557
FXUS61 KPBZ 312307
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
707 PM EDT MON AUG 31 2026
WHAT HAS CHANGED
WITH INCREASED AND PERSISTENT CLOUD COVER IN SOME AREAS, HIGH
TEMPERATURES WILL LIKELY BE IN THE LOW 80S WHILE THOSE IN
CLEARINGS WILL LIKELY SEE TEMPERATURES IN THE UPPER 80S. ADJUSTED
POPS HIGHER TUESDAY AND WEDNESDAY FOR POSSIBLE SHOWERS AND
THUNDERSTORMS. UPDATED FOR THE 00Z TAF ISSUANCE.
KEY MESSAGES
1) ADDITIONAL SHOWER AND THUNDERSTORM CHANCES AT TIMES THROUGH
LATE WEEK, WITH SOME POSSIBILITY FOR SEVERE STORMS.
2) HEAT AND HUMIDITY BUILD THROUGH MID WEEK
DISCUSSION
KEY MESSAGE 1...
A RIDGE IS EXPECTED TO BUILD EASTWARD FROM THE CENTRAL CONUS
THROUGH MID WEEK. THE HIGHEST 500MB HEIGHTS ARE PROGGED TO BE
ACROSS THE LOWER OHIO VALLEY REGION ON WEDNESDAY. AS THE RIDGE
BUILDS EASTWARD, SHORTWAVES ARE EXPECTED TO TRACK ALONG THE
NORTHERN/NORTHEASTERN PERIPHERY OF THE RIDGE, CROSSING THE LOWER
GREAT LAKES/UPPER OHIO VALLEY REGION. OCCASIONAL SHOWER AND
THUNDERSTORM CHANCES ARE EXPECTED AS THESE WAVES CROSS, ONE
TONIGHT (MAINLY NORTH OF THE FORECAST AREA,) WITH ANOTHER
POSSIBLE LATER TUESDAY. THERE REMAINS UNCERTAINTY IN THE
PLACEMENT AND STRENGTH OF THE RIDGE, AND THE RESULTING TRACK OF
ANY SHORTWAVES ON THE NORTHERN PERIPHERY.
THERE IS A CONDITIONAL POTENTIAL FOR SEVERE STORMS ON TUESDAY.
ML CAPE INCREASES TO BETWEEN 2000 AND 3000 J/KG BY LATE
AFTERNOON, WITH VEERING IN THE LOW LEVELS. AN INITIAL WARM
LAYER ALOFT COULD LIMIT CONVECTION, THOUGH A POSSIBLE SHORTWAVE
PASSAGE IN THE AFTERNOON COULD TRIGGER THUNDERSTORMS. THIS
SCENARIO REMAINS UNCERTAIN DUE TO THE REASONS MENTIONED ABOVE,
THOUGH IF STORMS ARE ABLE TO DEVELOP SEVERE WEATHER WILL BE
POSSIBLE.
THE DAY WITH THE LOWEST POTENTIAL FOR SHOWERS AND THUNDERSTORMS
APPEARS TO BE WEDNESDAY, WHEN THE RIDGE IS PROGGED TO BE THE
STRONGEST ACROSS THE OHIO VALLEY REGION. CURRENT INDICATIONS
ARE THE RIDGE SHOULD BEGIN TO BREAK DOWN LATE WEDNESDAY AND
THURSDAY, AS A SHORTWAVE AND SURFACE COLD FRONT APPROACHING. THE
POTENTIAL FOR SEVERE STORMS WILL ALSO INCREASE BY WEDNESDAY
EVENING, INCREASING AGAIN ON THURSDAY AS CONVECTION INCREASES IN
DIURNAL HEATING ALONG THE SLOW MOVING FRONT. INCREASING NW FLOW
ALOFT SHOULD RESULT IN INCREASED SHEAR AND DIURNAL INSTABILITY.
THE POTENTIAL CONTINUES FOR SEVERE STORMS INTO THURSDAY. THE
LATEST ML GUIDANCE INDICATES THE INCREASING SEVERE POTENTIAL,
ESPECIALLY LATE WEDNESDAY AND THURSDAY. DEPENDING ON HOW FAST
THE FRONT DRIFTS SOUTH, THIS POTENTIAL COULD CONTINUE FOR AT
LEAST SOUTHERN PORTIONS OF THE AREA INTO FRIDAY. DRY WEATHER
SHOULD RETURN BY THE WEEKEND AS THE FRONT EXITS AND HIGH
PRESSURE BUILDS IN.
KEY MESSAGE 2...
RISING 500MB HEIGHTS WITH THE BUILDING RIDGE SHOULD RESULT IN
WARMER TEMPERATURES EACH DAY THROUGH MID WEEK, WITH THE HEAT
PEAKING WEDNESDAY WHEN THE RIDGE IS STRONGEST ACROSS THE UPPER
OHIO VALLEY REGION. MOST LOCATIONS OUTSIDE OF THE HIGHER TERRAIN
SHOULD REACH THE 85 TO 90 DEGREE RANGE ON TUESDAY, THOUGH THERE
IS A CONTINUED POTENTIAL FOR CONVECTION AND/OR PATCHY CLOUD
COVER WHICH COULD AFFECT DAYTIME HIGHS. THE HEAT SHOULD PEAK
WEDNESDAY, AS HIGHS IN THE UPPER 80S TO LOWER 90S FOR MOST
AREAS. THE COMBINATION OF HEAT AND HUMIDITY SHOULD RESULT IN
HEAT INDEX VALUES IN THE MID TO UPPER 90S TUESDAY AND WEDNESDAY.
AVIATION /00Z TUESDAY THROUGH SATURDAY/
VFR WITH VARYING MID TO HIGH LEVEL BKN/OVC DECKS CONTINUE INTO
THE EVENING AND OVERNIGHT HOURS. ANOTHER ROUND OF MAINLY VFR
SHOWERS ARE CROSSING INTO OH FROM MI. CLOUD TOPS ARE ALREADY TO
BEGINNING TO WARM IN THESE SHOWERS AS THEY ARE ABOUT 3-4 HOURS
FROM OUR PORTS. THERE IS LITTLE TO SPARK MORE VIGOROUS GROWTH IN
THESE SHOWERS BUT PROB30 GROUPS HAVE BEEN INTRODUCED IN THE
04-08Z TIMEFRAME FOR THESE SHOWERS. EVENTUALLY AN UPGRADE TO
TEMPO OR PREVAILING MAY BE IN ORDER BUT GIVEN A WEAKENING TREND
ON RADAR AND WARMING CLOUD TOPS WE WILL HOLD THE LINE AT LOWER
CHANCES FOR NOW.
PROGRESSION OF EMBEDDED SHORTWAVES, THAT AREN'T WELL MODELED,
MAY CONTINUE OVERNIGHT INTO TUESDAY MORNING AND RESULT IN
ISOLATED/SCATTERED SHOWERS AND LOWER PROBABILITY THUNDERSTORMS
IF/WHEN THEY CROSS THE AREA. TIMING OF THESE WAVES AND THE
RESULTANT COVERAGE (OR POTENTIAL LACK THEREOF) REMAINS VERY
DIFFICULT, PREVENTING MUCH MENTION IN TAFS. BE PREPARED FOR
NEAR-TERM AMENDMENTS ADDING SHOWER/THUNDERSTORM MENTIONS
IF/WHEN CONFIDENCE IN OCCURRENCE INCREASES. AT THIS TIME PROB30
GROUPS HAVE BEEN MAINTAINED FOR MANY PORTS FOR THE MORNING
HOURS FROM STORM ACTIVITY CURRENTLY ACROSS THE MIDWEST.
OUTLOOK...
DURING NON-CONVECTIVE PERIODS WITH NO PRIOR RAIN OCCURRENCE, VFR
IS LIKELY UNDER THE INFLUENCE OF RIDGING TO THE SOUTHWEST.
SHORTWAVE MOVEMENT ALONG THE NORTHERN PERIPHERY OF THE RIDGE
COULD CREATE SHORT PERIODS THROUGH THE WEEK WHERE
SHOWERS/THUNDERSTORMS MAY OCCUR. DUE TO DIFFICULTIES MODELING
THESE FEATURES, TIMING/COVERAGE OF STORM POTENTIAL MAY BE
DIFFICULT UNTIL 6-12 HOURS BEFORE ARRIVAL AND CAUSE LARGER-
THAN-NORMAL FLUCTUATIONS IN TAF STORM TIMING. ADDITIONALLY,
STORM ENVIRONMENTS MAY BE CONDUCIVE TO GUSTY, ERRATIC WINDS PLUS
HEAVY DOWNPOURS THAT COULD CONTRIBUTE TO RESTRICTION
DEVELOPMENT.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...WM/LUPO
AVIATION...FRAZIER/AK
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