256
FXUS61 KCTP 031135
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
735 AM EDT THU SEP 3 2026
WHAT HAS CHANGED
* ISSUED A FLASH FLOOD WATCH FOR ALL OF OUR CWA THROUGH MIDNIGHT
THIS THURSDAY NIGHT.
KEY MESSAGES
1) LATE SUMMER SURGE OF HEAT AND HUMIDITY CONTINUES WITH A
SEVERE THUNDERSTORM AND EXCESSIVE RAINFALL THREAT THROUGH
THIS THURSDAY EVENING
DISCUSSION
KEY MESSAGE 1: LATE SUMMER SURGE OF HEAT AND HUMIDITY CONTINUES WITH A
SEVERE THUNDERSTORM AND EXCESSIVE RAINFALL THREAT THROUGH
THIS THURSDAY EVENING
MAIN CHANGE THIS FORECAST CYCLE WAS TO ISSUE A FLASH FLOOD
WATCH FOR THE ENTIRE CWA BASED ON THE CURRENT WIDE DISTRIBUTION
OF MODERATE TO HEAVY RAIN AND EMBEDDED/TRAINING TSRA ALONG WITH
A HREF/NAM/MRMS BLEND OF SHORT RANGE MODEL GUIDANCE AND REMOTE
SENSING.
A SEEMINGLY ENDLESS TRAIN OF MID/UPPER LEVEL IMPULSES RIDING ESE
ALONG THE SOUTHERN EDGE OF A PERSISTENT JET AND WITHIN A REGION
OF BROAD UPPER LEVEL DIFFLUENCE AND ANOMALOUSLY HIGH PWATS OF
NEARLY 2 INCHES WILL CONTINUE TO INTERACT WITH NUMEROUS,
CONVERGING CONVECTIVE OUTFLOW BOUNDARIES TO PRODUCE SEVERAL MORE
BOUTS OF HEAVY SHOWERS/TSRA TODAY THROUGH AT LEAST EARLY
TONIGHT.
BASIN "AVERAGE" RAINFALL ACROSS THE CWA WILL LIKELY RANGE
BETWEEN 0.75 TO 1.25 INCHES BUT AS WE SAW WED/WEDNESDAY NIGHT,
TRAINING/AND BACK-BUILDING TSRA COULD EASILY DUMP OVER 3 INCHES
OF RAIN IN JUST AN HOUR AND LEAD TO SIGNIFICANT FLASH FLOODING.
THE TARGET AREAS FOR THE HEAVIEST RAINFALL TODAY AND THIS
EVENING SHOULD BE THE SOUTHWEST HALF OF THE CWA AS A WELL-
DEFINED OUTFLOW BOUNDARY HAS PUSHED INTO SOUTHERN PA EARLY
TODAY. WE DO EXPECT THE AIRMASS TO RECOVER QUICKLY LATE THIS
MORNING/EARLY THIS AFTERNOON AS THIS FIRST MCS MOVES SE.
HOWEVER, A GLANCE JUST TO THE LEFT SHOWS ANOTHER DEVELOPING MCS
CLOSE ON ITS HEELS OVER WEST-CENTRAL LAKE ERIE. THIS FEATURE IS
PROGGED BY HIGH RES NEAR TERM MODEL GUIDANCE TO TRACK SE TWD
THE LAUREL AND DIMINISH BY 14-15Z. BY 19-20Z TODAY, MORE TSRA
FIRE ACROSS NORTHERN PA AND A SECOND LARGER AREA
FOLLOWS FOR THIS EVENING OVER A SIMILAR PART OF THE STATE THAT
EXPERIENCE THE HEAVY RAIN OVER THE PAST 24 HOURS.
ADDITIONALLY, INCREASED SOUTHWEST TO WESTERLY FLOW TODAY WILL
CONTINUE TO PUMP IN THE LATE SUMMER HEAT AND VERY HIGH
DEWPOINTS. A HEAT ADVISORY REMAINS IN EFFECT FROM 11A-8P
THURSDAY ACROSS A PORTION OF SOUTH CENTRAL PA WHERE MAX HEAT
INDEX VALUES ARE PROJECTED TO REACH/EXCEED 100F.
AS MENTIONED ABOVE, SPC'S SEVERE RISK ARE WILL ENCOMPASS
PRIMARILY THE SW HALF OF THE STATE WHERE ML CAPE WILL BE THE
HIGHEST, BUT THE MRGL RISK AREA WILL COVER PRACTICALLY THE
ENTIRE REST OF EASTERN PA.
AN UPPER LEVEL TROUGH PASSAGE FAVORS ONE FINAL ROUND OF SHOWERS
AND STORMS ON FRIDAY, BUT FORTUNATELY THE LABOR DAY WEEKEND IS
TRENDING DRY. THE UPPER RIDGE IS FORECAST TO RETROGRADE BY THE
END OF THE WEEK WHICH ALLOWS FOR A RETURN TO MORE SEASONAL
TEMPERATURES AND LOWER HUMIDITY THIS WEEKEND INTO EARLY NEXT
WEEK.
AVIATION /12Z THURSDAY THROUGH MONDAY/
HIGHLY VARIABLE FLYING CONDITIONS EXPECTED EARLY TODAY AND
AGAIN LATE IN THE DAY AND TONIGHT AS A FEW MORE DISTINCT, MID
AND UPPER LEVEL DISTURBANCES FUEL THE DEVELOPMENT OF SHOWERS AND
THUNDERSTORMS.
THE SE HALF OF THE CWA WILL SEE A 2-3 HOUR PERIOD OF IMPROVEMENT
THROUGH THE MID/LATE MORNING HOURS BEFORE ANOTHER FAST-MOVING
AREA OF NEW TSRA IMPACTS MUCH OF THE SOUTHERN HALF OF PA THROUGH
16Z WITH CONDITIONS DIPPING INTO THE MVFR RANGE.
MAINLY VFR WILL RETURN FOR MUCH OF THE 16Z TO 20Z PERIOD BEFORE
THE HEAT AND HUMIDITY AND INTERACTIONS OF OUTFLOW BOUNDARIES
HELPS TO FIRE UP NEW CONVECTION THAT EXPANDS AND CONTINUE
THROUGH EARLY TONIGHT WITH PERIODS OF POOR FLYING CONDITIONS AND
BRIEF, DANGEROUS LLWS CAUSED BY CONVECTIVE UPDRAFTS AND WET
MICROBURSTS.
THE EXACT TIMING OF WHEN EXACTLY ANY OF THIS SCATTERED ACTIVITY
COULD IMPACT A SITE REMAINS A BIT UNCERTAIN.
OUTLOOK...
THU...SCATTERED-NUMEROUS SHRA/TSRA WITH BRIEF RESTRICTIONS
POSSIBLE; MORNING FOG.
FRI...SCATTERED SHRA/TSRA SW. VFR ELSEWHERE AFTER MORNING FOG.
SAT-MON...VFR FAVORED; MORNING FOG POSSIBLE.
CTP WATCHES/WARNINGS/ADVISORIES
FLOOD WATCH THROUGH THIS EVENING FOR PAZ004>006-010>012-
017>019-024>028-033>037-041-042-045-046-049>053-056>059-
063>066.
HEAT ADVISORY FROM 11 AM THIS MORNING TO 8 PM EDT THIS EVENING
FOR PAZ026>028-035-036-056-057-059-063>066.
WHAT HAS CHANGED...LAMBERT
KEY MESSAGES...LAMBERT
DISCUSSION...LAMBERT
AVIATION...LAMBERT
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