Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 262327

Area Forecast Discussion
National Weather Service Blacksburg VA
727 PM EDT Wed Apr 26 2017

High pressure will build across the southeastern United States
resulting in a considerable boost to the temperature with above
seasonal warmth expected by the weekend. An increase in southwesterly
wind flow will bring enough moisture back into the area by late
Thursday to promote widely scattered afternoon and evening showers and
thundershowers over the mountains.


As of 710 PM EDT Wednesday...

With low pressure off the middle Atlantic coast pulling away and some
ridging aloft, expect quiet weather to prevail through tonight. Believe
there is enough ground moisture from recent rainfall to help moisten
the boundary layer and generate some patchy valley fog toward
daybreak. For Thursday, despite most energy guidance is becoming
a bit more enthusiastic and faster with the cold front
approaching from the west tomorrow. Precipitation will hold off
until the afternoon and there looks to be enough instability and
some shear to support some stronger storms/clusters. Have
bumped POPs up to high chance/likely to reflect this thinking.


As of 410 PM EDT Wednesday...

Unseasonably warm, summerlike weather expected with the potential
for showers and thunderstorms especially along and west of the Blue
Ridge Mountains heading into the latter part of the week.

Showers and thunderstorms will move east across the region Thursday
afternoon into Thursday evening. Partly cloudy conditions will
prevail Thursday night into Friday morning. Low temperatures
Thursday night will range from the mid 50s in the mountains to the
60s in the Piedmont.

Friday and Saturday feature the re-establishment of an amplified mid-
level ridge across a large part of the Southeastern CONUS.
Meanwhile, a mid-level trough will dig and deepen over the Four
Corners Region. The closed low will slowly edge northeast towards
the plains this weekend. A surface low develops in Texas Friday and
travels northeast into Saturday night. A warm front extends eastward
from the low center in the Ohio Valley, followed by cold front
trailing south. The frontal boundaries will serve as a trigger for
showers and thunderstorms.

On Friday, the air mass in low-levels is relatively capped, progged
instability aloft is around -2 to -4 Showalter indices and MUCAPES
in excess of 1000 J/kg. This supports isolated showers and
thunderstorms Friday afternoon into Friday evening mainly from the
Blue Ridge west. High temperatures on Friday will climb into the mid
70s in the mountains to the mid 80s in the Piedmont. Any convection
will taper off quickly Friday night. It will be a mild night with
readings from mid 50s in the mountains to the mid 60s in the

As the low center lifts northward Saturday, the combination of
heating and an unstable airmass will create a few showers and
thunderstorms along and west of the Blue Ridge. High temperatures
Saturday will moderate to around 80 degrees in the mountains to
around 90 degrees in Piedmont. It will be mild Saturday night with
lows generally from around 60 in the west to the upper 60s in the


As of 410 PM EDT Wednesday...

Very warm and humid conditions continue Sunday with the chance for
showers and thunderstorms, especially along the Blue Ridge. By
Monday, the vertically stacked upper closed low over the Midwest
will move into the Great Lakes region. This will push a vigorous
cold front into the area from the west with a good chance of showers
and thunderstorms through Monday afternoon into Monday night. High
pressure will then build on for Tuesday with cooler weather and
windy conditions. Moisture increases on Wednesday, with better
chances of rain Wednesday night into Thursday.


As of 725 PM EDT Wednesday...

Expecting widespread VFR conditions all sites through the early
portion of the TAF period. Then, decent radiational cooling
will combine with ambient ground moisture from recent rainfall
to generate some patchy valley (MVFR) fog early Thursday
morning. Any fog/stratus should burn off tomorrow morning and
effects of cold front approaching from the west look to hold off
lower cigs and chances for scattered convection until the
afternoon. Southerly winds will become a bit gusty from mid
morning on.

Extended Aviation Discussion...

Better flying weather is expected for the second half of the
week. Much warmer weather can be expected through the upcoming
weekend with temperatures much above normal. Warming surface
temperatures also mean increasing atmospheric instability. As
such, potential will exist for cloud build-ups and the risk for
isolated to scattered thunderstorms along the spine of the
Appalachians during the peak heating hours each afternoon.


As of 525 PM EDT Wednesday...

Flood warnings continues for the Dan and Roanoke Rivers

The Dan River has crested and is falling at Danville, and has
crested at Paces. At South Boston the river is slowly rising and
should crest after midnight tonight.

The Roanoke River at Randolph has crested and will begin falling
this evening.




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