Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
159 am EDT Friday Oct 9 2015
a cold front brings gusty showers Friday. High pressure builds in
for the weekend. A weak front brushes the area overnight Monday
into Tuesday and perhaps another one late in the week.
Near term /through today/...
200 am update... forecast on track.
1020 PM update...
no significant changes made. Still banking on Theta-E ridge / 850 mb
moisture transport from the SW for scattered rain showers to break out early
this morning. Clouds were on the increase across eastern Kentucky.
715 PM update...
added some scattered showers starting earlier tonight
in the warm air and moisture advection across the central and
eastern County Warning Area. Pretty much all models showing at least something
with this. Also have middle level moisture already showing up on
radar across OH/KY/WV...and showers on the scope in northern Tennessee.
the much advertised cold front will be affecting the area from
west to east Friday...with a band of showers...and possibly a
thunderstorm...moving eastward with the system. Going with Cat
probability of precipitation in this band of showers Friday. Instability not impressive so
will downplay thunder with this system. Will go on the slower side
given model consensus for frontal progression...as a wave of low
pressure forms along the front over the Tennessee Valley in
response to a secondary short wave diving in behind the primary
short wave. There is a question as to just how deep and far south
this secondary short wave and surface wave gets. However...even in
the slower models...front and band of precipitation looks progressive
enough to carry the system eastward across the area during Friday.
The front will reach the Ohio River by 18z Friday and into the by
00z Saturday. For tonight...an increase in middle clouds well ahead
of the front and showers...will limit fog to the more favored
River Valley areas. Temperatures tonight will be milder...but cooler on
Friday with the clouds and showers.
Short term /tonight through Sunday night/...
Friday night begins a messy Post frontal environment with the
exiting cold front and the trailing upper level trough. In the lower
levels...925mb winds will linger out of the north northwest which
will keep the mountains and adjacent West Virginia lowlands in low
clouds until a long enough period of daytime heating Saturday can
mix these clouds out. Mountains will be last to clear...likely after
noon. Held on to low end probability of precipitation...but can see future forecasts
settling in more on drizzle from the 06z to 18z time frame Saturday.
Will keep the mountains below guidance for highs in these damp
Going with rapid clearing into the overnight...and with drier
air/lower dewpoints...valleys look to clear out with the development
of valley fog likely given the wet ground.
High pressure makes enough southeasterly headway into the middle
Atlantic to turn the surface flow back around to a mainly southerly
components for Sunday. This brings temperatures back to near normal
values in mainly sunny conditions. This will also create a 30-40
degree diurnal temperature change going from Saturday night to
Long term /Monday through Thursday/...
a week front brushes the area overnight Monday into Tuesday
morning...but the parent low will trek near Hudson Bay so not a
real strong threat for much of anything except elevated probability of precipitation. High
pressure returns for another stretch of dry weather before another
weak front moves through late in the week.
One thing to keep in mind is that the residual moisture from
hurricane oho will be making its way east in fairly strong upper
level flow...so not sure how well models will handle this
feature though they seem to be in reasonable agreement bringing
the slug of moisture well north of the area.
Temperatures continue to remain 5 to 10 degrees above normal with
no killing frost foreseen.
Aviation /06z Friday through Tuesday/...
clouds already on the increase...which should keep most fog at
Bay overnight. IFR less likely at ekn...forecast only occasional MVFR visibility
there. Cold front approaches overnight and then crosses from west to
east Friday afternoon and evening...with gusty showers and possibly a
thunderstorm. Have MVFR during the most likely time frame in the
showers and storms...but IFR will be possible on a local scale in
and near heavier showers and storms. MVFR stratocu may form in the
mountains during the daylight morning hours on Friday.
MVFR stratocu is likely to form in the wake of the cold front Friday
nt...with MVFR mist at times as well...in the lingering overnight
low level moisture.
Light S to SW surface flow overnight will strengthen a bit and become
west to SW during the daylight morning hours Friday...and then switch to
west to northwest as the front crosses Friday evening...00z near the Ohio River
and 03z or so in the mountains. Moderate SW flow aloft overnight
will become moderate west on Friday and then light northwest on Friday nt.
Forecast confidence and alternate scenarios through 06z Saturday...
Forecast confidence...medium to high.
Alternate scenarios: timing and ceiling/visibility values in showers and
possible gusty thunderstorms Friday afternoon into Friday nt may vary.
Timing and extent of MVFR stratocu may vary in the mountains Friday
morning and throughout the area Friday nt.
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 Friday 10/09/15
UTC 1hrly 03 04 05 06 07 08 09 10 11 12 13 14
EDT 1hrly 23 00 01 02 03 04 05 06 07 08 09 10
crw consistency h h h h h h h M M M h h
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 M M h h
pkb consistency h h h h h h h h h h h h
ckb consistency h h h h h h h h h h h h
After 06z Saturday...
local IFR conditions are possible in Post rain drizzle/fog/stratus
Friday nt into Sat. IFR in valley fog possible late Sat nt into Sunday