Severe Thunderstorm Warning 170, NWS Blacksburg, VA

Area Forecast Discussion
National Weather Service Blacksburg VA
226 PM EDT Sun Jul 13 2025

.SYNOPSIS...
Showers and thunderstorms will remain in the forecast each
afternoon and evening through the week given warm and moist air
situated over the Mid-Atlantic into the Carolinas. A weak cold
front will start the week situated near the Ohio River, and push
south across the Mid-Atlantic during the middle of the week.
Temperatures across the region will be near to slightly above
normal for mid-July.

&&

.NEAR TERM /THROUGH MONDAY/...
As of 1200 PM EDT Sunday...

Key Messages:

1) Isolated severe threat and flash flooding threat mainly for the
eastern CWA this afternoon into evening.

2) Monday might be a similar story to today as the airmass and
environmental setup should have little to no change.

Issued a Flood Watch mainly in line with the Day 1 ERO Slight Risk
from WPC through this evening for parts of the eastern CWA in
coordination with neighboring offices. Nam Nest CAM has good
coverage of convection in line with the area and should be ample
CAPE and high PWATs to support not just efficient precip producers
for flash flooding threat but also wet microburst/damaging wind
potential from hydrometeor loaded downdrafts. Similar eastern part
of the area is also in a Day 1 Marginal Risk for severe storms from
SPC. Any impulses traversing the broadly SW flow aloft could enhance
development and of course outflow boundaries can trigger storms
almost anywhere when activity gets going.

Monday will not see much change if any to the environmental setup
and SPC did end up upgrading a similar area to a Day 2 Marginal
severe risk in the latest update. WPC again has part of our
area in a Day 2 ERO Slight mainly along and east of the Blue
Ridge so all in all it may be a wash, rinse, and repeat day.

Overnight low and afternoon high temps should remain above climo
norms. Any evening precip could result in morning patchy fog as well.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 1230 PM EDT Sunday...

Key Points:

1. Daily chances of showers/storms.
2. Isolated locally heavy rainfall/flooding possible.
3. Above normal temperatures.

A look at the 13 Jul 00Z NCEP Ensemble Mean 500mb Geopotential
Heights shows for Monday night a longwave trough pattern centered
over Hudson Bay. Shortwave troughs will be moving within the flow
regime of this longerwave trough, one centered near the
Ontario/Quebec border and one extending from Manitoba southwest to
the US Pacific NW. A broad region of high pressure will cover much
of CONUS south of roughly 40 N latitude. For Tuesday/Tuesday night,
little changes synoptically across North America on the broader
scale. However, the shortwaves troughs within the longerwave trough
pattern migrate eastward. One reaches the Canadian Maritimes, and
another dips south into US Northern Plains States. A third holds
fast over the Pacific NW. For Wednesday/Wednesday night, there is a
general push south of the longwave trough pattern over Canada to
into roughly the northern third of CONUS. The main trough axis is
expected to be over the Upper Mississippi Valley by the evening
hours.

At the surface, a weak frontal boundary will become situated over
the region Monday night. This feature will experience little
movement and/or wash out through Wednesday. High pressure will
remain situated off the US East Coast near 30 N latitude.

A look at the 13 Jul 00Z NAEFS Ensemble Situational Awareness data
shows 850mb temperatures will range from +19C to +21C across the
region. The upper end of this range falls within the 90 to 97.5
percentile of the 30-year CFSR climatology.

The above weather patterns offers the following forecast. With a
weak boundary arriving, and stalling over the region, daily chances
of showers and storms will continue. Most of these will occur during
the afternoon and evening hours. However, the presence of the front
may help keep the activity lingering longer than sunset.
Additionally, with expected relatively weak steering flow, any
showers/storms that form will likely be slow moving, and have the
potential to produce locally heavy rain in a short period of time.
Likewise, multiple showers/storms crossing the same area in a short
period of time may also yield locally heavy rain/flooding concerns.
Temperatures will continue to be above normal through the period.

Confidence in the above weather scenario is high.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 1230 PM EDT Sunday...

Key Points:

1. Threat of daily showers/storms continues.
2. Isolated locally heavy rain/flooding concern, especially Friday
into the weekend.
3. Above normal temperatures.
4. Heat Index values around or slightly over 100F far eastern areas.

A look a the 13 Jul 00Z NCEP Ensemble Mean 500mb Geopotential
Heights shows for Thursday/Thursday night depicts a longwave trough
over much of southern Canada and the northern quarter of CONUS. A
broad area of ridging is expected over most of CONUS south of 40 N
latitude. The strength of the ridge may increase across the SE US.
For Friday/Friday night, not a lot is expected to change on the
synoptic scale as compared to Thursday. The main trough axis remains
across the Great Lakes region, a shortwave trough is expected to be
over British Columbia, and the center of a broad w-e oriented ridge
remains over SE US. For Saturday/Saturday night, the trough axis is
expected to make progress eastward, reaching the eastern Great Lakes
and New England region. In response, the center of the broad ridge
shifts west a bit. For Sunday, little change is expected in
comparison to Saturday.

At the surface, a general area of weak localized low pressure is
expected to be across eastern portions of VA/NC/SC through Friday.
Heading into the weekend, a cold front will approach the region and
stall near the Ohio River Valley and Mason-Dixon Line region. High
pressure will be centered off the US East Coast with its ridge axis
over the SE US.

A look at the 13 Jul 00Z NAEFS Ensemble Situational Awareness data
shows 850mb temperatures on Thursday of +19C to +21C, on Friday of
+20C to +21C, on Saturday of +19C to +20C, and on Sunday +18C to
+19C.

The above weather patterns offers the following forecast. The region
will continue to be positioned within an airmass conducive the
development of primarily diurnal showers and storms, with locally
heavy rain a concern. The concern increases for the weekend as a
front approaches the regions stalls just to our north. This added
feature to the equation may be close enough to promote more than
just diurnal coverage. Temperatures will continue to be above normal
for this time of year. Additionally, the combination of heat and
humidity may result in Heat Index values reaching or going a little
above 100F across eastern parts of the forecast area during this
time frame, with Friday potentially seeing the highest values of the
four days.

Confidence in the above weather scenario is moderate to high. The
biggest question mark will be position of the advancing front this
weekend and its influence on our weather.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
As of 225 PM EDT Sunday...

VFR conditions mainly with cu field near 4-6 kft and scattered
diurnally driven showers and thunderstorms which could have
erratic gusty winds and reduced vsbys. Overnight patchy fog
could reduce vsbys with some low stratocu as well - currently
carrying in KLWB and KBCB sites. Expecting similar situation for
Monday with shower and storm coverage. Winds overall out of the
west to south under 10 kts during the day and light to calm
overnight.

.EXTENDED AVIATION OUTLOOK...

The weather pattern will change little through much of the
workweek, remaining conducive for isolated to scattered
afternoon & evening storms. Higher coverage of storms is
forecasted for Tuesday and Wednesday as a weak cold front
approaches from the northwest. Outside of storms, expect VFR
conditions but with the potential for locally dense fog and
MVFR/IFR stratus developing each night, especially for locations
that received significant rainfall during the evening prior.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...Flood Watch until 2 AM EDT Monday for VAZ019-020-023-024-034-
     035-044>047-058-059.
NC...None.
WV...None.

&&

SYNOPSIS...NF
NEAR TERM...AB
SHORT TERM...DS
LONG TERM...DS
AVIATION...AB/NF

Hazardous Weather Outlook
National Weather Service Blacksburg VA
147 PM EDT Sun Jul 13 2025

NCZ001>003-018>020-VAZ007-009>013-015-016-WVZ042>044-507-508-141800-
Ashe-Alleghany NC-Surry-Watauga-Wilkes-Yadkin-Tazewell-Smyth-Bland-
Giles-Wythe-Pulaski-Grayson-Carroll-Mercer-Summers-Monroe-
Eastern Greenbrier-Western Greenbrier-
147 PM EDT Sun Jul 13 2025

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

.DAY ONE...This afternoon and tonight.

Widely scattered thunderstorms will develop this afternoon and
evening. In addition to frequent lightning, there is a Marginal
Risk, level 1 of 4, that these storms will produce heavy rain that
may result in localized flash flooding. A few storms may also
produce strong winds gusts.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

Thunderstorms will redevelop each afternoon and evening through much
of the week. A few of the stronger storms will be capable of
damaging wind gusts and locally heavy rain that may result in flash
flooding.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

NCZ004>006-VAZ014-017-018-022-032-033-043-141800-
Stokes-Rockingham-Caswell-Montgomery-Floyd-Craig-Roanoke-Patrick-
Franklin-Henry-
147 PM EDT Sun Jul 13 2025

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

.DAY ONE...This afternoon and tonight.

Widely scattered thunderstorms will develop this afternoon and
evening. In addition to frequent lightning, there is a Marginal
Risk that these storms will produce either, or both, localized
damaging wind gusts, and heavy rain that may result in localized
flash flooding.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

Thunderstorms will redevelop each afternoon and evening through much
of the week. A few of the stronger storms will be capable of
damaging wind gusts and locally heavy rain that may result in flash
flooding.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

VAZ019-020-023-024-034-035-044>047-058-059-141800-
Alleghany VA-Bath-Botetourt-Rockbridge-Bedford-Amherst-Pittsylvania-
Campbell-Appomattox-Buckingham-Halifax-Charlotte-
147 PM EDT Sun Jul 13 2025

...FLOOD WATCH IN EFFECT THROUGH LATE TONIGHT...

This Hazardous Weather Outlook is for central Virginia, south
central Virginia and west central Virginia.

.DAY ONE...This afternoon and tonight.

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

   Flood Watch.

Widely scattered thunderstorms will develop this afternoon and
evening. In addition to frequent lightning, there is a Marginal
Risk, level 1 of 5, that these storms will produce localized
damaging wind gusts. There is also a Slight Risk, level 2 of 4, that
the storms will produce heavy rain that may result in flash
flooding.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

Thunderstorms will redevelop each afternoon and evening through much
of the week. A few of the stronger storms will be capable of
damaging wind gusts and locally heavy rain that may result in flash
flooding.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

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