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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRLX 271834
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
234 PM EDT Sat May 27 2017

.SYNOPSIS...
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Rounds of convection are expected this holiday weekend, until a
cold front crosses Sunday, followed by another Monday morning.
Additional cold fronts cross Tuesday and Wednesday.
-- End Changed Discussion --

&&

.NEAR TERM /THROUGH SUNDAY/...
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As of 230 PM Saturday...

Cap is finally breaking over the northern tier of counties where
the better clearing has taken place over the last couple of
hours. Still looking at a high CAPE and moderate bulk shear
environment, so expect the activity to continue on the upswing
heading into the late afternoon and evening. So far, the pace
has been more than manageable, but still have a few hours of
heating left and we have already hit the convective temperature.
Have both the hail and wind threat going forward. No changes to
the SPC slight risk for us in terms of severe.

Meanwhile, precipitable water values pushing 1.50in have
warranted the flash flood watch in place over much of the
southern portion of the CWA. Flash flood guidance values still
high, so thresholds for additional rain down in these areas is
low. Repetitive rounds of storms could easily become
troublesome.

Have tailored the POPs for a lull in the activity late this
evening and early tonight, before the front swings back
northward again as a warm front. Pre dawn convection expected to
move north through the area, and back into the slight risk area
for Sunday as the cold front passes again.
-- End Changed Discussion --

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 515 AM Saturday...

Additional convection Sunday and Sunday night will be dependent
upon previous convection leaving behind a worked over
environment. Several boundaries are likely to be in the area
Sunday, including at least one outflow boundary somewhere
across the south, and a more synoptically driven boundary to the
north. There may also be a north to south oriented boundary
crossing as a surface reflection of an upper level short wave
trough.

Model differences in moisture and instability on Sunday reflect
the possible effects of a cool pool from previous convection.
Models are in better agreement on most of the CAPE being
elevated and thickest in the hail growth layer. This somewhat
tempers the diurnal dependency of convection. Deep layer shear
is forecast to be in the 40 to 50 kt range.

All of this suggests showers and thunderstorms around from time
to time Sunday through Sunday night, with repetitive downpours
possible. Also, afternoon recovery would add surface based
instability to the equation, resulting in very strong, heavy
thunderstorms. Finally, to go along with these parameters,
sigtor values are forecast to climb to 1 to 1.5 in an axis ahead
of a cold front approaching from the west Sunday night.

The flood watch goes until 12Z Monday when the cold front goes
through, and the HWO also highlights the convective threat.

Yet another cold front crosses late Tuesday. While weaker and
with less available moisture than the weekend system, it will
still be able to garner enough moisture and shear for
thunderstorms.

No deviations from central guidance temperatures but values will
fluctuate with the convective complexes.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 515 AM Saturday...

This period features a large upper level low over eastern
Canada with long wave trough over the eastern United States.
This spells a cool, more tranquil pattern once a reinforcing
cold front crosses on Wednesday. PoPs increase again next
weekend, as that trough lifts out, and allows another system to
approach from the west or southwest.

Central guidance temperatures reflect the slightly below normal
pattern.

&&

.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
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As of 145 PM Saturday...

Convection/storms will be around through the evening. The
challenge, of course, is determining effects on individual
terminals.

With that said, attempted as best as possible with rapid update
high res models to time POPs on terminals and reflect that in
the TAFs, while trying to not overpopulate with VCTS/CB. Some
TEMPOs used in this case to cover, but can see AMDs being
needed as the storms evolve and move over the next several
hours. Gusty winds and hail are possible.

Expecting a lull during a portion of the overnight, with a warm
front returning and bringing morning convection back into the
fold.

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


FORECAST CONFIDENCE: Medium.

ALTERNATE SCENARIOS: Convection timing likely to vary as storms
evolve. May need fog tonight in brief clearing.


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       18   19   20   21   22   23   00   01   02   03   04   05
EDT 1HRLY       14   15   16   17   18   19   20   21   22   23   00   01
CRW CONSISTENCY  H    H    H    H    M    H    H    H    H    H    H    L
HTS CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    L
BKW CONSISTENCY  H    L    L    M    M    M    M    M    M    L    M    L
EKN CONSISTENCY  M    H    M    H    H    H    H    M    M    L    L    L
PKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    L    L
CKB CONSISTENCY  H    M    H    M    H    H    H    H    H    H    H    M

AFTER 18Z SUNDAY...
-- End Changed Discussion --

&&

.RLX WATCHES/WARNINGS/ADVISORIES...
WV...Flash Flood Watch through Monday morning for WVZ005>008-
     013>016-024>027-033-034-515>520.
OH...None.
KY...Flash Flood Watch through Monday morning for KYZ102-103-105.
VA...Flash Flood Watch through Monday morning for VAZ003-004.

&&

$$
SYNOPSIS...TRM/SL
NEAR TERM...26
SHORT TERM...TRM
LONG TERM...TRM
AVIATION...26