Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
434 PM EDT Tuesday Mar 11 2014
Spring like evening. Strengthening low pressure center crosses
Wednesday. Gusty winds and turning much colder Wednesday afternoon
and Wednesday night. Warming Friday. Weaker cold front Saturday.
Near term /through Wednesday/...
a nice Spring like evening pictures. Tried to have temperatures
bottom out between 03z to 06z...before steady in the east...and
rising in the west before the rain arrives.
The first shot of rain whips through 08z to 15z...could not rule out
an embedded thunderstorm...mostly in southeast Ohio...with this
initial shot of rain.
Tried to paint a brief break in southern counties before the cold
front whips through. Have the front nearing a ckb-crw at 18z
Wednesday. So best chance for thunder along front was further east
during the 18z to 20z period.
Was a bit faster with the cooling on Wednesday...but only by an hour
or two. As a result...have mostly 1 to 2 inches of snow in the
backlash in southeast Ohio into middle Ohio Valley. Where advisory
criteria is only 2 inches (1.5 inches rounded up) posted a Winter
Weather Advisory. Of course...snow amounts could be just as high or
higher in the counties where Winter Weather Advisory criteria is
higher...such as central WV mountain counties.
Also...with such rapidly cooling in the low levels...also posted a
Wind Advisory through the our 49 County area. Of course...thinking
the strongest gusts are Post frontal. For example...the 850 mb
temperature at crw drops from +9c at 18z Wednesday to minus 12c at
00z Thursday. That's a 21c drop in 6 hours...quite impressive.
Short term /Wednesday night through Friday/...
12z model runs didnt initialize the position of developing trough
over the northern plains very well..placing the vortmax over the
northern plains a little too far north...and the weak surface front
across the Delaware-Maryland-Virginia was positioned farther west in the
models...given this discrepancy chose a blend of GFS/NAM/Euro with
slight emphasis on 00z European model (ecmwf) that showed better continuity...short
term begins with exiting cold front moving east across eastern mountains
in the evening...cold air filters in quickly behind the front with
850mb temperatures dropping 20c in 12hrs across the Ohio River from 00z
Thursday to 12z Wednesday...snowfall in the shorterm will be light in the
wake of the cold front...higher elevations in northeast counties may
see an additional inch of snow after sunset Wednesday ending
sometime soon after midnight...Post frontal winds will remain strong
and a Wind Advisory has been issued and will expire at midnight
Wednesday...with wind gusts potentially between 40-50mph especially
in the mountains.
Fast moving upper level trough exiting to the east
allows amplified ridge to build across the Ohio Valley/middle Atlantic
later in the day Thursday...surface high over the southeast results
in surface winds shifting from northwest to southwest and warm air
starts to build back in out of the Tennessee Valley...after topping
out in the low to middle 30s fro most of US on Thursday...temperatures will
bounce back into the low 50s Friday.
Long term /Friday night through Tuesday/...
used a blend of the gefs mean and the ecwmf ensemble mean. This
pushes a cold front through Friday night and Saturday. The pattern
then stays active Sunday through Tuesday with multiple systems
possibly affecting the region. Confidence is low in these periods
due to the large spread between models.
Aviation /21z Tuesday through Sunday/...
VFR through 06z Wednesday. Conditions deteriorate with initial band
of rain arriving 08z to 13z...most widespread across southeast Ohio
and northern West Virginia...less coverage southern West Virginia.
Ceilings becoming 2 to 3 thousand and visibility 3 to 5 miles in
rain...possible embedded thunderstorm in southeast Ohio before 12z.
After the initial band of rain...may be a lull in West Virginia for
2 to 4 hours before the arrival of the associated cold front. Have
the cold front reaching near a ckb to crw line around 18z.
Widespread rain showers along and behind front with ceilings 1 to 2
thousand feet and visibility at or below 3 miles. Showers changing to snow showers in
southeast Ohio around 18z. Chance of thunderstorm along front
should increase east of ckb-crw line after 18z Wednesday.
Wind gusts increase in wake of the cold front...with gusts of 30 to
40 knots arriving in southeast Ohio by 18z Wednesday.
Confidence dropped to medium trying to time any lull Wednesday
morning...between initial shot of rain and the front.
Forecast confidence and alternate scenarios through 18z Wednesday...
Forecast confidence: medium.
Alternate scenarios: timing of the frontal passage may vary slightly
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 20 21 22 23 00 01 02 03 04 05 06 07
EDT 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 l h h h h h h h h h h h
pkb consistency h h h h h h h h h h h h
ckb consistency l l h h h h h h h h h h
After 18z Wednesday...
lingering IFR in backlash rain to snow showers and strong low level
winds 18z Wednesday through 06z Thursday.
WV...Wind Advisory from noon Wednesday to midnight EDT Wednesday
night for wvz005>011-013>020-024>040-046-047.
Winter Weather Advisory from 1 PM Wednesday to 2 am EDT
Thursday for wvz009-010-019.
Ohio...Wind Advisory from noon Wednesday to midnight EDT Wednesday
night for ohz066-067-075-076-083>087.
Winter Weather Advisory from 1 PM Wednesday to 2 am EDT
Thursday for ohz066-067-075-076-084.
Kentucky...Wind Advisory from noon Wednesday to midnight EDT Wednesday
night for kyz101>103-105.
Virginia...Wind Advisory from noon Wednesday to midnight EDT Wednesday
night for vaz003-004.