Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
720 PM EST Wednesday Dec 4 2013
slow moving cold front for Thursday and Friday with abundant
precipitation. Brief high pressure Saturday. Another wet system
Sunday and Monday.
Near term /through Thursday/...
700 PM update...
forecast on track.
warm front lifting north across County Warning Area this afternoon and should be
north of forecast area by middle evening. Best upper level support
stays west of County Warning Area...so expect most of the precipitation to stay west as
well. Hi-res near term models keep our County Warning Area dry but think an isolated
shower or two still possible in southeast Ohio over the next few hours.
Once the warm front clears...should have dry weather to start the
night...with probability of precipitation increasing from the west late as cold front
approaches. Isobars continue to tighten ahead of the cold
front...bringing some breezy to gusty winds across southeast Ohio and the
WV mountains tonight into tomorrow.
Exact timing generally within 3 hours or so for all models with cold
front Thursday. Expect the highest probability of precipitation along and just behind the
front. Have it entering western zones just before 16z-17z
Thursday...and then to the Ohio River around 20z...stalling out in
western WV by the end of the near term at 00z. Very skinny cape
profile ahead of cold front for Thursday afternoon...went back and
forth on whether to insert thunder into forecast or not...in the end
decided to leave it out based on previous several systems which had
similar cape with no thunder reported.
With good warm air advection tonight...blended towards the warmer met for lows
and even went a little non-diurnal for hourly temperatures at highest
elevations as 850s warm. Warmed temperatures across WV tomorrow...but
cooled them a bit closer to the front in southeast Ohio by blending in
European model (ecmwf) MOS guidance.
Short term /Thursday night through Saturday/...
cold frontal boundary along the Ohio River at the beginning of the
period...with low pressure wave riding northeast along boundary
Thursday night. This will create an enhanced area of rainfall
Thursday night...mainly in southeast Ohio...eastern Kentucky...and much of
the WV lowlands. Cold frontal boundary will slowly sink south
throughout the day on Friday...with additional waves riding along
the front Friday...creating periods of enhanced rainfall. With
plenty of moisture...aided by 40-50 knots low level jet...and precipitable water values rising to
around 1... in the 99th percentile for this time of year...will
see heavy rain at times. This will create rises on small streams and
creeks...and create ponding in low lying areas. Will also see rises
on area rivers. A Flood Watch will be issued for Thursday night
through Saturday morning for the WV lowlands...southeast Ohio...and
Most of the precipitation Thursday night and early Friday will be
rain...although parts of southeast Ohio...particularly northernmost
counties...could see a wintry mix on Friday...with periods of sleet
and freezing rain...changing to snow Friday evening. May end up
needing an advisory for these counties...and will allow future
shifts to monitor the need. All areas will transition to a brief
wintry mix Friday night...before becoming snow area wide overnight
Friday...except for parts of southwest Virginia and the southern Coal
fields...which may remain in the form of a wintry mix. At this
point...not expecting much in terms of accumulations...with the warm
ground as of late...and due to the overall brief duration of wintry
weather Friday night.
At this point...have coded around 2 to 2.5 inches of rain as a
general rule for much of the WV lowlands...eastern Kentucky...and parts of
southeast Ohio...with locally higher amounts possible. With 1 to 2
inches expected elsewhere.
Forecast area will gradually dry out on Saturday...as the low
pressure system and associated cold front moves off to the east.
Long term /Saturday night through Wednesday/...
generally followed wpc thinking with some tweaks for latest model
Period should begin with an area of low pressure off the la coast
and an area of high pressure over PA/NY.
The low is expected to lift north to the Great Lakes...with a warm
front lifting across the region by Monday morning.
Expect precipitation chances will increase from the south Saturday
night into Sunday. Surface temperatures Saturday night should begin below
freezing with temperatures aloft at or above freezing. Precipitation will
likely begin as a mixture of snow...sleet and freezing rain.
However...the precipitation should then change to all rain Sunday
across The Lowlands...with a wintry mixture expected to continue
across the higher elevations into Monday.
Have gone with categorical probability of precipitation across parts of the region Sunday
and Sunday night. In addition to any wintry conditions that
develop...rainfall amounts will also have to be monitored.
An associated cold front will push east on Monday...with a ridge
of high pressure finally building into the area by late Tuesday.
As the colder air filters in behind the front...precipitation may
mix with sleet and freezing rain before changing to snow Monday
Precipitation chances will come to an end across much of the area by
Aviation /00z Thursday through Monday/...
MVFR stratocu forming along the eastern slopes of the WV mountains
overnight tonight likely to bring 1-3 kft ceilings to bkw early Thursday
morning. Otherwise VFR through Thursday morning in warm sector ahead of a
strengthening low pressure center cutting up through the upper Great
Lakes. This low will drag a cold front toward the area Thursday.
Showers ahead of the cold front will cause conditions to deteriorate
to MVFR Thursday afternoon...beginning 16-17z /right near noon/ along the
Ohio River...around 20z central WV...and near the end of the taf
period /23z Thursday-00z Friday/ in the mountains.
Surface flow will be light S to southeast overnight...except near 10 kts on the
ridges. Surface flow becomes S to SW and gusty on Thursday...with peak gusts
reaching near 20 kts heights late Thursday from about 210. Flow aloft will
be moderate to strong SW...40-50 kts at 4-5kft.
Pkb ASOS remains ots - additional parts already on order should
Forecast confidence and alternate scenarios through 00z Friday...
Forecast confidence: medium to high.
Alternate scenarios: timing of MVFR ceilings bkw may vary overnight.
Onset of lower ceilings/visibilities ahead of cold front Thursday may vary.
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 00 01 02 03 04 05 06 07 08 09 10 11
EST 1hrly 19 20 21 22 23 00 01 02 03 04 05 06
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 M M M M M M M M M M h
ekn consistency h h M M M h h h h 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 00z Friday...
IFR possible in rain Thursday nt into Friday nt...mixed precipitation at the
WV...Flood Watch from Thursday evening through Saturday morning for
Ohio...Flood Watch from Thursday evening through Saturday morning for
Kentucky...Flood Watch from Thursday evening through Saturday morning for