Area Forecast Discussion
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FXUS61 KPBZ 192356
Area Forecast Discussion
National Weather Service Pittsburgh PA
756 PM EDT Wed Oct 19 2016
Advancing low pressure will spread more widespread rain over the
Upper Ohio Valley Region tonight and Friday.
.NEAR TERM /THROUGH THURSDAY/...
Some adjustments made to sky/PoP fields tonight through early
Thursday, primarily slowing the leading edge of the precipitation
down. Isolated thunder has been included for a few hours this
evening in far western zones to account for upstream convection
Additionally, most guidance including latest hi-res models
carve out the warm sector through West Virginia late tonight into
Thursday. Adjustments were made to tighten the gradient of PoPs
from northwest to southeast.
Previous Discussion Below...
Low pressure will develop along the front stretched over the Ohio
Valley and dig northeastward as mid level troughing amplifies over
the Plains. The advance of that system will push the frontal
boundary northward and increase precip probability over the Upper
Ohio tonight, and cumulate in categorical numbers for Thursday and
Thursday night as the exiting system pulls the frontal boundary
eastward again as a cold front.
Precip probability and QPF has been constructed for this scenario
with initial focus across western and northern zones due to
boundary positioning, followed by subsequent cold front precip. Have
used OHRFC guidance for the QPF of this system which projects a
general one to just-over-two inches over the next 48 hours.
The Storm Prediction Center has included the immediate area in a
"marginal/5 % severe risk on Thursday due to the shear levels on
the flank of the negatively tilting upper trough. Limitations will
be imposed by instability levels, which do not look healthy for
the situation depending on model; hence, no hazardous mention will
be included for now.
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
Precip is expected to fade eastward through Friday with progress
of the front and supporting mid level trough/wind field. Much
cooler weather will follow for the weekend as the upper trough
develops over the Eastern CONUS. Scattered showers will remain in
the forecast through Sunday, mainly for northern and ridge zones,
as cold advection continues and shortwaves in northwest flow
traverse the area.
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Dry, but seasonably cool conditions are anticipated as high
pressure builds for the start of the new work week. Slightly
modified Superblend guidance was used for the extended period.
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --VFR conditions will continue at all sites for the next few hours.
After that time, upstream convection may clip the NW portions of
the area as it rides NEward toward Lake Erie as a warm front
rides northward. Much of the SE portion of the area enters the
warm sector, thus likely remaining VFR throughout the period.
Farther to the NW, convection will start to settle SE toward the
area with falling CIG and VIS eventually by late on Thursday.
.OUTLOOK /THURSDAY NIGHT THROUGH MONDAY/...
Periodic restrictions are expected through Saturday as low
pressure and subsequent upper troughing cross the area.
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