Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
702 am EDT sun Aug 30 2015
increasing moisture and dynamics give a chance for showers/storms.
Weak steering flow and no surface fronts as September begins.
Near term /through Monday/...
forecast still on track previous discussion follows...patchy fog
developing this morning. Upper level disturbance will drift toward
forecast area today bringing moisture and instability with it
which could cause a few showers and thunderstorms to develop today. Middle
and low level flow is quite calm through the entire depth...but
fairly strong flow exists at the equilibrium level. This should
keep storms from becoming very strong as they shear out in the
upper levels. Most elements do not favorably align...so spotty
typical summertime showers are expected. The main vorticity maximum arrives
early Monday morning...so showers may continue overnight Monday.
Short term /Monday night through Tuesday night/...
models continue to show 500 mb vorticity maxes moving over the area
Monday. Despite of surface high pressure and weak flow
aloft...afternoon heating over elevated heat sources can produce
showers and storms. Kept chance probability of precipitation over the eastern mountains
and slight chance at lower elevations during the
afternoon...dropping at or below 14 percent Monday night.
Less coverage in rainfall activity expected on Tuesday...having
only slight chance and chance probability of precipitation over the eastern
mountains...keeping The Lowlands dry. Drier conditions expected
There will be a warming trend through the period...with
temperatures getting warmer Tuesday and Wednesday. Generally upper
80s Tuesday and around 90 degrees Wednesday afternoons. At
night...temperatures will drop into the middle to upper 60s. Went
with a combination of super blend and NAM numbers for temperatures
through the period.
Long term /Wednesday 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 /11z Sunday through Thursday/...
upper level disturbances approaching from the west and from the
S...will bring about an increase in moisture. There will be less
fog than recent nights...although IFR is still forecast for ekn. By
this 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.
Forecast confidence and alternate scenarios through 12z Monday...
Forecast confidence: medium to low.
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...but timing this is
difficult given the complexities playing out.
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 09 10 11 12 13 14 15 16 17 18 19 20
EDT 1hrly 05 06 07 08 09 10 11 12 13 14 15 16
crw consistency M M M h h h h h h h h h
heights consistency h h h h h h h h h h h h
bkw consistency h h h M M M M M h h h h
ekn consistency l l l M h h h h h h h h
pkb consistency M h h h h h h h h h h h
ckb consistency M M h h h h h h h h h h
After 12z Monday...
spotty IFR possible in dense valley fog during early mornings...mainly
in WV and highly dependent on cloud cover.