Special Weather Statement, NWS Blacksburg, VA

Area Forecast Discussion
National Weather Service Blacksburg VA
902 PM EDT Mon Aug 7 2017

.SYNOPSIS...
Low pressure progressing east northeast over central West
Virginia will continue through the mid Atlantic states tonight
before exiting into the Atlantic Ocean early Tuesday. This will
bring a cold frontal boundary through the area early on Tuesday
with high pressure settling in during the evening hours. The
frontal boundary is expected to push back north later in the
week, once again introducing precipitation chances to the
forecast area.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 845 PM EDT Monday...

Bands of mostly heavy rain producing showers and storms continue
across southern/eastern sections tonight, just south of a slow
moving surface front that lingers across the mountains. Ahead of
the boundary, still seeing some instability linger over the
southern half given Pwats of around 2 inches per GSO evening
raob, and more of a southwest trajectory. Latest short term
solutions continue to key in on more organized convection taking
shape espcly piedmont overnight, where the HRRR has heavier
rainfall lingering along 85h residual theta-e ridging until
just before dawn. Thus upping pops to categorical for a few more
hours southeast sections including a heavy rain mention.
Elsewhere will gradually trim back pops from northwest to
southeast overnight, overall similar to the previous forecast at
this point. Given cloudy skies overnight and very moist
conditions, expect some locations to remain in the 70s for lows
espcly east. Therefore nudged up in spots closer to the latest
Lav numbers overnight.

Previous valid discussion as of 300 PM EDT Monday...

Current surface observations show a warm/stationary front draped
nearly west to the east across the interstate 64 corridor in
WV/VA and a cold front hanging northeast to southwest across
central TN/KY. In between these boundaries, scattered showers
with a few rumbles of thunder continue to impact portions of the
forecast area, dropping locally heavy rainfall. These showers
and storms are expected to continue through the remainder of the
afternoon and evening as the frontal boundaries progress
eastward.

Axis of heaviest precipitation should shift slightly east this
during the evening hours, focusing along and east of the Blue Ridge
Mountains where better instability and higher Pwat values (2 -
2.25 inches) are located. Here, additional accumulation amounts
could range from a half inch to three quarters of an inch, with
amounts potentially exceeding an inch in a few isolated spots.
Luckily, with dry antecedent conditions, ponding of water and/or
flooding should remain isolated as we head into the overnight
hours, however, this could change if persistent downpours train
over the same areas.

The severe weather threat has been quiet thus far, but a few
breaks in the cloud deck in the warm sector has allowed for
1000 J/KG MUCAPE to form along and south of US 460. This,
combined with modest shear could be enough to support a few
potentially strong storms this afternoon/evening, located
primarily close to the VA/NC state line. Short term models have
the cluster of showers/storms moving out of eastern TN/KY as
being the primary forcing mechanism of these potential storms,
and remain rather bullish with their potential, especially
between 6pm - 8pm.

Tonight, heaviest rain/storm chances come to an end slowly NW
to SE as the boundary pushes through. This trend seems to be
persistently slowing with each model run, so have delayed
POPs/Clouds from exiting southeast of our area until mid to late
afternoon Tuesday. This trend will work to keep overnight lows
mild, settling in the mid 60s in the mountains to near 70 in the
Piedmont. Fog formation not out of the question, especially in
the higher elevations where precip may come to an end before
sunrise. High pressure settles over the region midday Tuesday,
allowing a clearing trend and drier conditions to take hold.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
As of 300 PM EDT Monday...

Northern stream shortwave expected to shift the frontal boundary
south of our region Tuesday night, but deeper moisture and boundary
stall not far, where there could be showers lingering Tuesday
evening south of the VA/NC border. Return flow around the high
should bring a return of isolated threat of showers Wednesday
afternoon to the southern Blue Ridge and adjacent areas into
Southwest VA and the NC foothills.

Temperatures should stay close to normal Tuesday night, with lows in
the mid to upper 50s mountains, to lower to mid 60s east.

With high pressure nearby Wednesday and east flow, temperatures
should stay below normal, with highs ranging from the 70s mountains,
to lower 80s piedmont.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 300 PM EDT Monday...

Active pattern remains this period as broad mean trough stays
situated from the Great Lakes into the Gulf Coast states. A frontal
boundary stays south of us Wednesday night gradually dissipating
while next upstream front slowly edges into the Ohio Valley by
Saturday, reaching the central Appalachians by Monday. Model
consensus showing best chance of showers/storms to be more diurnal at
times, with greater increase in 24 hour chances as the front moves
late in the weekend into Monday. This far out will see how the
pattern sets up in terms of rainfall amounts and flooding threats.

Temperatures will stay near normal given cloud cover most of the
time, and higher moisture content in the atmosphere.

&&

.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
As of 645 PM EDT Monday...

Bands/clusters of showers continue across the region this
evening with most deeper convection across far southern sections
mainly southwest of KDAN. However in between showers expect to
continue to see periods of sub-VFR in low clouds across the
mountains with overall VFR elsewhere outside of any heavier
downpours. Does appear that showers and storms may become more
widespread espcly over eastern/southern sections by midnight as
a cold front to the northwest sags in behind a departing wave
aloft. This may make for MVFR cigs/vsbys from KROA east into the
early morning hours with best coverage likely along the
KLYH/KDAN corridor where heavy rainfall will be possible. Thus
keeping in VCSH/VCTS mention at most sites while using a TEMPO
through this evening across the east for MVFR to IFR cigs/vsbys
within heavier downpours.

However still lower confidence on VSBYS/CIGS thanks to
the scattered nature of showers and storms across the region
after loss of heating. Cold front should begin to slowly move
through from northwest to southeast after midnight, resulting
in a wind shift from the northwest.

Expect lingering sub-VFR to persist over southern eastern
sections into Tuesday morning with showers around, and over the
mountains due to low clouds/fog early on. The frontal boundary
will continue south of the area Tuesday afternoon/evening
allowing for some drier weather and improvement in aviation
conditions. Appears most terminals should bounce back to VFR
cigs by early afternoon if not sooner pending how fast low vsbys
within fog increase. Any shra/tsra threat appears mainly south
and west of region so no mention of any convection later Tuesday
for now.

Extended Aviation Discussion...

The front to the south will remain to the south on Wednesday
before starting to return north Thursday. This will bring
showers and thunderstorms back to the forecast, especially at
the southern TAF locations mainly Thursday afternoon. As a
result MVFR ceilings and visibilities will likely return to
southern/western sections Thursday and perhaps across the region
Friday. Some improvement possible Saturday under weak high
pressure but still enough convective potential for localized
MVFR conditions Saturday afternoon. Late night/early morning
fog and low clouds also likely each night.

&&

.EQUIPMENT...
As of 200 PM EDT Friday Aug 4...

KFCX doppler radar will be down for the rest of the month due
to a failing bull gear. The radar will only be made operational
for brief periods if an imminent significant widespread severe
weather and/or hydrologic event occurs. Operating the system for
any amount of time until the bull gear is replaced risks a
catastrophic failure that would further extend system downtime.

&&

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

&&

SYNOPSIS...JM
NEAR TERM...JH/JM
SHORT TERM...WP
LONG TERM...WP
AVIATION...AMS/JH/JM
EQUIPMENT...WERT

Hazardous Weather Outlook
National Weather Service Blacksburg VA
959 PM EDT Mon Aug 7 2017

NCZ001>006-018>020-VAZ012>017-022-032>035-043>047-058-059-090200-
Ashe-Alleghany NC-Surry-Stokes-Rockingham-Caswell-Watauga-Wilkes-
Yadkin-Wythe-Pulaski-Montgomery-Grayson-Carroll-Floyd-Roanoke-
Patrick-Franklin-Bedford-Amherst-Henry-Pittsylvania-Campbell-
Appomattox-Buckingham-Halifax-Charlotte-
959 PM EDT Mon Aug 7 2017

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

.DAY ONE...Tonight.

Bands of showers and thunderstorms producing heavy rainfall are expected
into the overnight. Rainfall may be heavy enough to result in
localized flooding.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

There is a low probability for widespread hazardous weather.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

VAZ007-009>011-018>020-023-024-WVZ042>044-507-508-090200-
Tazewell-Smyth-Bland-Giles-Craig-Alleghany VA-Bath-Botetourt-
Rockbridge-Mercer-Summers-Monroe-Eastern Greenbrier-
Western Greenbrier-
959 PM EDT Mon Aug 7 2017

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

.DAY ONE...Tonight.

The probability for widespread hazardous weather is low.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

Special Weather Statement
National Weather Service BLACKSBURG VA
750 PM EDT MON AUG 7 2017

NCZ003-004-080030-
Stokes-Surry-
750 PM EDT MON AUG 7 2017

...A STRONG THUNDERSTORM WILL AFFECT
SOUTHEASTERN SURRY AND SOUTHWESTERN STOKES COUNTIES...

At 750 PM EDT, a strong thunderstorm was located near East Bend,
moving northeast at 25 mph.

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

Locations impacted include...
King...
Pinnacle...
Hanging Rock State Park...
Capella...
and Vade Mecum.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

LAT...LON 3626 8047 3626 8053 3628 8054 3646 8030
      3634 8017 3626 8029 3626 8045 3624 8045
TIME...MOT...LOC 2350Z 229DEG 24KT 3627 8048

RS

Special Weather Statement
National Weather Service BLACKSBURG VA
832 PM EDT MON AUG 7 2017

VAZ034-035-045-080115-
Amherst-Campbell-Bedford-
832 PM EDT MON AUG 7 2017

...A STRONG THUNDERSTORM WILL AFFECT
NORTHEASTERN BEDFORD...AND SOUTHWESTERN AMHERST COUNTIES AND THE CITY
OF LYNCHBURG...

At 832 PM EDT, a strong thunderstorm was located near Boonsboro,
moving east at 20 mph.

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

Locations impacted include...
Lynchburg...
Forest...
Coleman Falls...
Madison Heights...
and Boonsboro.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

LAT...LON 3738 7938 3751 7943 3751 7909 3735 7909
TIME...MOT...LOC 0032Z 262DEG 17KT 3744 7933

RS

Special Weather Statement
National Weather Service BLACKSBURG VA
848 PM EDT MON AUG 7 2017

VAZ046-080145-
Appomattox-
848 PM EDT MON AUG 7 2017

...A STRONG THUNDERSTORM WILL AFFECT
CENTRAL APPOMATTOX COUNTY...

At 848 PM EDT, a strong thunderstorm was located over Spout Spring,
moving east at 20 mph.

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

Locations impacted include...
Appomattox...
Stonewall...
Oakville...
Appomattox National Historic Park...
and Spout Spring.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

LAT...LON 3722 7880 3730 7895 3732 7895 3739 7899
      3745 7898 3742 7866
TIME...MOT...LOC 0048Z 278DEG 16KT 3734 7887

RS

Special Weather Statement
National Weather Service BLACKSBURG VA
932 PM EDT MON AUG 7 2017

VAZ044-080215-
Pittsylvania-
932 PM EDT MON AUG 7 2017

...A STRONG THUNDERSTORM WILL AFFECT
SOUTHERN PITTSYLVANIA COUNTY AND THE CITY OF DANVILLE...

At 932 PM EDT, a strong thunderstorm was located over Blairs, moving
northeast at 20 mph.

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

Locations impacted include...
Danville...
Chatham...
Blairs...
Java...
and Swansonville.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

LAT...LON 3655 7971 3674 7965 3695 7913 3655 7922
TIME...MOT...LOC 0132Z 244DEG 18KT 3671 7941

RS

Special Weather Statement
National Weather Service BLACKSBURG VA
1038 PM EDT MON AUG 7 2017

VAZ058-059-080315-
Halifax-Charlotte-
1038 PM EDT MON AUG 7 2017

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT
SOUTHEASTERN CHARLOTTE AND SOUTHERN HALIFAX COUNTIES...

At 1037 PM EDT, radar indicated strong thunderstorms were located
along a line extending from Ingram to near Roxboro. Movement was
northeast at 40 mph.

Winds in excess of 30 mph are possible with these storms.

Locations impacted include...
South Boston...
Halifax...
Redoak...
Clover...
and Turbeville.

Torrential rainfall is also occurring with these storms, and may
cause localized flooding. Do not drive your vehicle through flooded
roadways.

LAT...LON 3664 7857 3664 7858 3669 7865 3669 7868
      3668 7870 3659 7871 3656 7874 3654 7873
      3654 7905 3673 7917 3675 7917 3693 7863
      3682 7855 3670 7865 3668 7862 3665 7857
      3663 7855
TIME...MOT...LOC 0237Z 246DEG 35KT 3674 7915 3644 7894

DS

Special Weather Statement
National Weather Service BLACKSBURG VA
1040 PM EDT MON AUG 7 2017

VAZ044-080315-
Pittsylvania-
1040 PM EDT MON AUG 7 2017

...A STRONG THUNDERSTORM WILL AFFECT CENTRAL PITTSYLVANIA COUNTY...

At 1040 PM EDT, a strong thunderstorm was located over Chatham,
moving east at 30 mph.

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

Locations impacted include...
Chatham...
Gretna...
Java...
Dry Fork...
and Climax.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

LAT...LON 3688 7957 3699 7925 3680 7915 3679 7916
      3671 7948
TIME...MOT...LOC 0240Z 250DEG 25KT 3682 7945

DS