758
FXUS61 KCTP 020904
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
504 AM EDT THU JUL 2 2026
WHAT HAS CHANGED
* REORGANIZED THE HEAT PRODUCTS/TIMING, MAINLY EXTENDING THINGS
A BIT.
* DAYS 2 AND 3 NOW CARRY A SLIGHT RISK OF SEVERE THUNDERSTORMS
FOR MUCH OF THE CWA.
* DAYS 3, 4 AND 5 ALSO HOLD A MARGINAL RISK FOR EXCESSIVE
RAINFALL/FLOODING.
KEY MESSAGES
1) SIGNIFICANT, LONG DURATION, AND DANGEROUS HEAT WAVE EXPECTED
INTO INDEPENDENCE DAY.
2) A RATHER CONDITIONAL SEVERE WEATHER THREAT WILL EXIST FOR
FRIDAY AFTERNOON INTO SATURDAY NIGHT.
3) A LAZY FRONT OVER THE AREA WILL RESULT IN A MULTI-DAY THREAT
FOR THUNDERSTORMS. THIS COULD LEAD TO FLASH FLOODING OVER THE
WEEKEND AND INTO NEXT WEEK.
DISCUSSION
KEY MESSAGE 1: SIGNIFICANT, LONG DURATION, AND DANGEROUS HEAT
WAVE EXPECTED INTO INDEPENDENCE DAY.
TRIED TO KEEP TEMPS AND DEWPOINTS VERY SIMILAR TO WHAT WE'VE HAD
RUNNING FOR MANY DAYS. HOWEVER, WE DID EXTEND THE HEAT PRODUCTS
OUT IN TIME ON THE WHOLE. THE BIGGEST CHANGE WAS TO UPGRADE THE
LOWER SUSQ TO A WARNING FOR SAT - WHICH BASICALLY JUST EXTENDS
WHAT IS RUNNING RIGHT NOW. WHILE HI VALUES DO LOWER SOME ON SAT
ALL ACROSS THE CWA, THOSE SE ZONES WILL STILL BE CAPABLE OF
HITTING 105 SAT AFTN. THAT HAS LOOKED TO BE THE CASE FOR AT
LEAST A DAY, AND WE'RE NOW MORE CONFIDENT IN THAT OUTCOME.
-------------------------------------------------------
KEY MESSAGE 2: A RATHER CONDITIONAL SEVERE WEATHER THREAT WILL
EXIST FOR FRIDAY AFTERNOON INTO SATURDAY NIGHT.
WE SHOULD BE SUFFICIENTLY CAPPED TODAY (THURS) TO PRECLUDE ALL
BUT THE VERY ISOLATED OF STORMS. WE COULD SEE ONE POP UP NEAR
THE NY BORDER LATE IN THE DAY. BUT, WE'LL LIKELY NOT SEE ANY
DEEP CONVECTION UNTIL LATER TONIGHT WHEN A BIT OF UPPER FORCING
ROLLS W-E ON THE ZONAL FLOW JUST TO OUR N. AS WE WILL STILL BE
UNDER THE INFLUENCE OF THE STRONG UPPER RIDGE, WE MAY NOT BECOME
UNSTABLE ENOUGH AT NIGHT TO POP ANYTHING, BUT SOME
SHOWERS/STORMS MAY SLIDE IN FROM THE NW INTO THE NRN MTNS
OVERNIGHT.
A LOT OF CAPE IS STILL EXPECTED ON FRIDAY DUE TO THE HEAT AND
HUMIDITY, AND THE CAP MAY GET WEAKER THROUGH THE DAY, ESP IN
THE NORTH AS THE RIDGE COULD GET SUPPRESSED TO THE SOUTH
SLIGHTLY. LOTS OF THE GUIDANCE KEEPS THE AREA RAIN-FREE FOR ALL
OF THE DAY ON FRI AND ONLY BRINGS IN SOME CONVECTION FROM THE
WEST FRI NIGHT. THE HI-RES WRF MEMBERS OF THE HREF DO MAKE MORE
DAYTIME CONVECTION THAN THE OTHERS. SPC HAS PLACED ALMOST OUR
ENTIRE AREA IN THE SLIGHT RISK CATEGORY, MAINLY FOR WIND DAMAGE.
HOWEVER, WE'LL HAVE TO WAIT AND SEE JUST HOW MUCH INSTABILITY WE
CAN GENERATE AND FIND SOME LIFT IN ORDER TO OVERCOME THE CINH.
SATURDAY LOOKS SIMILARLY MARGINAL/TENUOUS. THE BEST INSTABILITY
AND SHEAR WILL BE IN THE NRN MTNS IN THE AFTN SAT AND THEN IT
LOOKS BETTER FOR THE SRN HALF OF THE AREA SAT NIGHT.
-------------------------------------------------------
KEY MESSAGE 3: A LAZY FRONT OVER THE AREA WILL RESULT IN A
MULTI-DAY THREAT FOR THUNDERSTORMS. THIS COULD LEAD TO FLASH
FLOODING OVER THE WEEKEND AND INTO NEXT WEEK.
A SLOW-MOVING COLD FRONT COULD LANGUISH OVER OR VERY CLOSE TO
THE STATE OVER THE WEEKEND AND INTO EARLY NEXT WEEK. THE CWA
WILL BE IN THE WARM SECTOR SAT WHEN SCATTERED STRONG/SEVERE
STORMS WILL THREATEN. BUT, THE FRONT WILL THEN DIP INTO PA FROM
THE NORTH AND SHOULD BRING REPEATED BOUTS OF THUNDERSTORMS AND
HEAVY RAIN. THIS IS LOOKING VERY MUCH LIKE A TYPICAL MADDOX
FRONTAL HEAVY RAINFALL SCENARIO WITH THE FRONT DRAPED W-E AND
AMPLE MOISTURE FLOWING IN FROM THE S/SW. AN UPPER LOW MOVING
DOWN FROM THE UPPER GREAT LAKES IN THE FIRST TO MIDDLE PART OF
THE WEEK COULD FINALLY SHOVE THE FRONT FAR ENOUGH TO THE SOUTH
TO ALLEVIATE OUR WORRIES FOR FLOODING.
AVIATION /07Z THURSDAY THROUGH MONDAY/
HIGH PRESSURE AT THE SURFACE AND ALOFT WHICH IS DELIVERING
UNSEASONABLE HEAT AND HUMIDITY WILL EXPAND AND CENTER MORE
CLOSELY TO PENNSYLVANIA OVER THE NEXT 48 HOURS.
THIS WILL PUSH ANY RIDGE-EDGE CONVECTION FURTHER NORTH AND EAST
OF PENNSYLVANIA THURSDAY AND FRIDAY. GOOD VFR WILL PREVAIL AT
ALL LOCATIONS THROUGH THE FORECAST PERIOD. WINDS WILL REMAIN
GENERALLY LIGHT AND WESTERLY WITH JUST ISOLATED AREAS (20%)
TOPPING 10 KNOTS DURING THE AFTERNOON HOURS.
BIGGEST CONCERN WILL BE DENSITY ALTITUDE OVER THE NEXT TWO DAYS.
HIGH RESOLUTION SHORT TERM MODELS FORECAST DEWPOINTS TO DROP
OVERNIGHT AND THEN FALL INTO THE 50S DURING THE AFTERNOON
THURSDAY. THIS SHOULD KEEP ANY WIDESPREAD FOG FROM FORMING
OVERNIGHT (<10%), BUT WILL HELP SURFACE TEMPERATURES CLIMB A FEW
DEGREES HIGHER THAN TODAY. IF YOU'RE FLYING ON THE HEAVY SIDE
AND/OR TAKING OFF FROM A RUNWAY ON THE SHORTER SIDE, DOUBLE
CHECK THAT VALUE AND ITS EFFECT ON YOUR PERFORMANCE.
OUTLOOK...
FRI-SAT...PATCHY AM FOG; OTHERWISE VFR. HOT & HUMID WITH PM
T-STORMS PSBL. HIGH DENSITY ALTITUDE CONCERNS POSSIBLE.
SUN...RESTRICTIONS POSSIBLE IN AFTERNOON T-STORMS.
MON...RESTRICTIONS POSSIBLE IN AFTERNOON T-STORMS.
CLIMATE
BRADFORD REACHED 89 DEGREES WED, BREAKING THE OLD RECORD OF 88
DEGREES SET IN 1963. HARRISBURG CAME UP ONE DEGREE SHORT OF
TYING THEIR OWN RECORD MAX WED.
TRIPLE DIGIT MAX TEMPS ARE FORECAST IN THE LOWER SUSQ VALLEY
(LSV) TODAY AND FRIDAY, AND 90S FOR SATURDAY.
THE LAST TIME HARRISBURG OBSERVED CONSECUTIVE DAYS WITH MAXT
GREATER THAN OR EQUAL TO 100F WAS BACK IN 2011 ON JULY 21-22.
THE RECORD NUMBER OF CONSECUTIVE DAYS WITH MAXT >= 100F IS 3
AND HAS OCCURRED 5 TIMES: (ALL IN THE MONTH OF JULY)
1999-07-16 TO 1999-07-18
1999-07-04 TO 1999-07-06
1991-07-19 TO 1991-07-21
1966-07-02 TO 1966-07-04
1936-07-09 TO 1936-07-11
THE LAST TIME HARRISBURG HIT THE CENTURY MARK WAS JULY 16TH IN
2024. PRIOR TO THAT, IT WAS JULY 19TH IN 2020.
HARRISBURG AVERAGES 1 DAY ANNUALLY WITH A MAXT >100F. THE MOST
NUMBER OF DAYS OBSERVED IN A YEAR IS 6 IN 1999.
THE RECORD MAXES FOR THE NEXT FEW DAYS ARE IN JEOPARDY:
STATION/DATE...07/02...07/03...07/04...07/05.
MDT.............104.....107.....104.....102..
IPT..............99.....100.....100.....100..
AOO..............97......97......97......94..
JST..............98.....100.....100.....101..
BFD..............90......91......91......91..
CTP WATCHES/WARNINGS/ADVISORIES
HEAT ADVISORY UNTIL 8 PM EDT FRIDAY FOR PAZ004>006-010>012-017-
018-024-033-037-041-042.
EXTREME HEAT WARNING UNTIL 8 PM EDT FRIDAY FOR PAZ019-025>028-
034>036-045-046-049>053-056-058-063.
HEAT ADVISORY FROM 8 PM FRIDAY TO 8 PM EDT SATURDAY FOR PAZ019-
026>028-036-045-046-049>053-056-058-063.
EXTREME HEAT WARNING UNTIL 8 PM EDT SATURDAY FOR PAZ057-059-
064>066.
WHAT HAS CHANGED...DANGELO
KEY MESSAGES...DANGELO
DISCUSSION...DANGELO
AVIATION...TEARE
CLIMATE...DANGELO/STEINBUGL/MARTIN
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