796
FXUS61 KPBZ 311815
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
215 PM EDT FRI JUL 31 2026
WHAT HAS CHANGED
NO SIGNIFICANT CHANGES WERE MADE TO THE FORECAST.
KEY MESSAGES
1) CONTINUED DRY THROUGH PART OF SATURDAY
2) SHOWERS AND THUNDERSTORMS RETURN LATE SATURDAY AND SUNDAY,
WITH UNSETTLED WEATHER NEXT WEEK.
DISCUSSION
KEY MESSAGE 1...
DRY WEATHER IS EXPECTED THROUGH AT LEAST EARLY SATURDAY AS HIGH
PRESSURE MOVES EAST ACROSS THE REGION. RISING 500 MB HEIGHTS UNDER
SHORTWAVE RIDGING SHOULD RESULT IN HIGH TEMPERATURES TO SLIGHTLY
ABOVE SEASONABLE LEVELS TODAY. A DIGGING SHORTWAVE TROUGH IS
EXPECTED TO BEGIN TO ADVANCE OUT OF THE MIDWEST TONIGHT INTO
SATURDAY. EXPECT AN INCREASE IN MID AND HIGH LEVEL CLOUDS TONIGHT
THROUGH SATURDAY MORNING IN ADVANCE OF THE TROUGH.
KEY MESSAGE 2...
THE SHORTWAVE TROUGH IS EXPECTED TO CONTINUE TO DEEPEN AS IT TRACKS
TOWARD THE UPPER OHIO VALLEY REGION LATE SATURDAY AND SUNDAY. AT THE
SAME TIME, AN ASSOCIATED SURFACE LOW IS PROGGED TO TRACK NE ACROSS
THE UPPER OHIO VALLEY/EASTERN GREAT LAKES REGION. INCREASING
MOISTURE AND ASCENT WITH AN INITIAL LEAD SHORTWAVE SHOULD RETURN
SHOWER AND THUNDERSTORM CHANCES SATURDAY AFTERNOON ACROSS OHIO,
OVERSPREADING THE REMAINDER OF THE AREA SATURDAY NIGHT.
PERIODS OF SHOWERS AND SCATTERED THUNDERSTORMS ARE EXPECTED ON
SUNDAY AS THE MAIN TROUGH AXIS APPROACHES, AND THE SURFACE LOW
TRACKS ACROSS THE REGION. CLOUDS COULD LIMIT INSTABILITY, WITH
ML CAPE CURRENTLY PROGGED AT 1000 J/KG OR LESS, HOWEVER, THERE
IS INCREASED AMOUNT OF VERTICAL WIND SHEAR (UP TO 30KTS).
CURRENT MODEL RUNS ARE HINTING AT THE CHANCE FOR DRY SLOTS TO
DEVELOP IN BETWEEN PERIODS OF RAIN ON SUNDAY. IF THESE DRY
PERIODS ARE ACCOMPANIED BY SOME CLEARING, THERE WOULD BE AN
INCREASE IN CAPE WHICH COMBINED WITH 30KTS OF VERTICAL WIND
SHEAR WOULD IMPROVE THE PROBABILITY FOR SEVERE WEATHER TO
DEVELOP.
LOCALLY HEAVY RAIN WILL ALSO BE POSSIBLE AS PWATS APPROACH 1.8
INCHES, THOUGH THE POTENTIAL DRY SLOT SUNDAY AFTERNOON AHEAD OF
THE SURFACE LOW COULD LIMIT THIS POTENTIAL. THE SURFACE COLD
FRONT IS CURRENTLY EXPECTED TO CROSS THE AREA LATE SUNDAY/SUNDAY
NIGHT.
MODEL ENSEMBLES THEN INDICATE A PERSISTENT TROUGH ACROSS THE
EASTERN GREAT LAKES AND OHIO VALLEY REGION EARLY IN THE WEEK.
THIS TROUGH SHOULD WEAKEN SOME THROUGH THE WEEK, THOUGH
SIGNIFICANT UNCERTAINTY EXISTS IN EXACT PLACEMENT AND STRENGTH.
OVERALL, EXPECT DAILY, DIURNALLY DRIVEN SHOWER AND THUNDERSTORM
CHANCES UNDER THIS PATTERN.
AVIATION /18Z FRIDAY THROUGH WEDNESDAY/
HIGH CONFIDENCE VFR CONTINUES THROUGH THE TAF PERIOD AS SURFACE HIGH
PRESSURE SLIDES EAST ACROSS THE REGION. SCANT BOUNDARY LAYER
MOISTURE WILL PRECLUDE MORE THAN A FEW DIURNAL CUMULUS CLOUDS
THIS AFTERNOON GIVING WAY TO INCREASING HIGH CLOUDS LATER
TODAY/TONIGHT AHEAD OF THE NEXT APPROACHING SHORTWAVE TROUGH.
WIND WILL BE LIGHT AT 5 KNOTS OR LESS.
EXPECT CLOUDS TO THICKEN AND LOWER INTO THE DAYTIME HOURS ON
SATURDAY AS THE COLUMN SATURATES. RAIN WILL APPROACH FROM THE
WEST IN THE LATE EVENING HOURS WITH CURRENT MOST LIKELY ARRIVAL
TIME TO PIT AMONG REFS MEMBERS AFTER 3AM, THOUGH NOTABLE UNCERTAINTY
STILL EXISTS WITH DISTRIBUTION AS WIDE AS AN ARRIVAL TIME
AROUND MIDNIGHT AND AS LATE AS DAYBREAK.
OUTLOOK...
A LINGERING TROUGH COULD MAINTAIN RESTRICTION POTENTIAL MONDAY
AND TUESDAY WITH SHOWER/THUNDERSTORM CHANCES, THOUGH MUCH TIMING
UNCERTAINTY ARISES INTO EARLY NEXT WEEK WITH EVOLUTION OF THE
TROUGH.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...WM/LUPO
AVIATION...MLB
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