301
FXUS61 KCTP 171052
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
652 AM EDT SUN MAY 17 2026
WHAT HAS CHANGED
* MINOR MODIFICATIONS
KEY MESSAGES
1) HOTTEST TEMPERATURES OF THE YEAR SO FAR FORECAST EARLY NEXT
WEEK WITH HIGHS PUSHING INTO THE 80S AND 90S.
2) A STRONG COLD FRONT TO BRING SHOWERS AND THUNDERSTORMS WITH
THE POTENTIAL FOR SEVERE WEATHER ON WEDNESDAY FOLLOWED BY
COLDER TEMPERATURES.
DISCUSSION
KEY MESSAGE 1: HOTTEST TEMPERATURES OF THE YEAR SO FAR WILL
OCCUR MONDAY AND TUESDAY.
DAYTIME HIGH TEMPERATURES WILL BE STEADILY RISING TODAY THROUGH
EARLY IN THE UPCOMING WEEK.
AN ANOMALOUS UPPER RIDGE AMPLIFYING OVER THE EAST-CENTRAL U.S.
WILL HELP TO CREATE VERY WARM TO HOT, SUMMERLIKE CONDITIONS
CENTERED ON MONDAY AND TUESDAY. 500 MB HEIGHTS PER THE GEFS
RISE ABOUT 120 DAM BETWEEN THIS MORNING AND LATE MONDAY WITH
STANDARDIZED ANOMALIES OF THESE HEIGHTS REACHING OVER +2 SIGMA
ALONG THE MID ATLANTIC COAST 18Z MONDAY THROUGH 18Z TUESDAY.
HIGH TEMPERATURES WILL PEAK IN THE MID 80S TO LOWER 90S MONDAY
AND TUESDAY AND COULD CHALLENGE DAILY RECORDS IN SOME LOCATIONS.
MANUAL ADJUSTMENTS WERE MADE TO LOWER NBM MAXT BY A FEW DEGREES
DUE TO A KNOWN SYSTEMATIC BIAS CORRECTION ISSUE IDENTIFIED
DURING THE SHOULDER SEASONS. THIS SHOULD ALSO KEEP MAX HEAT
INDICES UNDER 100F FOR THE MOST PART.
STILL, HEAT RISK IMPACTS WILL CONTINUE TO BE MONITORED GIVEN
THE QUICK RAMP-UP IN HEAT AND LIMITED ACCLIMATION TIME.
DEWPOINTS OVER 60F FOR MANY WILL ALSO FEEL QUITE HUMID RELATIVE
THE RECENT COOL STRETCH WE'VE HAD.
WITH A BOUNDARY JUST TO OUR NORTH AND SUFFICIENT INSTABILITY IN
THE WARM SECTOR OVER PA, THERE WILL BE A CHANCE FOR SOME STRAY
AFTERNOON AND EARLY EVENING SHOWERS OR THUNDERSTORMS MONDAY AND
TUESDAY. MOST FOLKS SHOULD STAY DRY, BUT THUNDERSTORMS COULD
DROP A QUICK 0.10 TO 0.25" OF RAIN IN ANY ONE LOCATION.
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KEY MESSAGE 2: A STRONG COLD FRONT TO BRING SHOWERS AND THUNDERSTORMS
WITH THE POTENTIAL FOR SEVERE WEATHER ON WEDNESDAY FOLLOWED BY
COLDER TEMPERATURES.
A COLD FRONT (ACCOMPANIED BY MORE WIDESPREAD AND FREQUENT
SHOWERS/T-STORMS) BRINGS RELIEF TO THE RELATIVELY SHORT BOUT OF
HEAT AND MODERATE HUMIDITY WEDNESDAY INTO THURSDAY. DOD MAX TEMP
DROP FROM TUESDAY TO WED WILL BE 20 DEG F OR GREATER IN MOST
LOCATIONS.
SOME OF THE AI GUIDANCE PAINTS AN ELEVATED RISK OF SEVERE
WEATHER ACROSS THE LOWER SUSQUEHANNA VALLEY ON WEDNESDAY
AFTERNOON IN THE PRESENCE OF PEAK HEATING AND SUFFICIENT
SHEAR/CAPE PROFILES. THE MAGNITUDE & LOCATION OF THE SEVERE
THREAT WILL BE HIGHLY DEPENDENT ON COLD FRONT PASSAGE TIMING AND
AMOUNT OF CLOUD COVER IN ADVANCE OF THE FRONTAL BOUNDARY. THE
EVENTUAL RISK AREA WILL HIGHLIGHT LOCATIONS ALONG AND DOWNSTREAM
OF THE COLD FRONT BETWEEN 12PM AND 8PM ON WEDNESDAY.
IN THE WAKE OF THE COLD FRONT, HIGH PRESSURE WILL BUILD IN FOR
A SHORT TIME. TEMPERATURES ARE FORECAST TO COOL DOWN BACK TO
HISTORICAL/CLIMO AVERAGES FOR LATE MAY FOR THE END OF NEXT WEEK.
EARLY INDICATIONS SHOW THE AFOREMENTIONED COLD FRONT STALLING
OUT SOUTH OF THE MASON-DIXON LINE LATE IN THE WEEK AND LIFTING
BACK NORTH ACROSS PA AS A WARM FRONT INTO MEMORIAL DAY WEEKEND.
THE CURRENT OUTLOOK FAVORS A COOLER/WETTER STRETCH THROUGH THE
HOLIDAY WEEKEND THANKS TO THAT WARM FRONT, BUT THERE IS STILL A
LOT OF TIME FOR THE FORECAST TO TREND IN A MORE
FAVORABLE/OPTIMISTIC DIRECTION FOR THE HOLIDAY WEEKEND THAT
MARKS THE UNOFFICIAL START OF SUMMER.
AVIATION /12Z SUNDAY THROUGH THURSDAY/
LOW-LEVEL MOISTURE FROM YESTERDAY'S SHOWERS + UPSLOPE
SOUTHWESTERLY FLOW IS CONTRIBUTING TO FLIGHT RESTRICTIONS
ACROSS THE NORTHERN TIER (KBFD) AND CENTRAL MOUNTAINS
(KJST/KAOO/KUNV/KIPT) EARLY THIS MORNING. THE SUN WILL WARM THE
SURFACE & MIX THE BOUNDARY LAYER, ULTIMATELY RAISING CEILINGS
AND SCATTERING THE LOW CLOUD DECK. REGIONWIDE VFR IS EXPECTED
BY THE AFTERNOON.
VFR WILL PREVAIL ON SUNDAY AS A RIDGE CONTINUES TO BUILD ALONG
THE EAST COAST ON SUNDAY. WITH THAT SAID, WEAK SHORTWAVES
EMBEDDED WITHIN THE NORTHERN PERIPHERY OF THIS RIDGE MAY
INITIATE SPOTTY CONVECTION. INSTABILITY WILL GROW SUPPORTIVE OF
CONVECTION AS THE DAY PROGRESSES, WITH HREF MEAN SBCAPE AROUND
1000 J/KG & NEGLIGIBLE CIN IN PLACE, THOUGH SYNOPTIC-SCALE
SUPPRESSION WILL TEMPER ACTIVITY OVERALL. COVERAGE AND TIMING
OF CONVECTION IS INCONSISTENT ACROSS CAMS GIVEN THE NEBULOUS
FORCING, WITH SHOWER/THUNDERSTORM COVERAGE EXPECTED TO BE BELOW
30% ACROSS THE REGION. ANY CELLS THAT DO DEVELOP WILL DISSIPATE
DURING THE EVENING AS DAYLIGHT ENDS AND RIDGING BECOMES FURTHER
ENTRENCHED ACROSS THE EAST COAST.
PATCHY FOG WILL BE POSSIBLE ONCE AGAIN SUNDAY NIGHT (MAINLY AFTER
06Z MONDAY) GIVEN LIGHT/VARIABLE WINDS, MAINLY CLEAR SKIES, AND
SURFACE DEW POINTS AROUND 60 DEGREES.
OUTLOOK...
MON-TUE...MAINLY VFR. PATCHY A.M. FOG. ISOLATED P.M. SHOWER OR
T-STORM POSSIBLE.
WED...RESTRICTIONS PROBABLE THROUGH WEDNESDAY NIGHT WITH
WIDESPREAD SHOWERS/STORMS ALONG CFROPA.
THU...LINGERING SHOWERS ACROSS S PA, RESTRICTIONS POSSIBLE.
CLIMATE
DAILY RECORD MAX TEMPERATURE FOR MAY 18-19:
5/18 5/19
HARRISBURG 94 IN 1962 95 IN 1962
WILLIAMSPORT 95 IN 1962 96 IN 1996
ALTOONA 91 IN 1962/1996/2017 92 IN 1996
BRADFORD 85 IN 1962 85 IN 1962
STATE COLLEGE 92 IN 1962 92 IN 1934/1996
PLEASE NOTE: STATE COLLEGE CO-OPERATIVE OBSERVATIONS ARE A
24-HOUR SUMMARY TAKEN ONCE PER DAY AROUND 7 AM (7AM-7AM).
THEREFORE, A MAX TEMP OCCURRING IN THE DAYLIGHT OR LATE IN THE
DAY IS USUALLY REPORTED IN THE _NEXT_ DAY'S OBSERVATION. ALSO,
THE SAME MIN TEMP MAY BE REPORTED ON TWO CONSECUTIVE DAYS IF THE
MIN OCCURS AT OBSERVATION TIME.
CTP WATCHES/WARNINGS/ADVISORIES
NONE.
WHAT HAS CHANGED...LAMBERT/BANGHOFF/MARTIN
KEY MESSAGES...LAMBERT/BANGHOFF/MARTIN
DISCUSSION...LAMBERT/BANGHOFF/MARTIN
AVIATION...TEARE
CLIMATE...DANGELO/STEINBUGL
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