National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRNK 220139
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
939 PM EDT Wed Aug 21 2019

.SYNOPSIS...
Weak high pressure will remain over the region tonight resulting in
a continuation of the muggy weather. A cold front approaches by the
end of the week bringing increasing chances of showers and
thunderstorms Thursday and Friday. This front should finally work
southeast through the area Saturday with less humid weather possible
Sunday.

&&

.NEAR TERM /THROUGH THURSDAY/...
As of 930 PM EDT Wednesday...

A few isolated showers linger across southside, otherwise
rain threat has pretty much ended. Evening RNK sounding
indicates dry air above 600 mb. This in addition to loss of
daytime heating should limit any additional shower activity. The
only area to watch for renewed activity will be along the
windward slopes...west side of the Appalachians, where weak
westerly winds overnight may provide enough convergence to
initiate some isolated showers late tonight.

Temperatures have been slow to fall where it did not rain
Tuesday, but overall expecting lows in the 60s to around 70.

A cold front will approach from the north Thursday. Scattered
showers and thunderstorms will develop especially during the
afternoon and evening hours. Better forcing remains to our north
and west, though we should still have enough convergence and
instability along the Blue Ridge and Alleghany Mountains for
storms to start in the high terrain and then travel east into
the Piedmont. There remains the potential for scattered pulse
severe storms with the strong instability. The SPC Day 2
highlights the chance for severe thunderstorms with a marginal
risk on Thursday. High temperatures on Thursday will vary from
the upper 70s in the mountains to the lower 90s in the piedmont.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 307 PM EDT Wednesday...

A cold front is expected to stall across the southern Ohio River
Valley Thursday night. A surface reflection will then track along
this boundary, moving to central/northern Virginia on Friday. With
the front close to the area, scattered mountains (isolated east of
the Blue Ridge) showers are possible Thursday night into Friday
morning. Friday afternoon, this surface reflection will move east of
the area and with strong heating (highs in the upper 80s), there is
a marginal risk for severe storms Friday afternoon and evening east
of the Blue Ridge. Morning clouds and rain should keep the
heating/instabilities low across the mountains. The primary threat
will be gusty winds. Torrential downpours are also possible but the
threat will mostly be localized/isolated.

As convection exits the area Friday evening, the cold front will
slide south into the Carolinas into the day Saturday. As the front
was slow to enter the region, it will also be slow to exit. Light
rain and thick clouds may linger along and south of the VA/NC border
through the day Saturday. Drier air will work into the region from
the north Saturday night. High temperatures Saturday will range in
the 70s.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 300 PM EDT Wednesday...

If the front sinks south into the Carolinas Saturday, cool northeast
winds will keep the area dry into Monday (ECM). The latest GFS has
an upper level trough moving northeastward across the Ohio Valley
with overrunning warm moist air moving over a wedge of cooler air.
We think the GFS is overdone on measurable precipitation, but think
it has the right idea with increasing cloud cover. The wedge is
expected to hang over the region into Tuesday morning then erode
with the passing of a weak front.

Temperatures will run 10F or cooler than normal Sunday and Monday.
Temperature return to normal Wednesday.

&&

.AVIATION /02Z THURSDAY THROUGH MONDAY/...
As of 930 PM EDT Wednesday...

Predominantly VFR anticipated through the overnight and during
the day Thursday. With light winds and low level moisture,
SCT-BKN areas of low cloud and patchy fog may develop late
tonight into early Thursday morning, but confidence low as to
whether it will be widespread. KLWB has the best chance for
IFR/LIFR fog overnight since it is near the river. KBCB may
briefly drop to IFR, also due to a light west wind causing drift
of fog off the New River and into the airport there. Otherwise
not expecting anything less than TEMPO MVFR due to fog/stratus
around daybreak Thursday which should dissipate with the morning
heating.

The hot and humid weather continues Thursday with scattered
MVFR showers and thunderstorms...buildups by noon yielding SCT-
BKN cumulus field with embedded deeper convection.

.Extended Aviation Discussion...

Weather pattern will continue to promote scattered showers and
thunderstorms. A cold front will approach from the northwest
late in the week, resulting in scattered to numerous
thunderstorm with potential for organized clusters of
thunderstorms to track across the Ohio Valley into the Mid-
Atlantic region.

Improving conditions with more in the way of VFR will be
possible for the late weekend, pending just how far south of
the Mid Atlantic area the front progresses. Some MVFR showers
are possible in the southwest portion of the forecast area
on Monday.

&&

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

&&

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