-- Discussion containing changed information from previous version are highlighted. --
870
FXUS61 KPBZ 271643
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
1243 PM EDT Fri Jun 27 2025

.SYNOPSIS...
Hot and humid through the end of the week with daily afternoon
storm, isolated flooding, and severe wind chances. Rain chances
decrease Sunday, followed by another active period Monday to
Tuesday before temperatures return to near normal and conditions
trend slightly drier mid-week.

&&

.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:

- Heat concerns continue through the afternoon for most of the
  area, with indices approaching 100F, hottest for valley and
  urban locations
- A marginal chance of severe wind into the afternoon and
  evening with downburst potential, especially in eastern Ohio
- Flood Watch issued for SW PA/northern WV - more isolated
  flooding issues possible in eastern OH
---------------------------------------------------------------

The main change this morning was the issuance of a Flood Watch
four our southwest PA and northern WV counties. The setup for
efficient, heavy rainfall is most apparent in these areas. The
PBZ morning sounding showed just shy of 2 inch precipitable
water values, representing the top end of climatology and a
record high for June 27th. Also, there is potential for
1500-2500 J/kg of mixed- layer CAPE by mid-afternoon, along with
impressive warm-cloud depths and very little shear/storm
motion. HREF neighborhood probabilities of 1"/hr rainfall rates
are highest in PA/WV, and guided placement of the watch,
especially with the rainfall over the past couple of days.
Cannot rule out issues in Ohio as well, but are likely to be
more isolated there. In fact, the threat of downburst wind this
afternoon is higher in that area as opposed to areas to the
east, due to better potential downdraft CAPE values. Outflow
from any such activity may help to enhance local rainfall rates.

Previous discussion...

Heading into the day, the overall pattern still features the
500MB ridge still centered over the Carolinas with return flow
continuing into the Middle Atlantic States. This will once again
set the stage for afternoon thunderstorm development. The
boundary that remains over the north will begin to align along
the ridges to the east.

This will put the Southwest PA and northern WV region in the
warm sector and most and thus in the axis of moisture advection.
This is the reason that a slight risk for excessive rainfall
has been issued along the ridges in PA and south into the WV
ridges. This area has been hit hard over the last 2 days and
will likely mean lower FFG. The NBM probs for 1 inch of rain
over a 24 hour period features some probs over 50% over SW PA
and along the ridges. Here, with the likely lower FFG values,
will expect some issues flooding again. Over to the severe side
of the house, a wind threat across the entire forecast area
seems likely again. In fact, the NBM probs are giving a 80% to
90% prob of SB CAPE values over 1500 J/Kg. This in conjunction
with DCAPE values again today into the 750 to 1000 J/Kg range.
This will lead to another day of downburst potential. Most
convection should initiate today by the 18Z to 20Z timeframe
and will likely go into the evening hours of the day. Another
day of Heat indices over 100 degrees will be likely and thus the
Heat Advisory is in effect for one more day.

Heading into the overnight, will expected some lingering
convection from the evening, but most of the severe threats
should come to an end by the 00Z to 02Z period. A few instances
of flooding may need addressed as well but most of the impacts
should come to an end by 06Z. Some instances of fog development
is expected through the dawn hours as well.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
KEY MESSAGES:

- Downburst wind and flooding threats in the afternoon and
  evening continue on Saturday.
----------------------------------------------------------------

For Saturday, a boundary sinking from the north in a similar
environment will continue to allow for downburst wind and
flooding threats. LREF mean analysis shows 1500 J/kg MLCAPE, 650
DCAPE, and PWATS back up near 1.8" to 1.9" in moisture pooling
along the boundary. Perhaps given the environment and slow
southward sagging boundary, flooding threats may be a bit higher
than days prior, depending on the coverage, with increased
training potential. A lull in convection is expected Saturday
night with the potential of fog development.

The boundary is forecast to sag south on Sunday with ML
techniques suggesting lower probabilities of severe weather, and
any chances of flooding most likely for northern West Virginia
in the vicinity of the boundary. Again, some patchy fog
development is possible Sunday night.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
KEY MESSAGES:

- Potential for storms and locally heavy rainfall through at
  least Monday and possibly on Tuesday.
-------------------------------------------------------------------

For Monday, at least some return flow is expected as the
boundary draws back north. Southwest flow prevails with
increasing precipitation chances yet again as temperature
spreads are mostly encompassed in the upper 80s to low 90s. Once
again, this will allow more wind and flooding threats.

A frontal passage is forecast sometime late Monday into Tuesday
that will maintain flooding chances before a cold front finally
clears the oppressive airmass out with a return to more normal
temperatures and moisture for mid-week. Clusters indicate this
pattern change, at least temporarily, is high confidence.

The Day 6 and 7 period for Wed and Thu highlight the return of
high pressure and a brief break in the constant daily
convection. Temperatures will also return to a more normal value
as well.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
Scattered to numerous showers and thunderstorms are expected to
fire after 18z again today, with localized potential for
restrictions. Most of these are more likely to track along a
line moving from eastern Ohio to western PA/northern WV in the
19Z to 02Z timeframe, but there is a chance of showers and
storms and a brief drop to MVFR vis and variable winds at any
time in the afternoon/evening. The most likely timing will be
covered in a tempo group.

Into tonight, chances of showers and storms decrease and ceilings
will lower from the east Friday night, generally impacting
terminals north and east of PIT in the most saturation and in
proximity to a back- door cold front trapped on the leeward side
of the ridges. More shower and storm chances return tomorrow
afternoon.

Outlook...
More numerous showers and thunderstorms are expected
Saturday afternoon and evening as the front wavers across the
region. There is a lesser potential for afternoon showers/storms
on Sunday as high pressure briefly brushes by to the north.
Showers/storms return again Monday with an approaching cold
front.
-- End Changed Discussion --

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
PA...Heat Advisory until 8 PM EDT this evening for PAZ013-014-
     020>022-029-031-073-075.
     Flood Watch until midnight EDT tonight for PAZ007>009-013>016-
     020>022-029-031-073>078.
OH...Heat Advisory until 8 PM EDT this evening for OHZ039>041-
     048>050-057>059-068-069.
WV...Heat Advisory until 8 PM EDT this evening for WVZ001>004-012-
     021-509-510.
     Flood Watch until midnight EDT tonight for WVZ001>004-012-021-
     509>514.
-- End Changed Discussion --

&&

$$

SYNOPSIS...Shallenberger
NEAR TERM...CL/Shallenberger
SHORT TERM...Shallenberger
LONG TERM...Shallenberger
AVIATION...Milcarek