Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
558 am EST Sat Nov 28 2015
a cold front will bring rain to the Ohio Valley for the weekend
as it waffles before moving through Tuesday night. Colder
Wednesday. High pressure builds in Thursday into Friday.
Near term /through tonight/...
at 06z the well advertised front was approaching Columbus...OH. It
will move into the forecast area today and waffle around through
the near term. Low pressure will ride along the front today
bringing with it categorical probability of precipitation for the Ohio counties this
morning. Don/T expect the likely probability of precipitation to reach Huntington until
16z and Charleston until 20z. It will take the longest to get to
Beckley and that won't be until 23z. Likely and categorical probability of precipitation
will continue through 12z Sunday. Included patch fog for the
overnight ours. Have increased probability of precipitation in places through today and
tonight but no big changes were made to the current forecast.
Due to the slow waffling of the front and the ground being
relatively dry and warm have raised afternoon temperatures in
WV...KY...and Virginia a degree or so today. Basically used a model
blend for temperatures leaning toward the warmer models.
Short term /Sunday through Tuesday night/...
NAM 00z run...with 00z European model (ecmwf) support...has the cold front sinking
southward into the New River valley Sunday...taking most of the probability of precipitation
with it and confining the likelies to the southern counties of the
County Warning Area. Meanwhile...the upper level low that had set up Camp over the
Great Basin region will begin its track into the plains...deepening
as it does. This will spawn a rapidly deepening surface low that
will lift from the Central Plains into the northern Great Lakes
area. This will bring the stationary front back to the north as a
warm front Monday and Monday night with the cold front passing
Tuesday into early Tuesday night.
In the forecast grids...this translated to some minor adjustments in
the probability of precipitation as a result of the expected oscillation of the frontal
boundary...particularly late Sunday. Cold sector temperatures will
be in the 40s...possibly only 30s for the northwest zones...and 50s
to near 60 in the warm sector. These regions change with the frontal
Long term /Wednesday through Friday/...
there are notable model discrepancies on the exit of this rather
complex upper low and cold front during the middle week period. They
range from the GFS being fastest with the cold front exiting Tuesday
night...to the CMC forming yet another wave on the front and thus
delaying the exit until Wednesday night. The solution is with the
uncertain timing of an approaching Pacific upper trough that will
kick the aforementioned upper low out of the southwestern U.S. Into
the Great Lakes. Given this uncertainty...will basically go with the
faster wpc solution due to a rather Stout Pacific upper jet. This
scenario will drive a warm front northward Monday night...followed
by a cold front Tuesday night. With a lot of moisture and upper
impulses lifting up ahead of the main ejecting upper low Monday
night and until the cold front exits...will go with high
probability of precipitation....rapidly diminishing behind the front with a relative dry
slot. Instability is such as to not include any thunder. Not bullish
on wraparound showers Wednesday behind the front...confining them to
mainly the northern and central mountains into Wednesday night.
Still not a real good feed of cold air behind the front...so will
confine any lingering postfrontal showers to the northern mountains
before mostly ending Wednesday night. Look for above normal
temperatures ahead of the cold front...to near normal temperatures
behind the cold front...as drier high pressure builds in for the
later half of the work week.
Aviation /12z Saturday through Wednesday/...
showers are beginning to move into southeast Ohio...but continue
to be very light in nature across the forecast area. Ceilings and
visibilities are generally MVFR and IFR right around the
front...just to our west. The front is expected to waffle for
several hours this morning as an impulse of low pressure rides
along it...making taf forecasting a challenge. At this time will
continue with VFR for sites east of the Ohio River until 14z. If
the front makes more progress this will have to be amended to
MVFR and even IFR.
After 14z have kpkb going to MVFR...followed by khts at 17z and
kckb at 18z. After 06z have widespread IFR conditions. There could
even be LIFR...but will hold off on adding to tafs.
Forecast confidence and alternate scenarios through 12z Sunday...
Forecast confidence: medium
Alternate scenarios: timing onset of MVFR and IFR conditions may
vary. LIFR conditions may be possible after 06z Sunday.
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 Sat 11/28/15
UTC 1hrly 10 11 12 13 14 15 16 17 18 19 20 21
EST 1hrly 05 06 07 08 09 10 11 12 13 14 15 16
crw consistency h h h h h h h h h h h M
heights consistency h h h h h h h h M M M M
bkw consistency h h h h h h h h h h h h
ekn consistency h h h h h h h h h h h M
pkb consistency h h h h M M M l l M M M
ckb consistency h h h h h h h h M M M M
After 12z Sunday...
IFR possible in low clouds and rain Saturday night into Monday.