Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 261920

Area Forecast Discussion
National Weather Service Blacksburg VA
320 PM EDT Thu Apr 26 2018

An upper level trough will cross over the Mid Atlantic and
provide rain showers for tonight. High pressure should arrive
to provide drier conditions for the upcoming weekend and into
early next week.


As of 315 PM EDT Thursday...

A potent upper level shortwave trough will approach northwestern
North Carolina this evening and cross overhead tonight. Showers
will spread northeastward along the reflected surface low
pressure area from this trough. Details are still a little
sketchy on the exact QPF and timing of the rainfall. The GFS is
a little quicker and wetter, while the ECMWF is slower and
drier. The consensus of the high resolution guidance favors the
GFS solution more but appears to be driven too much by
convection, and instability is barely there to support it
according to model soundings. We will need to monitor rainfall
rates for any possible minor flooding or any aggravation of the
ongoing river flooding situation in Southside Virginia. Confidence
was not high enough to warrant a Flood Watch at this time, so
the flood threat is mentioned in the HWO. Overall, about a half
to one inch of rain is expected tonight, but there should be
locally higher amounts if any banding or training takes place.

The showers should gradually fade during the early morning hours
of Friday, but the lingering moisture should provide low clouds
and patchy fog toward sunrise. As the area of low pressure
departs from the Mid Atlantic, winds should shift toward the
northwest and steadily increase during the day. This mixing
should scour out any fog and low clouds across the Piedmont by
midday. However, lingering moisture could keep low clouds a
little longer along and west of the Blue Ridge. In addition, the
upslope flow should provide showers along the higher elevations
west of a line from Lewisburg to Boone through most of the
daytime hours. It will be slightly cooler on Friday compared to
today, but temperatures should remain near seasonal values.


As of 230 PM EDT Thursday...

A disturbance over the Great Lakes Friday night will slowly track
east to New England by Saturday night. An inverted trough emerges
ahead of this system and along the western slopes of the Appalachian
Mountains Friday evening. This trough should only result in some low
clouds passing over the mountains into Saturday morning. Also ahead
of this system, winds back across the Tennessee-Ohio Valley. With
weak forcing and limited moisture as Gulf is blocked, light showers
are possible along western slopes and isolated showers across the
rest of the mountains Saturday afternoon into the early evening.
Showers will end quickly as the front slides across the area
Saturday evening. Even though dry air entrains into the region, some
light upslope rain/drizzle is likely along western Greenbrier as
short waves rounding the low to the north pass over the area.
Upslope precipitation will come to an end Sunday morning, then dry
high pressure builds over the region.

Being ahead of the front Friday night and Saturday, temperatures
will remain mild. Overnight Friday, 40s will be common to near 50F
across the piedmont. For Saturday, near seasonal temperatures
expected with low to mid 60s west and low to mid 70s east. Following
the front Saturday evening, temperatures drop into the 30s across
the mountains and low to mid 40s east.


As of 230 PM EDT Thursday...

Dry high pressure will be overhead Monday. With dry air and abundant
sunshine, temperatures will warm to near normal levels. The center
of the high will slide off the southeast coast on Tuesday. The
addition of southerly flow will push afternoon temperatures well
above normal Tuesday into Thursday. Expected temperatures through
the middle of the week to run 10F warmer than normal.


As of 145 PM EDT Thursday...

All sites should remain VFR for the rest of this afternoon, but
an approaching upper level trough will bring lower ceilings by
this evening. A slight chance of thunder is possible for DAN,
but confidence is not high enough to mention. Showers should
spread across the area and provide some temporary MVFR/IFR

There is greater confidence for poorer flying weather after
midnight tonight. Low clouds and patchy fog will likely bring
IFR and possibly LIFR conditions to all sites by Friday morning.
Gradual improvement to VFR is expected as the morning
progresses. Winds will be too light throughout the valid
forecast period to pose any issues, but they could pick up a
little later that afternoon.

Extended Aviation Discussion...

High pressure should build overhead during Friday night into
Saturday to bring VFR conditions for all sites by Saturday
afternoon. Good flying weather will persist through the
remainder of this weekend and into early next week.




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