Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Pittsburgh PA
655 PM EST Sat Nov 22 2014
several weak disturbances will cross the region this weekend. Low
pressure will bring widespread rain Sunday night.
Near term /until 6 am Sunday morning/...
updated probability of precipitation/sky for current trends. Mainly scattered rain showers
remaining currently. Expect coverage to continue to decrease this
evening...with a slight increase across the northwest later tonight with
a weak shortwave. Another brief dry interlude Sunday morning
before rainfall ramps up significantly by Sunday evening.
Temperatures updated per latest lamp guidance.
Short term /6 am Sunday morning through Tuesday/...
a broad upper trough will continue to develop and advance across the central Continental U.S.
Through the weekend. A shortwave is prognosticated to round the base of the trough
and advance across the Ohio Valley and Great Lakes region Sun night. With sufficient
deep moisture...low level jet and upper spprt maintained categorical rain
chances with it/S passage.
The main upper trough is expd to slowly advance into the Great Lakes to MS valley
region by Erly next weak. Another shortwave and associated cold front is
prognosticated for a Monday passage. Moisture is expd to be limited with frontal passage so
maintained chance probability of precipitation with this feature. In addition...gusty winds
are expd Monday as the pressure gradient tightens around a deepening upper Great
Lakes surface low.
Cold advection is expd Monday night into Tuesday under the broad upper trough.
Boundary layer flow is prognosticated to remain SW so no lake connection is expd.
Enough low level moisture may allow for a few snow showers in the ridges
but with moisture depth limited only included slight chance probability of precipitation. After well
above average temperatures Erly in the period...experimental readings below seasonal levels
again by Tuesday.
Long term /Tuesday night through Saturday/...
below average temperatures will remain through the week as the
eastern states sit under a broad longwave trough through the
period. A stronger shortwave will bring the chance for snow
showers Thursday...followed by a reinforcing shot of cold air into
Aviation /00z Sunday through Thursday/...
with area now completely in the warm sector...expect general VFR
for the forecast period. Isolated...non-restrictive showers are
possible this evening and light southerly winds will be the norm
Outlook.../Sunday night through Thursday/...
possible MVFR to IFR conditions Sunday night into Monday as the
next storm moves through. Possible restrictions Thursday in snow