Area Forecast Discussion

Pittsburgh, PA

Forecast Discussion for PBZ NWS Office
FXUS61 KPBZ 012118

Area Forecast Discussion
National Weather Service Pittsburgh PA
518 PM EDT Mon Jun 1 2020

Shower chances return tonight and Tuesday with a warm front. Strong
thunderstorms are then possible with a Wednesday cold front.


Clouds should increase later this evening in warm advection ahead of
an approaching shortwave in NW flow aloft, around a Central CONUS
ridge. The wave, and its associated sfc warm front, are expected to
cross the region overnight with showers returning. Maintained the
highest categorical POPs N of PIT where the most favorable moisture
and upper support is progged, though did increase POPs elsewhere as
the latest near term models trended southward with increased moisture
and lift/upper support.

The shortwave should complete its passage Tuesday morning, with
showers decreasing. Another weaker shortwave in NW flow aloft could
spawn some additional showers and thunderstorms mainly N and E of PIT
in the afternoon, with this area in close proximity to the sfc warm
front. Model progged instability is limited, though with marginal
shear an isolated strong to severe storm is possible, as indicated on
the SPC day 2 outlook. Will add a mention of this to the Hazardous
Weather Outlook.


A sfc low undergoing cyclogenesis East of Hudson Bay will stall as a
zonally oriented jet streak backbuilds near the Great Lakes. A
shortwave and lower-level jet on Wednesday morning should support
morning convection with elevated instability present.

As the jet stream strengthens, a cold front will approach from the
northwest Wednesday evening and prompt convective initiation in
tandem with a right jet-entrance circulation that provides near 50kts
in bulk shear. A sufficiently warm and moist surface courtesy of
Tuesday`s warm frontal passage will prime the thermodynamic
environment with 3000 j/kg of CAPE. Convection will respond to this
environment with initially strong, cellular storms capable of
upscaling and organizing into a severe QLCS.

As a consequence of the strengthening jet stream, a narrow band of
frontogenesis may lend a boundary that could locally add to
precipitation totals and cause flooding problems. Precipitation
accumulation and flooding threat will be more finely tuned in the
coming days.


Lingering boundaries amid the same occluding low pressure, as well
as a developing trough in the upper Midwest will present more
opportunities for showers and thunderstorms this weekend.
Temperatures will remain above normal.


General VFR is expected for most ports through most of the TAF
period, though some ocnl MVFR is possible with showers overnight and
Tue morning with a crossing shortwave and its associated sfc warm
front. The initial shortwave should exit Tue morning with showers
decreasing, though with FKL and DUJ still in close proximity to the
sfc warm front MVFR cigs are expected.

A second shortwave could result in local restrictions in sct shra/ts
Tue aftn, mainly N of PIT, though VFR should continue elsewhere as
shortwave ridging builds in.

Restrictions are likely in shra/ts with a Wed cold front, and Thu S
of PIT as the front stalls. Restriction potential returns again with
a Fri cold front.





NWS PBZ Office Area Forecast Discussion