Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
721 PM EDT Monday Sep 22 2014
Canadian high pressure builds tonight. It moves offshore middle week
as low pressure moves up along the Appalachians or the East Coast.
Another broad high pressure builds over the area late week.
Near term /through Tuesday/...
700 PM update...cleared sky out across lowlands faster than
previous forecast...but no significant changes made.
Previous discussion...quiet weather in the near-term period with
only minor tweaks from previous forecast per latest guidance. Some
lingering low stratus mainly in the eastern mountains at the
outset of the period 00z Tuesday this evening will quickly be eroding as
high pressure builds in out of the northwest...resulting in a
clear and calm overnight period and low temperatures dropping generally
into the low 40s across The Lowlands...with some low/middle 30s for
the normally- favored High Mountain valley locations in
Randolph/Pocahontas counties. At this point...not anticipating
those lowest temperatures to be widespread enough to warrant a frost
highlight...but will reassess as 12z data comes in today. Do
expect to see some frost at least in those aforementioned cold
spots however...and will at least continue patchy frost mention in
current severe weather potential statement to account for this.
High pressure will continue to dominate Tuesday as its center
continues to progress slowly eastward just to our north...with surface
winds veering to the north/northeast in response. Meanwhile upper
ridging over the miss valley continues to amplify with flow aloft
becoming nearly due-north. Any early morning fog will quickly
scatter...with a virtually clear sky on Tuesday for most and perhaps
a few flat-cumulus in the mountains. Maximum temperatures generally in the lower 70s
for The Lowlands still appears on track...with Lower/Middle 60s
expected for the higher elevations.
Short term /Tuesday night through Thursday night/...
surface high pressure shifts over the northeast of US to bring easterly
flow against the Appalachians Tuesday night through Wednesday night.
Dry weather conditions will prevail. Models show h850 temperatures
about 13c under east-southeast flow. This will bring some warmer temperatures over
the mountains Wednesday through Thursday. Some down sloping warming
can be expected as well over The Lowlands. Therefore...bumped up
temperatures during this time frame.
The flow weakens Thursday as the pressure gradient loosen up and a
new broad high pressure gradually builds from the Great Lakes
region...south across the Ohio Valley...WV and the Middle Atlantic States
through the weekend.
Left previous temperatures as they look good Thursday through
Long term /Friday through Monday/...
strong high pressure remains in control this weekend across the
Great Lakes region...the Ohio Valley and portions of WV...to bring
plenty of sunshine and dry weather. The warmest day seems to be
Sunday under near calm flow with temperatures reaching 80 across The
However...some differences are noted between the European model (ecmwf) and the GFS
models. The European model (ecmwf) develops a surface low pressure across the southeast
of the US...while the GFS shows a weak disturbance. The European model (ecmwf)
suggests the low pressure will ride northeast along the Appalachians
bringing some precipitation across our southeast and central mountains Monday
and Monday night. If this scenario materializes...then some rain
showers could be possible along the eastern mountains next Monday
and Monday night. Due to the discrepancy among these two
models...introduced only low probability of precipitation across our extreme southeast and
central mountains during this time frame.
Used HPC guidance for temperatures through the period...except for
Friday day 4 which used the bias corrected consensus raw.
Aviation /23z Monday through Saturday/...
still hanging onto MVFR ceiling at bkw...but expect this to dissipate
quickly. Did include a one hour tempo to account for this.
Otherwise...expect clear skies tonight which will give way to
dense valley fog. Agree with previous forecast that ekn should be
fog instead of frost...so no changes to that. Did add some fog at
bkw overnight...with a light NE flow envision some puffs of fog
drifting down from the New River gorge area...giving some variable
conditions at bkw through the early morning.
Fog will rapidly dissipate after 13z...may have just a few cumulus
across the southern County Warning Area by late afternoon with a calm to light
north wind through day.
Forecast confidence and alternate scenarios through 00z Wednesday...
Forecast confidence: medium.
Alternate scenarios: timing and extent of fog overnight tonight
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 M
heights consistency h h h h h h h h h h h M
bkw consistency h h h h h h M M M M M M
ekn consistency M M M M M M M M M h l l
pkb consistency M h h h h h h h h h h M
ckb consistency M M M M M M M M M M M M
After 00z Wednesday...
IFR in valley fog possible Wednesday morning...but should not be
as widespread as tonight.
WV...frost advisory from 2 am to 9 am EDT Tuesday for wvz046-047.