Severe Thunderstorms in the Northern Plains; Heavy Rainfall in the Mississippi and Tennessee Valleys; Critical Fire Weather in the Southwest

Severe thunderstorms, with a significant wind threat, will continue through tonight across the northern Plains. Wind gusts of 60 to 100 mph are possible. Heavy rainfall will continue through tonight from Oklahoma into Missouri, and in the Tennessee Valley through Monday. Critical fire weather conditions continue in the Southwest through Tuesday. Read More >

Here is the latest Area Forecast Discussion for Central PA

This text statement is the latest forecast reasoning from the NWS in State College, PA

See the links at the bottom of the page for previous issuances/versions of the statement as well as our other text statements.

821
FXUS61 KCTP 111639
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1239 PM EDT Thu Jun 11 2026

.WHAT HAS CHANGED...
Heat Advisory issued for Lancaster, York, Adams, Cumberland,
Dauphin, and Lebanon Counties for Thursday and Friday.

&&

.KEY MESSAGES...
1) Increasing heat and humidity will bring increased risk for
heat-related illnesses Thursday, and especially on Friday.

2) Daily shower and thunderstorm chances continue through the
end of the work week. Some strong to severe thunder with
damaging winds possible.

3) A refreshing decrease in humidity is a good bet this weekend
with high pressure moving in after a cold front.

&&

.DISCUSSION...
KEY MESSAGE 1: Increasing heat and humidity will bring
increased risk for heat-related illnesses Thursday, and
especially on Friday.

With an upper level ridge in place advecting in a very warm to
hot airmass, heat and humidity will continue to build today and
Friday, particularly for the eastern two thirds of the forecast
area.

There is quite a bit of uncertainty remaining in how high the
temperatures and heat index values get due to variable amounts
of alto cu from weak warm advection aloft and remnant cloud
cover from overnight/mid morning convection. Increasing chc
for late afternoon and evening SHRA/TSRA will also add to the
uncertainty of max temps.

The continued thinking is that the NBM is a bit too high with
both temperatures and dew points both days, especially given the
recent high bias. Therefore, similar to previous forecast
cycles, went a few degrees cooler than the NBM.

All of this being said, the forecast heat index for Thursday
and Friday still get to the upper 90s and low 100s for the
southeastern portions of the area on Thursday, particularly the
Harrisburg/Lancaster/York areas. Heat Advisories have been
issued for Lancaster, York, Adams, Cumberland, Dauphin, and
Lebanon Counties for Thursday and Friday where HREF
probabilities of heat index > 100F are highest.

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

KEY MESSAGE 2: Daily shower and thunderstorm chances continue
through the end of the work week. Some strong to severe thunder
with damaging winds possible.

Underneath a broad ridge of high pressure, a couple shortwaves
will drift across Pennsylvania over the next few days.
Sufficient instability in the presence of warm & moist air along
with weak but sufficient shear will lead to multiple rounds of
showers and thunderstorms today and Friday.

The first feature at the surface and aloft that will spark PM
SHRA/TSRA comes in the form of a compact shortwave trough
centered over Lake Erie/SW Ontario with its trough axis
extending south across Ecent/Scent Ohio and moving east at a
little over 30KT.

Meso-B lift and 1-2 deg C of cooling within the 700 mb layer
along with westerly 0-3 km bulk shear increasing to around 30 KT
will help to increase instability and organized updrafts in
TSRA that should push through much of our CWA in 2-3 linear
features, with the main severe wx threat coming in the form of
localized wind damage associated with mini bows/broken-S
signatures.

If these multicell clusters can develop large enough cold
pools, an elevated threat of damaging wind gusts may materialize
in the form of an MCS. Such a scenario cloud produce a swath of
more significant wind damage (most likely across the Mid/lower
Susq Valley late this afternoon/evening and potentially in any
part of the CWA on Friday. Slight Risks with 30% wind
probabilities have been issued for both today and Friday across
southeast PA.

A cold frontal passage will occur on Friday. An approaching upper
trough and high available moisture suggest severe thunderstorms
are possible. But, the small ridge that pumps up overhead late
Thu could be a setback for how widespread the threat will be.
The biggest question is timing/speed of the cold front. A faster
progression could mean the cold front clears our area before
peak heating (lower threat of damaging winds), while a later
arrival could spell more concern for severe weather.

It is worth noting that recent hi-res convective
allowing models actually bring most of the convection to NW PA
today and fail to initiate many storms at all in our forecast
area on Friday. Possible flies in the ointment to monitor.

The repeated shots of scattered to numerous SHRA/TSRA over the
next 2 days is likely to yield lower FFG thresholds and some
flash flooding would become possible, too. But, it has been very
dry recently, and everything is growing and thirsty, ready to
soak up as much as it can. As always, too much of a good thing
can be bad. We`ll keep an eye on the soil saturation and other
factors that could lead to flooding.

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

KEY MESSAGE 3: A refreshing decrease in humidity is a good bet
this weekend with high pressure moving in after a cold front.

Following the passage of the aforementioned cold front, much
more comfortable conditions will arrive on Saturday and Sunday.
Temperatures will remain warm (highs in the 80s and even some
lower 90s on Sunday), but dew points will be much lower (in the
50s and lower 60s, instead of the 70s). Then, cooler
temperatures arrive by Monday with highs in the 70s to lower
80s. This will be due to another cold front passage on Sunday,
which will bring a renewed chance for showers and
thunderstorms.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
VFR regionwide for the Central Mtns and Susq Valley through 20Z,
with earlier SHRA/TSRA impacting the NW Mtns and Laurel
Highlands with brief restrictions.

Multicell clusters & quasi-linear segments are the favored form
of convection given marginally favorable deep layer shear
(20-30 kts), along with threat for gusty to perhaps severe-
level winds given steep low- level lapse rates (8-9 C/km) and
moderate-high DCAPE (1000-1250 J/kg). Visibility restrictions
will be likely in these storms, especially given high moisture
content (PWATs around 1.5") which will bring heavy rain in
storms. Convective activity across central PA will downtrend
after 00Z as the shortwave progresses east of our area, with
patchy fog possible once again Thursday night given moist
environment & breaks in cloud cover.

Outlook...

Thursday afternoon...Restrictions possible in scattered-numerous
-SHRA/-TSRA.

Friday...Restrictions expected as FROPA brings line of -TSRA.

Saturday...Mainly VFR.

Sunday...VFR favored early, with restrictions possible as FROPA
brings chance of -SHRA/-TSRA later in the day.

Monday...Additional scattered -SHRA and associated restrictions
possible.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 8 PM EDT Friday for PAZ057-059-063>066.

&&

$$

WHAT HAS CHANGED...Lambert/Banghoff/Colbert
KEY MESSAGES...Lambert/Banghoff/Colbert
DISCUSSION...Lambert/Banghoff/Colbert
AVIATION...Lambert/Teare

Forecaster's
Discussion: