-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRLX 271942
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
342 PM EDT Thu Jul 27 2017

.SYNOPSIS...
Low pressure system brings rounds of showers and thunderstorms,
with heavy rain through Friday. High pressure with cooler and
less humid air follows for the weekend into next week.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 215 PM Thursday...

The HRRR and the RAP have been consistently depicted a relative
lull in the convection for about a 4 hour window or so, with the
timing depending on location, before the next wave of
convection moves through. After a morning of priming with
scattered storms, a flash flood warning is now in effect until
the front exits the region tomorrow evening.

PWAT values are in the 1.5 to 2.0 inch range again, hence the
heavy rain that has already been seen, with many cells giving
one half inch in 30 minutes being the norm. Instability is high
in the mixed and most unstable layers.

Convective debris is dissipating off to the west, so expect the
convection to fire again upstream, as mentioned earlier in
regards to the flash flood watch. Severe threat is marginal, and
most storms have not eclipsed the 35mph wind mark, nor have they
produced any hail.

High dewpoints keep the overnight lows near 70F for the
lowlands.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
As of 315 PM Thursday...

Models continue to target our area for heavy rain Friday. Waves
of low pressure will be moving up along a slow moving cold
front that will cross our area from west to east during the day
Friday. With very moist (PW`s above 2 inches) and unstable air
in place with the front, there is a Flash Flood watch through
the day Friday. The front will finally be kicked east of the
area Friday evening as an upper low drops south across the Great
Lakes and into our area. Showers will end from west to east
west of the Ohio River Saturday night, but showers will continue
through the day Saturday over much of West Virginia as the
upper low stalls over the Mid Atlantic states. The upper low
finally shifts far enough east for all rain to end saturday
night. It will be warm and humid ahead of the front, and much
cooler behind the front with temperatures going well below
normal.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
As of 335 PM Thursday...

A cool and dry period is on tap as Canadian high pressure will
be in control from Sunday into much of the next work week.
There will be a slow increase in high temperatures each day, but
it will be dry with temperatures at or below normal.
-- End Changed Discussion --

&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
As of 120 AM Thursday...

The general theme is rounds of showers and thunderstorms through
the TAF period. It is important to note, however, that in
thunderstorm environments, the atmosphere changes significantly
from the model initializations, and in many cases, renders the
second half of the forecast inaccurate. Thus, there will likely
be significant timing issues with the TSRA/VCTS in the forecast
beyond the 6 hour time frame.

Also carry lower ceilings in visibilities tonight, particularly
as rain subsides. This is primarily a 04Z to 14Z time frame,
different at each terminal.

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


FORECAST CONFIDENCE: Medium to high on the occurrence of
convective activity, low on timing.

ALTERNATE SCENARIOS: Timing of showers and thunderstorms, and
associated flight categories, could vary, with short term
amendments likely needed.

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    H    H    H    H    H    H    H    L
HTS CONSISTENCY  H    H    H    H    M    L    L    M    H    H    H    L
BKW CONSISTENCY  M    H    H    H    H    H    H    H    M    M    M    L
EKN CONSISTENCY  H    H    H    H    H    H    H    H    H    M    H    M
PKB CONSISTENCY  H    H    H    H    H    L    H    H    L    H    H    M
CKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    L    M

AFTER 18Z FRIDAY...
Brief periods of IFR conditions with thunderstorms likely
through Friday. Fog possible Friday night.

&&

.RLX WATCHES/WARNINGS/ADVISORIES...
WV...Flash Flood Watch from 8 PM EDT this evening through Friday
     evening for WVZ005>011-013>020-024>034-039-040-515>526.
OH...Flash Flood Watch from 8 PM EDT this evening through Friday
     evening for OHZ066-067-075-076-083>087.
KY...Flash Flood Watch from 8 PM EDT this evening through Friday
     evening for KYZ101>103-105.
VA...Flash Flood Watch from 8 PM EDT this evening through Friday
     evening for VAZ003-004.

&&

$$
SYNOPSIS...JMV/26
NEAR TERM...26
SHORT TERM...JMV
LONG TERM...JMV
AVIATION...26