Area Forecast Discussion
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FXUS61 KPBZ 260055 AAC
Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
855 PM EDT Sat Mar 25 2017
Temperature well-above normal will continue into next week.
Showers and thunderstorms are expected Sunday afternoon and
.NEAR TERM /THROUGH SUNDAY NIGHT/...
The zonally-oriented warm front over swrn New York earlier this
afternoon is in the process of reorienting itself meridionally
in response to a closed H5 low/deepening sfc low pressure in
Missouri. The narrow plume of showers associated with this
boundary has diminished as the front oozes across the northern
part of the forecast area, with reflectivity in the CWA seeming
to be associated with virga or light sprinkles.
The front will transect the forecast area tonight, leading to a
non-trivial gradient in overnight temperature. The far
eastern/northern zones could end up as cool as mid 40s
overnight given the cooler/drier sfc observations noted
upstream, while the swrn zones could end up in the mid 50s, if
Current showers and storms in association with the upper wave
will make slow ewd progress during Sunday morning, leading most
areas to remain dry for the first half of the day. The
convection will move into eastern Ohio late morning/early
afternoon and intensify modestly/develop ewd to near KPIT by
early evening as the upper low opens and phases into the nrn jet
Hi-res, convection-allowing models, coarser operational
synoptic models and text-based statistical forecasts all offer
congruent timing signals that a loosely-organized convective
line will be entering wrn Pennsylvania by early evening, likely
affecting the Pittsburgh area in the 26/2300-27/0100 UTC
timeframe. Instability profiles will be modest at best despite
decent shear, so little storm structure or organized severe
potential are expected beyond the rain.
Showers and storms will develop ewd across PA Sunday evening,
with only lingering light showers remaining west of the Laurels
by Monday morning. Although a sfc cold front technically will
accompany the departure of the upper wave, there does not appear
to be much in the way of cold air at the surface associated
with this feature. So there is not expected to be a dramatic
drop in overnight temp Sunday night, with minima remaining in
the lower 50s.
.SHORT TERM /MONDAY THROUGH TUESDAY/...
While the bulk of the rain will move east by Monday morning,
some lingering showers will remain possible. After a brief
period of dry weather, a cold front crossing the region Tuesday
will bring another round of showers. The precipitation with
that front doesn`t look as organized as previous model runs,
so have decided to stick with likely pops for now. Temperatures
will remain above normal through the period.
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
With high pressure settling in behind Tuesday`s cold front and
northerly flow developing, dry and seasonable weather is
expected Tuesday night through Thursday. By Thursday evening,
the GFS and ECMWF begin to show diverging forecasts, with one
model showing low pressure over Lake Huron by Saturday morning
and the other model showing low pressure across Tennessee. Have
stuck close to the Superblend through this part of the forecast.
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
VFR conditions are expected under shortwave ridging through
part of Sunday for most ports, though moist SE upslope flow
could result in MVFR ceilings overnight through Sunday for DUJ
and possibly FKL. E winds should veer to the SE as a weak
surface boundary/warm front moves N across the area.
Low pressure is progged to track across the OH valley/lower
Great Lakes region Sunday, with increasing shower chances and
condition deterioration to MVFR from W-E during the afternoon
and evening with it`s approach. A thunderstorm is possible
especially for ZZV though low chances and limited instability
preclude a TAF mention.
Restrictions are expected to continue Sunday night with the
crossing low. Restrictions are likely again Mon night/Tue with a
crossing cold front.