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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRLX 182353
AFDRLX

AREA FORECAST DISCUSSION
National Weather Service Charleston WV
753 PM EDT Thu Apr 18 2019

.SYNOPSIS...
Large storm system brings showers and a thunderstorms Friday,
along with cooler conditions. Upper level low pressure system
exits Sunday night.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 415 PM Wednesday...

Bumped up temperatures this afternoon to account for local and
regional observations depicting most areas extending up into the
mid-80s.

As of 155 PM Wednesday...

Cold front approaches the region overnight and pushes through
tomorrow. Widespread showers are expected as well as the
possibility of a few thunderstorms, and some could be quite
strong.

Inhibiting factors for storms tomorrow will be instability.
Current guidance indicates persistent cloud cover and on-going
showers entering the region after sunrise Friday. CAPE values
likely will be less than 500 J/kg, however wind profiles are
impressive. So once again, we will have high shear and low
instability, but if there are a few breaks of sun then maybe
some low topped storms could develop. Main threat would be for
damaging wind gusts.

Meanwhile, PWATs are forecast to be about 1.3", which is
slightly anomalous for this time of year. The fact that
convection could be limited should help us from seeing rainfall
rates that could produce flash flooding. Nonetheless, if
afternoon convection were to develop across the mountains, where
FFG values are lowest, then some water issues could pop up. At
this time, decided to hold off from any flash flood watch after
coordinating with surrounding WFOs.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 225 PM Thursday...

No significant changes to the evolution of the upper low as it
wobbles northeastward through the CWA. The Saturday time frame
will have reduced POPs from the near term due to some likely dry
air intrusion. While the forecast will not have an actual
mention of thunder, the possibility is definitely there on
Saturday with the steepening lapse rates from the cold pool
aloft. Any thunder should be isolated overall.

Conversely, the 1000-500mb thicknesses bottom out on Saturday at
536dkm, but there has developed some significant spread in the
model guidance for the high temps Saturday. Had to bring down
the blender values several notches as they looked to high.
Expect wet snow showers in the highest elevations Saturday
night. All precipitation effects from the upper low should end
Sunday night.

There is also more spread now in the forecast highs fir Sunday,
as the exit of the upper low and recovering low level warm air
advection may be pushed off another 12 to 18 hours. Still should
be easily warmer than Saturday, but have backed off the near 70F
lowland temps by several degrees.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 225 PM Thursday...

Keeping the theme of some inconsistencies in the models and
guidance, the nature of the baroclinic zone oscillation keeps
the forecast from going categorically wet or dry in the
extended. So as the features drifts south and north across the
CWA in response to differing synoptic scale upper wave setups,
it can be expected that the chances for showers and the
temperatures through Wednesday are going to be in some flux over
the next couple of days. With that said, not expecting any
extremes at this point.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
As of 750 PM Thursday...

VFR remains the primary flight category this evening ahead of
tomorrow`s FROPA. Gusty winds observed across all terminals
today will begin to subside with the loss of daytime heating,
with the exception of the mountain terminals of EKN and BKW,
where gusts are likely to continue through the overnight period.
Winds aloft begin to increase tonight in response to the next
approaching low pressure system, which could pose an issue for
low level wind shear for many TAF sites during the predawn hours
Friday morning. Therefore, included a period of LLWS at all
sites except for PKB and EKN. Confidence on timing and locations
of wind shear are still mediocre at best, but may become more
clear with the 06Z TAF issuance on whether or not ground winds
would be conducive to justify wind shear. Either way, low level
turbulence is anticipated Friday morning due to increasing winds
aloft.

The cold front pressing in from the west will enter into the
forecast region near daybreak Friday morning. Heavy rain and
afternoon thunderstorms will accompany the front, leading to
MVFR/IFR flight restrictions at times through the remainder of
the period. Winds will once again be gusty after sunrise, once
the nocturnal inversion erodes, as well as shift out of the
northwest in the wake of the front`s passage late in the TAF
period.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z SATURDAY...

ALTERNATE SCENARIOS: Timing and location of LLWS early Friday
morning may vary from forecast. Flight restrictions in regards
to showers and thunderstorms passing through the area will also
vary at all terminals.

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.

DATE                                                            FRI 04/19/19
UTC 1HRLY       00   01   02   03   04   05   06   07   08   09   10   11
EDT 1HRLY       20   21   22   23   00   01   02   03   04   05   06   07
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  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 00Z SATURDAY...
IFR possible in showers and thunderstorms late Friday night,
with additional brief IFR in showers over the weekend.

&&

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

&&

$$
SYNOPSIS...26/MPK
NEAR TERM...MPK/MEK
SHORT TERM...26
LONG TERM...26
AVIATION...MEK