Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
1046 PM EDT Sat Aug 29 2015
moisture continues to increase as middle / upper wave passes just
southeast Sunday night...with a chance for showers/storms. Weak
steering flow and no surface fronts as September begins.
Near term /through Sunday/...
1045 PM update...
forecast on track.
800 PM update...
forecast on track as evening convection slowly wanes.
some showers beginning to show up on radar as of 17z. Have
isolated showers across southeast Ohio and in the mountainous counties
this afternoon. Moisture continues to increase through the near
term period on light SW flow. This should keep more clouds
around...and limit development of dense fog overnight. Upper level
disturbance currently over southeastern US will drift toward
forecast area Sunday. While the bulk of the showers and storms
will remain south...did up probability of precipitation to middle-chance range across
the mountains. With the additional clouds...may be a degree or two
cooler Sunday afternoon than we are seeing today. Used a mav/met
blend for temperatures.
Short term /Sunday night through Tuesday/...
the middle level 500 mb vorticity maximum that moved up from the southern
Appalachians Sunday...gets sheered out to the east Monday morning.
How far north its influence gets...is in question. Left some 40
probability of precipitation early in our southeast... with 30 probability of precipitation elsewhere early Sunday
night...leaving 30 probability of precipitation through the night in the mountains.
Mostly just 20/30 probability of precipitation Monday night and Tuesday over the mountainous
counties. The model soundings on the sensitive NAM do show some
skinny cape to 30 to 35 thousand Tuesday afternoon in The
Lowlands...but for now will leave probability of precipitation at or below 14 percent.
Long term /Tuesday night through Saturday/...
with a weak steering flow and no fronts in our vicinity...the long
term will continue the Summer time pattern...despite the approach
of the Labor Day weekend.
Will type to have mostly a diurnal shower/storm possibility with
20/30 probability of precipitation most days. Of course...as we get closer...there will
probably be a day...where we can enhance or decrease those probability of precipitation.
A better chance of southeast flow Saturday...so slightly higher probability of precipitation
over the mountain counties compared to further west..for Saturday
Figuring a relatively dry ground...will try to have maximum
temperatures at or above GFS MOS guidance in The Lowlands.
Aviation /03z Sunday through Thursday/...
upper level disturbances approaching from the west and from the
S...will bring about an increase in moisture...clouds...and...for
Sunday...showers. There will be less fog than recent
nights...although IFR is still forecast for ekn. By Sunday
afternoon...thunderstorms will be possible as well...but the
coverage of showers and thunderstorms Sunday is expected to be too
scattered to code explicitly in the tafs other than a vicinity
mention in and near the mountains.
Light southeast surface flow overnight will become light S to SW on Sunday.
Flow aloft will continue light SW.
Forecast confidence and alternate scenarios through 00z Monday...
Forecast confidence: medium to high.
Alternate scenarios: timing/intensity of River Valley fog could
vary as clouds increase overnight. A shower or even a thunderstorm
may directly impact a terminal on 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 sun 08/30/15
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 M M M M M M
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 h h h h M l l l l l l l
pkb consistency h h h h h M M M M M h h
ckb consistency h h h h h M M M M M M h
After 00z Monday...
spotty IFR possible in dense valley fog during early mornings...mainly
in WV and highly dependent on clouds.