Area Forecast Discussion
Issued by NWS Pittsburgh, PA

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FXUS61 KPBZ 121103
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
703 AM EDT Mon Apr 12 2021

.SYNOPSIS...
Scattered showers are expected today with crossing low pressure. Dry
weather is expected Tuesday before another crossing low returns
shower chances for mid to late week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Made a few adjustments to early morning POPs based on latest radar
trends. Previous...A closed mid/upper level low is expected to track
across the Upper Ohio Valley region today. Increasing layer moisture
and ascent in the vicinity of the low should result in scattered
showers developing this morning. The showers should become more
numerous this afternoon during peak heating as convective
temperatures are reached.

Recent model soundings and instability progs indicate enough
instability could exist to produce a few isolated thunderstorms.
Latest RAP data shows limited sfc based CAPE, and lifted indices of
-1 to -2 across Wrn PA this afternoon. High temperatures are
 expected to be near seasonable levels.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
Shower coverage should wane tonight as the low tracks to the Mid
Atlantic coast, and temperatures fall below convective thresholds.
Dry weather is then expected Tuesday as shortwave ridging builds in
ahead of another low moving across the Upper Midwest.

Increasing moisture and shortwave support in SW flow ahead of the
next approaching low, and an associated sfc cold front, should
return scattered showers to the region on Wednesday. Scattered
showers should be maintained Wednesday night with the area in close
proximity to the upper low as it deepens across the Lower Great
Lakes. Temperatures should warm to around 5 degrees above average
Tuesday, before returning to more seasonable levels by Wednesday.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
Cool weather and scattered showers are expected again
Thursday/Thursday night as the upper low moves east across the Upper
Ohio Valley region. There could be enough cold air aloft for a few
snow showers mixing in, especially across the higher terrain.
Generally dry weather is then expected through early in the weekend
as weak ridging builds in behind the exiting low.

A longwave trough is then progged to set up across much of the
Eastern CONUS late in the weekend through early next week. Shortwaves
moving through the main trough should return shower chances to the
forecast by Sunday.

Continued to side with lower temperature guidance, going below NBM,
through late in the week with cold air aloft associated with the
upper low. Temperatures should gradually return to more seasonable
levels by the weekend.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
The passing of an upper level low, ample low level moisture, and
steepening lapse rates will yield MVFR cigs and sct showers through
much of the day. Showers will dissipate this eve as the low shifts
east, with slow w/nw to east cig clearing amid dry air intrusion and
increasing subsidence through Tuesday morning.

Confidence is lower on the timing of Tuesday morning cig clearing,
and interrelated potential for fog development. If clouds clear more
rapidly than forecasted and near sfc moisture remains prominent, more
fog may become more prevalent, favoring FKL/DUJ/ZZV/HLG.

VFR conditions and dry weather is expected by Tuesday aftn.

.Outlook...
Another chance for deterioration will be on Wednesday/Thursday with
crossing low pressure.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
PA...None.
OH...None.
WV...None.

&&

$$


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