NWS Forecast Discussion
308
FXUS61 KCTP 180155
AFDCTP
Area Forecast Discussion
National Weather Service State College PA
955 PM EDT Sun May 17 2026
.WHAT HAS CHANGED...
* Continue to trend afternoon highs below NBM guidance due to
known warm bias
* Changed wording for showers/storms Monday from probability
(Slight Chance) to coverage (Isolated).
&&
.KEY MESSAGES...
1) Hottest temperatures of the year so far forecast the next
couple of days with highs pushing into the 80s and 90s.
2) A strong cold front to bring showers and thunderstorms with
the potential for severe weather on Wednesday followed by
colder temperatures.
&&
.DISCUSSION...
KEY MESSAGE 1: Hottest temperatures of the year so far forecast
the next couple of days with highs pushing into the 80s and
90s.
Daytime high temperatures will be steadily rising today through
early week. An anomalous upper ridge amplifying over the east-
central U.S. will help to create very warm to hot, summerlike
conditions centered on Monday and Tuesday.
500 mb heights per the GEFS rise about 120 dam from Sunday
morning to late Monday with standardized anomalies of these
heights reaching over +2 sigma along the Mid Atlantic Coast 18Z
Monday through 18z Tuesday.
High temperatures will peak in the mid 80s to lower 90s Monday
and Tuesday and could challenge daily records in some locations.
See the Climate section for more details. Manual adjustments
were made to lower NBM maxT by a few degrees due to a known
systematic bias correction issue identified during the shoulder
seasons. This should also keep max heat indices under 100F,
precluding any need for Heat Advisories. Still, heat risk
impacts will continue to be monitored given the quick ramp-up in
heat and limited acclimation time.
Dewpoints over 60F for many will also feel quite humid relative
the recent cool stretch we`ve had.
With a boundary just to our north and sufficient instability in
the warm sector over PA, there will be a chance for some stray
afternoon and early evening showers or thunderstorms Monday and
Tuesday. Most folks should stay dry, but thunderstorms could
drop a quick 0.10 to 0.25" of rain in any one location.
New...
Rather strong cap noted on the 00Z Monday observed sounding over
ILN Ohio, so might be hard to see much activity on Monday.
Activity late this afternoon was isolated near the MD border,
then a few showers formed just east of State College early this
evening, most likely due to a weak lee-side trough.
-------------------------------------------------------------
KEY MESSAGE 2: A strong cold front to bring showers and thunderstorms
with the potential for severe weather on Wednesday followed by
colder temperatures.
A cold front (accompanied by more widespread and frequent
showers/t-storms) brings relief to the relatively short bout of
heat and moderate humidity Wednesday into Thursday. DOD max temp
drop from Tuesday to Wed will be 20 deg F or greater in most
locations.
Some of the AI guidance paints an elevated risk of severe
weather across the Lower Susquehanna Valley on Wednesday
afternoon in the presence of peak heating and sufficient
shear/CAPE profiles. The magnitude & location of the severe
threat will be highly dependent on cold front passage timing and
amount of cloud cover in advance of the frontal boundary. The
eventual risk area will highlight locations along and downstream
of the cold front between 12PM and 8PM on Wednesday.
In the wake of the cold front, high pressure will build in for
a short time. Temperatures are forecast to cool down back to
historical/climo averages for late May for the end of next week.
Early indications show the aforementioned cold front stalling
out south of the Mason-Dixon line late in the week and lifting
back north across PA as a warm front into Memorial Day weekend.
The current outlook favors a cooler/wetter stretch through the
holiday weekend thanks to that warm front, but there is still
a lot of time for the forecast to trend in a more favorable and
optimistic direction for the holiday weekend that marks the
unofficial start of summer.
&&
.AVIATION /01Z MONDAY THROUGH FRIDAY/...
VFR conditions look to prevail throughout Monday. Light and
variable winds are expected overnight. These gain strength in
the late morning and early afternoon and become more out of the
SSW with some gusts in the teens possible. Scattered daytime
cumulus are expected tomorrow afternoon as well after a clear
morning, ceilings are expected to remain VFR with this activity.
Convective showers and isolated thunderstorm activity is possible
in southern PA at the tail end of the TAF period, may introduce
-SHRA/-TSRA mentions in future TAFs.
Patchy fog remains a low (
NWS CTP Office Area Forecast Discussion
