Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
420 am EDT Monday Jul 6 2015
middle and upper level disturbance passes today into tonight. Cold
front approaches from Midwest late Tuesday...could stall/weaken
in vicinity Wednesday. Southeast Ridge tries to build north this week.
Near term /through tonight/...
we are still dealing with the pesky middle and upper level closed low
that has brought rounds of downpours over the last couple days.
However...the low will gradually weaken and open into the overall
trough through the day today. This will ease quantitative precipitation forecast amounts...however
still expecting showers with downpours today...especially across
northeastern quarter of County Warning Area. Have cancelled much of the Flash Flood
Watch that was in effect...still hanging onto the northern mountains
through the 6 am expiration time with ongoing showers there. Think
quantitative precipitation forecast will be low enough to not need an extension past 6 am in this
area. With the low opening up...flow will begin to pick up and keep
rainfall amounts in check. Will still mention downpours in severe weather potential statement
through this afternoon though.
Clouds begin to thin out from the west later today into
tonight...which should set the stage for River Valley fog tonight as
low level remain moisture laden. Have slight chance probability of precipitation moving back
into southeast County Warning Area very late tonight ahead of the next system.
Short term /Tuesday through Wednesday night/...
some time was devoted to monitoring rain and water levels on this
graveyard shift. Yet...it appears the common middle Summer
dilemma is setting up for this short term period. How far
south does a front get? Plus...does the overnight convection
Tuesday night drive the boundary...or focus of future convection...
The 00z NAM solution seems to have shifted the frontal convection
too far north. Did not make a major change toward its output.
However...on another issue...a bit concerned about a few renegade
showers forming Tuesday morning in the tri state and Ohio Valley.
The NAM solution has been hinting at this for past 2 days. Thinking
it is associated with low level confluent pattern with faster 925
to 850 mb flow to our west...and weaker flow still here at 12z
Tuesday...plus some warm air advection. So will include some 20
probability of precipitation Tuesday morning in our western counties.
In terms of the front...the 00z GFS seems to be a middle of the Road
solution with the 00z European model (ecmwf) being a bit further south. Will base
forecast on the front reaching near a cvg to pkb line toward 12z
Wednesday...then become nearly stationary from cvg toward ckb during
the day on Wednesday.
So will continue with the likely prefrontal convection probability of precipitation reaching
our southeast Ohio counties after 22z...with likely probability of precipitation reaching as far
south as Grayson-hts-crw-Summerville line overnight.
Will mention some strong to severe storms possible in our southeast Ohio
and pkb vicinity Tuesday evening in the hazardous weather
potential...and a water/flash flood concern for northern and central
counties overnight Tuesday night into Wednesday night.
This weekk's pattern favors the focus of convection to shift more
toward our northern and cetnral counties...compared to the south.
In terms of temperature...had to cut a few degrees off the maximum
from MOS guidance on Tuesday due to the wet vegetation. But with
increasing flow...still think middle and upper 80s likely in The
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 /08z Monday through Friday/...
upper level low will continue to spin over the region as it
gradually opens into trough later today. Very moist low levels
will lead to fog and low stratus early this morning. Some showers
drifting around out there as well. Expect shower activity to pick
up by middle morning...especially east of the Ohio River...but timing
any shower/storm into a taf site is very difficult as they could
pop up anywhere anytime. Went with general MVFR in showers today.
Start to clear out tonight...which should lead to dense fog
Forecast confidence and alternate scenarios through 06z Tuesday...
Forecast confidence: low.
Alternate scenarios: fog/stratus timing and density will vary
this morning. Timing of showers may vary...could get lower
flight categories in heaviest showers/storms.
After 06z Tuesday...
brief IFR possible in thunderstorms Tuesday through Friday with
the potential for low stratus and fog at night.
WV...Flash Flood Watch until 6 am EDT early this morning for wvz005-
Kentucky...Flash Flood Watch until 6 am EDT early this morning for kyz102-
Virginia...Flash Flood Watch until 6 am EDT early this morning for vaz003-
WV...Flash Flood Watch until 6 am EDT early this morning for