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000
FXUS61 KRLX 212318
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
718 PM EDT Fri Jul 21 2017

.SYNOPSIS...
Strong to severe thunderstorms possible this weekend. Frontal
system passes early next week. Cooler high pressure crosses
midweek.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 730 PM Friday...

Previous forecast remains on track. No changes necessary.

As of 2 PM Friday...

Bulk of convection across far eastern zones and starting to
exit east. Behind line of convection, area of stratiform rain
and lower clouds. Associated cloud cover is trying to thin a bit
on satellite to our east, and it`s possible an additional shower
or storm could refire, but initial thought is atmosphere is
probably fairly worked over, but left a slight chance to chance
in for the remainder of the evening.

Otherwise, another warm and humid night on tap. Thinking if
there are many breaks in the clouds overnight we could see
widespread fog development.

As has been the case, models are struggling to depict the
overall pattern, and this is the case for tomorrow. General
consensus is for frontal boundary to lift back north on
Saturday, with continued warm and humid conditions.
Wave of low pressure moving east along the boundary, combined
with general warm and unstable conditions, will lead to
additional rounds of showers and thunderstorms, particularly
across the north, where strong to severe thunderstorms will be
possible, as 0-6km shear increases to 35-40 kts. SPC has
northern zones in a slight risk for Saturday, with much of the
southern zones in a marginal. In addition, heavy downpours are
expected, with the possibility of localized flooding issues
again, as pw values rise to 1.7 to 2+ inches.

As far as a heat advisory on Saturday, am getting heat advisory
conditions across parts of the lowlands on Saturday, however,
still uncertain as to where/coverage of greatest precipitation
will be. Have elected to have the midnight shift reevaluate the
forecast and determine if one is necessary.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
As of 330 PM Friday...

Models differ on timing of a low pressure system moving through
the Great Lakes Saturday night through Sunday night. Leaned
toward the NAM solution for this period as it seems to have a
handle on current features. Upper level system tracks to our
north Saturday night into Sunday. As it passes, trailing cold
front will push southward across the CWA. With soupy airmass in
place, Any showers or Thunderstorms with the front could produce
heavy downpours with PWs near 2 inches over much of the area.

Low pressure over the plains will finally lift and cross the
Great lakes Sunday night Through Monday night. Left over frontal
boundary over the region will lift north as a warm front and
trailing cold front will push approach the area Sunday Night
and exit Monday evening.

SPC has us in a slight risk for severe wx Sunday with afternoon
heating and lifting frontal boundary along with increasing
instability throughout the day. Airmass stays rather soupy and
water concerns are defiantly possibility Saturday night through
Monday night. WPC has a slight risk of excessive rain for
Saturday night and Marginal risk through Monday.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 330 PM Friday...

Cooler and drier air associated with high pressure that builds
across the region on Tuesday and lasts through Thursday. This
will bring a welcome relief from the heat and humidity. Another
system or complex may approaches from west Thursday night into
Friday. This will bring showers and thunderstorms back into the
forecast.

&&

.AVIATION /23Z FRIDAY THROUGH WEDNESDAY/...
As of 730 PM Friday...

The atmosphere remains unstable tonight into Saturday. Isolated
light showers or small thunderstorms could move across the area
overnight. Abundant low level moisture and possible clear skies
could result in dense river valley fog. Coded IFR/LIFR
conditions with different starting times at most sites.

For Saturday, more unstable conditions compared with this
afternoon are expected with the stationary frontal boundary to
our north. Therefore, expect scattered to numerous showers and
thunderstorms to produce brief periods of IFR/LIFR due to heavy
rain along their patch particularly after 16Z. Strong gusty
winds, along with small hail will be possible with any storms.

More storms on Sunday.

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

FORECAST CONFIDENCE: Medium.

ALTERNATE SCENARIOS: Additional convection could develop this
evening. Widespread fog may not form overnight.

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       22   23   00   01   02   03   04   05   06   07   08   09
EDT 1HRLY       18   19   20   21   22   23   00   01   02   03   04   05
CRW CONSISTENCY  H    H    H    H    H    H    M    M    L    L    L    L
HTS CONSISTENCY  H    H    H    H    H    H    H    M    L    L    L    L
BKW CONSISTENCY  H    H    H    H    H    H    M    M    L    L    L    L
EKN CONSISTENCY  M    L    L    L    H    H    M    M    M    L    M    M
PKB CONSISTENCY  M    M    L    L    M    M    M    M    L    L    L    L
CKB CONSISTENCY  H    H    L    L    L    H    M    L    L    L    L    M

AFTER 00Z SUNDAY...
IFR possible Saturday night and Sunday in heavy showers and
thunderstorms.

&&

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

&&

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