Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
1244 am EST Wednesday Dec 11 2013
brief high pressure settles in tonight and departs Wednesday. Arctic
front crosses Wednesday night. Arctic high pressure Thursday exits
Friday. Low pressure crosses this weekend with mixed precipitation.
Near term /through today/...
1230 am update...
ingested recent observation. Forecast is generally on track.
930 PM update...tweaked hourly temperature grids per recent
trends/observations...otherwise...no changes needed.
Previous discussion follows...
last of the snow will be exiting either by the issuance of this
discussion or shortly there after. Local models still indicate
some light snow hanging on in the northeast mountains until around
20z...and dry through the remainder of the near term.
Column will dry fairly quickly...and clouds remaining tonight will
be largely dependent on the low level flow. 925mb thermal trough
helps keep some moisture in place over the northeast mountains
tonight...so do not think these areas will clear despite the shallow
nature of the moisture.
A weak low pressure system brings another cold front Wednesday...and
will increase the middle level moisture. No precipitation expected on
the front end of this feature before 00z Thursday. But this cold
front will usher in a reinforcement to the cold air coming in the
short term forecast period.
Short term /tonight through Friday/...
Arctic air charges in right at the start of the short term
period...and rules The Roost for most of it beneath upper level west-northwest
flow. Nice 485sm upper level vortex to start the period slowly
fills as it meanders about eastern Canada.
Still think system is too moisture starved for anything more than
upslope snow showers in the mountains in the wake of the front.
However did add flurries across The Lowlands up north as the Arctic
front crosses...which will be about 02z to 08z Thursday. Upslope
diminishes Thursday morning as cold trough passes...did linger flurries
into Thursday morning beyond sunrise.
High pressure sails across southern part of the area Thursday nt and
Friday. Thursday nt will be clear but with some wind across the north.
Blended in bias corrected versions of adjmet and allblend for lows
Wednesday nt...reached on the cold advection given clouds and some wind.
Blended in adjmet for highs Thursday...a little higher than previous.
Thursday nt is the best radiation nt and the nadir of this Arctic
spell...lowered the valleys S where the high crosses. Blended in a
part bias corrected adjmex per two parts previous for slightly
higher highs Friday...still below most guidance in the vacating Arctic
Long term /Friday night through Tuesday/...
still under the influence of high pressure Friday...surface winds
develop an easterly component early Saturday in response to
deepening low pressure across the Tennessee Valley...deepest
moisture will be cutoff by the Appalachians remaining south and east
of rlx. Nonetheless we will see precipitation mostly in the form of rain
Saturday afternoon and evening with some mixed snow and rain in southeast
Ohio and the higher elevations of eastern mountain counties...as
the system moves northeast Saturday night into Sunday...any precipitation on
the backside of the low will be in the form of snow...not
expecting any significant accumulation at this point...high
pressure and cold air builds in behind the front with some diurnal
upslope snow showers Sunday...next system approaches our southeast Ohio
counties by Tuesday.
Aviation /06z Wednesday through Sunday/...
VFR conditions expected for the period. West to southwest winds
expected for the taf period...with occasional gusts in the teens
across The Lowlands...and in the teens to upper 20 kts across the
higher terrain. Some middle and high clouds expected after 18z mainly
across northern locations on Wednesday with a dry cold
front...but no restrictions expected. Clouds will be lowering near
the end of the valid period across the northeast areas as a quick
moving disturbance brings a chance of some snow showers to that
area...but at this point it appears any sub-VFR ceilings or visible will
hold off until after 06z Thursday.
Forecast confidence and alternate scenarios through 06z 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.
Date Wednesday 12/11/13
UTC 1hrly 06 07 08 09 10 11 12 13 14 15 16 17
EST 1hrly 01 02 03 04 05 06 07 08 09 10 11 12
crw consistency h h h h h h l 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 l l l l l l h h h h h
pkb consistency h h h h h h l h h h h h
ckb consistency h h l l l l l l l h h h
After 06z Thursday...
IFR possible in snow...sleet...freezing rain and rain Saturday and
possibly lingering in snow showers Sunday.
kpkb ASOS remains ots...with additional parts on order. Augmented