183
FXUS61 KRLX 061642
AFDRLX

AREA FORECAST DISCUSSION
National Weather Service Charleston WV
1242 PM EDT Sat Jul 6 2024

.SYNOPSIS...
A cold front exits this morning, and high pressure brings dry
weather for the balance of the weekend. Increasing southwesterly
flow yields increasingly hot and humid conditions Monday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1000 AM Saturday...

No major changes were needed to the forecast at this time. Fair
weather cumulus field over the eastern half of the CWA will
persist, and likely will see similar develop in the rest of the
area as moisture from recent rainfall gets lifted to the top of
the boundary layer with daytime heating.


As of 700 AM Saturday...

Forecast on track, with the cold front through central WV and
approaching the mountains amid a potpourri of isolated showers,
patchy low cloud and fog.

As of 255 AM Saturday...

Thunderstorms had dissipated and showers had become very light
and spotty, as they advanced eastward ahead of an approaching
cold front. Crossing the Ohio River overnight, the front will
cross WV and southwest Virginia this morning. This, and the high
dew points ahead of the front, should keep at least showers
possible in and near the mountains through around daybreak this
morning. However, no appreciable uptick in convection is
anticipated.

Areas of stratus and fog forming overnight amid light low level
flow in the leftover moisture from the rain Friday, should lift
out after daybreak this morning, and low cloud areas should
further lift and scatter out by late morning.

High pressure will bring an afternoon cumulus field atop the
mixing layer, beneath the subsidence inversion, and then a
clear, calm night tonight. Areas of dense fog are likely to
form overnight tonight on account of the clear, calm conditions,
and recent rain.

Mid/upper-level flow remains southwest in the wake of the cold
front today and tonight, with heights hardly changing. Central
guidance reflects highs today and lows tonight still just a bit
above normal, but did go lower on lows tonight in valleys away
from rivers given the clear, calm conditions expected.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/...
As of 1240 PM Saturday...

Mid-level troughing moving into the Upper Mid-West Sunday night will
yield increasing southwesterly flow opening up the taps on Gulf
moisture into the region once again. This yields surface dew points
increasing back into the lower 70s by Monday afternoon amid
afternoon temperatures across the lower elevations in the lower to
mid 90s for both Monday and Tuesday with heat index values
approaching triple digits. Will need to keep an eye on potential for
a heat advisory for both days. These hot and humid days will also
yield at least some atmospheric instability, despite rather poor mid-
level lapse rates with isolated to perhaps scattered diurnally
enhanced convection with the best chances closer to the higher
terrain. The aforementioned mid-level troughing moves into the
Middle Ohio Valley late Tuesday afternoon with an associated cold
front. This should serve to focus chances for showers and storms.
Deep layer shear increases to around 40KTs Tuesday afternoon,
contingent on timing of cold frontal passage this could yield a
window for some organized stronger convection, overall limited by
instability due poor lapse rates. With steering flow nearly normal
to frontal motion could see some training with very efficient
rainfall production should instability come in a bit stronger than
advertised, but for now the threat for both severe storms and
flooding appears low.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 1240 PM Saturday...

In the wake of cold frontal passage Tuesday night into Wednesday,
upper level southwesterly flow progressively weakens as high
pressure over the Atlantic bulges east. This effectively cuts the
region off from better mid-level lapse rates from the Desert
Southwest while continually pumping tropical moisture toward the
Atlantic Coastal Plain. This yields 99th percentile moisture values
on the coastal plain with mere 80th to 90th percentile (around 1.6
to 1.9" PWATs) over a bulk of the forecast area, highest closest to
the mountains. Despite the aforementioned poor mid-level lapse
rates, afternoon highs in the mid to upper 80s (lowlands) and lower
to mid 70s (mountains) should yield diurnally enhanced convection
through the balance of the work week with the greatest chances in
the vicinity of the higher terrain in diurnal upslope flow. Flow
through the column will be fairly weak with deep layer shear ranging
from around 10 to 20KTs. This may yield somewhat more persistent
cellular clusters than dead flow up and down convection and with the
aforementioned juicy column coupled with deep warm cloud depths,
this could yield some localized flooding issues in any more
persistent and efficient convection.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
As of 700 AM Saturday...

A few last isolated showers with a cold front crossing early
this morning will have little if any impact on EKN and BKW.

BKW is starting out with IFR to LIFR stratus that may break at
times until mixing higher, to MVFR stratocumulus, by around 14Z,
and then scattering out into a VFR cumulus field for this
afternoon. EKN and CKB will have MVFR stratocu that will mix out
into a scattered cumulus field early this afternoon. PKB could
see IFR or MVFR ceilings briefly this morning, otherwise it,
HTS and CRW will be VFR today.

High pressure brings a clear, calm night that allows VLIFR dense
valley fog to form overnight. This is coded up for all sites
except BKW.

Flow surface and aloft will be light west, except surface flow
will become calm in the valleys tonight.

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


FORECAST CONFIDENCE: Medium.

ALTERNATE SCENARIOS: There is still brief opportunity for
visibility restriction first ting this morning. Ceilings could
bounce before mixing through this morning, and timing of
improving ceilings this morning could vary. Timing and extent of
dense fog development overnight tonight could vary.

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    H    H    H    H    H    H    H    H    H    H    H
EKN CONSISTENCY  M    M    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    L    H    H    H    H    H    H    H    H    H    H

AFTER 18Z SUNDAY...
VLIFR in dense fog briefly possible first thing Sunday morning.

&&

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

&&

$$

SYNOPSIS...FK/TRM/JP
NEAR TERM...FK/TRM
SHORT TERM...JP
LONG TERM...JP
AVIATION...TRM