Area Forecast Discussion
Issued by NWS Charleston, WV

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FXUS61 KRLX 180235
AFDRLX

AREA FORECAST DISCUSSION
National Weather Service Charleston WV
1035 PM EDT Mon Jun 17 2019

.SYNOPSIS...
Rounds of storms this tonight, repeat forecast likely on
Tuesday. Zonal flow aloft continues to bring unsettled/wet
conditions through the end of the week.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 1030 PM Monday...

Performed another refresh on PoPs for the evening, with most
scattered activity from the day coming to an end and the
development of a healthy line of storms crossing southern Ohio
ENEward this evening. While marginally severe as it enters the
area at this time, there have been observed signs of weakening
including a gust front and modestly warming cloud tops. Though
still expecting this MCS to track ENEward into the Ohio valley
and northern West Virginia in the coming hours, do think it will
tend to weaken as it does so, becoming more scattered overnight
especially across the southern two thirds of the area where
weak shear doesn`t support sustaining convective threat. A brief
break is expected in the pre-dawn hours as this wave exits to
the NE, however another wave is progged to intensify starting in
the tristate by daybreak, tracking eastward through the
morning.

As of 740 PM Monday...

Mainly minor tweaks to the forecast, mainly to tighten up PoP`s
with ongoing weak convection wafting up through interior west
Virginia and SE Ohio. Also adjusted temperatures a bit
overnight, mainly to bring dew points up in the vicinity of
expected overnight rain activity. Otherwise, forecast remains on
track.

As of 240 PM Monday...

 Flash Flood threat increases late today into this evening...

Quasi-stationary frontal boundary remains parked across central
Ohio and Pennsylvania today. Zonal flow aloft will continue to
attract shortwave energy from the west, recreating a similar
forecast to yesterday. Scattered convection is beginning to
develop in eastern Kentucky and southern Virgina this afternoon
in an area that received the most diurnal heating throughout the
day, while the majority of the CWA was plagued by low clouds
and fog. At the time of this issuance, convection has started
off rather benign, but with sunshine breaking through most of
Central Appalachia, these storms will be able to utilize rising
instability levels as they progress into West Virginia. SPC has
elected to bump up the southwest quadrant of the CWA to a Slight
Risk for severe thunderstorms, with intensifying cells capable
of wind damage and small hail. This increased risk for severe
storms has been addressed in the HWO.

Another area of focus later on this evening will be over
southeast Ohio, as the frontal boundary shifts a tad southward.
Biggest concern with these showers and storms will be the flash
flood potential that lies here due to the amount of rain that
has already fallen. The Flash Flood Watch will remain in effect
through the near term for counties that reside west of I-79.
Will continue to monitor radar trends through the course of the
shift and pass along to the upcoming shift the possible need
for more counties to be included in the Watch, pending storm
total amounts from tonight.

The environment will remain progged for convection Tuesday due
to features both aloft and at the surface showing no signs of
departing the region. Additional rainfall will continue to
advertise flash flooding concerns heading into midweek.
Temperatures on Tuesday will be slightly lower than today in
response to extensive cloud cover expected in the morning.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
As of 233 PM Monday...

While the unsettled zonal flow aloft will continue at the start of
the short term period, the shortwave trough axis from Tuesday will
be mainly east of the region late Tuesday night. Thus, coverage of
showers and storms will decrease through Wednesday morning with the
loss of more organized forcing in the region and decreasing
instability. This should transition us into a somewhat quieter
weather day on Wednesday. However, it will not be a dry forecast by
any means as weak impulses embedded within the quasi-zonal flow
aloft move across the region ahead of a shortwave trough that will
be pushing NNE across the mid Mississippi Valley on Wednesday
afternoon. Given the weaker and less organized forcing within an
environment of MLCAPE values around 1000-1500 J/kg, showers and
storms are still expected, but storm coverage should generally be
less than Tuesday. May still need to watch for the potential of some
hydro issues, but this will be largely dependent on where the
heaviest rains occur in the days leading up to Wednesday.

Shower and storm coverage should increase by Thursday as the
aforementioned shortwave trough and associated surface low move
across the Ohio Valley. As the surface low passes north of the
region on Thursday, a cold front will sweep across our region in the
afternoon and evening. With plenty of forcing for ascent, widespread
showers and storms are expected. Some strong storms are also not out
of the question at this point as the midlevel flow strengthens with
the approach of the trough axis. In addition, PWATs will be around
1.6-1.8 inches so heavy rainfall could occur with any of the storms
that develop. The cold front is then expected to move east of the
area late Thursday evening, with drier air moving in.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 233 PM Monday

Surface high pressure builds into the Great Lakes on Friday and
extends down into the region. While an isolated shower can`t be
ruled out (mainly near the mountains), most of the region
should finally be dry with temperatures in the upper 70s and low
80s.

Upper level ridge centered in the northern Gulf of Mexico will
extend up into the Ohio Valley and Great Lakes region by
Saturday. However, an upper level trough is expected to be
moving across the Intermountain West, allowing shortwave
impulses to eject ENE out of the Rockies. Several of these
impulses will move across the region throughout the weekend and
thus, a return of showers and storms is expected.

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
As of 745 PM Monday...

Repeat performance likely tonight thanks to a persistent, wet
pattern overall with a mix of restrictions possible. VFR tends
to prevail during the daytime, especially in the afternoon where
mixing heights bring cloud bases to SCT MVFR/VFR levels.
Overnight into the morning, SCT to BKN MVFR/IFR ceilings are
possible with a very humid airmass in place, as was the case
Monday morning. Meanwhile, waves of convection will impact TAF
sites especially in the Ohio Valley which are likely to bring
temporary IFR VSBY and in some cases CIG restrictions.

At this time, widely scattered showers and a couple storms
impact the region with relatively limited impacts, with the
exception of PKB and perhaps CKB in the coming hours. Another
wave is expected to impact mainly HTS/PKB overnight, between
roughly 04-08Z. Another wave is expected to scoot across the
area during the middle to late morning Tuesday. This, combined
with the aforementioned tendency toward lowered ceilings, is
likely to cause widespread MVFR ceilings during a portion of the
morning, IFR possibly at sites directly impacted by the brunt
of the wave, particularly at PKB.

Wind will prevail out of the SW, wavering slightly southerly ahead
of convective waves, and gusting during convection. While wind gusts
in the 15-25 kt range will be most common through the period,
stronger convection can produce wind gusts closer to 40 kts
tomorrow afternoon as daytime heating spurs convection.

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

FORECAST CONFIDENCE: High confidence in periodic restrictions;
medium to low confidence for timing.

ALTERNATE SCENARIOS: Timing convection and associated
restrictions will be difficult today and will likely result in
amendments.

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                                                            TUE 06/18/19
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    M
HTS CONSISTENCY  H    H    H    H    H    H    L    M    M    M    M    M
BKW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    M
EKN CONSISTENCY  H    H    H    H    H    H    M    M    M    M    M    H
PKB CONSISTENCY  H    H    H    H    H    L    H    H    M    L    L    L
CKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H

AFTER 00Z WEDNESDAY...
Brief IFR conditions likely at times as rounds of showers and
thunderstorms impact the region nearly each afternoon and
evening for the upcoming week.

&&

.RLX WATCHES/WARNINGS/ADVISORIES...
WV...Flash Flood Watch through late Tuesday night for WVZ005>011-
     013>020-027>032-039-040.
OH...Flash Flood Watch through late Tuesday night for OHZ066-067-
     075-076-083>087.
KY...Flash Flood Watch through late Tuesday night for KYZ101>103-
     105.
VA...None.

&&

$$
SYNOPSIS...MC/RG/MEK
NEAR TERM...MC/MEK
SHORT TERM...RG
LONG TERM...RG
AVIATION...MC



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