Area Forecast Discussion
Issued by NWS Blacksburg, VA-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KRNK 230114
Area Forecast Discussion
National Weather Service Blacksburg VA
914 PM EDT Mon Aug 22 2016
-- Changed Discussion --High pressure will slide east across the region overnight through
Tuesday afternoon, then reside along the Mid-Atlantic coast into
Wednesday. The next decent chance of showers, for at least areas
west of the Blue Ridge, will be Friday when a cold front moves
into the area.
-- End Changed Discussion --
.NEAR TERM /THROUGH TUESDAY/...
-- Changed Discussion --As of 855 PM EDT Monday...
Very comfortable overnight in store for late August with dewpoints
in the 50s in all except the far southern/eastern sections. Seeing
some high clouds stream across which looks to continue for the
next few hours before the upper wave axis to the south slides east
followed by surface high pressure building overhead late. This
should allow for mainly clear skies overnight with good radiational
cooling outside of patchy fog/stratus late. May still have to
watch for some patchy strato-cu near the Blue Ridge under the
steep inversion seen off evening soundings but think overall dry
air to win out overnight. Expect overall lows in the 50s except
perhaps around 60 south/southeast, with a few 40s possible deeper
valleys where fog is less, so lowered lows a few degrees overall.
Previous valid discussion as of 237 PM EDT Monday...
High pressure will continue to provide lower humidity through
Tuesday as it moves from the Ohio Valley east to the mid-Atlantic
coast. The cumulus out there today will fade somewhat after sunset.
The 12z NAM however lingers lower clouds throughout the night. Given
drier air aloft, not seeing this. At times, some thin cirrus will
pass by overnight. Overnight, expect lows to range from the lower to
mid 50s in deeper mountain valleys, to lower 60s in the piedmont.
Fog will also be present near the rivers in the west.
Tuesday will be mostly sunny. Flow turns more southeast as the high
shifts off the coast. Dewpoints slowly rise, but still favor a less
humid feel, than recent weeks. As 5h heights rise some, expect high
temps to range from the upper 70s to lower 80s west to mid 80s
east. Some cumulus should form in the heat of the day along the
slopes of the Blue Ridge given southeast flow.
-- End Changed Discussion --
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
As of 130 PM EDT Monday...
The center of high pressure will gradually work its way southeast
from near Pennsylvania to off the North Carolina coast by Thursday.
Concurrently, the upper trough pattern over the region will
transition to more of a zonal flow will increasing geopotential
heights. The result will be a trend towards temperatures around
normal to readings about five degrees above normal by Thursday.
Precipitation will slowly start to be reintroduced into the
forecast. On Wednesday, there may be enough of a southerly return of
moisture into the northern mountains of North Carolina for some
afternoon isolated showers or storms. By Thursday, that moisture
return will be even greater, and the influence of the capping of the
ridge less. Isolated to scattered coverage of afternoon and evening
showers and storms is expected across the mountains and just east of
the crest of the Blue Ridge. Any activity should dissipate quickly
around or after sunset.
Thursday night, a cold front will be approaching the region from the
northwest. Its influence may allow for some late night showers to
arrive across far western portions of the area.
.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 230 PM EDT Monday...
During this portion of the forecast we will transition back into a
more active pattern for daily chances of showers and storms. There
will be the potential for both diurnal and differential heating pop-
up showers and storms primarily across the mountains. We will also
have periodic shortwave troughs progress across the area and add to
the potential for additional, more organized precipitation.
Guidances varies as to the timing and magnitude of these
disturbances. However, the general consensus offers a solution that
the Sunday into Monday time frame will be when these will become
more frequent. The far eastern sections of the forecast area will
see the least amount of coverage.
Temperatures on Friday will average five to ten degrees above
normal. Each day slightly cooler conditions are expected so that
readings by Monday will be around, or slightly higher than normal.
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
As of 655 PM EDT Monday...
High pressure will drift slowly east across the region tonight into
Tuesday night before sliding to the Mid-Atlantic coast on
Wednesday. This will keep widespread VFR conditions in place under
scattered afternoon cumulus each day. The only exception will be
early morning fog mainly at western TAF sites, especially
KLWB/KBCB where IFR or worse will be possible.
Extended aviation discussion...
Thursday a bit more moisture will work its way north into western
parts of the area on the west side of a departing high pressure.
Isolated showers will be possible across the mountains, but for
the most part, VFR conditions will still prevail.
On Friday, there is a greater chance of showers, and possibly some
storms, with the approach of our next cold front. Pockets of MVFR
conditions will again occur briefly under the stronger showers or
The front should wash out across the region Saturday although
enough moisture will remain for diurnal mountain showers and
storms Saturday afternoon when periods of MVFR could occur.