173
FXUS61 KCTP 161807
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
207 PM EDT SAT MAY 16 2026
WHAT HAS CHANGED
* MINOR MODIFICATIONS TO TODAY'S RAINFALL CHANCES AS A DECAYING
LINE OF SHOWERS MOVES INTO AN INCREASINGLY DRY AIRMASS.
* NUDGED HIGH TEMPERATURES DOWN SUNDAY-TUESDAY TO ACCOUNT FOR
KNOWN BIASES IN THE NBM FORECAST IN PATTERNS LIKE THIS.
KEY MESSAGES
1) DECAYING LINE OF SHOWERS TO BRING LIGHT RAIN ACROSS WESTERN
PA THIS AFTERNOON, A SPRINKLE OR TWO POSSIBLE FARTHER EAST.
2) HOTTEST TEMPERATURES OF THE YEAR SO FAR FORECAST EARLY NEXT
WEEK WITH HIGHS PUSHING INTO THE 80S AND 90S.
3) STRONG COLD FRONT TO BRING SHOWERS AND STORMS WITH POTENTIAL
FOR SEVERE WEATHER ON WEDNESDAY FOLLOWED BY COOLER TEMPERATURES.
DISCUSSION
KEY MESSAGE 1: DECAYING LINE OF SHOWERS TO BRING LIGHT RAIN
ACROSS WESTERN PA THIS AFTERNOON, A SPRINKLE OR TWO POSSIBLE
FARTHER EAST.
A BROAD AREA OF LOW PRESSURE DRIFTING ACROSS THE SOUTHERN GREAT
LAKES IS BRINGING SHOWERS AND STORMS TO THE OHIO VALLEY EARLY
THIS AFTERNOON. AS THAT COMPLEX OF SHOWERS MOVES EAST, IT WILL
ENCOUNTER AN INCREASINGLY DRY AIRMASS WITH SURFACE DEWPOINTS IN
THE 40S AND SUFFICIENTLY DRY AIR ALOFT. HI-RES GUIDANCE AGREES
THAT THE EXTENT AND INTENSITY OF ONGOING SHOWERS WILL WANE WITH
EASTWARD EXTENT, THOUGH THE LONGEVITY OF SHOWERS REMAINS IN
QUESTION. AT THE VERY LEAST, ISOLATED SHOWERS/SPRINKLES ARE
POSSIBLE MAINLY ACROSS THE WESTERN HALF OF PA AND RAINFALL
AMOUNTS WILL REMAIN WELL BELOW 0.10". FARTHER EAST, VIRGA WILL
BE THE MOST LIKELY OCCURRENCE, BUT A FEW SPRINKLES CANNOT BE
RULED OUT. CLOUD COVER AND SHOWERS IN WESTERN PA SHOULD ALSO
HELP TEMPER AFTERNOON HIGHS, SO THE LATEST FORECAST PACKAGE
INCLUDES TEMPERATURES A COUPLE DEGREES LOWER THAN THE PREVIOUS
FORECAST ACROSS WESTERN PA.
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KEY MESSAGE 2: HOTTEST TEMPERATURES OF THE YEAR SO FAR FORECAST
EARLY NEXT WEEK WITH HIGHS PUSHING INTO THE 80S AND 90S.
DAYTIME HIGH TEMPERATURES WILL BE STEADILY RISING TODAY THROUGH
EARLY IN THE UPCOMING WEEK. AN ANOMALOUS UPPER RIDGE BUILDING
OVER THE EAST-CENTRAL U.S. WILL DELIVER SUMMERLIKE CONDITIONS
THIS WEEKEND THROUGH THE FIRST PART OF THE NEW WEEK. 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. HOWEVER, HEAT RISK IMPACTS
WILL CONTINUE TO BE MONITORED GIVEN THE QUICK RAMP- UP IN HEAT
AND LIMITED ACCLIMATION TIME. DEWPOINTS OVER 60S 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 3: STRONG COLD FRONT TO BRING SHOWERS AND STORMS WITH POTENTIAL
FOR SEVERE WEATHER ON WEDNESDAY FOLLOWED BY COOLER TEMPERATURES.
A COLD FRONT (ACCOMPANIED BY MORE WIDESPREAD AND FREQUENT
SHOWERS/T-STORMS) BRINGS RELIEF NEXT WEDNESDAY INTO THURSDAY.
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.
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 /18Z SATURDAY THROUGH THURSDAY/
MAINLY HIGH SCATTERED CLOUDS MOVING OVER CENTRAL PA THIS
AFTERNOON. VFR CLOUDS WILL INCREASE AND THICKEN WEST TO EAST AS
A SHORTWAVE TRACKS ACROSS THE NORTHERN PERIPHERY OF HIGH
PRESSURE OFF THE EAST COAST & ITS CONCURRENT RIDGE SATURDAY
AFTERNOON/EVENING, BRINGING SCATTERED SHOWERS WITH ANY FLIGHT
RESTRICTIONS LOOKING TO BE BRIEF AND UNLIKELY OUTSIDE OF ANY
LOCALLY HEAVIER SHOWERS. A FEW THUNDERSTORMS MAY DEVELOP ACROSS
THE ALLEGHENY PLATEAU (KBFD/KJST) WHERE THE HREF MEAN MUCAPE
VALUES ARE AROUND 100 J/KG. AS PRECIPITATION PROGRESSES
EASTWARD, HEIGHT RISES AND INCREASINGLY STABLE CONDITIONS WILL
RESULT IN A DOWNTREND IN ACTIVITY. CONFIDENCE IS STILL TOO LOW
TO MENTION LIGHTNING IN THE TAFS FOR THIS AFTERNOON GIVEN A
DOWNTREND OF LIGHTENING ACTIVITY AS THESE SHOWERS APPROACH FROM
EASTERN OHIO.
AS THE SHORTWAVE EXITS OUR AREA DURING THE EVENING, RIDGING
WILL CONTINUE TO BUILD ACROSS THE REGION, RESULTING IN RESIDUAL
LOW-LEVEL MOISTURE BECOMING TRAPPED BENEATH A SUBSIDENCE
INVERSION. AS A RESULT, MVFR/IFR RESTRICTIONS ARE POSSIBLE TO
DEVELOP AFTER 22Z-23Z SATURDAY ACROSS THE ALLEGHENY PLATEAU
(KBFD/KJST), WITH LESSER CONFIDENCE IN EVENING/OVERNIGHT FLIGHT
RESTRICTIONS EAST OF THE ALLEGHENIES DUE TO DOWNSLOPING FLOW AND
LESS ANTECEDENT MOISTURE. IT WILL BE A TRICKY FOG FORECAST GIVEN
THE DRY AIR IN PLACE CURRENTLY, BUT IF A GOOD RAIN SHOWER COMES
OVER A TERMINAL THAT WILL INCREASE THE CHANCE OF FOG DEVELOPMENT
FOR SUNDAY MORNING.
OUTLOOK...
SUN-TUE...MAINLY VFR. PATCHY A.M. FOG. ISOLATED P.M. SHOWER OR
T-STORM POSSIBLE.
WED...RESTRICTIONS PROBABLE THROUGH WEDNESDAY NIGHT WITH
SHOWERS/STORMS ALONG CFROPA.
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...BANGHOFF
KEY MESSAGES...LAMBERT/BANGHOFF/SMITH
DISCUSSION...LAMBERT/BANGHOFF/SMITH
AVIATION...BOWEN/TEARE
CLIMATE...DANGELO/STEINBUGL
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