-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KCTP 242150
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
550 PM EDT Wed Apr 24 2024

.SYNOPSIS...
Today will be cooler with scattered rain showers and a rumble of
thunder in spots as an upper level disturbance crosses the
region. Widespread frost and freeze conditions are expected
tonight and Friday morning, with high pressure providing dry
and mostly sunny conditions. Clouds increase late Friday leading
to a chance of showers Friday night and into the weekend before
it turns much warmer for Sunday and Monday.

&&

.NEAR TERM /THROUGH THURSDAY/...
500mb trough axis swinging offshore this afternoon with residual
trailing isold-sct shra traversing central PA mid to late
afternoon. This activity will dissipate with loss of diurnal
heating and decreasing deep layer moisture as the 5h axis moves
farther offshore.

Main focus tonight on cloud cover and light winds as high
pressure builds, and resultant minimum temperatures on Thursday
morning in areas where the growing season has begun. Consensus
is for clearing to occur from NNE to SSW from late tonight
through 12z Thu, with a light northerly breeze keeping up in
most areas. Widespread freezing temps expected along and north
of I-80, and upgraded to Freeze Warning from the earlier Watches
in these areas. Farther south, temps of 33F to 36F will be
widespread from northern parts of the Laurel Highlands through
the Ridge and Valley Region, but the light northerly winds may
limit frost to the most sheltered locations. Given these
temperature ranges and critical time in the growing season,
opted for wider goalpost frost messaging/headline and to
message the light wind potentially as a mitigating factor in
preventing frost.

1030+mb Canadian high pressure with origins over northern
Manitoba will drift southward to a position north of Lake
Ontario overnight. Frost/freeze risk outside of the headline
areas is highlighted in the HWO.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY/...
Chilly/cold start Thursday followed by mostly sunny conditions
allowing temps to warm into the mid 50s to around 60F. Very dry
air/below normal pwats ~0.20 inches combined with HREF ens min
and mixed Td sounding signal suggests a floor for minRH as low
as 10-15% across the northern tier. The abnormally dry air and
favorable radiational cooling conditions will support renewed
frost/freeze concerns tomorrow night into AM Friday. This risk
is highlighted in the HWO.

The sfc high strengthens to +2SD or ~1035mb as it drifts over
interior New England to Long Island by 12Z Saturday. Rain free
wx conditions will continue through the end of the week/Friday
with sun mixing with high clouds and max temps trending warmer
into the upper 50s to lower 60s.

Showers along a warm front are likely to reach western PA by
daybreak Saturday based on latest operational model/ens
consensus. No frost/freeze concerns for Friday night into AM
Saturday with increasing clouds and fcst lows 38-45F.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
The weekend appears somewhat unsettled, with a warm front
arriving Saturday and warm sector struggling to overspread
central PA. It won`t be raining all the time, but a couple of
showers are likely on Saturday with a t-storm possible on
Sunday.

Upper ridging should eventually win out by early next week,
allowing for drier wx and much warmer temps with highs surging
through the 70s and perhaps topping 80F across the south on
Sunday. The warmest day of the extended period will be Monday as
temperatures soar into the 80s areawide. A bit humid as well
with fcst Td around 60F. This could support overnight lows near
record levels next week (near 60F).

Precipitation will be tough to come by in the extended period
without much gulf moisture sourcing. Decaying systems that bring
severe weather to the Plains will struggle to stay together and
7-day precipitation forecasts show very little rainfall across
southeast PA through the middle of next week with amounts only
approaching 0.75" in northwest PA.

&&

.AVIATION /22Z WEDNESDAY THROUGH MONDAY/...
-- Changed Discussion --
A northwesterly flow continues to gust 15-25 kts heading into
the early evening hours. IFR cigs were observed across NW PA
(BFD), with borderline MVFR/VFR cigs down the western highlands
into JST and predominantly VFR conds elsewhere.

JST should see cigs drop to solidly MVFR overnight, while the
IFR cigs at BFD are expected to eventually scatter out. Expect
predominantly VFR conds to persist at the other central PA TAF
sites overnight. Wind gusts will diminish, although a light
northerly flow should persist in most areas.

Skies will clear areawide on Thursday, with widespread VFR conds
and a light northeasterly sfc flow of 5-10 kts expected.

Outlook...

Thu-Fri...Predominantly VFR conds under high pressure.

Fri night-Sat...Patchy rain developing from west to east.

Sun...Isold SHRA/TSRA possible.

Mon...Predominantly VFR.
-- End Changed Discussion --

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Freeze Warning from 2 AM to 8 AM EDT Thursday for PAZ004-005-
010-011-017>019-045-046-049>053.
Frost Advisory from 2 AM to 8 AM EDT Thursday for PAZ024>028-
056-057-059.

&&

$$

SYNOPSIS...DeVoir/Steinbugl
NEAR TERM...DeVoir/Steinbugl
SHORT TERM...DeVoir/Steinbugl
LONG TERM...Banghoff/Evanego
AVIATION...DeVoir/Evanego