Scientific Forecaster Discussion
fxus61 krlx 112054
Area forecast discussion
National Weather Service Charleston WV
354 PM EST Wed Dec 11 2019
disturbance with flurries north this evening. High pressure
through early Thu night. Next system approaches Fri. Active
pattern persists through the weekend and into next week.
Near term /until 1 am Thursday morning/...
as of 350 PM Wednesday...
Disturbance moving through Ohio is producing flurries that are
making it to the ground. Have updated the forecast to move
flurries through northern West Virginia this evening.
As of 1215 PM Wednesday...
Upper level trough continues to shift east of the area this
afternoon as a surface high in the Tennessee Valley builds into
the region. There has been an increase in mid-level moisture as
a weak impulse aloft moves through. This feature has produced a
scattered/broken cumulus field that is drifting across Ohio/in at
this time. Thus, cloud cover will increase this afternoon
across parts of the area, particularly northern areas, but not
expecting precipitation from this as soundings show plenty of
dry air near the surface. Cloud cover will then clear later this
evening as the aforementioned surface high moves over the
region. This will set the stage for a chilly night and fairly
solid radiational cooling conditions with light to calm winds.
Lows are expected to dip down into the low/mid 20s throughout
the area, but teens are likely in the mountains and even across
parts of southeast Ohio.
With plenty of solar insolation and return flow setting up
Thursday as high pressure moves towards the northeast,
temperatures will return to normal values across the area with
highs generally in the mid 40s. Cloud cover will then gradually
increase across the area late afternoon into the evening as the
flow aloft becomes more southwesterly ahead of a mid-level
trough,but not expecting any precipitation activity to occur in
the near term period.
Short term /1 am Thursday morning through Saturday/...
as of 228 PM Wednesday...
Surface high pressure in southern New England will wedge down the
eastern slopes of the mountains Thursday night, helping to maintain
a shallow layer of sub-freezing air near the surface. Meanwhile,
cyclogenesis will take place Thursday night across the northern Gulf
Coast as mid-level shortwave energy tracks across the southern US.
This will lead to the development of a coastal low that is expected
to lift northward along the southeast coast into Friday. Moisture
ahead of this coastal system will increase across our area from
south to north and override the shallow layer of sub-freezing
air near the surface, bringing an opportunity for a period of
mainly freezing rain across parts of the area as precipitation
initially arrives early Friday morning. Forecast soundings do
suggest that the dominant ptype should be freezing rain, but
some sleet/snow is also possible on the leading edge of the
precip. Areas at greatest risk for freezing rain will be across
the eastern sections of the County Warning Area where cold air damming effects
will be greatest. However, a brief period of freezing rain could
also occur across portions of north central WV as the system
initially arrives. Ice accumulation should be pretty light with
most of the area looking at 0.05" or less, but still enough to
cause travel concerns, particularly on untreated surfaces. Will
mention in the severe weather potential statement for now.
By Friday afternoon, thermal profiles will warm more than enough
for any precipitation across the area to be just rain. However,
few of the higher ridges in the mountains may stay cold enough
to maintain light freezing rain and/or sleet into the afternoon.
Any precip activity Saturday afternoon should be pretty light,
but with the coastal system tracking southeast of the area
Friday night into Saturday and a secondary low approaching from
the west, an increase in precipitation coverage across the
region is expected. This will result in periods of light to
occasionally moderate showers on Saturday with most of the area
expected to be rain, but some high elevation snow showers could
occur in the mountains during the afternoon.
Long term /Saturday night through Wednesday/...
as of 228 PM Wednesday...
As the aforementioned secondary low merges with the coastal low
in the mid-Atlantic region, this system will then strengthen as
it lifts northward and tracks into eastern Canada Saturday
night into Sunday. Colder air will move into the region as this
occurs and this could allow precipitation across the area to
transition from rain to snow Saturday night. The flow will then
become more favorable for upslope precipitation by Sunday, with
upslope snow showers possible in the mountains and light rain
showers across parts of The Lowlands.
A brief lull in precipitation chances across the area should
then occur by Sunday night as high pressure across the upper
Midwest briefly builds into the area. However, models then
indicate that a low pressure system will then develop across The
Ark-la-tex region on Monday, which is expected to lift to the
north-northeast towards our area by Monday night. This system is expected to
bring another round of rain and/or snow across the region Monday
into Tuesday, but with uncertainty on the track of the system
there remains uncertainty in the main ptype at this point. Have
maintained a consenus blend of pops for now until better model
Aviation /21z Wednesday through Monday/...
as of 1205 PM Wednesday...
Satellite imagery shows a scattered/broken cumulus field across the Ohio
Valley and this will drift across the region this afternoon and
evening as a weak upper-level disturbance moves through.
However, cloud bases with this activity are expected to be
between 4-7 kft, so VFR conditions are expected through the
remainder of the day.
Any cloud cover that forms today will dissipate tonight as high
pressure moves directly over the area overnight into Thursday.
This feature will promote clear to mainly skies across the
region through Thursday afternoon. Thus, VFR conditions will
continue through the end of the taf period. Winds will also be
light out of the south-southeast on Thursday, around 5-10 kts.
Forecast confidence and alternate scenarios through 18z Thursday...
Forecast confidence: high.
Alternate scenarios: none.
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 21 22 23 00 01 02 03 04 05 06 07 08
EST 1hrly 16 17 18 19 20 21 22 23 00 01 02 03
crw consistency h h h h h h h h h h h h
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 h
ekn consistency h h h h h h h M M h h h
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 h h
After 18z Thursday...
IFR possible in rain Friday/Friday night.