Special Weather Statement, NWS Blacksburg, VA

Area Forecast Discussion
National Weather Service Blacksburg VA
148 PM EDT SUN JUN 5 2016

.SYNOPSIS...
A strong cold front extends from Michigan to western Tennessee.
This front will move east today crossing the Appalachian
Mountains. By Monday morning the cold front will extend from off
the New England coast into the Gulf coast region.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 500 AM EDT Sunday...

Vigorous short wave was moving east through the Great Lakes with
vorticity axis and upper trough trailing south into the Mid-
Mississippi Valley. This trough is progged to move east and deepen
as another upstream impulse digs across the upper Mid-West. Deep
plume of subtropical moisture extends from the Gulf of Mexico
northward into the eastern Great Lakes ahead of this trough,
Precipitable Water (PW) values in excess of 1.50 inches.

Showers were advancing east across KY/TN and into the Appalachian
Mountains this morning. This activity will overspread areas west
of the Blue Ridge early this morning with rain likely from the
Greenbrier Valley of WV and Highlands of VA...south through the
New River Valley and into to the mountains of NC. Given the
extensive area of rain and clouds...think this will cut down on
overall surface heating and instability west of the Blue Ridge
today. East of the Blue Ridge there will likely be ample
sun/insolation yeilding a different outcome.

Main concern for this afternoon will be the potential for severe
thunderstorms. Per aforementioned clouds and showers, think this
potential will be limited across the mountains west of the Blue
Ridge. However, east of the Blue Ridge think there is a bonafide
risk per a number of factors... first and foremost being the ease
to increase CAPE with just a little bit of surface heating per the
tropical nature of the airmass. Surface dewpoints around 70
degrees F will be pervasive across the piedmont. This should
yield a moderately unstable airmass in spite of any cloud cover.
As the shortwave...upper trough axis...approaches the
Appalachians during the afternoon a broad belt of moderate to
strong 700-500 mb southwesterly winds will increase across the
region, yeilding 30-45 kt effective shear. Models also indicate
the development of a low level jet across the piedmont with a
magnitude of 30-40 kts. All things considered, ingredients are in
place for an active severe weather day, favoring areas from the
Blue Ridge to the Coast.

Storms should initiate mid-day across the mountains and spread
east over the piedmont during the afternoon. Main concern will be
rapid development of Multicell clusters which then evolve into a
quasi-linear convective system (QLCS) that moves east across the
piedmont. This suggests that damaging winds will be the primary
threat, but a brief tornado and/or marginally severe hail will
be possible per any supercell structures that develop within this
QLCS. Due to the high PW values, expect a torrential downpour to
accompany the storms today, however storm motion, which could
approach 45 mph, will limit residence time of the heavy rain.

Actual surface cold front will lag behind the development of the
prefrontal deep convection today. The anticipated QLCS which
evolves and moves east will be accompanied by its own outflow and
wind shift. The actual surface cold front will move through the
mountains this evening and may produce some lingering
showers...before moving east and allowing a more bonafide wind
shift and airmass transition to take place.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 400 AM EDT SUNDAY...

Frontal boundary will push east of our area Monday, but linger along
the Southeast coast.  Surface and low level winds turn to the west
behind the front as the eastern long wave trof becomes established.
Much drier air comes in behind the front but deeper moisture does
not get suppressed very far to the south. Model runs have become
wetter as a low pressure system tracks from the Gulf along the
boundary. High temperatures Monday will range from the mid 70s in
the mountains to the mid 80s in the Piedmont. The NAM,GFS and ECMWF
bring in some increased moisture Monday afternoon into Monday night
across southern portions of the forecast area. Will allow for an
isolated showers across the south. Low temperatures Monday night
will vary from the mid 50s in the mountains to the mid 60s in the
Piedmont.

The wave of low pressure which is off the South Carolina coast
Tuesday morning pushes northeast out into the Atlantic ocean
by Tuesday night.  At the same time, several shortwaves embedded in
the northwest flow will lead upslope precipitation. High
temperatures on Tuesday afternoon will climb into the mid 70s in the
west to the upper 80s in the southeast. Under clear to partly cloudy
skies, low temperatures Tuesday night will drop into the upper 40s
in the mountains to around 60 in the Piedmont.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 400 AM EDT Sunday...

Cooler air arrives for midweek, then temperatures moderate into
the end of the week. A secondary cold front slide across the area
resulting in a reinforcing surge of lower dewpoint air on gusty
west/northwest winds Wednesday. High pressure builds overhead on
Wednesday night and remains over the area through Friday. High
pressure over the area shifts offshore and heights begin to build
as upper ridging build eastward during the weekend. NHC keeps the
expected tropical feature coming out of the Gulf of Mexico well
south of the Mid Atlantic region. In general used the Superblend
for temperatures during the period.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
As of 140 PM EDT Sunday...

A long band of showers and thunderstorms extended from New York to
eastern Tennessee. Numerous thunderstorms will develop in the mid
Atlantic region this afternoon and move east through 03Z/11PM.
The thunderstorms will organize into linear segments and longer
lines with damaging winds possible with any of the stronger to
severe thunderstorms. Local WRF and other short range guidance had
a majority of the thunderstorms east of KLYH and KDAN by 03Z/11PM
this evening. High confidence in the occurrence of thunderstorms
before midnight...but lower confidence on the exact time of impact
for individual airports.

These storms were ahead of a cold front that extended from
Michigan to Louisiana. The front will move east tonight and will
reach the east coast by Monday morning. The deeper moisture will
be swept east of the area along with the front but guidance was
showing the potential for stratus development and IFR ceilings tonight
in the mountains.

Extended discussion...

The front is expected to stall along the southeast Atlantic coast
Monday and will become the focus for unsettled weather across the
deep south as a developing tropical depression moves northeast out
of the Gulf of Mexico and across northern Florida into Tuesday.
This will result in persistent cloudiness from the Carolinas
southward.

Aside for the system moving across the southeast states early in
the week, there could be a periods of upslope clouds and showers
across the mountains of WV through Monday night and again Tuesdaynight
into Wednesday morning impacting KLWB and KBLF the most with
showers and potential MVFR ceilings. Otherwise...conditions appear
to be largely VFR through Friday.

&&

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

&&

SYNOPSIS...PM
NEAR TERM...PM
SHORT TERM...KK
LONG TERM...KK
AVIATION...AMS/PM

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BLACKSBURG VA
620 AM EDT SUN JUN 5 2016

VAZ007-009-010-WVZ042-043-508-061030-
TAZEWELL-SMYTH-BLAND-MERCER-SUMMERS-WESTERN GREENBRIER-
620 AM EDT SUN JUN 5 2016

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHWEST VIRGINIA AND
SOUTHEAST WEST VIRGINIA.

.DAY ONE...TODAY AND TONIGHT.

THERE IS A MARGINAL RISK...5 PERCENT CHANCE...OF SEVERE
THUNDERSTORMS THIS AFTERNOON. THE PRIMARY THREAT WILL BE DAMAGING
WINDS AND A TORRENTIAL DOWNPOUR OF RAIN.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED.

NCZ001>004-018>020-VAZ011>020-022>024-032>035-043-WVZ044-507-061030-
ASHE-ALLEGHANY NC-SURRY-STOKES-WATAUGA-WILKES-YADKIN-GILES-WYTHE-
PULASKI-MONTGOMERY-GRAYSON-CARROLL-FLOYD-CRAIG-ALLEGHANY VA-BATH-
ROANOKE-BOTETOURT-ROCKBRIDGE-PATRICK-FRANKLIN-BEDFORD-AMHERST-HENRY-
MONROE-EASTERN GREENBRIER-
620 AM EDT SUN JUN 5 2016

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...TODAY AND TONIGHT.

THERE IS A SLIGHT RISK...15 PERCENT CHANCE...OF SEVERE
THUNDERSTORMS THIS AFTERNOON. THE PRIMARY THREAT WILL BE DAMAGING
WINDS, LARGE HAIL AND A TORRENTIAL DOWNPOUR OF RAIN.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED.

NCZ005-006-VAZ044>047-058-059-061030-
ROCKINGHAM-CASWELL-PITTSYLVANIA-CAMPBELL-APPOMATTOX-BUCKINGHAM-
HALIFAX-CHARLOTTE-
620 AM EDT SUN JUN 5 2016

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL NORTH
CAROLINA...CENTRAL VIRGINIA AND SOUTH CENTRAL VIRGINIA.

.DAY ONE...TODAY AND TONIGHT.

THERE IS AN ENHANCED RISK...30 PERCENT CHANCE...OF SEVERE
THUNDERSTORMS DURING THE AFTERNOON AND EARLY EVENING. THE PRIMARY
THREAT WILL BE DAMAGING WINDS, LARGE HAIL AND A TORRENTIAL
DOWNPOUR OF RAIN. AN ISOLATED TORNADO...2 PERCENT CHANCE...IS
ALSO POSSIBLE.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL LIKELY BE NEEDED.

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