358
FXUS61 KRNK 201737
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
137 PM EDT Thu Jun 20 2024

.SYNOPSIS...
High pressure will continue to sit over the region
through the end of the week and into the weekend, keeping the
weather mostly dry, though isolated showers and storms over the
mountains are possible over the weekend and into the beginning
of the work week. Better chances for storms come midweek. Above
normal temperatures and increasing humidity through the Monday
will lead to increasing risks of heat related impacts over the
weekend.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 130 PM EDT Thursday...

Key Messages:

1. Above normal temperatures continue through the forecast period.
2. More humid and warmer temperatures Friday, possible isolated
to scattered afternoon thunderstorms in the mountains.

A strong ridge of high pressure maintains over much of the eastern
US, centered over the Mid Atlantic and into the Atlantic Ocean.
Subsidence from this ridge and associated surface high pressure will
keep the weather dry over the area for the rest of the day and
Friday. The ridge weakens somewhat Friday, and begins to shift
to the southwest of the area. Surface winds will become more
south-southeasterly by Friday afternoon, the easterly component
weakening and thus meaning less flow off the Atlantic, and so
temperatures will be a few degrees warmer tomorrow than today.
This will also tap into the greater moisture to the south, thus
increasing the humidity, and making Friday feel hotter,
especially in the Piedmont, and southern Shenandoah and Roanoke
Valleys.

With the additional moisture present, and ample daytime heating
helping to destabilize the atmosphere, there is a slight chance for
showers and thunderstorms over the mountains during the afternoon,
though coverage would be isolated, and lack of deep layer shear will
limit any storms that do form from becoming severe.

High temperatures today will be in the low to mid 80s in the higher
elevations of the southern Blue Ridge of VA and NC, and southeast
WV, and in the upper 80s to near 90 in the valleys and east of the
Blue Ridge. Lows tonight will be in the low to mid 60s over most of
the area, upper 50s for the cold spots in the Mountain Empire of VA
and northwest NC. Tomorrow, expecting a few degrees warmer for
the highs temperatures

Forecast confidence is high.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 1100 AM EDT Thursday...

Key Messages:

1. The worst heat and humidity stay out of our forecast area,
but we will be hot and somewhat humid through Monday.

2. Weak front Sunday night into Monday will bring scattered
showers/storms mainly to the mountains.

3. Cooler and drier in the mountains behind the front for Monday.

High pressure at the surface drifts south and weakens its hold
somewhat over the Mid Atlantic on Friday night, and further
retreats east into the western Atlantic over the weekend. Aloft,
the oppressive ridge bringing heat to much of the area will be
over the TN Valley on Friday, and spreads west to cover most of
the southern/southwestern CONUS over the weekend. This puts us
just inside the envelope of the higher temperatures, and opens
the door for slightly higher humidity for the weekend. That
said, it is not exceptionally humid, with 925 dew points of
12-14C during this time close to the daily mean according to
ECMWF ENS percentiles for this time.

Looking at the Integrated Water Vapor forecast from NCEP, much
of the region`s mid and high level moisture actually funnels
clockwise from previous TS Alberto in northern Mexico, up
through the Plains and finally sags south from the OH Valley
Sunday and Monday.

A surface trough drifts into the area by Sunday night, and
should trigger showers and thunderstorms. A few storms may pop
up as early as Saturday afternoon over the higher terrain, but
spatial coverage will be low due to capping. For Sunday, models
indicate this feature may break up along the higher terrain, so
most if not all the measurable rain is expected over the western
mountains. CAPE does not look especially impressive, nor does
shear through the weekend, so if anything would be concerned
with brief heavy rain and lightning.

We are around 1-3 standard deviations above normal for
temperatures during this time, with temperatures in the 80s
and 90s for highs, and heat indices staying below 100 degrees,
even in the Piedmont. Overnight lows will be in the 60s with a
few 70s possible. Possible record high and record warm low
temperatures are in jeopardy Sunday and Monday, see Climate
section below. Of the 3 days, Sunday looks the worst as far as
heat, with the ECMWF Extreme Forecast Index pegging highest that
day for our area.

Confidence in the short term is high.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 1100 AM EDT Thursday...

Key Messages:

1. Heat and humidity continues, but remain below Advisory/
Warning criteria.

2. Scattered showers/storms Monday, but more widespread Wed/Thu.

On Monday we will be in NW flow aloft as a northern trough
swings east, and continues to push a weak front out of our
southwestern counties on Monday morning. The mountains remain a
touch cooler, with highs in the 80s, but the Piedmont remains
hot with heat indices just shy of 100 degrees.

Monday scattered showers and storms will be possible, mainly
over the mountains and ahead of and along a front which pushes
through in the heat of the day. Tuesday looks dry behind the
front, which will make things less humid, but it still looks
very hot, especially for the Piedmont. The heat continues in
this manner through mid week, with a stronger frontal passage
expected Wednesday or Thursday. 925mb dew points increase to
about 18C ahead of the front. CSU machine learning site show a
possibility of severe weather Monday and again Wednesday/
Thursday with these feature. Damaging winds currently look like
the main concern.

Heat indices remain below Heat Advisory/Excessive Heat Warning
criteria for both the mountains and the Piedmont, and this is
supported by GEFS probabilistic forecasts.

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

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
As of 135 PM EDT Thursday...

VFR conditions are observed across the area, and will continue
to do so through the TAF period, ending at 18Z Friday. The dry
weather continues through Friday, with partly to mostly sunny
skies for most. Clouds start to increase west of the Blue Ridge
towards the end of the TAF period Friday afternoon. There is a
chance of isolated afternoon showers and possible thunderstorms
for mainly southeast WV by Friday afternoon, due to increasing
moisture and temperatures, but confidence is low so have opted
to not include in any TAFs at this time. Light winds, up to
around 5 knots, generally turn more south-southeasterly through
Friday, but variable overnight. Some patchy river valley fog is
possible for a few hours Friday morning, so have included in
the KLWB TAF for now.

Forecast confidence is high, but low for precipitation chances
and coverage late in the TAF period.

EXTENDED AVIATION OUTLOOK...

Pattern favors dry conditions into Saturday with increasing
chance for storms Sunday into Monday. Overall VFR through the
period aside from any morning fog at LWB and storms Sunday and
Monday. Chances for showers and storms increase again for the
middle of next week.

&&

.CLIMATE...
As of 1100 AM EDT Thursday...

The following record high and record warm low temperatures may
be in jeopardy this week:

Sunday 06/23/2024
ROA record high minimum, forecast 73, record 75 (set in 1996)
LYH record high, forecast 97, record 98 (set in 1911)

Monday 06/24/2024
ROA record high minimum, forecast 73, record 72 (set in 2010)

Wednesday 06/26/2024
LYH record high, forecast 99, record 98 (set in 1952)

&&

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

&&

$$

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