Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 281154

Area Forecast Discussion
National Weather Service Blacksburg VA
754 AM EDT Fri Apr 28 2017

High pressure will build off the southeast Atlantic coast and
begin a trend for warmer and more humid conditions through the
upcoming weekend. A strong cold front will move through the area
Monday with showers and thunderstorms, followed by some cooler,
but near seasonal temperatures through the first part of next


As of 430 AM EDT Friday...

Surface front has pretty much washed out and will no longer
provide any sort of lifting focus for showers, so the only
weather concern, at least through the early morning (9AM) will
be fog. Clearing skies in the wake of yesterdays showers/storms
resulted in the formation of radiation fog during the overnight
last night. Satellite imagery indicates the fog is mainly
confined to the valleys, and is most prominent within the
mountain valleys where surface visibilities were as low as 1/4
mile. This fog will persist through daybreak then dissipate with
the mixing of the morning sun.

High pressure is forecast to build over the southeast CONUS
today...rising heights and thicknesses resulting in warming
temperatures with afternoon highs 10 to 15 degrees above normal.
Dewpoints in the 50s will help maintain mild conditions during
the overnight with lows tonight only dipping into the 55 to 65
degree range...quite comfortable for April.


As of 400 AM EDT Friday...

During this portion of the forecast, surface high pressure will be
anchored east of the coast of the Carolinas. As each day passes, a
strong cold front and its parent closed upper low, will approach the
region from the west, with the front arriving on Monday. The parent
low at that time will be crossing the Great Lake region.

The result for our forecast region will be increasing southerly
winds as the pressure gradient tightens between the approaching
front, and the nearly stationary offshore surface high.  These
stronger winds will advect both increasing moisture and warmer air
aloft into the region.

On Saturday, we are still expecting record, or near record, high
temperatures across the region thanks to the increasing warm air
advection. Please reference the CLIMATE section of this discussion
for details. Isolated showers or thunderstorms will be possible by
mid-day and continue into the afternoon, especially along and west
of the crest of the Blue Ridge.

Saturday night into Sunday, the warm air advection will continue.
However, moisture will still be on the increase in the from of
increased cloud cover. Sunday is expected to be cooler than Saturday
thanks to these clouds, along with isolated showers and storms
across the mountains.

Sunday night into Monday, low level winds increase significantly
ahead of the approaching cold front. By Monday morning, guidance
ranges from having anywhere between a 35 to 50 kt 850mb southerly
wind overhead. Anticipate a gustier day, along with increased low
level shear. Cloud cover will continue to be abundant with
increasing chances of showers and storms through the day. The
increased shear will lend itself towards an increased chance of
stronger storms.

On Monday night, the front passes quickly to our east. Expect
decreasing cloud cover, and drier and cooler air to progress into
the region.

Temperatures during this portion of the forecast will be above
average during, with each day`s average slightly cooler than the
prior day. On Monday, record warmth is expected with a mix of the
mid to upper 80s across the region. By Monday, highs in the upper
60s to lower 70s over the mountains with mid to upper 70s over the
Piedmont. Low temperatures Saturday night and Sunday night will be
fairly uniform with readings in the low to mid 60s. Monday night
behind the front, low to mid 50s are forecast.


As of 400 AM EDT Friday...

A general area of troughiness remains across the East Coast of the
U.S. while high pressure at the surface builds into the area.
Primarily dry and slightly above normal temperatures are expected
Tuesday and Wednesday. By Thursday, a shortwave trough progressing
through the broader trough pattern, will move into and through the
Lower Mississippi then Tennessee Valleys. The result will be
increasing clouds, better chances of showers and storms, and cooler
temperatures on Thursday for the region.


As of 745 AM EDT Friday...

Moist ground and clear skies last night yeilded widespread
radiational fog in the mountain valleys with LIFR within the
valleys, yet clear at ridge-top level. This fog should rapidly
clear mid-morning 13-14Z once the daytime mixing gets underway.
After 14Z/10am expect return of widespread VFR underneath a
building area of High Pressure.

Extended Aviation Discussion...

High pressure should build off the Southeast coast during this
weekend. Other than the potential for MVFR/IFR morning fog at
the usual river valley locations, VFR conditions should prevail
Saturday and Sunday. As a low pressure system approaches from
the west late Sunday and Sunday night, the potential for
afternoon showers and thunderstorms will increase. The cold
front associated with this system should reach the Appalachian
Mountains by Monday and depart offshore by Tuesday morning. As
such, expect the best chance of MVFR conditions during the
frontal passage.


Potential for high temperature records to be broken Saturday,
April 29.

 Current record/yearForecast
Roanoke            89/1915             89
Lynchburg          88/1974             90
Danville           91/1981             89
Bluefield          83/1996             86
Blacksburg         83/1974             86


VA...Dense Fog Advisory until 9 AM EDT this morning for VAZ007-
WV...Dense Fog Advisory until 9 AM EDT this morning for WVZ042>044-


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