Scientific Forecaster Discussion
fxus61 krlx 202340
Area forecast discussion
National Weather Service Charleston WV
740 PM EDT sun Oct 20 2019
cold front crosses late Monday into early Tuesday. High
pressure builds in for midweek.
Near term /through Monday/...
as of 510 PM Sunday...
tweaked sky cover grids this evening as more present across
south and west than currently forecast. Otherwise, no changes.
As of 150 PM Sunday...
Some clearing finally making inroads into the area this
afternoon. However, low stratus has been slow to erode east of
us119 and i79 corridor, as Stout low level inversion remains in
place. There may be some additional improvement over the next
few hours, but expectation is the mountains stay in the clouds.
For tonight, flow in boundary layer will remain weak for much
of the night and with inversion remaining, I suspect low stratus
and fog will be the rule. Flow will gradually veer to the south
and southeast late which would result in some downsloping
helping to eventually scatter out the low clouds after sunrise.
Some sunshine is expected once the stratus breaks but will
become filtered as cirrus overspreads the area ahead of the
approaching cold front. Still, impressive warm air advection will likely allow
temps to spike into the upper 70s across The Lowlands with 80-82
degrees not out of the question.
While there may be a few showers across southeast Ohio with a
preceding warm frontal passage, I think most of the area will
stiff arm rain for the daylight hours as downsloping flow keeps
showers close to the cold front.
Short term /Monday night through Tuesday/...
as of 230 PM Sunday...
Potent upper level trough will be deepening into a closed low across
the upper Great Lakes Monday night in response approaching 130kt
h250 jet streak. Meanwhile, low level mass response associated with
a second and slightly stronger jet streak exiting the base of the
trough over the Ohio River valley will begin pumping Gulf moisture
into our neck of the Woods in advance of a cold front associated
with the aforementioned low. Despite rather impressive dynamics with
this system, mid-level lapse rates sourced from the High Desert of
Mexico look to be extensively worked over by upstream convection
leaving US with little, if any instability to work with. Can't
completely rule out the risk of few rumbles of thunder given strong
forced ascent especially across extreme western portions of the
area Monday night, but potential appears too low to include in the
forecast at this time. H850 flow approaching 50kts could potentially
yield some gusty winds with any heavier showers, but we look
maintain low level warm air advection through column saturation
which will help to offset momentum Transfer. Precipitation totals
with this system look to fall into the half to one inch range,
which, when combined with the precipitation from last week and this
weekend should yield substantial improvements in the Thursday
drought map update for precipitation ending Tuesday. As is
typical when there is an interesting astronomical event (the
orionid meteor shower peaks Tuesday morning), sky are expected
to be overcast.
Precipitation tapers off from west to east through the afternoon
Tuesday as cold air begins filtering in. Winds in the boundary layer
do begin tapering off by this point, but enhanced momentum Transfer
to the surface with the cold air should yield some breezy to locally
Long term /Tuesday night through Sunday/...
as of 230 PM Sunday...
Skies clear Tuesday night as the column dries out, boundary layer
winds look to stay up, so despite surface dewpoints dipping to near
32f, overnight lows look to stay in the 40s. Breeziness continues
through the day Wednesday under mostly clear skies before winds
finally begin to wind down in the evening as surface high over the
Gulf Coast begins to drift northeast into the mid-Atlantic. Light
winds and clear skies Wednesday night into Thursday morning should
promote effective radiational cooling with some patchy frost
possible as lows in The Lowlands dip into the mid 30s.
Still quite a bit of model spread regarding solutions for
southern stream system Friday/Saturday/Sunday with ec/Canadian
based guidance suggesting a Texas Panhandle hook while GFS based
guidance is less aggressive with a still potent, but open
longwave trough. Net result is GFS guidance is about a day
faster arrival for US, but either solution will likely result
in another round of beneficial rainfall. Generally prefer the
slower, more potent solution clustered around the 00z eps mean
which would keep Friday dry, but will defer to nbm guidance
which keeps precip through the 3 day period with pops capped at
chance given aforementioned uncertainties.
In the wake of one of our driest septembers, October looks to have
the potential to close out as a top 10 wettest for many of our
Aviation /00z Monday through Friday/...
as of 735 PM Sunday...
IFR/LIFR cigs continue to remain across the higher terrain, and
will do so through at least 11-14z when gradual improvement to
VFR is expected. Otherwise, LIFR/vlifr fog and stratus is
expected to form across most of the area overnight, particularly
in the 03z through 14z time period, with gradual improvement
starting to occur after 09-10z particularly across The Lowlands
After 14z, mainly VFR conditions with south-southeast surface
winds developing, becoming gusty at times with gusts in the
teens to lower 20 kt range particularly after 17z.
Rain arrives from west to east after the taf period.
Forecast confidence and alternate scenarios through 00z Tuesday...
Forecast confidence: medium.
Alternate scenarios: timing the onset of IFR or worse cigs/visibility
may vary, along with the subsequent improvement into VFR Monday
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 22 23 00 01 02 03 04 05 06 07 08 09
EDT 1hrly 18 19 20 21 22 23 00 01 02 03 04 05
crw consistency M h h h h M h h h l l M
heights consistency h h h h h h h h h h h h
bkw consistency h M M h h l M h M l l l
ekn consistency M M M M h M l l M M M M
pkb consistency h h h h h h h h h h l l
ckb consistency h h h h h h h M l l M l
After 00z Tuesday...
cold front arrives Monday night into Tuesday, with IFR
conditions possible in rain and low cigs.