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091
FXUS61 KRNK 061457
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
1057 AM EDT Mon May 6 2024

.SYNOPSIS...
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An upper level trough of low pressure, over the lower Ohio
and Tennessee Valleys, will move east and across the mid
Atlantic Region today. This will result in the formation of
scattered to numerous showers and thunderstorms this afternoon
and evening. Storms this afternoon may contain heavy rain and
small hail. The weather pattern will remain unsettled for much
of the upcoming week with a daily threat of afternoon and
evening thunderstorms.
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&&

.NEAR TERM /THROUGH TONIGHT/...
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As of 1050 AM EDT Monday...

Key Messages:

1. Scattered to numerous showers and thunderstorms this
afternoon and evening.

2. A few strong storms possible between 3PM-7PM with small hail
and heavy downpours.


Morning sounding at RNK showed precipitable water around 1.15
inches, which is above the 90th percentile of climatology for
today, indicating a very moist atmosphere. Moisture is expected
to increase through the day via southwesterly flow. Temperatures
are already in the mid to upper 60s, some breaks in the clouds
over the New River and Roanoke Valleys, and east into the
Foothills helping temperatures in those areas reach 70. No major
changes made to the forecast this morning, just to blend in
current temperature and sky cover observations, as fog has
dissipated for much of the area, except for parts of the NC
Piedmont.


Previous discussion below...

As of 700 AM EDT Monday..

In spite of areas of low level stratus and fog this morning the
wedge of stable air east of the mountains is pretty much gone.
No longer see any easterly component to the winds at the
surface, and once mixing begins later this morning should see
southerly winds at the surface promoting rapid warm up. Short
wave trough which brought heavy rain to TX is now crossing the
lower OH and TN Valleys, this upper support progged to cross our
forecast area later this afternoon and evening. Current
forecast is for scattered to numerous showers and thunderstorms
and for the most part this sounds reasonable. Concern is that
timing of the vort axis and max PVA will occur during the peak
heating leading to MUCAPE of 1500 j/KG and possibly a little
higher over the piedmont. This suggest potential for a few
strong pulse type storms and/or cluster or two of loosely
organized storms which may produce small hail and heavy rain.
PWAT forecast of 1.30 RNK to 1.70 GSO will be tracking near max
value for the time of year, so would expect very rain efficient
airmass and potential for localized heavy downpours. In this
environment, QPF will be highly variable, but can`t rule out
localized thunderstorm which may dump up to 3 inches of rain
causing flash flood scenario. In general thinking a marginal
threat for severe if MUCAPE exceeds 1500 and marginal threat for
excessive heavy rain if PWATs verify 90th percentile or higher.


Used the warmer MAV MOS for temperatures this afternoon. MET
MOS looks too cool per loss of wedge. Dewpoints in the 60s are
forecast areawide, so it should feel rather humid.

Upper trough will exit the region tonight, showers/storms fading
with the loss of daytime heating. Will taper pops by midnight
with little or no activity after midnight.
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&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
As of 430 AM EDT Monday...

Key Messages:

1: Unsettled conditions leading to showers and thunderstorms each
day

A few shortwaves in the vicinity of a stalled front will maintain
unsettled weather in the area through Wednesday. Tuesday features
some mid-level ridging that will act to suppress more severe storm
formation. However, there still exists a marginal threat for
damaging winds or large hail up to 1" in size.

On Wednesday the instability in the atmosphere will be greater than
on Tuesday. In addition the mid-level ridge will be gone, replaced
by approaching troughing and overhead zonal flow. This setup lends
itself to scattered thunderstorms with some severe potential, with
the greatest threat being damaging winds. With less limiting factors
and encroaching troughing and a surface low in the west, highest
threat will be west of the Blue Ridge.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 500 AM EDT Monday...

Key Messages:

1. Warming trend to start the work week, cooler and dry next
weekend.

2. Showers and thunderstorm chances each day.

Thursday into Thursday night we will see more chances for
showers and thunderstorms. A slowly filling surface low will
move west to east across the OH Valley, putting us just south of
the triple point and well under dense cloud cover for most of
the area. Instability looks best for our northern NC counties,
which may see some strong thunderstorms. The initial short wave
trough associated with the upper level system will be positively
tilted and crosses the Appalachians Friday and Saturday,
pushing a cold front ahead of it. This will mean more widespread
rain and thunderstorms. While there are mixed signals as far as
severe thunderstorm chances, the chances for moderate to heavy
widespread rainfall leading to flooding increases each day
during this wet period, and at the moment looks like the bigger
threat.

High temperatures gradually decrease each day Thursday through
Saturday with overcast skies and the passage of the front. We
may finally see the sun either late Friday or Saturday. The
weekend looks cooler and drier with dew points dropping into the
30s and 40s, and this is supported by NAEFS situational
awareness projections.

Confidence in the long term is moderate for most parameters,
but lower for timing of showers and storms.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
As of 700 AM EDT Monday...

Dealing with patchy fog and stratus early this morning. Area of
dense fog ongoing generally east of LYH/DAN.

After morning stratus and fog, expect cloud buildups early
afternoon. Upper level trough over the lower OH and TN valleys
will cross the Appalachians during the peak heating of the day
so would anticipate formation of scattered to numerous showers
and thunderstorms this afternoon and persisting until loss of
daytime heating. Cloud bases will be highly variable today,
favoring sub VFR as a whole. Winds sfc and aloft will be from
the south and southwest, under 10 kts at the surface, but with
higher speeds/gusts near thunderstorms. Do think the showers and
storms may become loosely organized with clusters of storms
producing small hail and downpours of heavy rain.

Showers/storms are expected to fade will loss of daytime heating.
However, clouds will linger with reformation of sub-VFR stratus
and fog after midnight .

Forecast confidence is average, but lower on specific locations
of showers and storms this afternoon and evening.

Extended Aviation Outlook...

Unsettled weather is expected for much of the upcoming week.
Daily threat of SHRA/TSRA Tuesday through Friday. This will
bring periods of MVFR/IFR ceilings and visibilities at times.
Winds through Wednesday will favor a SW direction and may be
gusty at times.

&&

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

&&

$$

SYNOPSIS...PM
NEAR TERM...AS/PM
SHORT TERM...VFJ
LONG TERM...SH/VFJ
AVIATION...PM