Scientific Forecaster Discussion
fxus61 krlx 161841
Area forecast discussion
National Weather Service Charleston WV
241 PM EDT Mon Sep 16 2019
weak cold front crosses today with isolated showers possible.
High pressure and upper ridge dominate the rest of the week.
Another system due to approach for the end of the weekend.
Near term /through Tuesday/...
as of 219 PM Monday...
A wavy cold front stretches from northwestern PA into central Ohio
and central in, which is associated with a weak surface low in
the Northern Ohio valley. The frontal boundary will continue to
move east-southeast towards our region through the day as surface high
pressure in Ontario builds into the region this evening and
overnight. Upper level support associated with the front will be
weak, but with the heating this afternoon and fairly steep low
level lapse rates, a few short-lived showers may occur across
the area. A few of these showers have already developed near
the tri-state region, but the majority of the impact in this
area has just been an increase in mid- level clouds. Thus,
thinking the fropa will mainly just result in a wind shift from
near west winds ahead of the front to near north-northwest behind the front.
The front will push through most of the area overnight into
early Tuesday, but low level moisture lingering behind the
front overnight may support the development of River Valley fog
throughout parts of the area as many locations decouple. There
is uncertainty in the coverage of fog tonight given how dry the
ground is and little to no moisture contribution from the
ground, but with the subsidence inversion overnight and little
to no flow, at least some fog appears possible.
With surface high pressure north of the area on Tuesday,
expecting mainly dry conditions throughout the day. However,
have included slight pops in the forecast in the mountains as
enough orographic lift and instability could support a few
showers and an isolated thunderstorm threat. Elsewhere,
subsidence aloft will keep the remainder of the area dry, but
temperatures remain well above normal with highs expected to
reach the mid/upper 80s.
Short term /Tuesday night through Thursday/...
as of 230 PM Monday...
For the start of this forecast period a weak trough of low pressure
will move off to the southeast. High pressures at the surface
builds in from the north over the region on Wednesday. This
will promote fair and dry weather for the rest of this period
and into the next period. Temperatures will remain above normal
and also on the decline with mid 80's for highs and 50's
possibly into the 60's for lows into Thursday as a cooler
airmass slides closer in to the area.
Long term /Thursday night through Monday/...
as of 240 PM Monday...
With high pressure overhead planted at the surface along with an
extensive broad upper level ridge acting as an Omega block,
nothing but fair weather is in the long term forecast. Dry,
mainly clear skies along with very low probability for any
diurnal convection will continue into the weekend. Temperatures
will remain above normal in the mid to upper 80's and vary only
slightly over the week. Low 90's in certain spots is not out of
the question especially during the weekend. Night time lows
will increase slightly from what has previously been observed,
however will stay generally around the 60's for a greater part
of the area. Some models hint on the high pressure finally
breaking down and bring a system through sometime late in the
weekend, although they disagree on timing. Decided to agree with
central guidance and went with slight chance/chance pops
areawide for Sunday when the next system is anticipated.
Aviation /19z Monday through Saturday/...
as of 126 PM Monday...
Widespread VFR conditions are in place this afternoon with high
pressure in control.
Latest surface analysis shows a cold front across southeast Ohio
and western PA, associated with a weak area of low pressure in
the Northern Ohio valley. As this system moves to the east, the
cold front will continue to moving south-southeast towards the area through
the remainder of the afternoon and evening. Only real impact
from this feature will be a wind shift from west-northwest ahead of the
front to north-northwest behind the front.
The cold front will push south of the region overnight, with
high pressure in the Great Lakes quickly building int. Enough
low level moisture may remain tonight to bring a risk of River
Valley fog throughout the area, perhaps bringing IFR/LIFR
conditions to areas where fog develops.
By mid morning on Tuesday, any fog that develops will dissipate
and VFR conditions will return to the area. Diurnal cu field
will develop Tuesday afternoon, but any flight restrictions
Forecast confidence and alternate scenarios through 18z Tuesday...
Forecast confidence: medium.
Alternate scenarios: coverage of fog and timing tonight may
Experimental table of flight category objectively shows consistency
of weather forecast office 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 M l
heights consistency h h h h h h h h h h h h
bkw consistency h h h h h h h h h h h M
ekn consistency h h h h h h h h M M l l
pkb consistency h h h h h h h h h h h h
ckb consistency h h h h h h h h h h M M
After 18z Tuesday...
early morning dense River Valley fog possible each morning.