518
FXUS61 KRLX 041244
AFDRLX

AREA FORECAST DISCUSSION
National Weather Service Charleston WV
844 AM EDT Tue Jun 4 2024

.SYNOPSIS...
Warmer and quieter weather for today, cannot rule out an
isolated shower or storm. Showers and storms return Wednesday
ahead of a cold front on Thursday. Cooler for the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 844 AM Tuesday...

This morning`s forecast largely remains on track, but PoPs have
been updated across western West Virginia and northeast Kentucky
where isolated showers have developed.

As of 200 AM Tuesday...

Weak surface high pressure sort of fleets toward the southeast.
The good news is that upper level ridging will still cover the
area and keep most activity from developing. However, we cannot
rule out an isolated shower or storm with a 040FT Cu deck
forming in the afternoon. With temperatures climbing into the
mid to upper 80`s this afternoon, plenty of instability will be
available but we do have small caps to keep any agitated Cu from
fully developing.

One can imagine that activity can be still possible which is
why POPs and thunderstorm probability were added into the
forecast, but it should be very isolated in nature. Went with a
blend of Hi-res guidance which equated to slight chance to
chance POPs scattered among the area for this afternoon and
evening. Thereafter, chances increase late tonight, but thinking
it could increase during the late evening as well, in response
to a cold front moving closer to the area with activity out
ahead of it.

Lapse rates are well above environmental and PWATs are around
an inch with DCAPE values very high so there could be some
decent showers, but not thinking anything excessive or ones that
would cause water issues because we are dry in the mid to upper
levels. There is very weak shear and boundary layer flow with
no upper level support so anything that does form will be pulse
like cells that may move fairly slowly. The main focus will
likely be the mountains with smaller caps and elevated heat
effect helping out the development of cell growth.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 355 AM Tuesday...

Showers and thunderstorms may be ongoing Wednesday morning, as a
series of weak southern stream ripples cross, out ahead of a
better-defined mid-upper level short wave trough that crosses
late Wednesday night. This activity may limit heating ahead of
the main short wave, which will drive a surface trough/weak cold
front through the area overnight Wednesday night into early
Thursday morning.

The best chance for the strongest thunderstorms is ahead of
these nighttime features Wednesday evening. However, even then,
CAPE of just 500-1500 J/kg CAPE and modest shear of 20-30 kts
is not likely to support a severe threat, although strong wind
gusts are possible then. The CAPE does extend well up through
the hail growth layer, with the equilibrium level all the way up
past h20 Wednesday afternoon and evening.

Higher dew points, CAPE and shear just northwest of the forecast
area and closer to a low pressure center moving northeastward
through the eastern Great Lakes support a better chance for at
least marginally severe weather, as depicted in the SPC day one
convective outlook. A more intense low and better low level
south to southwest feed ahead of it could eventually seep the
severe weather threat southeastward into northwest reaches of
the forecast area Wednesday evening. The development of the low
level jet after sunset could also prolong the threat long
enough to carry it into the forecast area then.

PW values climb to the neighborhood of 1.75 inches Wednesday
afternoon, about as high as it gets in this area this time of
year, so heavy downpours are possible Wednesday afternoon and
evening, with a local high water threat wherever heavier
thunderstorms hit urban or other low lying, sensitive areas.

Shower and thunderstorm coverage decreases west to east after
sunset Wednesday night, as the mid-upper level short wave and
surface trough/weak cold front cross.

A large mid-upper level low over the west-central portion of
the continent digs in over the Great Lakes Thursday through
Thursday night, a short wave trough pivoting around the south
side of it drives a surface cold front through the area Thursday
afternoon and evening.

While the surface trough/weak cold front brings negligible if
any cooling, it does knock PW values down to around an inch.
Moreover, it takes out instability given the drier column and,
more notably, a stout mid-level cap that develops between the
last southern stream short wave exiting Wednesday night, and the
main mid- upper level system digging in. As such, convection
will be shallow, with minimal to nil threats ahead of the main
front the afternoon of June 6, even amid increased shear.

To be sure, precipitation coverage overall will be isolated to
scattered Thursday afternoon, and the convection will shut off
promptly at sunset, setting up a dry night.

Central guidance reflects above normal temperatures, until
Thursday night, with lows then finally closer to normal.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 430 AM Tuesday...

A large mid-upper level low digs into and then swirls about the
northeastern states heading into the weekend, setting up a long
wave trough in the east/ridge in the west pattern which
persists into the next work week. This brings cooler, mainly
dry and certainly not very impactful weather.

The cool air aloft atop strong June surface heating could
promote shallow diurnal convection beneath the stout mid-level
inversion. Timing and extent is also likely to be modulated by
short wave troughs pivoting through around the parent low. This
inversion may eventually erode over the weekend, as the low
swirls closer to the area, allowing for deeper convection. Even
then, CAPE is expected to remain narrow.

The 00Z operational GFS throws a monkey wrench in for the
latter half of the weekend, where by one of the short waves
pivoting around the parent low picks up a flat wave coming out
of the Rockies and across the central plains, and amplifies it
as it crosses the forecast area, or tracks just south of it, on
Sunday. This would bring a stout rain to end the weekend. Other
guidance depicts the flat wave passing harmlessly to the south
of the forecast area as it crosses the southeastern states, and
the forecast basically portrays this scenario.

Central guidance portrays below normal highs and near normal
lows for Friday and the weekend, with some moderation to begin
the next work week.

&&

.AVIATION /13Z TUESDAY THROUGH SATURDAY/...
As of 720 AM Tuesday...

Once the fog lifts around 13Z, VFR will take back control
through the period. Some Cu will form this afternoon and
possibly promote an isolated shower or storm which may affect a
site in particular the eastern sites. This would bring down VIS
temporarily and CIGs should stay around 040FT or above today.
More activity will come to fruition for Wednesday as showers and
storm will become more prevalent.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z WEDNESDAY...

FORECAST CONFIDENCE: High.

ALTERNATE SCENARIOS: None.




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       12   13   14   15   16   17   18   19   20   21   22   23
EDT 1HRLY       08   09   10   11   12   13   14   15   16   17   18   19
CRW CONSISTENCY  L    H    H    H    H    H    H    H    H    H    H    H
HTS CONSISTENCY  L    H    H    H    H    H    H    H    H    H    H    H
BKW CONSISTENCY  H    H    H    L    M    M    H    H    H    H    H    H
EKN CONSISTENCY  L    L    M    M    M    H    H    H    H    H    H    H
PKB CONSISTENCY  L    M    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 12Z WEDNESDAY...
Brief IFR conditions are possible in showers and thunderstorms
at times Wednesday into Thursday.

&&

.RLX WATCHES/WARNINGS/ADVISORIES...
WV...None.
OH...None.
KY...None.
VA...None.

&&

$$

SYNOPSIS...TRM/JZ
NEAR TERM...JZ/JMC
SHORT TERM...TRM
LONG TERM...TRM
AVIATION...JZ