Harrisburg, Pennsylvania 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

041
FXUS61 KCTP 081810
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
210 PM EDT Tue Jul 8 2025

.SYNOPSIS...
* Flash flooding and damaging thunderstorm wind risk this
  afternoon and evening across the southeastern portion of
  central PA
* Similar setup for Wednesday with renewed damaging wind and
  flash flooding risks focused over southeast PA
* Continued seasonably warm and humid with scattered afternoon
  and evening thunderstorms through the weekend

&&

.NEAR TERM /THROUGH TONIGHT/...
Thunderstorms are beginning to develop early this afternoon
along and ahead of an outflow boundary associated with morning
convection that has moved in from the Ohio Valley. As this
convection moves eastward with time through the afternoon, it
will encounter a more unstable and sheared airmass, likely
helping it to take on a more linear mode. With this evolution,
the likelihood of damaging wind gusts will increase.

Pwats eclipsing 2" over southeast PA will support a flash flood
threat where any tstms train. We issued a flood watch starting
18Z today for a portion of the Lower Susquehanna Valley in
coordination with WFO LWX. In addition to the robust and
anomalous pwat values, very efficient warm-rain processes could
lead to rain rates >2"/hr at times resulting in potential
instances of flash flooding.

Ahead of the rain, there also remains some concern for max HX
values to reach or exceed the century mark in parts of the LSV.
However, not thinking that this will be widespread enough to
warrant a Heat Advisory.

Hires models show the majority of showers/storms will shift to
the east before midnight (in fact, most guidance has the bulk of
the convective activity winding down before 8 PM). Min temps
will be a bit cooler than last night, with fog likely forming
in the valleys through the predawn hours Wednesday.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
Similar overall synoptic setup on Wednesday & Thursday with
gradual southward shift to the severe t-storm and FF risk areas
coincident with zone of max PW. Conditions will remain humid and
with daytime highs in the 80s.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
The forecast for Friday and the weekend is more uncertain, with
some guidance suggesting a break in the unsettled pattern, and
others suggesting active weather continues. An active pattern
would favor continue heat/humidity while a quieter pattern could
support the intrusion of lower dewpoints and more refreshing
conditions.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
Thunderstorms ahead of a slow-moving cold front will continue
to impact the central Pennsylvania airspace over the next couple
of hours, with highest confidence in impacts along a north-
south line extending from UNV to HGR and areas east.
Thunderstorms will bring about localized drops in visibility
with heavy rainfall and frequent lightning near UNV from 18Z-20Z
Tue, MDT/LNS between 19Z-23Z Tue, with lower probabilities of
thunderstorm impacts at airfields at AOO (closer to cold front;
however, non-zero chance from 18Z-19Z) and IPT (best instability
further south; however, non-zero chance between 19Z-21Z). The
most recent guidance does show fair agreement in thunderstorm
potential; however, main difference in timing with regards to
precipitation as the cold front continues to progress eastward
this evening.

In the wake of the cold front, areas that have received locally
heavy rainfall this evening will have higher potential for fog
and widespread visibility restrictions overnight. At this time,
have progged AOO/UNV towards LIFR conditions overnight; however,
model guidance indicates some potential at all airfields except
for MDT/LNS. Have stuck with guidance trends; however, will
have to continue to monitor trends at MDT/LNS with heavy
rainfall and fog potential overnight.

After sunrise on Wednesday (12Z Wed - 18Z Wed), model guidance
shows fair agreement with respect to restrictions being lifted
by 12Z for most airfields. The 18Z TAF package does set the goal
post slightly wider, with widespread restrictions lifting
closer to 13-14Z give some lingering low-level moisture in RAP
model soundings.

Outlook...

Wed...Best chance for storms and restrictions in southern PA.

Thu-Sun...Potential for showers and thunderstorms, mainly
aftn/eve.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Flood Watch until midnight EDT tonight for PAZ057-059-065-066.

&&

$$

SYNOPSIS...Steinbugl/Colbert
NEAR TERM...Steinbugl/Colbert
SHORT TERM...Steinbugl/Colbert
LONG TERM...Lambert/Colbert
AVIATION...NPB