Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
709 PM EDT Monday Mar 10 2014
mild air dominates through Tuesday with weak disturbances in west-northwest
aloft. Strengthening low pressure center crosses Wednesday. Cold
Thursday. Warming Friday. Cold front Saturday.
Near term /through Tuesday/...
a Spring fever alert.
Though having difficulty figuring extend/coverage of any lower
clouds forming on the western slopes 06z to 12z Tuesday before
lifting and evaporating toward 15z. The last of the Monday morning
stratus evaporated over southeast Kentucky before 18z today. Will
include some scattered to broken low clouds on either side of
dawn...mainly in WV. Thinking 12z NAM a bit overdone though on this
low level moisture.
Also weak middle level disturbances passing overnight...could still
result in patches of middle clouds. Will leave pop around 10 percent.
No major changes in temperature. Though with cloud coverage in
question for the predawn hours...and wind stirring on
hilltops...that compounds low temperature overnight.
Even with higher temperatures on Tuesday...dew points also creep
higher. So minimum relative humidity mostly in the 30s.
Short term /Tuesday night through Thursday/...
main attention for the short term revolves around the low pressure
system moving up the Ohio River valley Tuesday night and Wednesday.
Models all track the low across or just west and north of
County Warning Area...which will keep forecast area out of the best snow zone in
central to northern OH/PA. The European model (ecmwf) is the farthest south...NAM
farthest north and the GFS in the middle.
Increased probability of precipitation...with maximum probability of precipitation entering west predawn
Wednesday...crossing County Warning Area during the day and then decreasing in the
mountains overnight. Did linger higher probability of precipitation longer in the
mountains...as the 500mb trough comes in right behind the surface
low which should keep lift going. Things then transition to a quick
dose of upslope snow showers late Wednesday night into Thursday
afternoon. Have generally .4 to .6 quantitative precipitation forecast across southern County Warning Area...with .6
to .8 north. A lot of this will fall as rain...especially south.
Also have some thunder in the forecast across southeast half of County Warning Area. The
cold front will Cross County warning area Wednesday...so have non-diurnal temperatures with
a good drop behind the front...with rain changing to snow. Also
increased snow amounts some...with generally an inch or less of snow
south of I-64...a dusting up to 2 inches heading north...and 1-3 in
the mountainous counties of WV. This matches up fairly well with wpc
westward forecast lending some additional confidence. Do have 2 inch
average in Perry County Ohio...so will add to severe weather potential statement at this point.
As the surface low passes...it should be deepening...so will get
some gusty northwest winds with tight pressure gradient. Upped wind speeds
and gusts from around 21z Wednesday to 03z Thursday. Even though just below
Wind Advisory criteria...will include wind gusts in severe weather potential statement. Looks like
a very chilly Wednesday night...with most places at or below
freezing Thursday despite some peeks of sun late in the day.
Long term /Thursday night through Monday/...
after a rather cold night Thursday...moderating temperatures will ensue for
Friday. A weak cold front will cross on Saturday with small chance
for a shower early in the day. Models diverge somewhat on magnitude
of the upper trough moving to round out the weekend with the GFS on
the colder side. This leads to important differences heading into
next week...specifically handling some energy diving in on the back
side of the mean trough and ecwmf continues to advertise this closing
off into a potent upper low as it crosses the southeast states...inducing
surface cyclogenesis and thus a stormy pattern across the region.
The GFS dampens out this energy and allows the upper trough to
overwhelm the east Continental U.S. With cold air and storm. Gonna side close to
HPC solution which gives greater weight to more consistent ecwmf
versus the waffling GFS and GFS ensembles. Although even ecwmf is
not entirely stable regarding whether it becomes separated from the
mean trough or not. Nevertheless...preferred solution has a surface
low organizing along the southeast coast early next week with some
influence for our sensible weather anticipated but too early for
specifics at this range.
Aviation /00z Monday through Saturday/...
models showing that some MVFR clouds could form over northeastern
West Virginia late tonight...persisting through middle day Tuesday.
Outside of this deck...expect VFR conditions.
Forecast confidence and alternate scenarios through 00z Wednesday...
Forecast confidence: high this evening and Tuesday
afternoon...medium late tonight and Tuesday morning.
Alternate scenarios: timing of deck forming /or whether cloud deck
even forms/ over northeastern WV could 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.
Date Tuesday 03/11/14
UTC 1hrly 00 01 02 03 04 05 06 07 08 09 10 11
EDT 1hrly 20 21 22 23 00 01 02 03 04 05 06 07
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 l
ekn consistency h h h h h h h h l l l l
pkb consistency h h h h h h h h h h h l
ckb consistency h h h h h h h h h h l l
After 00z Wednesday...
IFR possible as strengthening low pressure system and associated
cold front passage Wednesday...with rain showers changing snow
showers late Wednesday and lasting into Wednesday night.