Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
819 am EDT Thursday Aug 28 2014
drier today as weak high pressure noses in from the north. Hot and
more humid Saturday. Deeper moisture Sunday associated with
Near term /through tonight/...
cold front almost all the way through the County Warning Area...and anticipate it to
clear to the south of the County Warning Area this morning. Still...enough lingering
moisture to keep some token probability of precipitation across mainly Virginia counties into
early this afternoon. Expect fog and low stratus through the
mountains and much of the WV lowlands initially this morning...which
should scatter out and lift into cumulus through the morning.
Met continues to perform well on high temperatures in this pattern...so
leaned that way...cooling highs mainly across the north. Used a
consensus blend for lows...cooling the north a touch and warming the
Short term /Friday through Sunday/...
the convection on our graveyard shift this morning over southern
West Virginia had some dumpers. Maximum measured/observed amounts of
1 to 1.5 inches in an hour. Luckily the duration of that cluster of
showers/storms was about an hour...keeping maximum rain totals under
2 inches. Time was devoted to radar and hydrology...and thus less
time than usual allotted for updating this short term.
A weak southeast component to the low level winds on Friday...so continued
the 20/30 probability of precipitation mostly over the mountainous counties...but also
tailing west to catch northeast Kentucky by late in the day or
Friday evening. The axis of the 500 mb ridge should be passing on
Friday. The old low level dew point gradient should be in eastern
Kentucky then...before lifting back north overnight Friday night
The 925 mb flow does increase Friday night our of the south and
southwest. Some low level forcing associated with that increase in
the low level wind flow...could keep a slight chance pop lifting
north for a shower or storm overnight Friday night.
The last remnants of the drier mean relative humidity that penetrated all the way
down into the deep south...tries to lift back through US on
Saturday...but had to leave some 20 and 30 probability of precipitation for many counties.
00z NAM soundings indicate Narrow Cape with equilibrium level 35 to
40k in the more humid air.
Was a bit faster increasing probability of precipitation in the Ohio Valley overnight
Saturday night into Sunday morning...as middle level disturbance rides
northeast in the increasing SW middle level flow. Did decrease maximum
temperature a bit on Sunday due to expected clouds and precipitation.
Long term /Sunday night through Thursday/...
used wpc thinking with some tweaks. Westerly middle-level
flow...along with several middle-level disturbances...will result in
on and off chances of showers and storms through Tuesday. A cold
front will approach from the northwest Tuesday night...with this
feature expected to push southeast of the area by Wednesday
Wpc temperatures looked good and were generally used.
Aviation /12z Thursday through Monday/...
low stratus in place across much of the County Warning Area...and anticipate it
will take a while still to start scattering out...especially from
ekn-crw and east. Pkb has already lost the clouds...and think ckb
and heights should scatter out next. The low clouds and fog will
scatter and lift into a VFR cumulus deck by middle to late morning.
Generally expect light northerly winds today. Could get an
isolated T-shower across the extreme southern County Warning Area today...but
should not impact any taf sites. Another somewhat difficult
forecast for tonight as models show middle to high clouds beginning
to stream back into County Warning Area from the SW. Think northern County Warning Area should
remain fairly clear with fog developing tonight. Farther south it
will depend on just how thick the clouds are.
Forecast confidence and alternate scenarios through 12z Friday...
Forecast confidence: medium.
Alternate scenarios: timing and density of fog/low stratus may vary
this morning and again 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 11 12 13 14 15 16 17 18 19 20 21 22
EDT 1hrly 07 08 09 10 11 12 13 14 15 16 17 18
crw consistency M M M M M M h h h h h h
heights consistency M M M M M h h h h h h h
bkw consistency M h h M M M M M M h h h
ekn consistency l l l h M M h h h h h h
pkb consistency l l M h h h h h h h h h
ckb consistency h h h M M h h h h h h h
After 12z Friday...
IFR possible in showers/storms Sunday.