169
FXUS61 KRNK 050111
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
911 PM EDT Tue Jun 4 2024

.SYNOPSIS...
Warm and humid conditions will persist through Wednesday with
another opportunity for showers and thunderstorms during the
afternoon and evening. A cold front will cross the area
Thursday, temperatures cooling for the weekend. A brief break in
the wet weather pattern is expected behind the front on Friday
and Saturday.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
As of 900 PM EDT Tuesday...

Key Message:

1. Additional summer-type thunderstorms Wednesday.

Most of the convection has moved out of the forecast area or is
continuing to weaken. Still a few isolated showers that will
crop up overnight and into tomorrow morning with areas of
vorticity slipping under the mid level ridging we currently have
aloft. CAMs are highlighting additional showers and storms
moving west to east between about 5 to 10 AM, and then reforming
in the afternoon and evening.

Storms today were generally weak but very heavy rainers,
but a few storms took advantage of our instability and produced
wet downbursts which knocked down a few trees and power lines.
Expect similar activity tomorrow, with most of the severe threat
out of our area. We should still have enough instability, lift
and moisture to produce a few strong to severe storms.



As of 200 PM EDT Tuesday...

Key Messages:

1. Warm and humid.

2. Scattered showers and thunderstorms.

3. Marginal Risk of excessive rainfall, localized flash
flooding possible.

Upper air soundings support SBCAPE ranging from 1500 j/kg over
the mountains to 2500 j/kg over the piedmont through this
evening...enough buoyancy for scattered showers and
thunderstorms. Mean wind ranges from 6-12 mph out of the
southwest...so expecting slow cell movement and potential for
localized heavy rain. DCAPE near 700 j/kg also suggest some of
the stronger storm cores will contain modest downdraft winds.
The ROA ASOS has already sampled one of these gusts...observing
30 kts just after 2PM this afternoon.

For tonight, our area will continue to be under the influence of
a weak upper level ridge, although the axis is shifting to the
east and allowing for increased southwest flow aloft. The
southwest flow contains impulses aloft, short wave energy,
which will enhance precipitation chances over the next 24
hours. Current airmass features PWATs running 1.2 to 1.5 inches,
and these numbers are expected to increase into Wednesday per
increasing moist southwest flow. Temperatures tonight will
remain mild with lows mainly in the 60s. Dewpoints also in the
60s suggests a moist night with high humidity and potential for
patchy fog.

For Wednesday, much of the day is expected to be mostly cloudy,
especially over the mountains. Short wave trough may introduce
showers across the mountains early, then become more prolific
during the afternoon as CAPE increases over the piedmont. Attm
thinking weather hazards Wednesday will be mainly from the
localized heavy rain. Not sure that we see enough sun to
promote severe, but can`t rule out some healthier downdraft
winds similar to what occurred with the 30 kt gust at ROA Tue.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 200 PM EDT Tuesday...

Key Messages:

1. Moderate to heavy rain may lead to localized flooding
Wednesday. 2. Warmer than normal temperatures through
Thursday, cooler Friday.

A negative-tilted trough over the Great Lakes will push a pre-
frontal trough over the region Wednesday. Timing of this trough
will help determine the areal coverage of strong to severe
storms. As of now, models have convection coming across the
mountains after sunset, which would limit intensity due to loss
of heating. However, momentum of these storms coming across the
southern Ohio Valley may maintain as this line continues to move
through an unstable airmass. At this time, the severe threat is
low, but above normal PWATs will lead to a marginal risk of
flooding from excessive rainfall.

The surface front will move across the area Thursday. Some
modest instabilities may be present to trigger a few storms in
the piedmont Thursday afternoon. Friday looks to be dry, but
breezy given the decent cold air advection behind the front.
Cooler and drier air works its way into the region following the
frontal passage, so temperatures will drop a few degrees for
Friday and heading into the weekend.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 200 PM EDT Tuesday...

Key Messages:

1. Cooler temperatures through the weekend.
2. Chances for afternoon showers and storms continue.

The mid level trough will be situated over southern Canada and
the eastern US through the weekend, with a few shortwaves
rotating through the trough, keeping chances for showers and
possible storms each afternoon and evening in the forecast,
especially over the mountains. Some long range models are
showing a surface low and cold front developing in the south
central Plains by late Saturday, reaching the Mid Atlantic by
Sunday, bringing another round of heavy rain and possible
storms. However, with considerable differences in the models
with the evolution of the upper trough over southern Canada,
there is uncertainty in the forecast for the beginning of the
work week. That being said, there is potential for unsettled
weather to continue into Tuesday.

Temperatures will be on the cooler side through the weekend,
near to  a few degrees below normal, following the passage of
the cold front during the week, and dewpoints will drop a few
degrees as well. By the beginning of the work week, temperatures
will start gradually warming to near normal.

&&

.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
As of 900 PM EDT Tuesday...



Expect cloud build-ups with widely scattered showers/storms
through sunset, favoring both mountains and piedmont, but with
little organization. Downdraft wind gusts up to 30 kts may be
associated with some of the stronger storm cells. The activity
is expected to diminish after sunset, although may linger later
that usual due to lift from approaching shortwave energy aloft.

Fog will likely form late tonight with MVFR to IFR at most
sites, highest confidence for LWB to get fog.

Short wave trough will cross the forecast area Wednesday and
Wednesday night resulting in greater coverage of showers and
thunderstorms. Sub-VFR is favored Wednesday due to low cigs and
the abundance of shower activity with variable visibilities.


EXTENDED AVIATION OUTLOOK...

Passage of a cold front is expected Thursday with scattered
showers and thunderstorms, flight restrictions favoring MVFR (or
lower).

Friday is expected to be drier and a better probability of VFR
conditions behind the front. A few showers possible Sat 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