951 
FXUS61 KRLX 231728
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
128 PM EDT Tue May 23 2017

.SYNOPSIS...
High pressure gives way to a low pressure system moving south and 
east today and tonight. Upper level low brings chances of 
showers Wednesday into Friday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1000 AM Tuesday...

Added to the sky cover over the mountains to completely
overcast, stretching back into the I79 corridor as well. Much of
the radar returns still not reaching the ground at this point,
although do have rain reported at BKW in the southern 
mountains.

As of 330 AM Tuesday...

High pressure will provide dry and cool conditions early today.
Abundant clouds and dry air in place can account for comfortable
temperatures. A series of mid level shortwaves will bring 
additional moisture from the south southeast to bring an chance 
for showers or storms mainly across the eastern half of WV 
through tonight.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 245 AM Tuesday...

Models have remained fairly consistent with deep upper
trough/low impacting our region Wednesday into Thursday. GEFS
indicating an anomalous jet max for this time of year at 4 to 5
standard deviations above normal. We will be in a good spot in
the left front quad of this jet max as it pushes north around
the trough. Current blend of forecast guidance is spitting out 
about a 1 inch bullseye of QPF over Central through Eastern West
Virginia, with Euro a bit further west than the GFS at this 
time. PWATs aren't overly impressive and low CAPE values as well
based on forecast soundings, so thunderstorm and flood threat 
will be minimal . However, with upper trough swinging in and 
cold temps aloft, I do believe there will be some embedded 
thunderstorms within a wide band of showers Wednesday afternoon 
through early Thursday morning. 

The upper level low will remain over the area on Thursday and
more showers and isolated thunderstorms are possible. Temps 
will be quite a bit cooler as well, with highs only mid 60s in
the Lowlands and 50s in the mountains.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 300 AM Tuesday...

Upper trough kicks to our east and a zonal pattern is left in
its wake. Guidance in fairly decent agreement with a brief dry
period on Friday as weak ridge pushes in. However, the weekend
is looking quite unsettled at this time. Strong warm air and
moisture advection with H850 showing southwesterly return flow
from the Gulf of Mexico. Should definitely have the instability
in place this weekend, but timing of short waves moving through
the flow will determine severe weather potential. Confidence
remains quite low at this time due to some differences within
the guidance, so have stuck with a blend of ensemble and
operational guidance for this period and have mentioned the 
chance for thunder in the forecast simply because of instability
that is likely to be in place.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
As of 125 PM Tuesday...

Have some wholesale changes in effect for the afternoon issuance
of the TAFs, primarily dealing with earlier arrival and longer 
duration of rain across the region thanks to an upper level wave
moving in from the southwest. Expect coverage to increase from 
development of showers as much as showers moving in. Biggest 
concern off the top is duration of the rain that can often times
lead to ceilings collapsing down to IFR, but have held this off
in the forecast until after 00Z and later, with the expectation
of convective rain keeping to lowest levels churned enough. 
Have quite a bit of IFR in the forecast however once this upper 
level wave exits, which could give the lesser seen IFR ceilings 
and visibilities as winds approach calm. The timing is tough as 
well.

Higher chances for showers return after 10Z Wednesday, but
southeast wind should help lift ceilings after sunrise.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z WEDNESDAY...
     
     
FORECAST CONFIDENCE: Low to medium. High confidence on rain
overall, but timing and subsequent conditions when periods of
rain end are tricky.

ALTERNATE SCENARIOS: Timing of rain could vary. May need to be
more aggressive with IFR or LIFR tonight. 

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       15   16   17   18   19   20   21   22   23   00   01   02
EDT 1HRLY       11   12   13   14   15   16   17   18   19   20   21   22
CRW CONSISTENCY  H    H    H    H    H    H    H    L    L    M    L    L
HTS CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    L
BKW CONSISTENCY  L    M    M    M    M    M    M    M    M    M    M    L
EKN CONSISTENCY  M    H    M    M    M    H    H    H    H    H    H    L
PKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    M
CKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    M

AFTER 18Z WEDNESDAY...
Upper level low keeps IFR chances in play through Thursday night.

&&

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

&&

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