684
FXUS61 KRNK 060134
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
934 PM EDT Wed Jun 5 2024

.SYNOPSIS...
A warm and moist airmass will remain over the area through
Thursday promoting showers and thunderstorms. A cold front will
move through the region Thursday night introducing drier and
cooler weather to start the weekend.

&&

.NEAR TERM /THROUGH THURSDAY/...
As of 925 PM EDT Wednesday...

Key Message:

1) Activity ending for now, additional storms by morning across
the north, and moving south through the day.

2) Severe weather likely for the Piedmont region of VA and NC
tomorrow afternoon and evening, with damaging winds the main
threat.

The short wave energy that brought scattered showers and storms
to our area this afternoon and evening continues to move
northeast. Most of the cells produced heavy rain but were moving
at a faster clip than they were yesterday. There were a couple
storms that produced gusty winds...but lacked focus. A few
lingering showers were currently drifting ENE across the
Piedmont. We should have a dry few hours before a cold front
approaches, reaching our SE WV and northern VA counties around
dawn, and spreading southeast through the day Thursday.

Showers and storms may weaken as they cross the Blue Ridge in
the morning, then reinvigorate over the Piedmont tomorrow
afternoon and evening. MUCAPE looks to be between 1000-1500
J/kg, and effective shear improves to about 30 kts. PWATs will
again be quite high near the boundary, so heavy rain is likely
again. With favorable timing of the frontal passage for severe
weather, steep LL lapse rates, and the above parameters, we
will see some strong to severe storms producing damaging winds,
mainly over the Piedmont.

As we remain in the warm sector, temperatures and humidity
levels will remain on the warm/high side until the frontal
passage. Expect stratus and patchy fog overnight.



As of 230 PM EDT Wednesday...

Key Messages:

1) Warm humid conditions will persist through Thursday before
turning cooler Friday.

2) Scattered to numerous showers and thunderstorms expected
through Thursday.

Forecast focus the next 24 hours will be the opportunity for
showers and thunderstorms. Coverage of showers/storms will be
the greatest between now and sunset, then again with the frontal
passage on Thursday.

Regional soundings from 12Z were very moist with PWATs 1.60 to
1.80. Mean wind is from the west-southwest at 20 kts...so
storms are moving a bit faster today compared to
yesterday...20-25 mph forward speed. This should cut down on
residence time of the heavy rain, but with PWATs above normal,
activity will be very rain efficient and still justifies
marginal risk for excessive rainfall and localized flooding.
DCAPE is less than yesterday but trade off will be faster mean
wind, so still think there is modest wind threat with down-draft
wind speeds on the order of 30 kts with potential for isolated
wind damage. Stronger cores may also contain pea size hail.

Weather map shows cold front from the upper Mid-West to North
Texas with Gulf moisture streaming north ahead of the front, the
eastern CONUS bathed in near 70 degree dewpoints. There are a
couple of MCVs embedded within the moist southwest flow ahead of
the front, one of which was moving E along the Mason Dixon, and
the other over the southern Appalachians...both features
providing lift for better thunderstorm organization today,
compared to yesterday. The Vort entering the southern
Appalachians will be the primary focus for thunderstorms across
our CWA through this evening. With the favorable thermodynamic
and dynamic set-up, will maintain high chance for measurable
rainfall through sunset. With PWATs near 2.0 inches, expect high
rain rates...2-4 inches/hr possible. Had some reports
yesterday with the storms producing .80" in 15 minutes.

In general, expecting shower/storm coverage to wane with loss of
daytime heating, with lull in activity before the actual surface
front arrives. Models bring front to our doorstep by daybreak
Thursday so looking at opportunity for increasing shower
activity late tonight across our WV and far western VA
counties. Not sure if the band of showers associated with the
front will be continuous enough to cross the mountains Thursday
or just fade and then redevelop east of the mountains Thursday
afternoon. For now, will maintain high pops areawide Thursday,
in spite of the potential for a hydraulic jump.

Until the front clears the area Thursday, dewpoints will remain
elevated. Given the nature of the airmass, the rain just makes
it more muggy, providing little in the way of evaporational
cooling when it does rain, and downright steamy if the sun is
out.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 230 PM EDT Wednesday...

Key Messages:

1. Drier weather returns Friday and Saturday.
2. Cooler temperatures through the weekend.

An upper level low will drift east of the Great Lakes towards
Ottawa Canada through the period. Shortwaves coming around
this low will bring strato-cumulus clouds across the area Friday
and Saturday. Any measurable rain will be along the western
slopes of SE WV and possibly a sprinkle over the rest of the
mountains Thursday night into Friday.

Dry high pressure will track southeast across Tennessee Friday,
then settle over Georgia/South Carolina Friday and Saturday.
With the Gulf blocked, any disturbance coming from the Plains
should only result in an increase in clouds.

Since the area will remain under the influence of the low in
Canada, cooler than normal temperatures are likely Friday and
Saturday. High temperatures through the period will range from
the upper 60s to mid 70s west of the Blue Ridge to the lower 80s
east.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 230 PM EDT Wednesday...

Key Messages:

1. Chances for showers and possible storms Sunday and again
Wednesday.
2. Cooler temperatures through the start of the work week.

Models are in agreement with a cold front moving across the area
on Sunday, but differ on rainfall amounts. Since the flow will
mainly be out of the west and high pressure blocking the Gulf
through at least Saturday night, rainfall amounts should be at
or under a tenth of an inch. This front is expected to stall
across North Carolina on Monday then lift north as a warm front
on Tuesday. The chance for rain increases on Wednesday as a
disturbance from the Midwest tracks over the region.

Cooler than normal temperatures expected through the period.
Temperatures will possibly trend back to normal on Wednesday

&&

.AVIATION /01Z THURSDAY THROUGH MONDAY/...
As of 920 PM EDT Wednesday...

Deep convection has largely ended, with just a few areas of
showers.

Expect a lull in the storms overnight with winds subsiding. Fog
may develop overnight but cloud cover and an approaching cold
front associated with more showers may limit this so kept vsbys
no worse than MVFR mainly in the mountains. -SHRA/-TSRA likely
for all terminals after 12Z through about 20Z. +TSRA possible
for LYH, DAN, and ROA after 15Z.

Forecast confidence is average on all elements.

EXTENDED AVIATION OUTLOOK...

Passage of a cold front is expected Thursday with scattered
showers and thunderstorms, flight restrictions favoring MVFR (or
lower). Showers/storms could be close to BLF/LWB by 12z Thu.

Friday is expected to be drier and a better probability of VFR
conditions behind the front. A few showers possible Sat-Sun in
the mountains but mainly VFR.

&&

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

&&

$$

SYNOPSIS...PM
NEAR TERM...PM/SH
SHORT TERM...RCS
LONG TERM...RCS
AVIATION...PM/SH