Area Forecast Discussion

Pittsburgh, PA

Forecast Discussion for PBZ NWS Office
FXUS61 KPBZ 191811

Area Forecast Discussion
National Weather Service Pittsburgh PA
111 PM EST Tue Nov 19 2019

Broad upper-level troughing will maintain cooler temperature
along with patchy drizzle today. Drizzle or freezing drizzle may be
possible late tonight before warmer temperature returns during the
second half of the week. The highest chance for precipitation will
come late Thursday and Friday.


Low-level moisture has been maintained through much of the day
beneath a stout inversion near H8, helping cloud cover to persevere.
As a result, heating/mixing have been limited, and a near-saturated
low-level thermal profile has remained.

A shortwave trough crossing this afternoon and evening will support
modest lift of this saturated layer, ensuring continuous overcast and
patchy drizzle/sprinkles this afternoon and evening.

In the wake of the wave, weak nwly flow across Lake Erie will provide
orographic lift to this saturated airmass. But a lack of ice crystals
suggests any precipitation will be drizzle/freezing drizzle,
especially in nrn zones and the ridge zones, where sfc cold air may
be sufficient for modest ice development.

At this time, low confidence and complicating factors like warm
ground and patchy coverage preclude any headlines, but this concern
will need to be monitored this evening. The concern will be included
in the HWO.


Dry conditions and a warming trend are expected Wed and Thu as
ridging builds sfc high pressure across the region, with forecast
maxima on Thu reaching slightly above seasonal average.

Rain onset has trended slower the last few days, with minimal morning
chances and probability increasing only slightly late Thu afternoon.


Precipitation chances will increase markedly late Thu night in
advance of a cold front, which is expected to bring more widespread
precipitation to the region. Best chances at this time look to be
late Thu night-Fri morning, although forecasted amounts appear to be

Temperature Thu and Thu night will be comparatively mild as cloud
cover and warm advection on swly flow will limit typical diurnal
trends. Models are in fairly good agreement with frontal passage
during the day on Fri, with a return to below-average temperature.

Although medium-range details vary among ensembles/members, the
general idea of broad ern-CONUS troughing into early next week
appears consistent until ridging builds mid-week. Below-average
temperature is expected through Tue, with a potential warm-up on


Low-level moisture under an upper-level trough should maintain MVFR
into Wednesday. With light winds and overnight lows falling towards
the crossover temperature, fog should form at FKL/DUJ.

Winds are expected to shift from the northwest early Wednesday as
the upper-level trough exits east. Cold advection over Lake Erie
will reinforce MVFR stratocu coverage for areas northeast of HLG
into the late evening; there may be brief periods of IFR for FKL/DUJ.
FKL may observe freezing drizzle or rain/snow mix for a brief period
of time near 12Z, however confidence is not high enough to mention
in the TAF. Building high pressure in Central Ohio should eliminate
restrictions from west to east late Wednesday/early Thursday morning.


More widespread restrictions are expected with a late-week frontal






NWS PBZ Office Area Forecast Discussion