Area Forecast Discussion
Issued by NWS Charleston, WV

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FXUS61 KRLX 280658
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
258 AM EDT THU JUL 28 2016

.SYNOPSIS...
A weak east to west frontal boundary just to our north will
move little. Several disturbances and copious moisture will bring
heavy rainfall potential Thursday into Friday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Sent an update per latest radar and lightning data showing
clusters of showers and storms moving north across the KY and wV
border. Increase PoPs to likely. Additional showers or storms
would develop overnight into the morning hours. A Flash Flood
Watch remains in effect for portions of northeast KY, southeast
OH and WV through 12Z Friday.

Previous discussion below...
745 PM UPDATE...
One band of showers and storms currently over E KY will shift
into S WV and SW VA over the next couple of hours while
dissipating as it does so. This disturbance passes to the east
this evening while the quasi zonal flow becomes more amplified and
out of the SW toward morning. This will allow a potent wave to
track into the area for Thursday along with copious amounts of
moisture. There still exists some discrepancy in the near term and
short term models regarding the heavies axis of qpf with this
feature with some taking it more into SE OH and along the OH River
and others focused further SE. Complicating matters is extent of
convection tomorrow which would enhance rainfall amounts. There
should be quite a bit of cloud cover to limit heating but with the
tropical atmosphere we are in it still looks like a general 1 to 2
inches with isolate higher amounts possible along wherever the
main qpf axis sets up and in any convection. Flash flood watch
will continues as is.

PREVIOUS DISCUSSION BELOW...

Broad and very moist upper level low over the southern
Mississippi Valley this afternoon...having pw`s above 2
inches...will move northeast later tonight and Thursday. There is
model consensus of tracking the system across our area and
targeting our area with heavy rain potential Thursday...a general
1 to 2 inch swath with locally heavier amounts in any training of
storms. Enough instability available for thunderstorms despite
the expected cloud shield...but does not look like a severe
thunderstorm threat scenario at this time. Thus...with much of the
area nearly saturated from yesterday...have issued an FFA with
this system from 12z Thursday to 12Z Friday for a good part of our
area. Have started conservatively...omitting parts of southeast
Ohio and far southeast portions of the area from the watch based
mainly on not receiving yesterdays rainfall. Otherwise any
convection this afternoon...mainly in the south...will wane fairly
early this evening with loss of heating. As the above mentioned
system approaches...there will be a large shield of clouds ahead
of it. Given that this system is very nearly tropical in
nature...it probably will not be as dependent on solid diurnal
heating to generate convection as we are used to. Thus...more
confidence in issuing the FFA.

It will continue to be warm and muggy tonight with the high
dewpoints and increasing clods overnight. For Thursday...somewhat
cooler only because of the clouds and showers and storms...but
quite muggy. Highs in the lower to mid 80s.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
Heavy rain threat to continue across the area Thursday night into
early Friday...as upper shortwave trough and surface wave push east
through the cwa. Still model differences between exact timing and
track of these features...but overall...heaviest threat through
early Friday looks to be across northern/eastern zones. In addition
to heavy rain...a few storms Thursday night could be on the stronger
side...with 30-40kts shear and decent cape...the potential for
strong storms...with damaging winds a primary threat exists. The
flash flood watch for the period will be in effect until 12Z Friday.

Additional showers and thunderstorms are possible later in the day
Friday and Saturday...particularly across the north in the vicinity
of stalled frontal boundary....as multiple upper disturbances cross
the region. There will still be a threat for heavy downpours with
any convection...and with an overall light flow...localized flash
flooding may continue to be a concern.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Weather looks to remain unsettled for most of the extended period as
additional disturbances move through the region. Drier weather
possible early to mid next week as upper ridging strengthens across
the region. Another front late week.

&&

.AVIATION /07Z THURSDAY THROUGH MONDAY/...
VFR/MVFR conditions will prevail outside showers or storms
overnight. Radar and lightning data indicate clusters of showers
and storms moving north northeast across the KY and WV border.
Although some areas show diminishing lightning, some storms could
move over WV and southeast OH overnight producing mvfr/ifr
conditions along their path. Areas of IFR patchy fog will develop
over areas that receive rainfall and along some river valleys.

IFR conditions is expected in dense fog, low stratus along river
valleys through 12Z. Any fog will lift into low status by 13Z.

After 12z Thursday...organized shield of showers and storms
spreading northeast across the area with conditions lowering to
MVFR/IFR especially in convection.

CONFIDENCE AND ALTERNATE SCENARIOS...

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z FRIDAY...

FORECAST CONFIDENCE: Medium.

ALTERNATE SCENARIOS: Fog potential tonight depends greatly on
cloud coverage.

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                              THU 07/28/16
UTC 1HRLY       06   07   08   09   10   11   12   13   14   15   16   17
EDT 1HRLY       02   03   04   05   06   07   08   09   10   11   12   13
CRW CONSISTENCY  L    L    L    L    L    L    L    M    M    M    M    M
HTS CONSISTENCY  L    L    L    L    L    L    L    M    M    M    M    M
BKW CONSISTENCY  H    H    H    H    H    M    L    H    M    M    M    M
EKN CONSISTENCY  M    L    L    L    L    L    M    M    H    H    H    H
PKB CONSISTENCY  M    M    L    L    L    L    M    M    H    H    H    M
CKB CONSISTENCY  M    M    L    L    L    L    M    M    H    H    H    H

AFTER 06Z FRIDAY...
IFR conditions in showers and thunderstorms through Thursday
night.

&&

.RLX WATCHES/WARNINGS/ADVISORIES...
WV...Flash Flood Watch from 8 AM EDT this morning through Friday
     morning for WVZ005>009-013>020-024>032-036>040-046-047.
OH...Flash Flood Watch from 8 AM EDT this morning through Friday
     morning for OHZ083-085>087.
KY...Flash Flood Watch from 8 AM EDT this morning through Friday
     morning for KYZ101>103-105.
VA...None.

&&

$$
SYNOPSIS...JMV/SL
NEAR TERM...ARJ/JMV/30
SHORT TERM...MZ
LONG TERM...SL
AVIATION...ARJ



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