Scientific Forecaster Discussion
fxus61 krlx 221832
Area forecast discussion
National Weather Service Charleston WV
232 PM EDT sun Sep 22 2019
very warm for the last day of Summer with high pressure aloft
and at the surface. Cold front on Monday, followed by high
pressure mid week. Weak front Thursday.
Near term /through Monday/...
as of 230 PM Sunday...
Main topic of discussion for today will be the abnormally warm
afternoon temperatures. Ridging aloft and surface high pressure
parked over the Carolinas will support southwesterly flow and
warm air advection. Temperature readings over the past few hours
have already surpassed guidance, so adjusted today's Max
temperature up a few degrees. Dry air mixing down along
sufficient momentum Transfer will continue to drop dew points
by a few degrees this afternoon, resulting in relative
humidities falling towards the low 30 percent range.
The ridge breaks down for the first day of fall as an encroaching
trough and associated surface cold front interrupts the dry
weather pattern. Hi-res models have a line of weakening showers
on the doorsteps of southeast Ohio near 8 am, crossing into the
mountains by the afternoon. While instability is not absent
along the front, precip accompanying this feature will lack
distinctive thunderstorm qualities and will remain more in the
shower variety. Activity along the mountains taper down at the
conclusion of the near term period, with drier air filtering in
along the northwesterly flow in the wake of the frontal passage.
Short term /Monday night through Wednesday night/...
as of 210 PM Sunday...
Low level Post-fropa cloudiness should gradually erode from
west to east Monday night, with temps dropping faster late in
the night as drier near sfc air finally settles into the region.
Sfc high pressure center is prog to move east overhead during
the day Tuesday, with a rather flat cloud deck possible across
the eastern half of the County Warning Area...where some lingering moisture will
persist around the 850 mb layer. Max temps on Tuesday will likely
be the coolest of the week. High pressure then shifts east
Tuesday night, and especially Wednesday. This will result in a
gradual development of sswrly low level flow by Wednesday
morning. If the llvl flow is rather slow to develop, then a few
areas across the low lands may dip into the 40s for Wed night
lows, with scattered areas in the mountains likely falling into
the 30s, with isolated sheltered/microclimate driven locations
in the extreme NE County Warning Area flirting with the upper 20s.
Significant warming of the atmospheric column is likely on
Wednesday as high pressure shifts away from the area. Given dry
soils along with a dry profile, temps will likely rocket
upwards between mid and late morning...with afternoon highs
much warmer than tuesday's values.
Long term /Thursday through Sunday/...
as of 210 PM Sunday...
12z GFS and 00z European model (ecmwf) is a little more aggressive with pushing
a front into the County Warning Area on Thursday. Should this occur, the front
will likely stall along the mountains before shifting back
northward as a warm front. Another notable warming trend is then
likely for late in the work week, and especially over next
weekend, as some impressive mid level ridging is prog to
influence area weather across much of the southern and eastern
Continental U.S.. would not be surprised to be flirting with record highs
at times for late this week and into next weekend, especially
with mainly dry conditions persisting.
Aviation /18z Sunday through Friday/...
as of 130 PM Sunday...
VFR will Triumph today with only increasing high clouds Worth
mentioning ahead of a weak frontal system arriving on Monday.
Otherwise, another broken cu field has sprouted along the higher
elevation for the afternoon and evening hours, then expected to
scatter out and diminish after sunset. Shower and storm chances
remain east of all terminals today. South to southwesterly flow
will be breezy at times this afternoon as the pressure gradient
tightens ahead of tomorrow's frontal passage, but strongest
gusts remain below 20 kts east of the Ohio River.
850 mb winds will be on the increase during the overnight hours,
and with dry air filtering in along southwest flow, the chance
for fog will be almost slim to none. However, there could still
be decoupling in the deep valleys, which will have to be
monitored at ekn.
Upper level trough and surface cold front swings through the
area on Monday, with showers attached to the frontal boundary.
The front itself will become moisture starved and weaken upon
arrival, but sites in The Lowlands will be teetering down near
MVFR cigs with the onset of showers. Further ceiling drops will
be possible along the mountains beyond this taf period.
Otherwise, breezier conditions ahead of the frontal passage is
possible during the afternoon timeframe.
Forecast confidence and alternate scenarios through 18z Monday...
Forecast confidence: high.
Alternate scenarios: decoupling may lead to fog near ekn
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 M M l
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 Monday...
IFR or worse along the mountains overnight Monday night, in
stratus and Ridgetop fog, in the wake of a weak cold front.