Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 040751
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
351 AM EDT Thu Jun 4 2020

.SYNOPSIS...
Warm and humid conditions will continue today into Saturday with
isolated to scattered afternoon thunderstorms. Cooler and less
humid air will arrive Saturday night and promote pleasant and
dry weather Sunday through Tuesday. Expect temperatures and
humidity levels to trend higher into midweek ahead of the next
frontal system.

&&

.NEAR TERM /THROUGH TONIGHT/...
Mostly clear skies, light winds and wet ground will result in
patchy fog across north-central valleys early this morning. Fog
will dissipate quickly after sunrise. Can`t rule out an
isolated shower before noon across the southwest 1/2 of the
area, but in general hires CAMs keep things dry through ~16Z.

By early to mid afternoon, MLCAPE from 1000 to 1500 J/kg is
expected across south-central PA. Storms are expected to
develop over the higher terrain and along lee trough as the
boundary layer destabilizes. Vertical shear will remain weak,
but 25-35 kt deep layer flow will support storms spreading east
off the higher terrain, possibly evolving into loosely organized
multicell clusters capable of strong to damaging water-loaded
downburst wind gusts. SPC has increased the risk level up one
notch to SLGT (2 out of 5) from the southern Alleghenies into
the lower Susquehanna Valley.

Scattered storms may evolve slowly to the east and train as the
flow becomes aligned with quasi-stationary front draped over
CPA. WPC expanded the D1 MRGL ERO to cover the entire area with
00Z HREF mean showing spotty 1-2" amounts. This rainfall could
produce some isolated flooding particularly in urban areas, but
the overall risk of FF is low especially given 14-day rainfall
departures that are generally 25-50% of normal.

Isolated to scattered convection will fade into early tonight
with mostly cloudy skies into Friday morning. Max/min temps
will be above average with the largest departure from normal in
lows tonight.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
Warm and humid conditions continue on Friday with isolated to
scattered aftn storms expected to form again in weakly forced
environment along the terrain/lee trough axis and drift slowly
east/southeast. 00Z HREF mean shows PWs climbing to 1.75 inches
over parts of south central/southeast PA with 1000-2000 J/kg of
MUCAPE expected during peak heating. The main threat will be
locally heavy rain as pulse storms become nearly stationary.
Given recent rainfall departures, an isolated FF risk would be
confined mainly to the more vulnerable/urban areas where heavy
rain rates may occur. Expect convective coverage to diminish
again into Friday night.

An upper trough over Ontario and Quebec will deepen across the
Northeast and Mid-Atlantic vicinity on Saturday. A moist boundary
layer will be in place as a cold front moves southeast across
the region during the morning and afternoon. Some strong storms
may be possible ahead of the front during the afternoon across
the southeast 1/2 of the area, but guidance varies with regards
to timing and coverage.

Cooler and drier/less humid air will arrive in the wake of the
front by Saturday night.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Pleasant and comfortable weather expected Sunday through
Tuesday with a mix of sun/clouds and low humidity.

We should see a warming trend heading into the middle of next
week, as the remnants of TS Cristobal move up the MS valley and
help build an upper-level ridge over the eastern United States.

&&

.AVIATION /07Z THURSDAY THROUGH MONDAY/...
As of 03z, the last remaining showers and thunderstorms have
slipped to the south and east of the Lower Susq Valley. All
areas will become VFR overnight, with just some patchy mist or
light fog that may drop a few areas to MVFR near sunrise.

Thursday looks to have a dry start with VFR conds. Scattered
showers and thunderstorms will developing during the mid
afternoon and may cause brief reductions. Did not try to
pinpoint timing at this point, but mentioned TS wording for the
afternoon hours.

Outlook...

Fri-Sat...Chance of showers/t-storms.

Sun-Mon...VFR/no sig wx.

&&

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

&&

$$
SYNOPSIS...Steinbugl
NEAR TERM...Steinbugl
SHORT TERM...Steinbugl
LONG TERM...Evanego
AVIATION...Fitzgerald


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