505
FXUS61 KCTP 191700
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
100 PM EDT TUE MAY 19 2026
WHAT HAS CHANGED
* INCREASING ODDS FOR A NOTICEABLY COOLER AND RATHER WET START
TO MEMORIAL DAY WEEKEND
* SPC EXPANDED THE MARGINAL RISK FOR SEVERE THUNDERSTORMS THIS
AFTERNOON INTO THE LOWER SUSQUEHANNA VALLEY.
KEY MESSAGES
1) SUMMERLIKE HEAT WAVE PEAKS TODAY WITH RECORD CHALLENGING
TEMPERATURES IN THE MID 80S TO MID 90S
2) SCATTERED STRONG TO SEVERE THUNDERSTORMS ARE POSSIBLE ACROSS
CENTRAL PA LATER TODAY/TONIGHT AND SOUTH CENTRAL PA WEDNESDAY
AFTERNOON
3) MAJOR COOLDOWN ARRIVES THURSDAY AND LASTS INTO MEMORIAL DAY
WEEKEND WITH WIDESPREAD SOAKING RAINFALL LIKELY FRIDAY AND
SATURDAY
DISCUSSION
KEY MESSAGE 1: SUMMERLIKE HEAT WAVE PEAKS TODAY WITH RECORD
CHALLENGING TEMPERATURES IN THE MID 80S TO MID 90S
ANOTHER SCORCHER TODAY WITH MAX TEMPS 85-95F APPROACHING DAILY
RECORDS (SEE CLIMATE SECTION). MAX HEAT INDICES ARE FCST TO
REACH THE UPPER 90S, JUST SHY OF HEAT ADVISORY CRITERIA ACROSS
THE LSV. RECORD HIGH MINIMUM TEMPS ARE ALSO ON THE TABLE FOR
TONIGHT. THE ONE AREA OF UNCERTAINTY REGARDING THIS TEMPERATURE
FORECAST IS THE SHOWERS AND THUNDERSTORMS THAT HAVE DEVELOPED
OVER THE LAUREL HIGHLANDS EARLY THIS AFTERNOON. THESE MAY HELP
TO KEEP HIGH TEMPERATURES IN THE LOW TO MID 80S FOR THE AREAS
THAT SEE THESE SHOWERS AND STORMS.
--------------------------------------------------------------
KEY MESSAGE 2: SCATTERED STRONG TO SEVERE THUNDERSTORMS ARE
POSSIBLE ACROSS CENTRAL PA LATER TODAY/TONIGHT AND SOUTH
CENTRAL PA WEDNESDAY AFTERNOON
WIDELY SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE TO POP
UP THROUGH THE REST OF THE AFTERNOON IN A MODERATELY UNSTABLE
AIRMASS. WIND SHEAR IS VERY WEAK (0-6 KM SHEAR IS GENERALLY LESS
THAN 20 KNOTS), SO ANY CELLS THAT DEVELOP MAY STRUGGLE TO
MAINTAIN THEMSELVES FOR LONG. THAT BEING SAID, STEEP LOW-LEVEL
LAPSE RATES AND DRY MID-LEVELS MAY SUPPORT A FEW STRONG TO
MARGINALLY SEVERE DOWNBURSTS IN ANY LONGER-LIVED STORMS. THE
BEST THERMODYNAMIC ENVIRONMENT FOR DOWNBURSTS IS OVER THE LOWER
SUSQUEHANNA VALLEY, WITH DCAPE VALUES EXCEEDING 1000 J/KG THIS
AFTERNOON, BUT DRY AIR MAY LIMIT THE COVERAGE OF STORMS IN THAT
PART OF THE FORECAST AREA. SPC HAS EXPANDED THE MARGINAL RISK OF
SEVERE STORMS TO HIGHLIGHT THIS POTENTIAL.
A WEAKENING LINE OF SHOWERS AND THUNDERSTORMS IS EXPECTED TO
MOVE INTO NORTHWEST PA DURING THE LATE EVENING AHEAD OF A COLD
FRONT. SPC HAS MAINTAINED A SLIGHT RISK OF SEVERE WEATHER ACROSS
NORTHWEST PA AS THIS LINE MAY PRODUCE STRONG TO SEVERE WIND
GUSTS AS IT MOVES THROUGH. THE LINE WILL QUICKLY ENCOUNTER A
MORE STABLE ENVIRONMENT AS IT PROGRESSES SOUTHEASTWARD, SO THE
THREAT FOR SEVERE WIND GUSTS SHOULD QUICKLY DECREASE AS IT MOVES
FARTHER INTO THE FORECAST AREA.
CONVECTIVE FOCUS SHIFTS TO SOUTH CENTRAL PA ON WEDNESDAY WITH
NARROW PLUME OF WEAK TO MODERATE CAPE FCST AHEAD OF THE
AFOREMENTIONED COLD FRONT. STEEP LOW LEVEL LAPSE RATES MAY
SUPPORT A FEW INSTANCES OF STRONG TO SEVERE WINDS. THE MAGNITUDE
& LOCATION OF THE SEVERE THREAT WILL BE HIGHLY DEPENDENT ON
CFROPA TIMING AND AMOUNT OF CLOUD COVER. SPC MRGL RISK (LEVEL
1/5) COVERS THE SOUTHEAST HALF OF THE CWA WHERE MAX TEMPS ARE
FCST BTWN 80-90F.
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KEY MESSAGE 3: MAJOR COOLDOWN ARRIVES THURSDAY AND LASTS INTO
MEMORIAL DAY WEEKEND WITH WIDESPREAD SOAKING RAINFALL LIKELY
FRIDAY AND SATURDAY
RELIEF FROM THE EARLY SEASON HEAT WAVE ARRIVES IN EARNEST ON
THURSDAY WITH MAX TEMPS 20-30 DEGREES LOWER VS. WEDNESDAY ACROSS
THE SOUTHEAST HALF OF THE FORECAST AREA. STRONG HIGH PRESSURE
SLIDES FROM THE LOWER GREAT LAKES TO OFF THE NEW ENGLAND COAST
TO CLOSE OUT THE WEEK. MODEL DATA SHOWS THE HIGH CHANNELING
SOUTHWARD DOWN THE EAST-SIDE OF THE APPALACHIANS, SETTING UP A
COLD AIR DAMMING TYPE EVENT HEADING INTO MEMORIAL DAY WEEKEND.
WE MAY NOT BE BEARISH ENOUGH ON DAYTIME TEMPERATURES. IT ALSO
APPEARS PROBABLE THAT PERIODS OF SOAKING RAIN WILL DAMPEN AT
LEAST THE START OF THE HOLIDAY WEEKEND. WPC 48HR QPF AMOUNTS ARE
QUITE WET WITH A WIDESPREAD 1-2.5 INCHES FCST FROM 12Z FRIDAY
TO 12Z SUNDAY.
AVIATION /18Z TUESDAY THROUGH SUNDAY/
PATCHY LOW-LYING FOG HAS DEVELOPED IN SPOTS WHERE RAIN FELL
OVERNIGHT & SKIES BRIEFLY CLEARED OUT. THIS FOG SHOULD CLEAR OUT
BY 13Z-14Z AS DAYLIGHT MIXES OUT THE BOUNDARY LAYER. OTHERWISE,
PREVAILING VFR IS FAVORED THROUGH THE 12Z TAF PERIOD, WITH THE
MAIN EXCEPTIONS BEING VISIBILITY RESTRICTIONS IN ANY HEAVIER
SHOWERS/THUNDERSTORMS THAT DEVELOP & CLOUD CEILINGS LOWERING TO
MVFR-IFR ACROSS THE NORTHERN TIER (KBFD) AFTER 06Z WEDNESDAY.
CHANCES FOR SPOTTY SHOWERS/THUNDERSTORMS WILL PICK UP AGAIN
THIS AFTERNOON AND EVENING, PRIMARILY BETWEEN 16Z-00Z, AS WEAK
SHORTWAVES MOVE ACROSS THE PERIPHERY OF A RIDGE OVER THE WESTERN
ATLANTIC. SIMILAR TO YESTERDAY, GUSTY WINDS MAY ACCOMPANY THESE
SPOTTY SHOWERS/STORMS GIVEN THE MODERATELY UNSTABLE AIRMASS
(HREF MEAN SBCAPE AROUND 1000-1500 J/KG) AND STEEP LOW-LEVEL
LAPSE RATES (>8 C/KM) IN PLACE, THOUGH PLACEMENT/TIMING
UNCERTAINTIES REMAIN GIVEN THE WEAK FORCING MECHANISMS IN PLACE.
MOST CONVECTION WILL DIMINISH AFTER 00Z WEDNESDAY WITH THE LOSS
OF DAYTIME HEATING, THOUGH SOME MODELS ARE HINTING AT AN MCS
ASSOCIATED WITH AN APPROACHING COLD FRONT REACHING KBFD AROUND
03Z-06Z WEDNESDAY, BRINGING THE POTENTIAL FOR GUSTY WINDS AND
VISIBILITY RESTRICTIONS. MCS TIMING AND IMPACTS WILL BE
SENSITIVE TO ITS DEVELOPMENT/EVOLUTION ACROSS THE OHIO VALLEY
THIS AFTERNOON & EVENING, WITH TAF MENTIONS NOT INCLUDED AT THIS
TIME GIVEN HIGH MODEL VARIABILITY.
LASTLY, LLWS MENTIONS WERE INCLUDED AT OUR NORTHERN TERMINALS
(KBFD/KIPT) THROUGH THE EVENING/OVERNIGHT HOURS AS 900 MB WINDS
INCREASE TO AROUND 40 KTS DUE TO PRESSURE GRADIENT BETWEEN LOW
PRESSURE OVER SOUTHERN CANADA & BERMUDA HIGH OVER THE WESTERN
ATLANTIC.
OUTLOOK...
WED...RESTRICTIONS PROBABLE THROUGH WEDNESDAY NIGHT WITH
WIDESPREAD SHOWERS/STORMS ALONG CFROPA.
THU...LINGERING SHOWERS ACROSS S PA, RESTRICTIONS POSSIBLE.
FRI...RESTRICTIONS LIKELY WITH RAIN MOVING IN FROM SOUTH TO
NORTH, LASTING INTO FRI NIGHT.
SAT...RESTRICTIONS LIKELY WITH RAIN.
CLIMATE
THE FOLLOWING CLIMATE SITES ACROSS CENTRAL PENNSYLVANIA SET NEW
DAILY HIGH TEMPERATURE RECORDS FOR MAY 18TH:
* A RECORD HIGH TEMPERATURE OF 92 DEGREES WAS SET IN ALTOONA,
BREAKING THE PREVIOUS RECORD OF 91 DEGREES INITIALLY SET BACK
IN 1962. THIS RECORD WAS TIED TWO TIMES PREVIOUSLY, BACK IN
1996 AND 2017.
* A RECORD HIGH TEMPERATURE OF 86 DEGREES WAS SET IN BRADFORD,
BREAKING THE PREVIOUS RECORD OF 85 DEGREES SET BACK IN 1962.
** NOTE: THE HIGH TEMPERATURE FOR STATE COLLEGE WILL BE REPORTED
AROUND 7AM ON 5/19. THIS IS DUE TO THE STATE COLLEGE CO-OP
OBSERVATIONS RUNNING 7AM-7AM. THUS, TODAY'S (5/18) HIGH
TEMPERATURE WILL BE REPORTED IN TOMORROW'S (5/19) OBSERVATION.
THIS RECORD, FOR REFERENCE, IS 92 DEGREES SET IN 1962.
---------------------------------------------
ABNORMALLY WARM TEMPERATURES WILL CONTINUE ON MAY 19TH, THUS
MULTIPLE SITES COULD CHALLENGE DAILY RECORD HIGH TEMPERATURES.
DAILY MAXIMUM HIGH TEMPERATURES FOR MAY 19TH:
* HARRISBURG: 95F SET IN 1962
* WILLIAMSPORT: 96F IN IN 1996
* ALTOONA: 92F SET IN 1996
* BRADFORD: 85F SET IN 1962
* STATE COLLEGE: 92F SET IN 1934, TIED IN 1996.
CTP WATCHES/WARNINGS/ADVISORIES
NONE.
WHAT HAS CHANGED...STEINBUGL/BAUCO
KEY MESSAGES...STEINBUGL/BAUCO
DISCUSSION...STEINBUGL/BAUCO
AVIATION...TEARE
CLIMATE...BEATY
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