Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
550 am EST sun Jan 25 2015
next system approaches today and moves through tonight and Monday.
High pressure briefly arrives Wednesday. The cold parade continues
with clippers Thursday and again Saturday night.
Near term /through tonight/...
545 am update...
Tweaked probability of precipitation this afternoon along warm front based on latest hrrr. This
resulted in some -ra streaking into ckb/ekn for a few hours this
afternoon before lifting north.
Previous discussion below...
Busy weather pattern rolls on...
Will be tracking an upper level disturbance with an associated
surface low dropping through an amplifying trough. It still appears
the bulk of the precipitation today will focus along a developing warm
front from aforementioned surface low. Where this warm front sets up
is critical in terms of not only quantitative precipitation forecast but eventually precipitation type. The
models are relatively tightly clustered on track of surface low and
warm front. The warm front is expected to develop across S Ohio and
extend into north WV this afternoon. As isentropic upglide
increases...light precipitation will break out along the warm front...first
across our north southeast Ohio zones and then overspreading the north fringes of our
north WV zones...including pkb/ckb/ekn for a time late this afternoon.
Thermal profiles indicate light rain at onset...save for the higher
elevations of Randolph Colorado. Think any snow accumulations up there
would be meager through 00z. A decent spike in temperatures will be realized
this afternoon across SW Virginia/Coal fields/Kanawha valley/and up along
and east of the i79 corridor to the west slopes...courtesy of S to southeast low
level downsloping flow. Look for highs in upper 40s with maybe a 50
showing up across the Coal fields and Kanawha valley.
By this evening...the surface low will be tracking through east Kentucky with
the upper level trough axis lagging a little behind. The warm front
will have oriented itself more into an inverted surface trough across
WV. As such...the low level warm wedge will hold through 06z except
across the higher elevations in the mountains and Perry Colorado. A few
inches may accumulate across the high terrain. Perry County is
tricky as just a 20 mile shift in overall track to the S would mean
the difference between 1 to 2 inches vs 2 to 3. The NAM and sref
would have only North Perry reaching criteria while some of the other
models are a bit more generous. After coordination with surrounding
offices...elected to hoist an advisory for 1 to 3 inches...with the
higher end across North Perry. Will start it at 21z this afternoon and
run it until noon Monday. Elsewhere as the low tracks through S WV and
into Virginia and the upper trough crosses...the rain/snow line will begin
to collapse through southeast Ohio and NE Kentucky during the predawn hours...where a
coating of snow is possible through 12z...mainly across remainder of southeast
Ohio zones. The rain/snow line by 12z looks to be just east of the Ohio
Short term /Monday through Tuesday night/...
precipitation from the clipper will gradually move eastward out of
the area on Monday. With cold air advection late Monday and Monday
night however...some low level over turning and upslope snow showers
become a possibility. Models showing that moisture will initially be
fairly limited with in the west...so best chance of snow should be
in the mountains.
A weak disturbance also moves over late Monday night into
Tuesday...increasings moisture in the western and southern counties.
This could produce some light snow...but models are not nearly as
robust with this feature as they were last night.
High pressure finally builds in on Wednesday.
Long term /Wednesday through Saturday/...
close to wpc thinking with positive pna this period. Clipper
systems reinforce the cold air just prior to the start of the
period...and then again Thursday-Thursday nt and Sat nt. The one just prior
to the start of the period is prognosticated to evolve into a sizable and
rapidly intensifying storm system off the East Coast Mon-Tue.
High pressure cuts off upslope snow showers in the wake of the first
clipper Tuesday nt...and then sails across on Wednesday. Warming aloft Wednesday
may not be realized at ground until Thursday...in the srly flow ahead of
the second clipper. This system is likely to provide a good but
brief upslope snow event Thursday nt. While still at a distance where
the models are still in flux...the weekend system may be more
interesting than just a clipper.
Little changes were needed to temperatures which were close to wpc.
The gfs40 was employed Thursday morning and Sat morning...the better
radiative cooling nights. The fast moving systems in the baroclinic
zone create bust potential in this period.
Aviation /12z Sunday through Thursday/...
looking at generally 4 to 5 thousand foot ceilings this morning for
all terminals except kekn/kckb...where low end MVFR ceilings will
hold. Expect kekn and kckb to sneak into low end VFR ceilings 15 to
A warm front will develop across southeast Ohio and north WV today...with
precipitation breaking out along this feature...mainly in the form of
rain...clipping kpkb and kckb later this afternoon with perhaps
some MVFR cigs/vsby. The warm front will lift north this evening and
Orient itself more into an inverted surface trough across WV....as
a low pressure center traverses Kentucky and into S WV toward end of taf
period. Rain will overspread the rest of the terminals after 00z
with ceilings/visibility lowering into MVFR and eventually IFR. The rain
will change to snow across southeast Ohio this evening with ceilings lowering
into IFR or worse along with visibility. This transition slow works southeast
to heights/pkb by end of taf period. Some snow is expected in the
higher elevations of the north mountains with IFR and LIFR conditions.
Wind will generally be out of the S for kcrw/khts/kekn and south-southeast for
kbkw in the warm sector. Wind directions generally NE for kpkb/kckb
today. Flow generally light...on the order of 5 to 10 kts.
Forecast confidence and alternate scenarios through 12z Monday...
Forecast confidence: medium.
Alternate scenario: ceilings may stay low end MVFR for kekn/kckb
instead of IFR...before lifting later this morning. Timing precipitation
and thus aviation conditions may vary this evening.
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 11 12 13 14 15 16 17 18 19 20 21 22
EST 1hrly 06 07 08 09 10 11 12 13 14 15 16 17
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 l l h h h h h h h h h h
ekn consistency h h M M h h h h h h h h
pkb consistency h h M M l l l h h h h h
ckb consistency h h h M h h h h h h h h
After 12z Monday...
IFR in snow showers Monday morning in southeast Ohio...KY...and the
northern WV mountains. IFR possible in snow Monday night in the
northern and central WV mountains.
Ohio...Winter Weather Advisory from 4 PM this afternoon to noon EST
Monday for ohz066.