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131
FXUS61 KRNK 212313
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
713 PM EDT Fri Jun 21 2024

.SYNOPSIS...
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High pressure will remain over the area into the weekend,
keeping the weather mostly dry through early Sunday. A front
drops down Sunday into Monday with increasing chances for
storms. Above normal temperatures and increasing humidity will
lead to an increased risk of heat related impacts.
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&&

.NEAR TERM /THROUGH SATURDAY/...
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As of 700 PM EDT Friday...

Key Messages:

1. Isolated showers/storms possible in the mountains this
Saturday afternoon.

2. Weatherwise, Saturday will be similar to today, but slightly
warmer/more humid for the Piedmont.

Temperatures continue to increase but dewpoints are still
running in the tolerable level of 50s to lower 60s. A weak
convergence zone across the Alleghanys of WV led to a few
showers/storms earlier but trend in radar and models is for this
activity to be gone by 9pm. Cannot rule out patchy fog tonight,
but the drier antecedent conditions will likely make it
limited.

Previous discussion...

A sprawling ridge of high pressure continues to dominate much
of the southern and central CONUS, bringing heat and humidity to
millions. By Saturday night, the center will stretch from the
desert SW and eastward to encompass TX and some of the Gulf
Coast. An area of troughing north of the dome of hot air will
help with the formation of a deepening surface low over the
northern Plains. A weak surface trough was indicated on visible
satellite imagery as towering cumulus clouds across northern
VA and into WV this afternoon. Relatively low dew points in the
low to mid 60s and moderate subsidence will keep anything
substantial from forming, but we may see a sprinkle over SE WV
this afternoon.

Tonight, subsidence, calm winds, and clear skies will allow
temperatures to drop into the 60s. On Saturday, SW winds and
mostly to partly sunny skies along with the anomalously warm
air mass in place will support high temperatures in the mid 80s
to mid 90s. Dew points will edge upward, especially east of the
Blue Ridge, and heat indices will reach the upper 90s there.
This is shy of our Heat Advisory criteria of 105 to 109F for at
least 2 consecutive hours in the Piedmont. However, it is still
important to take extra precautions if you work or spend time
outside, such as drinking more water and taking breaks in air
conditioning. Heat exhaustion/stroke can happen to anyone.

For areas west of the Blue Ridge Saturday, lower dew points
will keep heat index values in the 80s to low 90s. There is
another small chance for isolated to widely scattered showers
and storms tomorrow afternoon and evening for the mountains, but
again coverage will be quite low.

Confidence in the near term is high.
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&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
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As of 200 PM EDT Friday...

Key Messages:

1: Hot Sunday

2: Front and storms cool back down for Monday

As most of the southern CONUS sits under a subtropical ridge,
temperatures will be ticking up this weekend. Being in the warm
sector of an approaching front will also work to push those
thermometers up. Heat indices on Sunday will likely cross over the 3-
digit threshold in the Piedmont, though only just. No heat
advisories in the cards just yet, as heat index values are forecast
to remain under 105 F.

A front is expected to pass over southwestern VA during peak heating
on Sunday afternoon. This could result in strong to severe
thunderstorms on Sunday. A few counties north of I-64 are outlooked
with a Marginal Risk of severe thunderstorms Sunday, with damaging
wind gusts being the greatest concern. The later the timing of the
front, and thus clouds and showers, the hotter the temperatures will
get.

Post-frontal environment and some cooling effects from showers and
storms will drop temperatures 5-10 degrees from Sunday to Monday. A
few showers could linger into the morning hours Monday, but the
stronger storms will have occurred Sunday.
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&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
As of 230 PM EDT Friday...

Key Messages:

1). Increasingly unsettled and variable weather through the
period.

2). Monday through Tuesday bring a respite from the heat and
humidity.

3). Hot temperatures surge back into the region for Wednesday
ahead of another cold front.

4). Widespread showers and thunderstorms expected Thursday with
notably cooler temperatures headed into the weekend.

A strong upper trough and frontal system will be developing to
our west and is slated to reach the region late Wednesday into
Thursday. This system will bring a definite end to the
hot/humid/lack of rainfall conditions of the past couple of
weeks.

However, the cooling and rainfall won`t occur until the area
experiences one more hot day on Wednesday. MEX guidance has
several sites within and north/east of the CWA reaching the
upper 90s on Wednesday. The record high 850mb temperature for
Blacksburg since upper air soundings were done at this location
(~1994) is +26C, which occurred on June 29, 2012. So the model
advertised 850mb temperatures of +22C to +24C at 850mb is
certainly pushing the upper end of the envelope!

As the front and upper trough move into the region Wednesday
night into Thursday, widespread showers and thunderstorms are
expected. Given the hot temperatures and instability ahead of
the front, some strong severe thunderstorms would seem to be a
good possibility contingent on the amount of upper-level capping
which would appear to be minimal given the notable height falls
and colder temperatures aloft associated with the deepening
trough.

At any rate, guidance is already advertising likely to near
categorical pops for the late Wed-Thu period and this seems
reasonable given the synoptic signals advertised by many of the
long range models. Caveats to widespread significant rainfall
will be the potential capping aloft and some indication of an
area of convection focusing along the Gulf Coast, hence the
C-Star effect! Temperatures will cool notably from the 90s on
Wednesday to highs only in the 70s west to 80s east Thursday and
Friday.

/Confidence Levels in Forecast Parameters/
- Moderate Confidence in Temperatures,
- Moderate to High Confidence in Precipitation Probabilities,
- Moderate Confidence in Wind Direction and Speed,
- Moderate to High Confidence in Thunderstorm Potential.

&&

.AVIATION /23Z FRIDAY THROUGH WEDNESDAY/...
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As of 700 PM EDT Friday...

Mainly VFR through the 24 hour TAF.

The only TAF site that may see brief fog is LWB, where dew
point depressions may become small enough, but confidence is too
low overall to add it in the forecast.

Winds remain light and south to SSW through tomorrow.

Forecast confidence is high.

EXTENDED AVIATION OUTLOOK...

Pattern favors VFR/dry conditions into Saturday night with
perhaps a chance for an isolated -TSRA near BLF or LWB in the
18-00Z time frame. Increasing chances for storms in brief MVFR
or lower conditions Sunday into Monday, mainly in the
afternoons. 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 Wednesday.
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&&

.CLIMATE...
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As of 200 PM EDT Friday...

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

Sunday 06/23/2024
Record High Minimum:
Roanoke - Forecast 73, Record 75 (set 1996)
Blacksburg - Forecast 68, Record 70 (set 1896)

Record High:
Roanoke - Forecast 97, Record 98 (set 1914)
Lynchburg - Forecast 97, Record 98 (set 1911)

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

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

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

&&

$$

SYNOPSIS...SH/WP
NEAR TERM...SH/WP
SHORT TERM...VFJ
LONG TERM...RAB/VFJ
AVIATION...SH/WP
CLIMATE...SH/VFJ/WP