Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
358 PM EDT sun Jul 5 2015
closed middle/upper level low opens into trough tonight or Monday as
it passes over. Cold front approaches from Midwest late
Tuesday...could stall/weaken in vicinity Wednesday.
Near term /through Monday/...
scattered convection breaking out over southeast WV and SW Virginia where some breaks
in the clouds in the dry slot has allowed instability to develop.
Expect the coverage of these to only increase as the afternoon wears
on. The center of the upper level system looks to track in the
vicinity of the Ohio River through the overnight and first half of
Monday. Of concern is potential for S to north training toward the WV
mountains...parallel to the flow. Think the heaviest rains will fall
over these locations with another maximum over the mesoscale circulation
coming out of southeast Kentucky and into The Lowlands late this afternoon and evening.
With the loss of heating...think the coverage of rain showers/thunderstorms and rain will
decrease significantly after midnight as middle level dry air wraps
around from the west.
For Monday...aforementioned upper low will open up into a wave
into east Ohio in the afternoon. As such expect rain showers/thunderstorms and rain to redevelop and
expand in coverage across north zones in the afternoon. So have the
highest probability of precipitation over the north by late in the day. Expect some breaks in
the clouds across NE Kentucky/S WV/southeast Ohio after any fog and low stratus
Short term /Monday night through Wednesday night/...
models have the upper low lifting northward away from the area
Monday night. This should provide a brief break in the
precipitation. Mesoscale NAM then shows some showers/storms moving in
Tuesday morning. Other models do not have this line...but tracing
the moisture back into the Midwest shows it is currently associated
with convection. This lends some credence to the NAM...so will
introduce some probability of precipitation Tuesday morning with this feature.
A cold front then approaches Tuesday night and Wednesday.
Models have been trending northward with the stall position of
this boundary. With most of the upper level energy well north of the
region...think this trend will continue. Therefore will hedge a bit
in case future runs continue this trend.
Long term /Thursday through Sunday/...
will use a blend of the models and ensembles for Thursday and
Friday...and then rely more on a blend of the European model (ecmwf) and gefs
ensemble means for the weekend. With a front waffling around the
forecast area...big question is where will it be at any particular
time. For now...will allow the remains of the front to remain near
the area...producing chances of precipitation.
Aviation /20z Sunday through Friday/...
upper level low spinning over Kentucky currently will slowly track NE in
the vicinity of the Ohio River through Monday. An uptick in
rain showers/thunderstorms and rain will be the rule through the early evening hours...with
the greatest concentration expected over SW Virginia and WV mountains any
rain showers/thunderstorms and rain will contain downpours with localize IFR conditions.
Otherwise MVFR in rain showers/thunderstorms and rain coded up.
The coverage of rain showers/thunderstorms and rain will wane and shift into PA by 06z. This
leaves another tough aviation forecast overnight. Expect some low
stratus to develop with patchy areas of dense fog where more holes
in the clouds are realized. For now followed close to guidance
with generally IFR or worse stratus with some MVFR/IFR visibility.
The upper low will open up into a wave and shift into NE Ohio on
Monday. Stratus and/or fog will be slow to lift in this low flow
moist environment...generally after 13-14z. Rain showers/thunderstorms and rain will
redevelop in the afternoon heating...mainly north taf sites.
Forecast confidence and alternate scenarios through 18z Monday...
Forecast confidence: medium.
Alternate scenarios: timing of showers may vary...could get lower
flight categories in heaviest showers/storms. Fog/stratus timing
and density may vary tonight.
After 18z Monday...
Brief IFR possible in thunderstorms Tuesday through Friday.
WV...Flash Flood Watch through late tonight for wvz005-006-013>016-
Kentucky...Flash Flood Watch through late tonight for kyz102-103-105.
Virginia...Flash Flood Watch through late tonight for vaz003-004.