Area forecast discussion
National Weather Service Charleston WV
334 PM EDT Sat may 18 2013
Synopsis...
moist air mass with weak steering current in place through Sunday.
Remnants of middle and upper level wave adds support for convection too
this weekend. New front approaches Wednesday and Thursday.
&&
Near term /through Sunday/...
upper level trough axis has now crept closer providing upper level
support for the generation of ascent. Otherwise...there has not
been much change to the overall atmosphere from the last couple of
days. Precipitable water values pushing 1.5 inches with a
convective temperature in the middle 70s. Hitting that in many
locations already. Flow through the upper levels resembles July
and August more so than may...but do have enough steering flow to
take cells south to north. Otherwise...will keep the pulse nature
of the event through the evening.
Need to watch additional rainfall amounts over an area just north
of the I-64 corridor west to just north of the Ohio River...across
portions of the Coal fields...and in the mountains. Nothing
alarming at this point in time...and will not issue any watches
for potential water problems with the feeling that any issues
would be isolated.
Probability of precipitation to wane tonight...and should see clouds trying to scatter
out. Have hit the potential for River Valley fog...especially for
places that get wet again today.
Upper level trough axis still lingers into Sunday...so carry a
persistence type forecast through 00z Monday.
&&
Short term /Sunday night through Tuesday night/...
with the weak upper low drifting east of the area by Monday and a
weak upper ridge taking over Monday and Tuesday...this period looks
to be generally dry. Still...enough low level moisture and marginal
instability aided via increased sunshine...gives rise to just a
small chance for an afternoon storm in a few places. Will keep probability of precipitation
low and mostly in the afternoon. In any event...temperatures will
warm into the 80s both days with the sunshine...and may actually be
just a bit on the muggy side with relatively high dewpoints...while
night time lows will be well into the 60s.
&&
Long term /Wednesday through Saturday/...
HPC/European model (ecmwf) trending to go with a stronger/faster upper trough and cold
front pushing across the area Thursday. Raised probability of precipitation to chance
Wednesday ahead of the front in the warm moist and unstable
air...and up to likely Thursday when the actually front crosses. Rain
ends Thursday night with passage of the front. Strong high pressure
over Canada ridges in...with a chilly air mass filtering in Friday
and Saturday.
Previous discussion...
extended period begins with County Warning Area in NE portion of an upper
ridge...however a SW trough resides on eastern periphery of this ridge
and is slow to push east. This should keep our area in disturbed
weather through day 4...with primarily diurnally driven showers and
thunderstorms in the WV mountains. Little Break...if any...in the
agitated weather pattern as next system is quick to move in from
the west Tuesday. GFS and European model (ecmwf) diverge solutions with the handling of
the upper level low track through the Great Lakes. Reluctant to go
any higher than chance probability of precipitation with timing differences between operational
guidance. Stayed near wpc guidance with temperatures through the extended
save for local adjustments.
&&
Aviation /20z Saturday through Thursday/...
very little change in the atmosphere than that seen over the last
couple of days. Diurnal rain showers/thunderstorms and rain setting up as of the time of
this taf issuance with a general south to north motion. Cells are
isolated to scattered at the moment...but will expect an increase
in coverage through the afternoon. Between 18z and 00z
Sunday...have had to add tempos for changing conditions in
shra/tsra. Keep the conditions conservative with only MVFR
expected. Convection to wane in the evening...and should see cloud
cover scatter out a bit during the overnight. As with the past
couple of days...should be able to get River Valley fog without
the sky going completely clear...especially in locations that
receive rain before hand.
Forecast confidence and alternate scenarios through 18z Sunday...
Forecast confidence...medium.
Alternate scenarios: the overall pattern is set in place...but the
specifics in terms of timing of showers and storms likely to vary.
Amend possible.
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 M M
heights consistency h h h h h h h h h h h M
bkw consistency h h h M M M M h M h h h
ekn consistency h h h h M h h M M M h l
pkb consistency h h h h h h h h h h h M
ckb consistency h h h h h h h h h h M M
After 18z Sunday...
brief/intermittent IFR possible in heavier showers/thunderstorms
through early next week. IFR fog possible in overnight hours.
&&
Rlx watches/warnings/advisories...
WV...none.
Ohio...none.
Kentucky...none.
Virginia...none.
&&
$$
Synopsis...fb/26
near term...26
short term...jmv
long term...jmv
aviation...26
