735
FXUS61 KPBZ 310029
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
829 PM EDT SUN AUG 30 2026
WHAT HAS CHANGED
MORE SOUTHERN TRACKING OF MID-LEVEL SHORTWAVES HAS RESULTED IN
HIGHER CHANCES FOR GENERALLY LIGHT RAIN SHOWERS OVERNIGHT
TONIGHT INTO MONDAY. THE ADDITIONAL CLOUD COVER LIKELY MEANS
TEMPERATURE UNDER PERFORMS PREVIOUS MODEL CONSENSUS, THUS
MONDAY HIGHS HAVE BEEN TRENDED TOWARD LOWER END OF GUIDANCE.
KEY MESSAGES
1) AXIS OF MID-LEVEL MOISTURE OFFERS LOWER PROBABILITY RAIN PLUS
EXTRA CLOUD COVER THROUGH MONDAY.
2) HEAT RISKS INCREASE THROUGH MID-WEEK.
3) DEPENDENT ON UPSTREAM STORM OUTCOMES, SEVERE STORMS COULD
DEVELOP TUESDAY THROUGH THE REST OF THE WEEK.
DISCUSSION
KEY MESSAGE 1...
IDENTIFICATION OF A MID-LEVEL VORT MAX MOVING OVER THE REGION
NOW PLUS A SECOND ONE TRAILING IN NORTHERN IL HAS RESULTED IN
FAR GREATER CLOUD COVERAGE AND LIGHT RAIN SHOWERS THIS EVENING.
WHILE THE FOCUS OF BOTH REMAINS ALONG THE I-80 CORRIDOR, LIGHT
RAIN/SPRINKLES COULD REACH AS FAR SOUTH AS THE I-68 CORRIDOR
THROUGH MONDAY. THIS NEWER IDEAL IS BOLSTERED BY THE 00Z
SOUNDING SHOWING A NEARLY SATURATED 750MB-300MB LAYER OVER A
MARGINALLY DRY SUB-750MB LAYER, MEANING RAIN WITH SHORTWAVE
PASSAGES (BUT ACCUMULATIONS ARE GENERALLY LESS THAN 0.10").
PREVIOUS FORECASTS STRUGGLED CAPTURING THIS IN POP DUE TO
TIMING/SPATIAL COVERAGE/AMOUNTS THAT, BY NOT OVERLAPPING WITHIN
A 1 HOUR TIMEFRAME, SUPPRESSED PROBABILITIES. EXAMINATION OF 6
HR PROBABILITIES OF GREATER THAN 0.01" (MEASURABLE RAIN) BETTER
SHOWS THE RAIN POTENTIAL AS PERCENTAGES RANGE FROM AROUND 20% TO
UPWARDS OF 80%.
THE SIDE EFFECT OF THESE CLOUDS/SHOWERS IS THE POTENTIAL
SUPPRESSION OF HEATING FOR MONDAY. 18Z HI- RES MODEL DATA
HIGHLIGHTS THE LACK OF STRONG 700MB DRY ADVECTION (ASSOCIATED
WITH THE RIDGE AXIS) UNTIL NEAR SUNSET MONDAY THAT WOULD BE
NEEDED TO CREATE CLEARER/LONGER CLOUD-FREE WINDOWS. THIS MEANS
THE PREVIOUSLY DISCUSSED HEAT RISK STARTING MONDAY IS TRENDING
LESS LIKELY AND IS FULLY CONTINGENT ON PROLONGED BREAKS WITHIN
THE MID TO HIGH LEVEL CLOUDS TO MANIFEST.
KEY MESSAGE 2...
WHILE CONFIDENCE HAS DROPPED WITH RESPECT TO HEAT FOR MONDAY, IT
REMAINS HIGH FOR THOSE HOT AND HUMID CONDITIONS TO RETURN
BY TUESDAY AND PERSIST THROUGH MID- WEEK AS A RIDGE AXIS BUILDS
ACROSS THE GREAT LAKES OVER THE NEXT 24 HOURS. AS A RESULT,
TEMPERATURES WILL CLIMB INTO THE UPPER-80S AND LOW-90S ACROSS
THE REGION, WITH AT LEAST THREE CONSECUTIVE DAYS OF HOT AND
HUMID WEATHER EXPECTED THROUGH WEDNESDAY. THE PROBABILITY OF
TEMPERATURES REACHING THE LOW-90S RANGES FROM 40-90% DURING THIS
TIME PERIOD, WITH PROBABILITIES TRENDING HIGHER ESPECIALLY ON
WEDNESDAY.
OVERNIGHT TEMPERATURES WILL PROVIDE LITTLE RELIEF, WITH LOWS
GENERALLY REMAINING IN THE UPPER-60S AND LOW-70S. THIS
COMBINATION OF WARM DAYTIME TEMPERATURES AND LIMITED OVERNIGHT
COOLING WILL CONTRIBUTE TO INCREASING HEAT STRESS.
KEY MESSAGE 3...
SUBTLE VARIATIONS IN SHORTWAVE POSITIONING CAUSING ALTERATIONS
IN EXPECTED CONDITIONS TONIGHT INTO MONDAY WILL CONTINUE TO
LEAVE THE MID TO LATE WEEK PERIOD IN FLUX IN RELATION TO
TIMING/COVERAGE/INTENSITY OF POTENTIAL SHOWERS AND
THUNDERSTORMS. BROADLY, THESE WAVES WILL SLOWLY SHIFT THE UPPER
RIDGE SOUTHWARD WHILE TRAVERSING AN INCREASINGLY WARM AND HUMID
ENVIRONMENT. LATEST NBM MEAN SBCAPE VALUES DURING PEAK AFTERNOON
HEATING HOVERS ANYWHERE FROM 1000-2500 J/KG STARTING TUESDAY
THROUGH FRIDAY. THIS BASIC MEASURE OF STORM-AVAILABLE ENERGY
SUGGESTS THAT A MULTI-DAY SEVERE HAZARD RISK CAN'T BE RULED OUT,
WHICH SPC HAS BEGUN NOTING WITH A MARGINAL RISK HIGHLIGHT FOR
TUESDAY, 15% PROB SEVERE OUTLOOK FOR WEDNESDAY/THURSDAY, PLUS
ADDITIONAL DISCUSSION POINTS INTO FRIDAY.
TO RESTATE THE TOP POINT, WHILE SEVERE HAZARD RISKS ARE POSSIBLE
THROUGH MUCH OF THE UPCOMING WEEK, KEY DETAILS ABOUT
COVERAGE/TIMING AS WELL AS INFLUENCES FROM PRIOR CONVECTIVE
EVOLUTION MAY BE DIFFICULT TO DISCERN UNTIL THE MORNING OF (OR
POTENTIALLY EVEN 6-12 HOURS BEFORE). THE BEST ADVICE IS TO BE
AWARE OF THE POTENTIAL AND FOLLOW FORECAST DISCUSSIONS IN THE
COMING DAYS TO GET A SENSE FOR WHERE TRENDS RAISE OR LOWER THE
SEVERE RISK FOR A GIVEN DAY.
AVIATION /00Z MONDAY THROUGH FRIDAY/
INCREASING MID AND HIGH CLOUDS EXPECTED OVERNIGHT ALONG WITH
SOME OCCASIONAL LIGHT SHOWERS OR SPRINKLES MAINLY NORTH OF I-70.
NO RESTRICTIONS ARE ANTICIPATED WITH THIS ACTIVITY, ASIDE FROM A
BRIEF PERIOD OF LOWER CIGS AT FKL/DUJ TOWARDS SUNRISE MONDAY
WHICH GUIDANCE IS SUGGESTING COULD BE POSSIBLE (THOUGH LOW
PROBABILITY). SHOWERS TAPER OFF MONDAY MORNING, GIVING WAY TO
CONTINUED MID-LEVEL CLOUDS WITH VFR CEILINGS AND GENERALLY LIGHT
WINDS ACROSS THE AREA.
OUTLOOK...
GENERAL VFR IS EXPECTED FOR MUCH OF THE AREA THROUGH MID WEEK
UNDER A BUILDING RIDGE. AREAS MAINLY NORTH OF PIT COULD SEE A
FEW SHOWERS OR THUNDERSTORMS TUESDAY INTO TUESDAY NIGHT AS A
WAVE SKIRTS PAST THE AREA TO THE NORTH. THE RIDGE SHOULD BREAK
DOWN LATER WEDNESDAY AND THURSDAY, WITH SHOWER AND THUNDERSTORM
CHANCES INCREASING ACROSS THE REGION WITH A CROSSING SHORTWAVE
TROUGH IN NW FLOW ALOFT.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...WM/HEFFERAN/FRAZIER
AVIATION...CERMAK
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