Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 301049

Area Forecast Discussion
National Weather Service Blacksburg VA
649 AM EDT Fri Jul 30 2021

A cold front will cross the Mid Atlantic region today with a
chance of showers and thunderstorms mainly over North Carolina
this afternoon, then slightly cooler and drier conditions on
Saturday. The chance of precipitation returns Saturday night
and Sunday, then a second cold front passes through Sunday
night. Dry weather and less humidity will follow that front for


As of 420 AM EDT Friday...

 Probability of showers and thunderstorms remains low today...

The eastern end of a long band of showers and thunderstorms
extended into extreme southwest Virginia and northwest North
Carolina this morning. HRRR had a reasonable depiction of the
location of the rain, including the scattered showers that were
forming in eastern West Virginia. Followed this model but
adjusted a few hours faster for probability of precipitation

The cold front will pass through the area this morning, leaving
the better low level convergence and more unstable air over the
Carolinas in the afternoon. Have trimmed the probability of
precipitation for southern Virginia and northern North Carolina
this evening. Some signals in the guidance and in a few of the
convective allowing models that isolated showers and
thunderstorms may pop up around Buckingham county late today.
But, not enough consensus between models to include any chance
at this time.

The wind turns to the northwest then north behind the front
leading in drier air. Dew points lower into the 50s for much of
the region by Saturday morning. Starting with a large shield of
cirrus over central and southern Virginia and much of North
Carolina this morning. Along with a slightly cooler air mass
coming in, the clouds will limit some heating. Highs today will
be a tad cooler than on Thursday. Stayed close to NBM numbers
for lows tonight.


As of 230 AM EDT Friday...

The Appalachians will be in westerly flow through the weekend and
into early next week, located in the stronger belt of flow
associated with the southern edge of troughing. This trough
encompasses eastern Canada as well as the United States. By Monday
evening, a digging short wave will reconfigure the main trough axis
to our west, putting our area in SW flow. This pattern more or less
holds for much of the week. Unfortunately this pattern in summertime
will translate to numerous bouts of precipitation.

While Saturday looks dry under high pressure, a baroclinic zone to
our south will begin to edge back north Saturday night into Sunday.
We will see some WAA showers overnight with thunderstorms possible
across the region Sunday. By late Sunday night, a cold front in the
Ohio Valley will have been pushed south by the digging short wave
mentioned above. Any convection should end across our area as drier
air filters in from the north. Monday looks mostly dry during the
day, but the baroclinic zone remains in the vicinity and may move
north again. This will keep a threat for showers and thunderstorms
around mainly in the afternoon and evening.

Temperatures during this time will be a few degrees below average
along and west of the Blue Ridge with readings in the mid 70s to low
80s. The piedmont and Southside VA will be closer to normal values
and in the mid 80s.


As of 230 AM EDT Friday...

On Tuesday we have more moisture to work with, along with a
significant short wave overhead, in addition to a frontal boundary
nearby. Because of this, Tuesday looks to be the day this week for
more widespread convection. By mid week the upper level trough which
has dominated the eastern CONUS for at least a week will begin to
break down. There will be enough cyclonic flow and surface heating
each day for the remainder of the week to generate showers and
thunderstorms in the afternoons, but nothing will be very organized.
Temperatures will continue to drop in the drier and cooler air mass.
Tuesday through Thursday will be the coolest days, with highs in the
low 70s to low 80s northwest to southeast across the area. It will
begin to warm back up for the end of the week.


As of 645 AM EDT Friday...

High clouds from storms over the Tennessee Valley extended into
central and southern Virginia and northern North Carolina. MVFR
clouds were along the western slopes of the central
Appalachians as well as some MVFR to IFR fog and stratus.

A cold front will cross West Virginia and Virginia this morning
then North Carolina this afternoon. The probability of showers
and thunderstorms along and ahead of the front was too low to
include in area TAFs. Models were showing drier and slightly
cooler air advecting into the Mid Atlantic region today.
Conditions over the mountains will improve back to VFR by

The wind will turn to the northwest then north behind the
front. Gusts of 15 to 25 knots are likely once mixing begins
today. The wind will decouple and become light and variable in
most locations after sunset. This light wind combined with
little to no cloud cover may result in fog along the rivers
overnight. KLWB may have IFR to LIFR fog early Saturday morning
but confidence was too low to include in the TAF at this time.

Average confidence for wind and ceiling.
Below average confidence for visibility.

Extended Aviation Discussion...

The next chance of showers and thunderstorms will be on Saturday
night and Sunday along with MVFR ceilings and visibilities with
any of the storms.

Sunday night a cold front comes through the region with a
chance of showers and thunderstorms and associated sub VFR
conditions. Monday will be dry and VFR behind the front.
Precipitation and sub VFR conditions return to the area on




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