Special Weather Statement, NWS Blacksburg, VA

Area Forecast Discussion
National Weather Service Blacksburg VA
736 PM EDT Tue May 25 2021

.SYNOPSIS...
A near stationary front remains draped north-south along the spine
of the Appalachians this afternoon. Convection is starting to fire
along this front and will continue to do so this afternoon, into
this evening. A daily threat for showers can be expected the rest
of this week along with very warm and humid conditions. The best
chance for widespread wetting from showers and storms is expected
to occur Friday as an area of low pressure passes across the
region.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
As of 710 PM EDT Tuesday...

Thunderstorm coverage is waning this evening, with the exception
of NW NC mountains and foothills. These storms are surviving in
an unstable airmass where CAPE values are around 1800-2000
J/Kg. These modest instabilities linger into the evening with
these storms tracking as far east as Stokes and Patrick
counties. However, models keep storms going into the early
morning hours, so have low confidence PoPs deep into the night
east of the Blue Ridge and along the VA/NC border.

As of 215 PM EDT Tuesday...

     Isolated To Scattered Convection Along The Mountains Today
Followed By More Widespread Thunderstorm Chances Wednesday
Afternoon And Evening...

The back door cold front remains draped over the region at the
moment, though not for much longer. This front will start to mix
out today and lift back out of the area, serving as a focal
point for convection initiation for this afternoon and evening.
In fact, we are already watching convection fire up along this
boundary stretching through the NC mountains, New River Valley,
and into the Greenbrier Valley. CAMs continue to bring this
line eastward over the next few hours before dissipating as it
tries to make it over the Blue Ridge. While most won't see
precipitation from these storms, those lucky enough should get
some beneficial rainfall as PWATs today are ~1.25 inches.

POPs decrease overnight as the front continues to slip out of
the area: isolated areas of fog are expected with a warm,
saturated airmass in place. Best locations for it will be those
that receive rainfall today.

Tomorrow features an inbound degrading trough that will bring
several forecast points. With this system coming, we will be in
the warm sector of the system so temperatures remain at the
high side of forecast guidance with many in the east climbing
into the 90s. Prior to the trough, ample diurnal heating with
subsequent instability combined with final departing energy
from the back door front will lead to scattered convection in
the afternoon focused in the east. It won't be until late
afternoon early evening before rain chances start to actually
pick up in the west for the trough, though when it arrives it
will be rather anemic so anything widespread is not expected.

Forecast confidence is moderate.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 200 PM EDT Tuesday...

     Above normal temperatures persists through the end of the
workweek with increasing chances for widespread rain by Friday....

Our stretch of hot weather looks to continue through at least Friday
as a front and surface low pressure system move toward the area.
With the front slow to get here our upper level ridge will remain
with downsloping westerly to southwesterly flow aloft. This will
keep temperatures on the hot side of things especially in areas east
of Roanoke where highs will remain in the upper 80s and low 90s. Out
west temperatures will be a tad cooler with a better bet for and
isolated shower or storm due largely in part to orographic lifting
around the mountains, weak shortwave energy pivoting through, and
our cold front slowly sagging south into the region. No severe
weather is expected with overall energy in the form of deep layer
shear focused well off to our north and west across the lower Ohio
River Valley. 12z model soundings from the NAMnest, NAM, ARW, and
GFS also support this with unidirectional winds out of the west and
southwest acting as a barrier with storms mainly confined to areas
along and west of the Blue Ridge.

Overall coverage looks to remain widely scattered to isolated over
the mountains Wednesday evening before diminishing with the loss of
daytime heating Wednesday night. Meanwhile our surface cold front
looks to finally push into the region from our north late Wednesday
night into Thursday morning before stalling somewhere in the
vicinity of the Shenandoah Valley. The 12z GFS brings the front as
far south as southwest Virginia while the 0z Euro and 12z Canadian
keep it hung up across central Virginia. Either way with the front
nearby the chance for isolated showers and storms looks to continue
especially in areas along and west of the Blue Ridge where the
mountains will aid in some extra lift during the peak heating hours.
Severe weather once again will not be a concern with the best low
level moisture depth and deep layer shear remaining north and west
of the region.

The upper level ridge completely breaks down Friday with an
incumbent surface low pressure system that looks to ride into the
region from the Ohio River Valley. Some model uncertainty remains in
where the low will track based on the placement of our ashed out
boundary for the late week timeframe. Both the 12z GFS and Canadian
along with the 0Z Euro all firmly agree on a widespread much needed
rainfall scenario for the region. The 12z GFS and Canadian carry the
low east through Ohio into western Maryland Friday morning into late
FRiday afternoon. The 0z Euro drops the low further south into
central Virginia during the same time frame. With that said this
could be the difference of who sees the heaviest rain along with any
severe weather concerns. As of now we are not outlooks for severe
weather or excessive rainfall, but will be something to look at in
further model runs.

Confidence remains high for above normal temperatures and storm
chances Thursday. Moderate confidence on timing and heaviest
precipitation placement for the end of the workweek.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 200 PM EDT Tuesday...

     An unsettled start to the holiday weekend gives way to drier
conditions early next week...

Considerable uncertainty remains about the timing and magnitude of
the upper level shortwave passing through for the start of the
weekend. The GFS remains the most optimistic with direr conditions
settling in as early as Saturday afternoon and Saturday night. The
12z Canadian and 0z Euro take more of an approach closer to central
guidance in lingering shower and storm chances through the day
Sunday before high pressure barrels in. As of now we will go with a
blend of the 3 model solutions with a trend toward lowering PoPs
late Saturday into Sunday.

It will not be a wash out by any means, so no need to cancel those
plans just yet. Sunday and Monday appear to be the better weather
days of the period as high pressure builds from the north. This
would lend to a return of drier and seasonable conditions across the
region. The high slides east toward the coast Tuesday warming
temperatures once again before our next storm system midweek.

Speaking of temperatures, we actually look to trend slightly below
normal for the weekend. With extra clouds and rain chances Saturday
temperatures will struggle to get out of the 60s and 70s. Similar
readings look to be expected Sunday before a warming trend with
return flow early next week.

Confidence remains moderate in the long term.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
As of 725 PM EDT Tuesday...

Thunderstorms may impede travel from KROA to KCLT this evening.
Coverage of these storms seems to be waning, but lingering
instabilities may keep them around through 02Z/10P.

Tonight, areas of fog are expected for those that had rain this
afternoon (KLWB/KBCB). Abundant low level moisture left-over
from stratus deck across the piedmont today may lead to another
stratus deck tonight. If this cloud deck does not form as winds
come around to the south, then patchy fog is possible for
KDAN/KLYH.

Tomorrow fog will quickly mix out followed up be yet another
scattered cumulus deck developing. In the early afternoon,
isolated thunderstorms are once again expected, but with the
concentration being on the eastern side of the Blue Ridge.
Later in the day outside of the TAF period, a decaying front
should enter from the west bringing mainly shower chances for
the west.

Extended Aviation Discussion...

A more organized weather system arriving Thursday into Friday
will bring more widespread shower and thunderstorm chances both
days. Scattered rain chances and subsequent sub VFR flight
conditions are expected to persist into the weekend before a
more prolonged period of better weather conditions are expected
at the start of next work week.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.

&&

SYNOPSIS...PM/RR
NEAR TERM...RCS/RR
SHORT TERM...BMG/ET
LONG TERM...BMG/ET
AVIATION...RCS

Hazardous Weather Outlook
National Weather Service Blacksburg VA
1238 PM EDT Tue May 25 2021

NCZ001>006-018>020-VAZ007-009>020-022>024-032>035-043>047-058-059-
WVZ042>044-507-508-261645-
Ashe-Alleghany NC-Surry-Stokes-Rockingham-Caswell-Watauga-Wilkes-
Yadkin-Tazewell-Smyth-Bland-Giles-Wythe-Pulaski-Montgomery-Grayson-
Carroll-Floyd-Craig-Alleghany VA-Bath-Roanoke-Botetourt-Rockbridge-
Patrick-Franklin-Bedford-Amherst-Henry-Pittsylvania-Campbell-
Appomattox-Buckingham-Halifax-Charlotte-Mercer-Summers-Monroe-
Eastern Greenbrier-Western Greenbrier-
1238 PM EDT Tue May 25 2021

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

.DAY ONE...This afternoon and tonight.

The probability for widespread hazardous weather is low.

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

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

Special Weather Statement
National Weather Service BLACKSBURG VA
441 PM EDT Tue May 25 2021

NCZ002-VAZ015-016-252130-
Alleghany-Grayson-Carroll-
441 PM EDT Tue May 25 2021

...A STRONG THUNDERSTORM WILL AFFECT
NORTHEASTERN ALLEGHANY COUNTY IN NORTHWESTERN NORTH CAROLINA...
SOUTHWESTERN CARROLL AND SOUTHEASTERN GRAYSON COUNTIES IN
SOUTHWESTERN VIRGINIA AS WELL AS THE THE CITY OF GALAX...

At 440 PM EDT, a strong thunderstorm was located over Cumberland
Knob, or near Ennice, moving east at 10 mph.

Winds in excess of 40 mph are possible with this storm.

Locations impacted include...
Galax...
Ennice...
Barrett...
Lambsburg...
and Pipers Gap.

Locally heavy rain will quickly reduce visibility and result in
ponding of water on roadways, standing water in low lying areas, and
minor flooding of creeks, streams, and areas of poor drainage.
Drivers are urged to slow down and use extra caution to avoid
hydroplaning.

LAT...LON 3647 8104 3667 8099 3674 8089 3658 8071
      3656 8077 3656 8090 3654 8092 3651 8093
TIME...MOT...LOC 2040Z 287DEG 8KT 3656 8095

RAB

Special Weather Statement
National Weather Service BLACKSBURG VA
548 PM EDT Tue May 25 2021

NCZ018-019-252245-
Wilkes-Watauga-
548 PM EDT Tue May 25 2021

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT
CENTRAL WILKES AND EASTERN WATAUGA COUNTIES...

At 548 PM EDT, radar indicated strong thunderstorms were located
along a line extending from Blowing Rock to near Elkville to
Sawmills. Movement was northeast at 15 mph.

Winds in excess of 40 mph are possible with these storms.

Locations impacted include...
Boone...
North Wilkesboro...
Wilkesboro...
Blowing Rock...
Traphill...
Deep Gap...
and Mc Grady.

Locally heavy rain will quickly reduce visibility and result in
ponding of water on roadways, standing water in low lying areas, and
minor flooding of creeks, streams, and areas of poor drainage.
Drivers are urged to slow down and use extra caution to avoid
hydroplaning.

Frequent cloud to ground lightning is occurring with these storms.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

LAT...LON 3609 8146 3612 8155 3612 8172 3614 8174
      3633 8162 3627 8157 3624 8148 3629 8141
      3629 8137 3637 8136 3636 8126 3640 8119
      3643 8117 3642 8113 3643 8108 3637 8102
      3637 8099 3600 8132
TIME...MOT...LOC 2148Z 210DEG 14KT 3613 8165 3601 8145 3583 8146

RAB

Special Weather Statement
National Weather Service BLACKSBURG VA
638 PM EDT Tue May 25 2021

VAZ032-252315-
Patrick-
638 PM EDT Tue May 25 2021

...A STRONG THUNDERSTORM WILL AFFECT
SOUTHWESTERN PATRICK COUNTY...

At 637 PM EDT, a strong thunderstorm was located near Ararat,
drifting northeast around 5 mph.

Winds in excess of 30 mph are possible with this storm.

Locations impacted include...
Ararat...
sections of the Blue Ridge Parkway...
and Meadows Of Dan.

Locally heavy rain will quickly reduce visibility and result in
ponding of water on roadways, standing water in low lying areas, and
minor flooding of creeks, streams, and areas of poor drainage.
Drivers are urged to slow down and use extra caution to avoid
hydroplaning.

LAT...LON 3656 8061 3661 8062 3666 8059 3664 8054
      3666 8050 3665 8049 3666 8049 3668 8046
      3670 8045 3672 8046 3674 8045 3675 8043
      3674 8040 3675 8039 3658 8031 3655 8043
TIME...MOT...LOC 2237Z 264DEG 2KT 3657 8057

RAB

Special Weather Statement
National Weather Service BLACKSBURG VA
647 PM EDT Tue May 25 2021

NCZ019-252315-
Wilkes-
647 PM EDT Tue May 25 2021

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT
Northern WILKES COUNTY...

At 646 PM EDT, radar indicated strong thunderstorms were located
along a line extending from near Glendale Springs to Fairplains.
Movement was east at 20 mph.

Winds in excess of 40 mph are possible with these storms.

Locations impacted include...
North Wilkesboro...
Wilkesboro...
Traphill...
Wilbar...
Mc Grady...
Mulberry...
and Stone Mountain State Park.

Locally heavy rain will quickly reduce visibility and result in
ponding of water on roadways, standing water in low lying areas, and
minor flooding of creeks, streams, and areas of poor drainage.
Drivers are urged to slow down and use extra caution to avoid
hydroplaning.

These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

LAT...LON 3629 8137 3636 8136 3637 8132 3636 8126
      3640 8119 3643 8117 3642 8113 3643 8111
      3643 8108 3642 8108 3641 8104 3639 8104
      3637 8102 3637 8098 3640 8097 3633 8087
      3628 8087 3611 8118
TIME...MOT...LOC 2246Z 254DEG 18KT 3634 8134 3619 8117

RAB

Special Weather Statement
National Weather Service BLACKSBURG VA
731 PM EDT Tue May 25 2021

NCZ003-260000-
Surry-
731 PM EDT Tue May 25 2021

...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN SURRY COUNTY...

At 731 PM EDT, a strong thunderstorm was located near Pilot Mountain,
moving northeast at 5 mph.

Winds in excess of 40 mph and pea size hail are possible with this
storm.

Locations impacted include...
Mount Airy...
Flat Rock...
Pilot Mountain...
Woodville...
White Plains...
Ararat...
and Westfield.

Locally heavy rain will quickly reduce visibility and result in
ponding of water on roadways, standing water in low lying areas, and
minor flooding of creeks, streams, and areas of poor drainage.
Drivers are urged to slow down and use extra caution to avoid
hydroplaning.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

LAT...LON 3645 8069 3656 8052 3655 8051 3655 8044
      3638 8045 3632 8056
TIME...MOT...LOC 2331Z 241DEG 5KT 3641 8056

RAB

Special Weather Statement
National Weather Service BLACKSBURG VA
757 PM EDT Tue May 25 2021

NCZ003-004-VAZ032-260045-
Stokes-Surry-Patrick-
757 PM EDT Tue May 25 2021

...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN SURRY...
NORTHWESTERN STOKES AND SOUTHWESTERN PATRICK COUNTIES THROUGH
845 PM EDT...

At 757 PM EDT, a strong thunderstorm was located over Woodville, or
near Francisco, moving northeast at 10 mph.

Winds in excess of 40 mph are possible with this storm.

Locations impacted include...
Ararat...
Francisco...
Woodville...
Collinstown...
and Westfield.

Locally heavy rain will quickly reduce visibility and result in
ponding of water on roadways, standing water in low lying areas, and
minor flooding of creeks, streams, and areas of poor drainage.
Drivers are urged to slow down and use extra caution to avoid
hydroplaning.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

LAT...LON 3640 8045 3654 8060 3672 8041 3650 8020
TIME...MOT...LOC 2357Z 232DEG 7KT 3652 8046

RAB