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000
FXUS61 KPBZ 180627
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
227 AM EDT Thu Apr 18 2024

.SYNOPSIS...
Showers will end late this evening. After a brief dry period
Thursday, another cold front moving through very late Thursday
night and Friday will bring another round of showers before a
period of cool and dry weather moves in for Saturday through
Monday.

&&

.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:

-  High temperature expected to be approximately 10 degrees
   above the seasonal average.

------------------------------------------------------------------

Surface ridging plus height rises aloft will support dry weather
today and slowly clear areas of morning stratocu through the
afternoon. Insolation and only marginal changes to the airmass
is expected to support another day of above normal temperature,
and likely the highest reading for the upcoming week.

Clouds will increase overnight amid warm, moist advection ahead
of the next shortwave system set to traverse the Ohio River
Valley Friday. Limited cooling is likely as thicker cirrus
limits nocturnal radiational cooling, keeping low temperature
above normal and likely the highest reading for the upcoming
week.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
KEY MESSAGES:

- Showers and low probability thunderstorms are expected ahead
  of a cold front Friday.
- Seasonable temperature and dry weather expected through the
  weekend.
- Potential for frost and/or freeze impacts each of Saturday and
  Sunday mornings.
----------------------------------------------------------------

A pivoting shortwave within the broad western Great Lakes trough
is expected to promote broad ascent that, combined with a
passing surface cold front, will generate showers and low
probability thunderstorms Friday morning into the early
afternoon. Subsidence and dry slotting of the upper trough will
quickly end precipitation chances behind the passing cold front,
while more notable cold advection begins to lower area readings.

Ensembles favor the trough axis transition over the Upper Ohio
River Valley to occur Saturday with quasi-zonal flow developing
into Sunday. Saturday`s axis cross will push a reinforcing shot
of cooler air during the later afternoon hours, pushing area
temperature slightly below average each day. Lack of column
moisture should preclude shower generation Saturday, though
there is some hint of potential Lake Erie enhancement that could
light rain for northwest PA.

The biggest potential impact is the development of frost/freeze
conditions during the overnight periods Saturday and Sunday as
all but Tucker County is in an active growing season. Saturday
night into Sunday is the more likely period for freezing
temperature for northwest PA (30-50% probability) as elevated
winds should prevent frost formation. Sunday night into Monday
is the more likely period for frost given lighter winds and
clearer skies.

&&

.LONG TERM /MONDAY THROUGH WEDNESDAY/...
KEY MESSAGES:

- Next precipitation chances are likely to be Tuesday into
  Wednesday with crossing low pressure.
- Ensembles favor dry conditions outside of that period.
-------------------------------------------------------------------

Confidence is growing that dry weather and seasonable
temperature plus plenty of insolation is likely for Monday as
ensembles push a crossing upper trough well south of the region.

This sets up Tuesday into Wednesday as the next period for
potential precipitation chances with shortwave movement within
the broad eastern CONUS trough pattern. Trough depth and axis
timing remains varied among ensemble members, but they all favor
a shower environment with limited lightning potential as
temperatures hover near seasonal averages.

Long range ensembles favor ridge building over the western Great
Lakes in response to a deepening trough over the western CONUS
for the late week period. The expectation is for area
temperature to once again rise with any passing shortwave posing
greater thunderstorm potential.

&&

.AVIATION /07Z THURSDAY THROUGH MONDAY/...
Behind the cold front, expected winds to be west-northwest
through dawn. This will bring in some stratocumulus through the
morning hours and through dawn. Thus, expect some MVFR and IFR
cigs through dawn and into mid-morning. The probability is
higher for FKL and DUJ becoming IFR. There should be an
improvement in conditions by midday as a return to VFR is
anticipated at all ports except FKL and DUJ.

Winds will remain light through the period topping out at 10
knots at the most from the west-northwest.

.Outlook...
Restrictions remain possible Thursday night into Friday under
another passing upper trough and associated chances for rain.
Prevailing VFR returns over the weekend.

&&

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

&&

$$

SYNOPSIS...Frazier
NEAR TERM...Frazier
SHORT TERM...Frazier
LONG TERM...Frazier
AVIATION...Shallenberger