Area Forecast Discussion
Issued by NWS Charleston, WV

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453
FXUS61 KRLX 192345
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
745 PM EDT Sat May 19 2018

.SYNOPSIS...
Upper system exits tonight. Weak disturbances cross early next
week. Cold front crosses mid week, followed by high pressure to
end the work week. Unsettled to start the Memorial Day weekend.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 740 PM Saturday...

Previous forecast on track.

As of 1245 PM Saturday...

Upper trough will swing through the CWA this evening, with
increasing chances for showers and thunderstorms as it does so.
Still overall expecting a low chance for anything to become
severe, with overall lack of significant wind shear and strong
dynamics, but will continue to highlight the potential in the
HWO with SPC placing much of the CWA in a marginal risk for
today. There are some breaks in the clouds noted on satellite,
which of course will aid in thunderstorm development. Any
storms that do develop will be capable of brief heavy downpours,
with the anomalously high PW air mass in place. However, storms
should overall move well, so widespread flooding risk is not
expected, but could see issues in low lying spots/poor drainage
areas.

Trough pushes to the east of the CWA late tonight. Much of the
area will start out quite cloudy on Sunday, particularly across
northern/eastern zones where low stratus is expected to develop.
Some clearing possible towards morning across extreme western
zones. Otherwise, weather on Sunday looks to be drier, with a
more stable pattern setting up, but can`t completely rule out a
pop up shower or storm, so maintained the slight chance during
the afternoon hours. Models hinting at the possibility of
increasingly unsettled weather late Sunday night, into the short
term period.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 335 PM Saturday...

NAM12 and HIRESWnmm develop a convective complex over southwest
Ohio Sunday afternoon, in response to a low level jet max and
moisture feed out of the SSW, intersecting with a west to east
oriented front sagging down from the north, possibly enhanced
by an outflow boundary from upstream convection tonight. They
then prog this complex to move ESEWD across the forecast area
Sunday night, with rainfall totals up to two inches from the
NAM12, and a much more confined axis of up to 1.5 inches off the
HIRESWnmm.

HIRESWarw shows this to a lesser extent, and faster, more of a
late day event than a nocturnal one. Other models are not so
bullish on this scenario, but show smaller pockets of convection
to the south, and to the north, and central guidance reflects
the smoothing resulting from a blended solution.

The details of the forecast remain fuzzy through Tuesday,
beneath zonal upper level flow, with the surface boundary
remaining north of the area. Ripples in the zonal flow, and left
over outflow boundaries will focus convection, which will be
diurnally enhanced during the afternoon and evening hours.

A cold front is forecast to cross or at least approach Tuesday
night, from northwest to southeast, but most of the forcing and
the better bulk shear is is progged to pass north of the
forecast area, and the day 3 SPC marginal outlook for severe
looks good.

Above normal temperatures continue.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 335 PM Saturday...

Models continue to differ on the timing of a cold front crossing
Tuesday night into Wednesday, and central guidance reflects this
with the chance for showers and thunderstorms south on
Wednesday.

Models do concur on dry weather Thursday and Friday, with high
pressure beneath upper level ridging.

A mid stream short wave trough approaching from the northwest,
a southern stream low approaching from the south, and low level
southerly flow of increasingly warm and moist air, will all
conspire to bring unsettled weather back into the area in time
for the start of the Memorial Day weekend.

Temperatures remain above normal in the wake of the cold front.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
As of 745 PM Saturday...

Radar images show lines of convection moving across the area
northeast. These lines of showers and thunderstorms are
producing brief periods of IFR conditions along their path.

PWATS are around 1.7 inches tonight. This could produce
localized downpours and IFR/LIFR conditions.

Convection should decrease in coverage after 03Z, however,
widespread MVFR cigs are expected to develop, particularly
across the mountains and across areas that received rainfall.

Southwesterly winds, with occasional gusts 15-20kts through
03Z. Gradual improvement to VFR after 15Z Sunday.

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

FORECAST CONFIDENCE: Medium

ALTERNATE SCENARIOS: Development and extent of low stratus or
fog overnight may vary from 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.

DATE                                                            SUN 05/20/18
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    L
HTS CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    L
BKW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    L
EKN CONSISTENCY  M    H    H    L    H    M    M    M    H    H    H    L
PKB CONSISTENCY  H    H    H    H    H    H    H    H    M    M    M    L
CKB CONSISTENCY  H    H    H    H    H    H    H    M    M    H    M    M

AFTER 00Z MONDAY...
Brief periods of IFR possible in showers and storms into the
beginning of the work week.

&&

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

&&

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



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