Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
405 am 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.
Near term /through tonight/...
a rarity this month...no rain forecast...though at 08z a sprinkle
may be spotted to our north...near the Mason Dixon line.
Frost advisory remains posted for our coldest lowland counties in southeast
Ohio. Most readings there are in the middle 30s with not many clouds.
In the low level thermal trough...patches of stratocumulus linger
mainly over West Virginia this morning. The northeast flow tries to
advect these SW...but with thinning moisture...these clouds have
been evaporating on their trip S and SW.
The last of the 850 mb cool pocket lingerings over central WV
through about 14z. Areas that are clear at dawn could see some
regeneration of cumulus 12z to 16z.
Peaceful evening pictured. Only brought a slight chance pop into
Dickenson County Virginia by 12z Wednesday with the weakening southern
stream system. With light wind and not many clouds figured. Tried
to stay on low side of minimum temperature guidance tonight.
Short term /Wednesday 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 /08z Tuesday through Saturday/...
stratocumulus clouds in the low level thermal trough lowering to
some MVFR 2 to 3 thousand feet ceilings along the western slopes including
ckb to ekn 06z to 12z Tuesday...and may reach down toward bkw. Some
MVFR in valley fog may develop in deep sheltered valleys vicinity ki16
and S toward Grundy Virginia for 08z to 12z Tuesday.
Otherwise...mostly scattered to broken clouds at 3 to 5 thousand feet above ground level
through 18z then 4 to 6 thousand feet above ground level mostly scattered.
Mostly clear 00z to 06z Wednesday.
Forecast confidence and alternate scenarios through 06z Wednesday...
Forecast confidence: high.
Alternate scenarios: lower ceilings over WV mountain counties may
linger longer Tuesday before lifting by 18z.
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 Tuesday 04/28/15
UTC 1hrly 08 09 10 11 12 13 14 15 16 17 18 19
EDT 1hrly 04 05 06 07 08 09 10 11 12 13 14 15
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 M M h h M M M M h h h h
ekn consistency M l M M M M h h h h h h
pkb consistency h h h h h h h h h h h h
ckb consistency h h M M M M h h h h h h
After 06z Wednesday...
IFR conditions possible Thursday and Thursday night in rain showers.
IFR ceilings may linger Friday morning over WV mountain counties.
Ohio...frost advisory until 9 am EDT this morning for ohz066-075-