Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
625 am EDT Friday Jul 3 2015
low pressure moves through area tonight...then to our east on
Independence day. Drier air tries to ooze southeast Saturday
afternoon. Middle level disturbance eastern slopes Sunday-Monday.
Near term /through tonight/...
slow moving showers are slowly drifting back into the County Warning Area from the
southwest early this morning. This is in response to a surface low
over the lower Ohio River valley...that will strengthen some today
as an upper level shortwave trough crosses the Midwest and Great
Lakes regions. The surface low should move through the County Warning Area today
into tonight with showers and thunderstorms. Models have trended a
bit farther west and north with the precipitation into this
evening. Expect fairly slow storm movement with weak flow. Due to
this...added a tier of counties to the Flash Flood Watch across southeast
Ohio and central WV. Downpours are just as likely across the north
where the Flood Watch is not in place...but this area has had some
time to dry out since the last significant rain. Will still need
to watch for the potential of localized issues should a slow
moving cell or repetitive cells cross a specific area.
Some guidance showing a dry slot of sorts moving into the WV Coal
fields today. Not sure the low will get spun up enough to pull in
enough dry air to be a true dry slot...but would not be surprised to
see a bit spottier coverage or less intense precipitation amounts
here. Did try to show a bit lower probability of precipitation as well...although still have
likely numbers. As the low head to the northeast tonight...drier air
will slowly try to work in from the northwest. While precipitation should
gradually come to an end across the west...think low stratus will
likely stick around across the forecast area through the near term
Used a mav/met blend for temperatures...which did not make any huge
swings from the previous forecast.
Short term /Saturday through Sunday night/...
a bit leery/skeptical of the 00z NAM pushing the drier air
quickly southeast on Saturday and even keeping our eastern slopes dry
Sunday. Will trend toward a slower drying trend in our southern
counties Independence day afternoon...as low clouds try to break
up. Yet...was still faster in removing probability of precipitation Saturday in our middle
Ohio Valley counties...including Athens...Marietta...and
Parkersburg...then our previous thinking. Any chances of thunder
Saturday should restricted to mountain counties on east.
With drier air into southeast Ohio...tried to lower minimum
temperatures Saturday night in our western counties. In the gradient
or transition zone...included fog forming ckb-ekn to crw vicinity
overnight Saturday night.
A weak steering flow on Sunday into Monday with a weak 500 mb low
possible over the central Appalachians. A weak east and southeast
wind flow in the low levels...so will hold onto probability of precipitation Sunday and
Sunday night in our mountain counties especially Snowshoe...Beckley
on SW toward Grundy.
At least the precipitable water should be lowering during the short
term...compared to the current near term.
Long term /Monday through Thursday/...
a frontal boundary remains south of the area. With weak middle level
disturbances passing by...a chance for afternoon showers and
thunderstorms each day will continue with afternoon heating mainly
extreme southern sections through Tuesday.
A cold front approaches from the northwest Wednesday...crossing
Wednesday night into early Thursday. Coded high chance probability of precipitation with
this feature for now. Another weak high pressure should develop
behind the front Thursday into the end of the period.
Went with wpc guidance for temperatures through the period.
Aviation /10z Friday through Tuesday/...
dense fog did not really form as initially thought...mainly due
to some puffs of winds and thicker clouds. As a low pressure
system and weak front moves through...expect MVFR to linger much
of the day in rain...storms and or low stratus. As rain ends this
evening...will likely be left with low stratus mixed with fog
lingering through the night.
Winds north of the front will be NE to east...with SW winds south of
the front. The front should slowly drift northward through the
Forecast confidence and alternate scenarios through 12z
Forecast confidence: low.
Alternate scenarios: timing and extent of downpours and storm
today may vary. Spatial extent of fog and stratus in
After 12z Saturday...IFR expected in valley Fog/Mountain clouds
Saturday night into Sunday morning...mainly in WV. IFR possible in
showers and/or low ceilings along eastern slopes Sunday night.
WV...Flash Flood Watch through this evening for wvz005>008-013>016-
Ohio...Flash Flood Watch through this evening for ohz083-086-087.
Kentucky...Flash Flood Watch through this evening for kyz101>103-105.
Virginia...Flash Flood Watch through this evening for vaz003-004.