Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
128 PM EDT Tuesday Apr 28 2015
high pressure ridges southeast from Great Lakes today. Moisture
stays mainly south Wednesday as southern system passes. Upper level
low sweeps through Thursday night with increase coverage of showers.
Near term /through Wednesday/...
overall...quiet weather in the near term period. Scattered cumulus deck will
dissipate late tonight...for a clear sky area wide.
Clouds will increase across the region on Wednesday...as a weak
low pressure system moves east across the southeastern U.S. This
will spread -shra back into the area...mainly across southwest Virginia
and eastern WV zones.
Increased maximum temperatures across the area for Wednesday as models
indicating more sunshine across the western 2/3 of County Warning Area than
Short term /Wednesday night through Friday/...
two main features to concentrate on during the short term period.
The first is a southern stream system...that models continue to
trend south with. Followed the models and trended south with the
higher probability of precipitation...and taking likely probability of precipitation out of the forecast. Second
feature is an upper low dropping through the Great Lakes. Some model
differences on the track of this system. NAM/European model (ecmwf) are fairly close
with the low location on Thursday morning over NE Illinois and then
dropping south through Tennessee and into the Carolinas by Thursday night.
However they differ some on the strength of the system with the NAM
keeping the low cut off while the European model (ecmwf) opens it up into the overall
trough. The GFS stays with the cutoff...but is quite a bit farther
east on the overall track...taking it right over our County Warning Area Thursday
night. The track will ultimately have an impact on quantitative precipitation forecast amounts and
timing...but felt there was enough similarity to go with a broad
area of likely probability of precipitation across the County Warning Area Thursday and Thursday evening.
Then have probability of precipitation exiting to the east Thursday night into Friday.
Did not make any real significant changes to temperatures. Ended up a
degree or two warmer on Wednesday...thinking we may get some
additional sun with the best moisture staying farther south. Then
Thursday should be a tad cooler with rain and clouds. Overnight lows
should be at or just below normal with plenty of clouds limiting
Long term /Friday night through Monday/...
long term Marks a pattern change with the upper level low lifting
off the middle Atlantic coast with zonal flow taking over...evolving
into slight ridging by day 7. Overall...500mb heights will
increase...so will see a warm up into next weekend. Baroclinic zone
will set up over the northern County Warning Area which could become a focus for
convection...but will leave thunder out of the forecast for now
given the low probability of precipitation that do not climb higher than low end chance.
Aviation /17z Tuesday through Saturday/...
scattered cumulus deck will dissipate after sunset. With VFR conditions
and light surface winds expected overnight. May see some patchy
MVFR River Valley fog develop after 06z. Any fog will dissipate
Clouds will thicken and lower on Wednesday out ahead of an
approaching low pressure system...along with -shra developing
towards the end of the taf period across southwest Virginia and the
mountains of WV. Conditions will remain VFR during the period.
Forecast confidence and alternate scenarios through 18z
Forecast confidence: high.
Alternate scenarios: track of low pressure system could change
path on Wednesday...resulting in more -shra than currently
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 18 19 20 21 22 23 00 01 02 03 04 05
EDT 1hrly 14 15 16 17 18 19 20 21 22 23 00 01
crw consistency h h h 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 h h h h h h h h h
ekn consistency h h h h h h h h h h 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 18z Wednesday...
IFR conditions possible Thursday and Thursday night in rain showers.
IFR ceilings may linger Friday morning over WV mountain counties.