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361
FXUS61 KCTP 100029
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
829 PM EDT Thu May 9 2024

.SYNOPSIS...
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- A stationary front will continue to be present across
  southwestern PA to northern VA for the next 24 hours as a few
  waves of low pressure move east along it.
- The front will push southeast to the Delmarva Coast late
  Friday.
- Several upper level troughs will move across PA through
  Saturday, bringing periods of light to moderate rain.
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&&

.NEAR TERM /THROUGH FRIDAY/...
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Showers are expected to continue across central PA through the
near-term with enough elevated instability along the southern
tier to promote an isolated thunderstorm. Showers will be
scattered in nature, but widespread enough to promote high-end
PoPs throughout the overnight period. Generally expect any
severe potential to steer south of the Mason-Dixon Line where
recent model guidance outlines the best moisture and
instability. As stronger showers move further east into the
Lower Susquehanna Valley, more stable air will limit
thunderstorm potential.

Enhanced lift over a quasistationary front will allow for some
periods of heavier rainfall rates overnight along the
Alleghenies and northeastern PA. Six hour flash flood guidance
remains fairly high (2.5+ inches) across most of the area, but
some period of locally heavy rainfall could lead to moderate
rises on small creeks/streams and ponding of poor drainage
areas, as outlined in the D1 Excessive Rainfall Outlook from the
Weather Prediction Center.

The upper low and an inverted sfc trough will become collocated
over the area Friday morning, bringing a continuation of widespread
thick clouds and frequent showers, if not periods of steadier
rain and drizzle) will be the result. The best chances for
rainfall shift towards eastern Pennsylvania later in the day
Friday as the upper-level low moves towards the east.
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&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
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Some uncertainty on timing of the upper-level low continues SChc
of PoPs for the beginning of the short-term. Have cut back from
NBM PoPs with a brief period of height rises across W PA to keep
the best chances of precipitation (if any) towards the Poconos
and Endless Mountain regions of central PA.

Height falls ahead of another sfc low is progged by
deterministic model guidance to move towards the area, allowing
for another period of unsettled weather into the weekend. There
remains some uncertainty on strength of the sfc low pressure
and associated cold front, with ECMWF guidance indicating a
slightly weaker solution which will bring more scattered
coverage in precipitation while the GFS brings about a slightly
stronger solution with higher chances of precipitation.

Some instability later in the afternoon/evening hours on both
Saturday and Sunday will allow for some thunderstorm potential,
especially in areas where the best forcing is present.
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&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Tendency to have a large scale upper level ridge over the west
this weekend, will result in much below normal 500 mb heights
over the east into next week.

While some milder and drier conditions will be possible Monday
into Tuesday, much of the time it will be cooler than normal
and wet from time to time for much of the upcoming week. Sunday
will be one day that will feature gusty winds and cold temperatures.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
A surface low approaching Central PA is supporting developing of
widespread light to moderate rain across the airspace. This will
continue through the evening hours and overnight with
coincident lower cigs and visbys.

Reductions in visibility will develop early tonight with CIGS
lowered into the IFR to LIFR range later tonight and continue
through at least the midday hours on Friday.

Latest guidance has the surface low tracking to the south of
Pennsylvania, meaning the heaviest rains and greatest instability
for widespread t-storms will also track to the south, but cant
rule out a rumble or two/vcts mainly across srn airfields.

Outlook...

Fri...Low cigs/drizzle possible, especially in the morning.

Sat...PM showers/low cigs possible, mainly W Mtns.

Sun...AM low cigs possible W Mtns. Sct afternoon showers/brief
vis reductions possible.

Mon...AM dry and mainly VFR. Showers return PM.

Tue...Showers and tstms.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

SYNOPSIS...NPB
NEAR TERM...NPB
SHORT TERM...NPB
LONG TERM...Martin/Gartner
AVIATION...Lambert/Gartner