Scientific Forecaster Discussion
fxus61 krlx 211033
Area forecast discussion
National Weather Service Charleston WV
633 am EDT Wed Aug 21 2019
isolated to scattered showers today with weak mid-level
disturbances continue to cross the area. Increasing
precipitation chances Thursday with the approach of a cold
front. Drier and cooler for the weekend.
Near term /through tonight/...
as of 630 am Wednesday...
Trimmed thunderstorm chances over the western half of the
forecast area this morning with weak wave evident in satellite
imagery nearing the Ohio River at this hour not producing much
upstream. Should move into a slightly less stable environment
over the next couple hours but with rather limited instability
to work with may not produce much.
As of 420 am Wednesday...
Weak mid-level disturbances will continue to cross the area
today with shower and thunderstorms chances increasing by this
afternoon. Significant convective overturning associated with
yesterday's complex will limit overall destabilization potential
with less than 1000j/kg MLCAPE across the northeastern 2/3rds
of forecast area and 1000 to 1500j/kg to the southwest. Deep
layer shear 20kts or less suggests limited potential for storm
organization, but may still see an isolated damaging wind gust
or two, especially across our southwestern counties where
instability is maximized and dcape values approach 1100j/kg.
Convective activity will diminish during the early overnight
before increasing again early Thursday morning from the north
with the approach of a slow moving cold front.
Remaining convective debris along with a developing
stratocumulus field this morning will limit insolation through
at least late morning keeping high temperatures today 4 to 8
degrees cooler than Tuesday, mostly in the upper 80s to lower
90s for The Lowlands.
Short term /Thursday through Friday night/...
as of 340 am Wednesday...
The start of this forecast period kicks off with unsettled
weather as as the precipitation shield ahead of a cold front to
the northwest blankets the area with rain and likely pops
through Thursday. Thunderstorm chances will be at their highest
on this day as well with possible severe storms with all the
modest shear, moisture, instability and lifting who will have
their ducks in a row. Expect some fair rainfall amounts
generally less than an inch in total through Friday although
isolated higher amounts will be possible within storms.
The area is forecast to be in an marginal risk for excessive
rainfall during frontal passage so we will have to keep an eye
on Hydro issues as pwats, instability and divergence aloft will
be relatively high. The front should progress through to where
it would limit any significant Hydro issues, however any storms
that train or backbuild can cause minor issues in low lying and
poor drainage areas.
On Friday, the front will push through just as the sun starts
to fade and thunderstorm and shower chances will fade as well.
Cooler drier weather begins overnight Friday and onto Saturday
as highs will have trouble surpassing the 80 degree mark. For
the rest of Saturday there may be some lingering showers in the
southern most parts of the area and confined to the eastern
mountains where a wave is forecast to form along the
aforementioned frontal boundary .
Long term /Saturday through Tuesday/...
as of 400 am Wednesday...
A very amplified ridge Parks overhead late Saturday promoting
fair weather into Sunday. The ridge will slide east and allow an
upper level trough to surge in and pull sufficient moisture
from the Gulf to raise chances for showers and diurnally driven
storms through Monday. Temperatures will stay generally cooler
with 80s for highs and low 60s for lows. Cooler air exits the
area as more high pressure builds in on Tuesday into Wednesday
bringing warmer temperatures back to the area as well as lower
chances for showers and storms for fair weather to dominate.
This however will be short lived as the next weather maker looks
to be headed our way on possibly Thursday.
Aviation /10z Wednesday through Sunday/...
as of 630 am Wednesday...
Mid-level convective debris from remnants of upstream
convective complex will limit dense valley fog formation this
Substantial upstream convective overturning overnight,
especially across northern portions of the forecast area will
limit destabilization potential today with isolated to scattered
thunderstorm coverage after 19z as a weak wave crosses the
region. Outside of any morning valley fog and in the vicinity of
any locally heavier showers this afternoon conditions are
expected to remain VFR through late tonight. Approaching cold
front will bring increased precipitation chances and deteriorating
ceilings Thursday morning.
Forecast confidence and alternate scenarios through 12z Thursday...
Forecast confidence: medium.
Alternate scenarios: afternoon storm coverage may vary. Valley
fog and stratus Thursday morning may be more extensive if
afternoon storms produce more precipitation than expected or we
partially clear out prior to arrival of slow moving cold front.
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 10 11 12 13 14 15 16 17 18 19 20 21
EDT 1hrly 06 07 08 09 10 11 12 13 14 15 16 17
crw consistency h M h h h h h h h h h h
heights consistency h h h h M M M M M h h h
bkw consistency h h h M M M M M M h h h
ekn consistency l l l M M M M M M h h h
pkb consistency h h l l h h h l M h h h
ckb consistency h h M M M M M M M M h h
After 12z Thursday...
increasing shower/thunderstorm potential along a sagging cold
front through the day Thursday and Friday with widespread
MVFR/IFR ceilings. Cold front slowly sags south through Friday
evening with cooler and drier conditions expected Saturday.