a
WNW mid level flow and a warm SW low level flow. Pops Thu into early
Fri should resultantly skew near or below climo coverage, with highs
in the 80s Thu (70s higher elevations) and 80s to near 90 Fri (near
80 higher elevations). By Fri/Sat, a deep polar low tracking
eastward over northern portions of the Great Lakes region will help
tamp down the Southeast ridge, with increasingly fast and gently
cyclonic mid level flow ahead of an approaching associated cold
front. Expect the highest pops from late Fri through Sat night, with
a potential nocturnal lull late Fri night into Sat morning. The
front is expected to settle just to our S, as the mid level low
tracks into New England through Mon then drifts out over the far NW
Atlantic by Tue. Temps should cool off a bit but remain near or just
above normal early next week, with pops no more than isolated to
scattered, mainly in the mountains.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
As of 1250 PM EDT Tuesday...

As of early this afternoon most locations across the CWA have
improved to MVFR or VFR conditions with mainly ceiling
restrictions. A large mid and upper level cyclone centered
across the OH Valley will drift northeast into the central
Appalachians by Wednesday evening. This will support an
unsettled period with hazardous aviation conditions with
scattered showers and thunderstorms this afternoon and evening
followed by a period of low clouds and fog tonight before widely
scattered showers and storms develop again Wednesday afternoon.

Ceilings have lifted to MVFR or VFR status with daytime heating
and VSBY restrictions are largely associated with showers/storms.
The heating has led to shower and thunderstorm activity
expanding with increasing coverage and intensity over the past
few hours. An axis of greater convective coverage extends from
the northern NC Piedmont north and across the Roanoke Valley.
This and other convection will persist and develop through the
afternoon into the evening resulting in local areas of MVFR to
IFR restrictions. The convection should wind down during the
evening with just a few showers expected overnight.

Aviation conditions are expected to deteriorate overnight as
areas of IFR to LIFR CIGs and VSBYs develop and continue into
much of Wednesday morning before improving by late morning.
Scattered showers and a few storms are expected to develop again
on Wednesday afternoon although with a little bit less coverage
than today. Winds will be favored from the east and southeast
through the period at 5 to 10 kts during the daytime hours and
light overnight.

EXTENDED AVIATION OUTLOOK...

An unsettled weather pattern will continue through the period with a
threat of mainly diurnally driven scattered showers and storms.
Storm chances will decrease a bit on Thursday and into Friday. A
cold front will move across the area on Saturday with increased
storms chances with decreased rain chances on Sunday. There's a
chance of some morning stratus and fog each day, especially
through Friday in locations that rainfall the previous day.
-Blaes

&&

.HYDROLOGY...
As of 150 AM EDT Tuesday...

Rainfall amounts are running higher in the NC mountains/Blue
Ridge to Floyd than previous forecast, and making the ground
saturated. Amounts were in the 2-7 inch range highest in Watauga
County where flooding of the Watauga river is ongoing and the
headwaters of the New River also in Ashe County.

Think coverage of showers/storms today will be less, but any
bands that form and thinking maybe more deep convection with
some sunshine may allow for higher rainfall rates. Will leave
the watch as is, but may need to edge it west into the I-81
corridor from Blacksburg to Marion, but will see how storms fire
up later today.

Overall looking at the main stem rivers staying below flood
stage.

&&

.EQUIPMENT...
As of 945 AM EDT Monday...

The National Weather Service Weather Forecast Office in
Blacksburg, VA will be conducting a required, scheduled update
to their Advanced Weather Interactive Processing System (AWIPS)
from Tuesday, May 13, 2025 through approximately Thursday, May
15, 2025.

During the time of the update, forecast operations will be
conducted by our service back-up office in Raleigh, NC to
minimize any potential interruption to services. No impacts to
our core services of forecast products and weather watches,
warnings and advisories are expected during this period.

However, limited impacts will occur to the following services:

NOAA Weather Transmitters: All NOAA Weather Radio Transmitters
maintained by NWS Blacksburg will be off the air through the
time of the update.

This includes the following transmitters in North Carolina,
Virginia, and West Virginia:

Mount Jefferson (WNG88 – 162.500 MHz)
Richlands (WZ2543 – 162.425 MHz)
Wytheville (WZ2500 – 162.450 MHz)
Roanoke (WXL60 – 162.475 MHz)
Lynchburg (WXL92 – 162.550 MHz)
South Boston (KJY86 – 162.525 MHz)
Hinton (WXM72 – 162.425 MHz)

Water Level Forecasts: Water level forecast services will be
degraded due to a less frequent update cycle. Forecasts will
remain on https:/water.noaa.gov/wfo/rnk through this period.

Local graphical forecast maps that are hosted in numerous places
on www.weather.gov/rnk will not be updated.

This includes all maps on the Graphical Hazardous Weather
Outlook page (https:/www.weather.gov/erh/ghwo?wfo=rnk), the
majority of the graphics on the Briefing page
(https:/www.weather.gov/rnk/emer), some experimental fire
applications (https:/www.weather.gov/rnk/fire), climate graphs
for Blacksburg Forecast Area
(https:/www.weather.gov/rnk/climatePlots), and the Weather
Story (https:/www.weather.gov/rnk/weatherstory).

The forecast office in Blacksburg, VA will remain open and
staffed through the period for public and partner phone calls
and additional functions that can be completed without AWIPS.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...Flood Watch until 8 PM EDT this evening for VAZ015-016.
     Flood Watch through late tonight for VAZ017-022>024-032>035-
     043>047-058-059.
NC...Flood Watch until 8 PM EDT this evening for NCZ001>003-018>020.
     Flood Watch through late tonight for NCZ004>006.
WV...None.

&&

SYNOPSIS...Blaes
NEAR TERM...GIH
SHORT TERM...GIH
LONG TERM...GIH
AVIATION...Blaes
HYDROLOGY...AMS
EQUIPMENT...AMS

Hazardous Weather Outlook
National Weather Service Blacksburg VA
608 AM EDT Tue May 13 2025

NCZ001>003-018>020-VAZ015-016-141015-
Ashe-Alleghany NC-Surry-Watauga-Wilkes-Yadkin-Grayson-Carroll-
608 AM EDT Tue May 13 2025

...FLOOD WATCH REMAINS IN EFFECT THROUGH TUESDAY EVENING...

This Hazardous Weather Outlook is for north central North Carolina,
northwest North Carolina and southwest Virginia.

.DAY ONE...Today and tonight.

A marginal risk (level 1 of 5) for severe weather is forecast for
today. Afternoon thunderstorms may produce strong to severe wind
gusts, and hail up to the size of quarters.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Flood Watch.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Excessive rainfall from scattered thunderstorms may result in
localized flash flooding Wednesday, that may cause creeks and
streams to rapidly rise out of their banks and threaten nearby roads
and bridges.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are requested to report hail of any size, as well
as any damage caused by thunderstorm winds in their area.

NCZ004>006-VAZ017-022>024-032>035-043>047-058-059-141015-
Stokes-Rockingham-Caswell-Floyd-Roanoke-Botetourt-Rockbridge-Patrick-
Franklin-Bedford-Amherst-Henry-Pittsylvania-Campbell-Appomattox-
Buckingham-Halifax-Charlotte-
608 AM EDT Tue May 13 2025

...FLOOD WATCH REMAINS IN EFFECT THROUGH LATE TUESDAY NIGHT...

This Hazardous Weather Outlook is for north central North Carolina,
central Virginia, south central Virginia, southwest Virginia and
west central Virginia.

.DAY ONE...Today and tonight.

A marginal risk (level 1 of 5) for severe weather is forecast for
today. Afternoon thunderstorms may produce strong to severe wind
gusts, and hail up to the size of quarters.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Flood Watch.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Excessive rainfall from scattered thunderstorms may result in
localized flash flooding Wednesday, that may cause creeks and
streams to rapidly rise out of their banks and threaten nearby roads
and bridges.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are requested to report hail of any size, as well
as any damage caused by thunderstorm winds in their area.

VAZ007-009>014-018>020-WVZ042>044-507-508-141015-
Tazewell-Smyth-Bland-Giles-Wythe-Pulaski-Montgomery-Craig-
Alleghany VA-Bath-Mercer-Summers-Monroe-Eastern Greenbrier-
Western Greenbrier-
608 AM EDT Tue May 13 2025

This Hazardous Weather Outlook is for southwest Virginia, west
central Virginia and southeast West Virginia.

.DAY ONE...Today and tonight.

A marginal risk (level 1 of 5) for severe weather is forecast for
today. Afternoon thunderstorms may produce strong to severe wind
gusts, and hail up to the size of quarters.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Excessive rainfall from scattered thunderstorms may result in
localized flash flooding Wednesday, that may cause creeks and
streams to rapidly rise out of their banks and threaten nearby roads
and bridges.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

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