Dangerous Heat Wave Continues; Enhanced Area of Severe Thunderstorms Today

A prolonged, dangerous heat wave will continue today in the Midwest and Mississippi Valley, and persist through the Independence Day weekend across the Ohio Valley, Mid-South, and East Coast. Widespread moderate to extreme HeatRisk is forecast. Scattered wind damage and large hail are expected from severe thunderstorms impacting parts of Nebraska into Iowa today. 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.

647
FXUS61 KCTP 031943
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
343 PM EDT Fri Jul 3 2026

.WHAT HAS CHANGED...
* Severe thunderstorm watch issued for much of the area for the
evening (til 03Z).

&&

.KEY MESSAGES...
0) Severe storm threat has increased through the evening

1) Dangerous heat persists today through Independence Day then
eases next week

2) Risk managing severe thunderstorm and excessive rain outlooks
Saturday through Monday

&&

.DISCUSSION...
KEY MESSAGE 0: Severe storm threat has increased through the
evening

Storms have flared up across the northern mountains along the
lake breeze boundary. Tall cores with DCAPE values >1000J. Hail
aloft may not reach the ground but the melting could further
increase the downdraft strength. Damaging winds are the main
threat. Near term model data solutions generally similar that
convection will continue to the SE, but not very well on
timing/SEwrd extent. Collab with neighboring offices and SPC has
resulted in a appropriately generous areal coverage to the
watch. The NW counties should be out of the woods shortly with
post-storm stabilization, but the SE may not have things get
through the cap until much later (past 00Z) - if they do. As
usual, shear is better N and cap stronger S.

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

KEY MESSAGE 1: Dangerous heat persists today through
Independence Day then eases next week

The strong upper ridge responsible for this significant and
dangerous heat wave today through the holiday weekend should
flatten as we head into next week. This pattern transition will
allow temperatures to return to values more typical of early
July.

Extreme heat headlines remain in effect today and Saturday, with
the only change being the addition of Fulton County to the heat
advisory on July 4th.

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

KEY MESSAGE 2: Risk managing severe thunderstorm and excessive
rain outlooks Saturday through Monday

The overall potential convective evolution over the next 3 days
remains uncertain/unclear. Proximity to the heat dome core
casts some doubt for today with warm mid levels and marginal
deep layer shear profiles (0-3 KM Bulk shear ranging from 20-25
kts across south PA to around 30 kts over the north), although
most CAMS (including HREF and REFS) seem to agree that widely
scattered storms could develop near the Lake Erie Breeze
boundary near and just SE of the I-90 corridor and track east
southeastward later this evening.

A small-scale mid/upper level low seen in water vapor imagery is
drifting slowly north from the KY/OH border late this AM and
will enhance diffluent flow/diff PVA aloft across Eastern Ohio
and Western PA to create a more favorable environment for the
convection to break the warm mid level cap and grow into pulse
or multicell clusters of strong to svr tsra.

We`ll also be watching the SWD progression of an outflow
boundary shooting out from TSRA moving across the Niagara
Frontier of Western NY/SE Ont, and an ill defined MVC that will
be heading across the Southern tip of Lake Huron shortly and
along the North shore of Lake Erie by early this afternoon.

Otherwise, rather low confidence and predictability forecast in
severe wx terms extends through the holiday weekend, with the
strongest precip signal in the Sunday through Monday timeframe.
WPC now has a pair of level 2/4 excessive rain outlooks covering
much of CPA in what appears to be a favorable heavy rain setup
complete with hi pwats pooling along a wavy, east to west
oriented frontal zone.

&&

.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
VFR conditions are expected through the TAF period with mainly
dry conditions likely through the rest of this morning.

Scattered showers and thunderstorms are expected to develop
along and north of I-80 this afternoon (probably first just SE
of Lake Erie and the I-90 corridor), but there is still quite a
bit of uncertainty regarding the exact timing and coverage of
storms. For now, we have added PROB30s for BFD, UNV, and IPT to
highlight the thunderstorm potential, but this will need to be
refined throughout the day as confidence increases. It is
possible that storms could develop farther to the south as well,
but there is less than a 30 percent chance that they impact any
of the other TAF sites. Some of the storms that develop will be
capable of producing strong wind gusts, potentially in excess
of 40 knots. Heavy rainfall may also briefly reduce visibility
if storms move directly over any airfields.

Very hot conditions are expected once again today, with highs
expected to be in the 90s/low 100s. This will continue to lead
to density altitude concerns across Central PA.

Outlook...

Sat...Patchy AM fog; otherwise VFR. Hot & humid with PM
t-storms psbl. High density altitude concerns possible.

Sun-Tue...Restrictions possible in afternoon t-storms.

&&

.CLIMATE...
Bradford reached 90 degrees yesterday afternoon 7/2. This tied
the old record of 90 degrees set back in 1966.

Williamsport reached 100 degrees, breaking the old record of
99 degrees set back in 1911 and 1931.

Harrisburg did reach 102 degrees, just short of the record of
104 degrees set back in 1966.

Many record highs were set in 1966 around this time of year,
while record lows were common back in 1982.

Earlier information below.

Bradford reached 89 degrees Wed, breaking the old record of 88
degrees set in 1963. Harrisburg came up one degree short of
tying their own record max Wed.

Triple digit max temps are forecast in the Lower Susq Valley
(LSV) today and Friday, and 90s for Saturday.

The last time Harrisburg observed consecutive days with maxT
greater than or equal to 100F was back in 2011 on July 21-22.

The record number of consecutive days with maxT >= 100F is 3
and has occurred 5 times: (all in the month of July)

1999-07-16 to 1999-07-18
1999-07-04 to 1999-07-06
1991-07-19 to 1991-07-21
1966-07-02 to 1966-07-04
1936-07-09 to 1936-07-11

The last time Harrisburg hit the century mark was July 16th in
2024. Prior to that, it was July 19th in 2020.

Harrisburg averages 1 day annually with a maxT >100F. The most
number of days observed in a year is 6 in 1999.

The record maxes for the next few days are in jeopardy:

Station/Date...07/02...07/03...07/04...07/05.
MDT.............104.....107.....104.....102..
IPT..............99.....100.....100.....100..
AOO..............97......97......97......94..
JST..............98.....100.....100.....101..
BFD..............90......91......91......91..

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 8 PM EDT this evening for PAZ004>006-
010>012-017-018-024-033-037-041-042.
Extreme Heat Warning until 8 PM EDT this evening for PAZ019-
025>028-034>036-045-046-049>053-056-058-063.
Heat Advisory from 8 PM this evening to 8 PM EDT Saturday for
PAZ019-026>028-035-036-045-046-049>053-056-058-063.
Extreme Heat Warning until 8 PM EDT Saturday for PAZ057-059-
064>066.

&&

$$

WHAT HAS CHANGED...Lambert/Steinbugl
KEY MESSAGES...Lambert/Steinbugl
DISCUSSION...Lambert/Dangelo/Steinbugl
AVIATION...Lambert/Bauco/Beaty
CLIMATE...Dangelo/Steinbugl/Martin

Forecaster's
Discussion: