761
FXUS61 KPBZ 241723
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
123 PM EDT FRI JUL 24 2026
WHAT HAS CHANGED
FEW CHANGES FOR THE LONG-RANGE FORECAST.
KEY MESSAGES
1) THE HIGHEST CHANCE OF SEVERE WEATHER OVER THE NEXT WEEK
OCCURS ON MONDAY AND TUESDAY WITH INCREASED POTENTIAL FOR
MESOSCALE CONVECTIVE SYSTEMS (MCSS).
DISCUSSION
KEY MESSAGE 1...
A WEAK MID-LEVEL SHORTWAVE TROUGH MAY DROP ACROSS THE AREA THIS
EVENING, IN AN ENVIRONMENT WHERE EVEN THE "HIGH-END" CAPE WILL
BE A COUPLE HUNDRED J/KG. GIVEN THE WEAK FORCING AND LOW
INSTABILITY, A FEW SHOWERS AND STORM DAY DEVELOP, THOUGH SEVERE
THREATS ARE NOT ANTICIPATED. THE SAME CAN GENERALLY BE SAID FOR
SATURDAY AFTERNOON, THOUGH CAPE MAY BE A BIT HIGHER (UP TO 1000
J/KG), THOUGH DRY AIR ALOFT AND A SUBSIDENCE INVERSION FAVORS
KEEPING CONVECTION SHALLOW. SPC AND ML OUTLOOKS TO NOT FAVOR
SEVERE DEVELOPMENT.
SUNDAY, ONLY A LOW CHANCE FOR SEVERE WEATHER EXISTS. MID LEVEL
FLOW AND ORGANIZED STORMS FAVORS TRACKS OVER THE MIDWEST TO
WEST-CENTRAL OHIO. THE POTENTIAL OF STORMS ONLY EXISTS ON SOME
LAKE BOUNDARY OR OUTFLOW, BUT EVEN THEN SFC-6KM FLOW IS QUITE
SLOW (>20KTS), AND DCAPE DECREASES AS MOISTURE RETURNS WITH LREF
50TH PERCENTILE DCAPE ~600 J/KG, ASSUMING A PARCEL MAXIMIZES
ITS POTENTIAL. IF ANYTHING, THIS WOULD ALLUDE TO A MARGINAL
FLOOD THREAT. THAT BEING SAID, IF SUBSTANTIAL UPPER LEVEL WIND
FORECASTS CHANGE, RESULTING IN INCREASING MCS POTENTIAL TO THE
EAST OF THE CURRENT FORECAST, OUR CHANCES WOULD GO UP LOCALLY.
THE POTENTIAL FOR WIDESPREAD STRONG TO SEVERE STORMS BECOMES
MORE FAVORABLE MONDAY INTO TUESDAY AS THE RIDGE OVER THE
NORTHERN GREAT LAKES WEAKENS, OPENING THE DOOR FOR UPSTREAM MCSS
TO PROPAGATE INTO THE REGION OR THAT REMNANT OUTFLOW BOUNDARIES
OF DECAYING MCSS REDEVELOPMENT DURING PEAK HEATING. IF
MESOSCALE CONVECTIVE SYSTEMS (MCSS) DO DEVELOP AND TRACK INTO
OUR REGION, FORECAST SOUNDINGS INDICATE AN ENVIRONMENT CAPABLE
OF SUPPORTING ALL SEVERE WEATHER HAZARDS, INCLUDING HAIL,
DAMAGING WIND GUSTS, TORNADOES, AND HEAVY RAINFALL. AND MOST
IMPORTANTLY, THERE IS LOW CONFIDENCE IN WHEN IF IF THESE SHOULD
OCCUR LOCALLY.
NCAR MACHINE-LEARNING GUIDANCE HAS A 5-10% OF SEVERE WEATHER
OVER OUR REGION ON SUNDAY; 15 TO 45% CHANCE FOR MONDAY AND
TUESDAY. COLORADO STATE UNIVERSITY (CSU) MACHINE LEARNING HAS
5-15% CHANCE OF EXCESSIVE RAINFALL (FLASH FLOODING) MONDAY INTO
TUESDAY. THE WEATHER PREDICTION CENTER HAS ISSUED "MARGINAL" (1
OUT OF 4) RISKS FOR BACK-TO-BACK DAYS.
THE EVENTUAL EVOLUTION OF THIS THREAT WILL LARGELY DEPEND ON
THE AMPLITUDE OF THE EASTERN U.S. TROUGH AND THE STRENGTH AND
POSITION OF THE UPPER- LEVEL RIDGE, WHICH WILL INFLUENCE THE
TRACK AND INTENSITY OF ANY MCSS.
THE THREAT FOR SEVERE STORMS AND PRECIPITATION IS EXPECTED TO
REMAIN LOW WEDNESDAY INTO THURSDAY IN THE WAKE OF A DEPARTING
COLD FRONT AND BUILDING HIGH PRESSURE.
AVIATION /18Z FRIDAY THROUGH WEDNESDAY/
VFR CONDITIONS WILL CONTINUE TO PREVAIL THROUGH TOMORROW
MORNING UNDER HIGH PRESSURE. SOME LINGERING CIRRUS CLOUDS
FORECAST TO PERSIST THROUGH THE DAY WITH A SCATTERED CU FIELD
LIKELY BETWEEN 6-8 KFT.
TONIGHT, HIGH CLOUDS ARE EXPECTED TO LINGERING. THIS WILL LIMIT
NIGHTTIME RADIATIONAL COOLING AND INHIBIT THE DEVELOPMENT OF FOG
TOMORROW MORNING. DURING LATE MORNING/EARLY AFTERNOON, THERE IS
A SLIGHT CHANCE FOR A POP-UP SHOWER/THUNDERSTORM MAINLY IN
WESTERN PA.
OUTLOOK... SHOWER AND THUNDERSTORM CHANCES RETURN ON SUNDAY AND
MONDAY WITH AN APPROACHING COLD FRONT.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...HEFFERAN/MILCAREK
AVIATION...LUPO
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