High Wind Watch 3, NWS Blacksburg, VA

Area Forecast Discussion
National Weather Service Blacksburg VA
330 AM EDT Thu Oct 31 2019

.SYNOPSIS...
A warm front will head north through North Carolina and Virginia
today. An intense cold front moves across our area this
afternoon and evening followed by colder high pressure for the
weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 315 AM EDT Thursday...

Deepening closed upper low will cross into the Great Lakes today and
tonight and will push an intense cold front across the Mid Atlantic
region this afternoon and evening. Models were similar with the
timing and synoptic features of this system. Southwest Virginia,
southeast West Virginia and northwest North Carolina will start the
day in the warm sector. Forcing is strong with the right rear
quadrant of the 140 knot upper jet aiding in lift.

Abundant moisture streaming north out of the Gulf of Mexico has
precipitable water values well above normal. Storm motion and the
speed of the front will limit flooding potential but rates withing
the line of thunderstorms along the front will be heavy. Will
mention the threat in the Hazardous Weather Outlook, especially
since leaves will be blown down and may clog urban drainage systems.
Deeper moisture exits the east by midnight with clearing east of the
Blue Ridge overnight but low level upslope clouds will remain over
the mountains through Friday morning.

Enhanced threat of severe thunderstorms unchanged in the latest Day
One Storm Prediction Center outlook. CAPES up to 1200 J/Kg this
afternoon along with impressive shear and helicity values in the 300-
600 range support the primary threat of damaging wind.

850mb temperatures drop 15 deg. C in 12 hours with this front. The
strong cold air advection will combine with large pressure rises, in
the range of 10 to 15 mb/6hrs, to produce very gusty wind. Will be
issuing wind advisory for the foothills and to the west and a high
wind watch from Roanoke north into the Greenbrier Valley and the
Alleghany Highlands. The greatest threat of damaging winds will be
immediately behind the front through about 09Z/5AM but the longer
expiration is a buffer for what the next round of guidance suggests.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
As of 300 AM EDT Thursday...

Windy conditions will begin to relax on Friday as high pressure starts
to build in behind the strong cold front. Lingering upslope clouds and
any showers/flurries west of the Blue Ridge will dissipate during the
morning with a good deal of sunshine for the afternoon. However, the
strong surge of cold air behind the cold front will make for notably
colder conditions with temperatures running well below normal as we
start November. Quite chilly Friday night with frost/freeze conditions
possible east of the Blue Ridge.

Temperatures will rebound a bit on Saturday ahead of another cold front
rapidly approaching from the northwest. Moisture is limited with the
front so not much to speak of in terms of precipitation or clouds, but
expect winds to become a bit blustery again followed by a good surge of
upslope clouds for the evening and through Saturday night. Another
chilly night with frost/freeze conditions possible east of the Blue
Ridge.

Sunday will see a return to high pressure and a good amount of sun with
any lingering clouds west of the Ridge dissipating during the morning.
However, the surge of cold air behind the most recent cold front will
again take a toll and keep high temperatures on Sunday well below
normal. And if the growing season is still active east of the Ridge,
Sunday night will offer another good chance for a frost/freeze.

&&

.LONG TERM /MONDAY THROUGH WEDNESDAY/...
As of 315 PM EDT Wednesday...

A ridge of high pressure will set up over the Mid Atlantic and should
keep dry conditions overt the region through Monday night as it exits
offshore.

Afterward, forecast confidence decreases considerably as the ECMWF
and the GFS differ on the timing and initialization of a new area of
low pressure developing somewhere near the Southeast coast. Rain
chances seem to generally creep up slowly during Tuesday and
Wednesday although rainfall amounts do not appear impressive.
However, the overall discrepancies of the synoptic picture in the
models make it difficult to give more than just low chance PoPs at
this time.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
As of 155 AM EDT Thursday...

Expect poor aviation conditions through the period with only
brief intervals of MVFR or VFR expected mainly late this
morning as south-southwest winds work to scour out the lower
ceilings ahead of the cold front. High confidence forecast for
sub-MVFR ceilings/vsbys thru 14Z/10AM with intermittent rain,
moderate to possibly heavy at times, especially east of the Blue
Ridge.

Southerly flow increases above the inversion early this morning
with low level wind shear expected at most sites. The wind shear
is expected to become less of a threat today as mixing works
gusts down to the surface. Wind gusts from the south to
southwest ahead of the front will be 15 to 25 knots.

A quasi-linear convective system is expected to move east and
across the mountains this afternoon, associated with a strong
cold front. This line of deep convection is expected to reach a
KLWB to KTNB line between 18-20z/2pm-4pm, then move east
through KROA,KLYH and KDAN between 20z-00z/4pm- 8pm. Embedded
thunderstorms within this line of showers may contain damaging
wind gusts (50 kts).

Behind the front winds turn to the west-northwest with gusts
increasing to 25 to 35 knots. Higher elevations, especially
north of KROA have the potential for even stronger wind.

Above average confidence on the timing of the front and the
improvement to VFR this afternoon.
Average confidence on ceiling improvement this morning ahead of
the front once mixing begins.

Please note, the automated observing equipment at KROA has
detected an error with the ceilometer. The current observations
look reasonable but still use caution. Technichians will
evaluate the sensor later this morning.

.Extended Aviation Discussion...

The wind is expected to diminish by Friday evening with a
return to VFR. High pressure is expected to provide VFR weather
through the weekend. A secondary, dry front, will cross the
area Saturday night. The biggest by-product from this feature
will be enhanced winds across the ridges and some low MVFR
cloudiness in the WV mountains Saturday night into Sunday
morning.

&&

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

&&

SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...MBS
LONG TERM...MBS/PW
AVIATION...AMS/PM

Hazardous Weather Outlook
National Weather Service Blacksburg VA
344 PM EDT Wed Oct 30 2019

NCZ001-002-018-VAZ007-009>020-WVZ042>044-507-508-311945-
Ashe-Alleghany NC-Watauga-Tazewell-Smyth-Bland-Giles-Wythe-Pulaski-
Montgomery-Grayson-Carroll-Floyd-Craig-Alleghany VA-Bath-Mercer-
Summers-Monroe-Eastern Greenbrier-Western Greenbrier-
344 PM EDT Wed Oct 30 2019

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

.DAY ONE...This afternoon and tonight.

Moderate to heavy rain may produce localized flooding.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

A line of showers and thunderstorms Thursday may produce damaging
winds, localized flooding, and perhaps an isolated tornado. Strong
winds are also expected Thursday night into Friday morning.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed on Thursday.

NCZ003-004-019-020-VAZ022>024-032>035-043-311945-
Surry-Stokes-Wilkes-Yadkin-Roanoke-Botetourt-Rockbridge-Patrick-
Franklin-Bedford-Amherst-Henry-
344 PM EDT Wed Oct 30 2019

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...This afternoon and tonight.

Moderate to heavy rain may produce localized flooding.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

A line of showers and thunderstorms Thursday may produce damaging
winds, localized flooding, and perhaps an isolated tornado. Strong
winds are also expected Thursday night into Friday morning.

In addition, areas of frost are likely for Friday night into
Saturday morning.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed on Thursday.

NCZ005-006-VAZ044>047-058-059-311945-
Rockingham-Caswell-Pittsylvania-Campbell-Appomattox-Buckingham-
Halifax-Charlotte-
344 PM EDT Wed Oct 30 2019

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

.DAY ONE...This afternoon and tonight.

There is a low probability for widespread hazardous weather.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

A line of showers and thunderstorms Thursday may produce damaging
winds and perhaps an isolated tornado. Strong winds are also
expected Thursday night into Friday morning.

In addition, areas of frost are likely for Friday night into
Saturday morning.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed on Thursday.

PW

Special Weather Statement
National Weather Service BLACKSBURG VA
440 AM EDT Thu Oct 31 2019

VAZ043-044-310915-
Henry-Pittsylvania-
440 AM EDT Thu Oct 31 2019

...A STRONG THUNDERSTORM WILL AFFECT CENTRAL PITTSYLVANIA AND EAST
CENTRAL HENRY COUNTIES...

At 439 AM EDT, a strong thunderstorm was located near Sandy River,
or near Axton, moving northeast at 40 mph.

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

Locations impacted include...
Chatham...
Blairs...
Callands...
Java...
Leatherwood...
Swansonville...
and Dry Fork.

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

LAT...LON 3672 7979 3694 7946 3680 7915 3678 7916
      3661 7949
TIME...MOT...LOC 0839Z 237DEG 34KT 3668 7963

MBS