934 
FXUS61 KRLX 040918
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
518 AM EDT Tue Jul 4 2017

.SYNOPSIS...
A weak frontal boundary will sag south and stall out across the
area through mid week before moving back north. Cold fronts 
Thursday night and Friday night. Cooler and less humid weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 515 AM Tuesday...

Weather becomes more active today. Frontal boundary at 830Z stalled 
out near Ohio River. Still progged to sag a little farther south 
today, and will be a focal point for convection later this 
afternoon. Main player today however will be a wave of low pressure 
that will move east out of the Mississippi Valley region towards the 
CWA, with showers and thunderstorms, particularly across southern 
and eastern zones. Storms will be slow movers, and with the high 
moisture content of the air, will produce heavy rainfall. Flooding 
threat should remain low however.

With the expected cloud cover/convection today, temperatures should 
be slightly cooler across much of the area than recent days. 
Southeast Ohio may however be a bit warmer than other parts of the 
CWA due to less convection/cloud cover. 

Bulk of activity decreases tonight with loss of heating, and as low 
pressure wave moves east of the area, with a cloudy, muggy night on 
tap.

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
As of 515 AM Tuesday...

Active early July pattern this period, with upper level split
flow that unifies and amplifies, with a trough in the east, and
a large upper level high over the intermountain west.

A short wave trough in the southern stream, over the central
plains early this morning, reaches the mid Mississippi valley
Wednesday morning, and the forecast area Thursday night. It, and
weak ripples ahead of, along with an aging front in the area,  
in the very warm and humid air, spell rounds of showers and 
thunderstorms Wednesday into Thursday night, timing and 
location to be further modulated from outflow boundaries.

The forecast area is hydrologically dry, but PW values are
progged to climb over 2 inches with these waves. With light 
deep layer flow Wednesday, thunderstorms will be slow movers, 
and could produce locally excessive rainfall. The flow increases
Thursday but, by then, some areas may have become primed.

As the pattern amplifies Friday and Friday night, a cold front
drops southeastward through the area, with another round of
showers and thunderstorms. There may not be quite as much
moisture available by Friday, but the flow will be stronger, so
the opportunity for severe weather will be better if the storms
arrive early enough, which is currently forecast to be the 
case.

Temperatures close to a guidance blend. The MAV was low and the
MET high on highs Wednesday, on account of a wetter solution 
depicted by the GFS, compared with the NAM. Slowed cooling and 
drying a bit from central guidance overnight Friday night, but 
cooler and less humid air will be on the way in the wake of the 
front.

&&

.LONG TERM /SATURDAY THROUGH MONDAY/...
As of 515 AM Tuesday...

This period is characterized by continued troughing in the east,
while an upper level high remains parked over the intermountain
west.

A short wave trough crosses Saturday, followed by cool Canadian
high pressure Sunday. A rather cool Sunday morning is on tap, 
if the high builds in quickly enough.

Canadian high pressure, with cooler and much less humid air, 
will filter in on Saturday. This feature should remain in 
control of our weather into Monday. Low level southeast flow 
around the back side of the high exiting to the north, may 
bring showers back into the WV mountains Sunday or Monday.

A short wave trough is progged to back the upper level flow, 
and generate cyclogenesis over the area on Tuesday, although 
the latest ECMWF backs away from this idea.

Central guidance temperatures accepted, which show a cool 
weekend, and then values moderating back toward normal early 
next week.

&&

.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
As of 130 AM Tuesday...

Mainly vfr conditions with light surface winds overnight,
although patchy river valley mvfr and ifr fog possible, mainly
after 08Z. Any fog will dissipate after 12Z. 

Showers and thunderstorms will be on the increase after 16Z,
particularly across southern WV, the mountains, and southwest
Virginia. Expect brief MVFR conditions in showers/storms. Bulk
of convection will begin to dissipate after 00-02Z.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z WEDNESDAY...
     
FORECAST CONFIDENCE: Medium.

ALTERNATE SCENARIOS: More widespread fog may develop tonight
than currently forecast. Timing of showers and storms on Tuesday
may vary from forecast.

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                    TUE 07/04/17
UTC 1HRLY       08   09   10   11   12   13   14   15   16   17   18   19
EDT 1HRLY       04   05   06   07   08   09   10   11   12   13   14   15
CRW CONSISTENCY  H    H    H    H    H    H    H    H    H    M    M    M
HTS CONSISTENCY  H    H    H    H    H    H    H    H    H    M    M    M
BKW CONSISTENCY  H    H    H    H    H    H    H    H    H    M    M    M
EKN CONSISTENCY  M    M    M    M    M    H    H    H    H    M    M    M
PKB CONSISTENCY  H    H    H    M    H    H    H    H    H    M    M    M
CKB CONSISTENCY  H    H    H    H    H    H    H    H    H    M    M    M

AFTER 06Z WEDNESDAY...
IFR possible in showers and thunderstorms Thursday into Thursday
night, and late Friday.

&&

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

&&

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