Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
806 PM EDT Sat Aug 30 2014
turning hot and more humid this afternoon in deep southwest flow.
Moisture increases in that flow...with an upper level disturbances
crossings through Monday.
Near term /through Sunday/...
745 PM update...
trimmed back probability of precipitation this evening east of Ohio River per latest hrrr/RUC
runs. Still appears NE Kentucky and especially southeast Ohio will be in the
cross-hairs for rain showers/thunderstorms and rain overnight with several vorticity maxes
traversing across the region. One of these may push the rain showers/thunderstorms and rain
into The Lowlands between 09-12z as suggested by the hrrr. With
somewhat tropical moisture feed and precipitable waters climbing over 2
inches...downpours appear to be a good bet and efficient rain
producers. Will monitor radar trends and how everything begins to
evolve but do no anticipate issuing a Flash Flood Watch for southeast Ohio
at this time.
Previous discussion below...
a change in weather pattern is expected tonight into Sunday.
Radar and satellite images show convection and associated clouds
approaching from the west across central Kentucky and along the in and
Ohio border. Eventually...clouds will thicken over southeast Ohio and
WV tonight...with showers and/or storms spreading west to east
overnight. This activity is associated with a cold front expected
to move across the area Sunday afternoon. However...convection
ahead of the front could produce strong thunderstorms with very
heavy rain Sunday into Sunday night.
Models indicate a series of 500 mb shortwaves moving across the local
area tonight. Yet another descent shortwave passes on Sunday along
the cold front...with ample low level moisture as seen on precipitable waters
exceeding 2 inches...and dewpoints in the lower 70s. Surface based
cape increases as well. Believe showers and storms will be brief
tonight...and stronger in intensity and coverage on Sunday into
Expect a mild temperatures through the period per moisture and
some temperature advection tonight under southwest flow...and
plenty of clouds and cooling showers Sunday afternoon. Went with
previous temperatures as they go along with latest bias corrected
Short term /Sunday night through Tuesday/...
second wave of showers and embedded thunder should be pushing
east/NE-Ward across the area at the outset of the short-term period 00z
Monday. This is about three or so hours slower versus previous model runs
yesterday at this time. Precipitable waters of 2-in plus also accompanying...and
there continues to be some concern for flash flooding with
repetitive training. In collab with near-term forecaster and
surrounding offices...will continue to keep flash flooding concerns
in the severe weather potential statement for now. Still expecting the bulk of the organized precipitation
to be exiting the northeast zones around the 07z-09z time frame and
overall...still anticipate a general half inch to inch of precipitation but
some higher amounts certainly still possible should training occur.
No wholesale changes made to Labor Day forecast from previous forecast. Area
still under SW flow aloft and with high dewpoints continuing...will
maintain mainly afternoon slight chance to low chance probability of precipitation area-wide
with the middle chance probability of precipitation in the northeast mountains. Middle 80s for The
Lowlands still appear on track...but with more sun may see some
upper 80s. Monday night remains warm and tranquil...but another
front approaches on Tuesday with an accompanying short wave trough in the
mean flow aloft. Brought in likely probability of precipitation across the northwest zones
by the 15z-18z time frame with these features.
Long term /Tuesday night through Saturday/...
long term period can generally be characterized by zonal flow aloft.
Leaned wpc for the most part with a few tweaks here and there. Warm
and muggy conditions will continue through the period...with no heat
waves or abnormally cool spells in sight. A cold front will push
across Tuesday night with another front approaching Sat night...with
subsequent higher probability of precipitation during those periods. In between...Thursday
and Friday look mostly sunny to perhaps partly cloudy with only
minimal chances for precipitation each day.
Aviation /00z Sunday through Thursday/...
rain showers/thunderstorms and rain will be on the increase this evening across southeast Ohio but
most of the activity should stay away from the terminals until
after 06z...when a more potent upper level impulse approaches from
the SW. As such...have some MVFR rain showers in khts/kpkb/kcrw taf sites
with some prob30 groups incorporated to handle thunderstorms and rain possibility.
A brief lull lasting until perhaps late morning for most of the
taf sites...with rain showers/thunderstorms and rain continue for southeast Ohio. There should be some MVFR
stratus generally northwest of Ohio River but may affect khts/kpkb. Another
disturbance will approach from the SW by 18z with all terminals
coded up with MVFR convection with prob30 IFR groups.
Forecast confidence and alternate scenarios through 00z Monday...
Forecast confidence: medium.
Alternate scenarios: timing of rain showers/thunderstorms and rain tonight may vary by an hour or
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 08/31/14
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 M M M h h h
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 l l M
pkb consistency h h h h h h h h M M h h
ckb consistency h h h h h h h h h h h h
After 00z Monday...
IFR in dense early morning valley fog early next week.