Severe Thunderstorm Warning 155, NWS Blacksburg, VA

Area Forecast Discussion
National Weather Service Blacksburg VA
229 PM EDT Fri Jul 28 2023

.SYNOPSIS...
Afternoon showers and thunderstorms are expected through the
weekend, with the greatest chance for severe weather this
afternoon and again Saturday. On Sunday a cold front pushes
through. Monday into Wednesday should be mainly rain-free with
dry high pressure in place. Temperatures will be above normal
through Saturday before trending slightly cooler.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 155 PM EDT Friday...

...Heat Advisory this afternoon and again for Saturday for
eastern sections...

...Strong storms with damaging winds expected this afternoon and
again Saturday afternoon/evening...

A linear MCS with embedded severe storms was moving through the
OH Valley and into WV this afternoon, and continues to move
east. Additional isolated cells were continuing to develop over
the Blue Ridge in the heat of the day. This is due to a moderate
short wave moving into the area and interacting with a lee
trough.

Strong heating today along with dew points a couple degrees
either side of 70F has produced ample buoyancy for strong
thunderstorms in our region. Most concerning is the very
elevated low to mid level lapse rates that develop as the mid
level wave nears this afternoon...on the order of 9-11 C/km up
through almost 10 kft. This is indicative of a well mixed but
dry layer, which will almost certainly produce damaging
downbursts.

PWATs are around 1.5" or better, with deep warm cloud layers
that will support brief heavy downpours. Movement of the cells
over the Blue Ridge is very slow and easterly, and may pose
problems for flooding (over the higher terrain especially). Any
storms arriving from the NW presumably will have faster speeds
as the cold pool increases. Synoptic flow this far south is
rather weak today however. A few models are showing additional
showers and isolated storms overnight north of I-81 as leftover
MCS activity nears.

There is an even higher chance for widespread thunderstorms
with damaging winds Saturday afternoon and evening. CAPE values
and our synoptic position should be improved as a surface front
gets closer from the north.

Before the rain arrives Saturday though, heat indices reaching
or exceeding 105F will be possible again for our eastern
counties including Roanoke. Thus a Heat Advisory has been issued
for tomorrow as well. If we see too many debris clouds through
the overnight and into Saturday from upstream convection, it is
possible we will not see these numbers, which is a good thing.

Confidence in the overall near term forecast is high, but lower
on specific areas that may receive damaging winds.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
As of 145 PM EDT Friday...

 Weekend storms...

A cold front will be in the process of passing through our area on
Saturday night. This front will begin to slow down and continue
moving southward as an east west oriented front by Sunday afternoon,
clearing the area by Sunday night. The forcing from this front in
addition to moderate to large CAPE values >1500 J/kg Saturday night
as well as Sunday afternoon could lead to significant convection
throughout the weekend. Severe storms are a possibility, the
greatest threat being damaging winds from a thunderstorm.

On Monday, behind the front, we will see a total change in the
prevailing weather conditions. High surface pressure will begin to
dominate the synoptic setup, with a center over the Great Lakes
starting to push east. The subsidence associated with this high, as
well as drier air behind the front, will keep the weather dry and
quiet on Monday.

Temperatures will cool a bit following the cold front's passage.
Highs on Sunday will be in the low 80s to mid 90s in the Piedmont.
This will cool to 70s and mid 80s on Monday behind the front.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 220 PM EDT Friday

 Despite some mid-level troughing, surface pressure will remain high
for several days as the center of a surface high slowly transits
eastward. We likely won't have active weather again until late in
the week. A frontal system will make it into the TN/OH valley either
Thursday or Friday, which will aid in pre-frontal showers forming
late in the week. Timing and strength of these features remains to
be exacted, but most of the workweek will be quiet before another
potentially active late week/weekend.

&&

.AVIATION /16Z FRIDAY THROUGH TUESDAY/...
As of 155 PM EDT Friday...

A linear MCS with embedded severe and tornado warned storms was
moving through the OH Valley and into WV this afternoon.
Additional isolated cells were continuing to develop over the
Blue Ridge in the heat of the day. Any of these storms could
produce damaging downbursts with plenty of dry air to work with
through about 10 kft. Moderate to heavy rainfall could briefly
lower ceilings and visibilities to MVFR.

Although coverage will diminish after sunset for the more
terrain-driven storms, additional MCS development in the OH
Valley may continue into the overnight period and impact LWB and
BLF with -TSRA/SHRA through 12Z or so. Any further storms will
probably not redevelop until after 18Z Saturday as the
atmosphere will need time to recover.

EXTENDED AVIATION OUTLOOK...

On Saturday and Sunday there will be additional numerous
SHRA/TSRA that develop in the afternoon and evening as a
frontal boundary nears or crosses the southern Appalachians.
Gusty winds and restrictions will be possible in the vicinity
of SHRA/TSRA.

On Monday and Tuesday, expect mainly VFR conditions expected in
dry high pressure.

&&

.CLIMATE...
Friday 07/28/2023

Site  MaxT Year  MinT Year  LoMax Year  HiMin Year
KBLF    99 1952    51 1924     64 2001     70 1919
KDAN   103 1966    54 1962     69 2001     79 1922
KLYH   103 1936    53 1962     68 2001     77 1930
KROA   104 1930    50 1962     69 2001     80 1930
KRNK   100 1952    45 1962     69 2001     68 2022

Saturday 07/29/2023

Site  MaxT Year  MinT Year  LoMax Year  HiMin Year
KBLF    95 1952    51 1918     65 1984     70 2011
KDAN   104 1952    57 1946     70 1962     78 1932
KLYH   101 1930    53 1920     63 2001     75 1993
KROA   102 1952    52 1925     65 2001     81 1930
KRNK    99 1952    34 1905     63 2001     76 1901

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...Heat Advisory until 7 PM EDT this evening for VAZ022>024-
     033>035-044>047-058-059.
     Heat Advisory from noon to 8 PM EDT Saturday for VAZ022-023-
     033>035-044>047-058-059.
NC...Heat Advisory until 7 PM EDT this evening for NCZ006.
     Heat Advisory from noon to 8 PM EDT Saturday for NCZ006.
WV...None.

&&

SYNOPSIS...SH
NEAR TERM...SH
SHORT TERM...VFJ
LONG TERM...VFJ
AVIATION...DB/SH
CLIMATE...SH

Hazardous Weather Outlook
National Weather Service Blacksburg VA
452 PM EDT Fri Jul 28 2023

VAZ007-009>014-018>020-WVZ042>044-507-508-292100-
Tazewell-Smyth-Bland-Giles-Wythe-Pulaski-Montgomery-Craig-
Alleghany VA-Bath-Mercer-Summers-Monroe-Eastern Greenbrier-
Western Greenbrier-
452 PM EDT Fri Jul 28 2023

...SEVERE THUNDERSTORM WATCH 558 IN EFFECT UNTIL 11 PM EDT THIS
EVENING...

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

.DAY ONE...Tonight.

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

   Severe Thunderstorm Watch.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Strong to severe thunderstorms are possible Saturday and Sunday. The
primary impact will be damaging winds. Locally heavy rainfall rates
may result in a risk of flash flooding.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed. Reports should be submitted by
phone by calling 1-866-215-4324, social media, by email at
rnk.skywarn@noaa.gov or online at www.weather.gov/rnk.

VAZ017-292100-
Floyd-
452 PM EDT Fri Jul 28 2023

This Hazardous Weather Outlook is for southwest Virginia.

.DAY ONE...Tonight.

Strong thunderstorms are possible late this afternoon and evening.
The primary impacts will be damaging winds and locally heavy
rainfall.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Strong to severe thunderstorms are possible Saturday and Sunday. The
primary impact will be damaging winds. Locally heavy rainfall rates
may result in a risk of flash flooding.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed. Reports should be submitted by
phone by calling 1-866-215-4324, social media, by email at
rnk.skywarn@noaa.gov or online at www.weather.gov/rnk.

NCZ006-VAZ033>035-044>047-058-059-292100-
Caswell-Franklin-Bedford-Amherst-Pittsylvania-Campbell-Appomattox-
Buckingham-Halifax-Charlotte-
452 PM EDT Fri Jul 28 2023

...HEAT ADVISORY IN EFFECT UNTIL 7 PM EDT THIS EVENING...
...HEAT ADVISORY IN EFFECT FROM NOON TO 8 PM EDT SATURDAY...

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

.DAY ONE...Tonight.

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

   Heat Advisory.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

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

   Heat Advisory.

Strong to severe thunderstorms are possible Saturday and Sunday. The
primary impact will be damaging winds. Locally heavy rainfall rates
may result in a risk of flash flooding.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed. Reports should be submitted by
phone by calling 1-866-215-4324, social media, by email at
rnk.skywarn@noaa.gov or online at www.weather.gov/rnk.

VAZ022-023-292100-
Roanoke-Botetourt-
452 PM EDT Fri Jul 28 2023

...HEAT ADVISORY IN EFFECT UNTIL 7 PM EDT THIS EVENING...
...SEVERE THUNDERSTORM WATCH 558 IN EFFECT UNTIL 11 PM EDT THIS
EVENING...
...HEAT ADVISORY IN EFFECT FROM NOON TO 8 PM EDT SATURDAY...

This Hazardous Weather Outlook is for west central Virginia.

.DAY ONE...Tonight.

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

   Heat Advisory.
   Severe Thunderstorm Watch.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

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

   Heat Advisory.

Strong to severe thunderstorms are possible Saturday and Sunday. The
primary impact will be damaging winds. Locally heavy rainfall rates
may result in a risk of flash flooding.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed. Reports should be submitted by
phone by calling 1-866-215-4324, social media, by email at
rnk.skywarn@noaa.gov or online at www.weather.gov/rnk.

VAZ024-292100-
Rockbridge-
452 PM EDT Fri Jul 28 2023

...HEAT ADVISORY IN EFFECT UNTIL 7 PM EDT THIS EVENING...
...SEVERE THUNDERSTORM WATCH 558 IN EFFECT UNTIL 11 PM EDT THIS
EVENING...

This Hazardous Weather Outlook is for west central Virginia.

.DAY ONE...Tonight.

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

   Heat Advisory.
   Severe Thunderstorm Watch.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Strong to severe thunderstorms are possible Saturday and Sunday. The
primary impact will be damaging winds. Locally heavy rainfall rates
may result in a risk of flash flooding.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed. Reports should be submitted by
phone by calling 1-866-215-4324, social media, by email at
rnk.skywarn@noaa.gov or online at www.weather.gov/rnk.

NCZ001>005-018>020-VAZ015-016-032-043-292100-
Ashe-Alleghany NC-Surry-Stokes-Rockingham-Watauga-Wilkes-Yadkin-
Grayson-Carroll-Patrick-Henry-
452 PM EDT Fri Jul 28 2023

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

.DAY ONE...Tonight.

Thunderstorms are possible late this afternoon. Gusty winds and
brief, heavy downpours of rain are possible with the stronger
thunderstorms. The probability of widespread hazardous weather,
though, is low.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Strong to severe thunderstorms are possible Saturday and again
Sunday. The primary impact will be damaging winds. Locally heavy
rainfall rates may result in a risk of flash flooding.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed. Reports should be submitted by
phone by calling 1-866-215-4324, social media, by email at
rnk.skywarn@noaa.gov or online at www.weather.gov/rnk.

RCS

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