721
FXUS61 KRLX 211858
AFDRLX

AREA FORECAST DISCUSSION
National Weather Service Charleston WV
258 PM EDT Fri Jun 21 2024

.SYNOPSIS...
The heat wave continues into the weekend courtesy of a broad
upper level ridge. A cold front crosses Sunday night, bringing
showers and storms to the area, and an end to the heat wave.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 110 PM Friday...

Ridge of high pressure will continue to remain in control through
Saturday, with above normal temperatures, and occasional showers and
storms during peak heating hours. Showers and storms this
afternoon/evening will mainly fire up along the mountains, and
across the north as a weak boundary sags south towards the area.
Severe is not anticipated at this time, but storms will be slow to
move with brief heavy downpours. Bulk of storms should dissipate
this evening with loss of heating, but there could still be an
isolated shower or storm overnight from any passing weak wave.
Otherwise, hot again on Saturday, with additional showers and storms
particularly during peak heating hours.  Fog possible again in
favored river valleys Saturday morning.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 255 PM Friday...

The upper level ridge associated with the current heat wave gets
shunted off to the deep south/southwestern U.S. this weekend, as
a mid-upper level short wave trough approaches. Increasing
forcing and modest 0-6 km bulk shear of 20-30kts acting on the
afternoon instability amid the hot, humid air mass, with CAPE
building to 2-3 KJ/kg in an axis ahead of the front, leads to
the potential for strong to marginally severe thunderstorms
Sunday afternoon and evening across the lowlands. The severe
threat decreases as convection crosses the mountains overnight
Sunday night, as instability decreases.

Showers and thunderstorms will have modest motion so, while PW
values up around two inches could result in locally excessive
downpours, widespread high water instances are not expected.

Central guidance evinces a very arm and humid Saturday night,
with rising temperatures on Sunday intercepted by increasing
clouds and developing convection, soon enough to preclude
extending the heat advisory into Sunday. Lows Monday morning
will be perceptibly lower across northwest portions of the
forecast area, slightly lower southeast, compared with Sunday
morning.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 255 PM Friday...

A cold front exits the forecast area Monday morning, bringing an
end to the prolonged heat wave. Its trailing positively-tilted
short wave trough, extending southwestward from a mid-upper
level low crossing northern New York and New England Monday,
crosses Monday morning and midday.

Showers will be limited to the mountains by dawn Monday, where
there may still also be a thunderstorm, depending upon the
timing of the front. This precipitation will gradually
dissipate during the day, with little if any opportunity for a
diurnal resurgence, as cooler and much drier air advects in
beneath the crossing short wave trough, with a strong post-
frontal/subsidence inversion.

High pressure builds in Monday afternoon, crosses Monday night,
and then exits Tuesday morning. This will bring about a clear,
comfortably cool night Monday night, with calm conditions
allowing valley fog to form.

The upper level ridge associated with the current heat wave
remains shunted off to the deep south/southwestern U.S. next
week, allowing west to northwest mid-upper level flow with
embedded short wave troughs/convective complexes over the area.
With low level south to southwest gradient flow behind the
exiting high feeding increasing warmth and moisture back into
the area, showers and thunderstorms become possible Tuesday
night, and then remain so until a deep enough short wave trough
pushes a cold front through the area Wednesday night or
Thursday.

Central guidance reflects temperatures and dew points lower by
several degrees compared with those during the current heat
wave, but enough to bring perceptible relief. The heat returns
Tuesday and Wednesday of next week as heights rebuild, but with
the ridging off to the southwest of the area, it will not be as
hot as this week. The heat will also be not as persistent, given
the passage of cold front later in the week.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
As of 115 PM Friday...

Isolated showers and storms through 02Z across the higher
terrain and possibly SE Ohio and north central WV, with brief
MVFR conditions. Otherwise, VFR area wide with light surface
winds, except for patchy MVFR/IFR or worse valley fog generally
08-12Z.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z SATURDAY...

FORECAST CONFIDENCE: High.

ALTERNATE SCENARIOS: Coverage and density of valley fog Saturday
morning may differ from forecast. More coverage of storms may
occur this afternoon than currently forecast.

EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH:   TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW:    TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.

UTC 1HRLY       15   16   17   18   19   20   21   22   23   00   01   02
EDT 1HRLY       11   12   13   14   15   16   17   18   19   20   21   22
CRW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
HTS CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
BKW CONSISTENCY  H    M    H    H    H    H    H    H    H    H    H    H
EKN CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
PKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
CKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H

AFTER 18Z SATURDAY...
No widespread IFR conditions are expected at this time.

&&

.RLX WATCHES/WARNINGS/ADVISORIES...
WV...Heat Advisory until 8 PM EDT Saturday for WVZ005>011-013>020-
     024>032-039-040.
OH...Heat Advisory until 8 PM EDT Saturday for OHZ066-067-075-076-
     083>087.
KY...Heat Advisory until 8 PM EDT Saturday for KYZ101>103-105.
VA...None.

&&

$$

SYNOPSIS...TRM/SL
NEAR TERM...SL
SHORT TERM...TRM
LONG TERM...TRM
AVIATION...SL