341
FXUS61 KCTP 060526
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
126 AM EDT Mon Jul 6 2026

.WHAT HAS CHANGED...
* Severe threat has ended for the most part, but flash flood
  threat will continue through at least midnight.

&&

.KEY MESSAGES...
1) Thunderstorms are weakening/losing vertical development.
Flood threat remains.

2) Breakdown of heat wave pattern gives rise to severe storms
and torrential downpours today and tonight; flood risk lingering
in the east on Monday.

&&

.DISCUSSION...
KEY MESSAGE 1: Thunderstorms are weakening/losing vertical
development. Flood threat remains.

Current (930 PM EDT) assessment of environment over Central PA
is that the severe threat is just about over. Most places have
stabilized at the lowest layer. This will make it difficult for
additional wind damage to occur. Will leave the watch up for
just another 30 mins, but should be able to clear the rest of it
shortly.

As anticipated, the threat is now flash flooding. Many places
have picked up >1" of rain across the CWA, with 3-5" amounts
reported in the Harrisburg area. Considerable flash flooding has
been on-going for a few hours, starting in Tyrone/Blair Co, and
shifting to the east. The flooding in the SE will continue for
a few more hours with a few new instances of flooding before
midnight. What should be the last batch of very heavy rainfall
is moving through the SE now. Lone FFW over State College should
see the water start to go down in an hour or so.

High moisture and light wind will cause fog over most of the CWA
overnight. Will likely need a dense fog advisory at some point.

KEY MESSAGE 2: Breakdown of heat wave pattern gives rise to
severe storms and torrential downpours today and tonight; flood
risk lingering in the east on Monday.

40 severe thunderstorm warnings issued in the past 2 days. The
days following a transition from an extreme heat pattern are
often marked by severe/active weather, and that trend continues
through at least Monday. As the heat dome shifts to the west and
troughing develops over the Great Lakes/Ohio Valley/Northeast, the
upcoming week will feature relatively cooler (more seasonal)
temperatures with a bullish signal for almost daily rain chances
particularly early and late in the week.

Another active wx day ahead with dual severe T-storm and flash
flood risks. We anticipate another diurnal uptick in convective
development within a very warm, moist and increasingly unstable
environment indicative of steep low-mid level lapse rates.
Pockets of stronger deep layer shear 30+ kt may exist in the
upper OH Valley and eastern PA, but the general expectation is
for pulse to multicell storms to once again merge/form into line
segments with some cold pool organization to promote damaging
wind potential from mid afternoon into the evening. Terrain
boundaries will also play an important role in initiating/organizing
convection given lack of other strong forcing. SPC placed the
highest damaging wind probs near/southeast of I81/78 where max
temps should reach 90F.

Focus will evolve from severe to flash flood/hydro ops by later
this evening and continue into Monday as a robust +RA signal
continues to manifest over east-central PA. Atmos conditions
will be quite favorable for heavy rainfall and flash flooding
potential with 2+ inch pwats correlating to intense rain rates
>2 in/hr. Still some question on degree of repeating/back-
building storms along q-stnry/wavy frontal zone. Latest
HREF/REFS mean QPF guidance is signaling 1-3" in the 24hr period
ending 00Z Tue with PMM/LPMM max values exceeding 5 inches. WPC
coordinated a targeted and relatively small moderate excessive
rainfall outlook (level 3/4) within a broader level 2/4 or SLGT
risk area. We issued a relatively large/broad flood watch along
with WFO PHI as there remains some spatial uncertainty to
exactly where the greatest rainfall will occur. The setup
(multiple rounds of slow moving/torrential downpours) favors
locally significant flash flooding particularly in terrain areas
and highly urbanized corridors. One limiting factor is
obviously the drought conditions and corresponding elevated FFG
values that may offset the overall risk to some extent.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
Drier weather is expected for the rest of the night, though a
few showers or storms remain possible. Widespread fog and low
clouds will produce a mix of MVFR and IFR conditions, though
confidence is low on how low ceilings and visibility get at each
TAF site. Persistent easterly flow will lead to little
improvement in ceilings tomorrow, with MVFR or IFR ceilings
likely persisting for much of the day. The exception will be at
BFD, JST, and AOO where a period of VFR will be possible in the
afternoon.

Additional showers and thunderstorms will develop during the
afternoon, but instability will be more limited than it has been
the past few days. As a result, we will keep thunder mentions
limited to BFD, JST, and AOO for now. Showers and thunderstorms
will produce very heavy rainfall, leading to reduced visibility
as they move over any airfields. Another night of low clouds and
fog appears likely for Monday night behind these showers and
storms.


Outlook...

Tue...Restrictions possible in A.M. fog and P.M. T-storms. Wed-
Fri...Restrictions possible in showers/storms, most widespread
on Friday.

&&

.CLIMATE...
Rare Heat at Harrisburg: 3 consecutive days with maxT >= 100F
from July 2-4, 2026. The last time this streak occurred was
July 1999 (2x) and is only the 6th time on record going back to
1888.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Flood Watch through this evening for PAZ017>019-024>028-
033>036-042-045-046-049>053-056>059-063>066.

&&

$$

WHAT HAS CHANGED...Dangelo
KEY MESSAGES...Dangelo/Steinbugl/Colbert
DISCUSSION...Dangelo/Steinbugl/Colbert
AVIATION...Bauco
CLIMATE...Steinbugl