653
FXUS61 KCTP 271756
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
156 PM EDT SAT JUN 27 2026
WHAT HAS CHANGED
INCREASING CONFIDENCE IN A SIGNIFICANT, POTENTIALLY DANGEROUS
HEAT WAVE TO START THE MONTH OF JULY.
KEY MESSAGES
1) DRYING TREND FOR THIS AFTERNOON AND TONIGHT WITH JUST SPOTTY
LIGHT SHOWERS. ANOTHER FEW TO SEVERAL HOUR ROUND OF AFTERNOON
SHOWERS IS LIKELY SUNDAY.
2) SIGNIFICANT, POTENTIALLY DANGEROUS HEAT WAVE TO START THE
MONTH OF JULY
DISCUSSION
KEY MESSAGE 1: DRYING TREND FOR THIS AFTERNOON AND TONIGHT WITH JUST SPOTTY
LIGHT SHOWERS. ANOTHER FEW TO SEVERAL HOUR ROUND OF AFTERNOON
SHOWERS IS LIKELY SUNDAY.
THICK, LAYERED CLOUDS WERE HOLDING TOUGH ACROSS ALL OF THE CWA
OUTSIDE OF THE NORTHERN TIER OF PENN WHERE A MIX OF SUN AND
CLOUDS AND SLIGHTLY LOWER SFC DEWPOINTS IN THE UPPER 50S WERE
FOUND.
THE CLOUDS AND AREA OF STEADY LIGHT TO MODERATE RAIN EXITING
EAST ACROSS THE MIDDLE SUSQ VALLEY AND POCONOS ALONG WITH
SHOWERS OVER THE LOWER SUSQ VALLEY WILL BE FOLLOWED BY JUST
ISOLATED TO SCATTERED -SHRA THIS AFTERNOON AS THE EARLIER AREA
OF MODERATELY STRONG, SOUTHERLY ISENTROPIC LIFT IS REPLACED BY
MUCH WEAKER LIFT WITHIN THE 925-850 MB LAYER.
HREF CLOUD PANELS INDICATE THAT WE SHOULD SEE BRIGHTENING SKIES
THIS AFTERNOON ACROSS THE AFOREMENTIONED OVERCAST AREA OF
CENTRAL AND WESTERN PA WITH TEMPS CLIMBING ANOTHER 7-8 DEG F
FROM THEIR 15Z VALUES.
AREAS OF FOG TO PRECEDE ANOTHER DIURNAL UPTICK IN RAIN SHOWERS
AND A FEW T-STORMS THROUGH SUNDAY AFTERNOON, MAINLY TO THE
SOUTH OF I-80. MAX TEMPS ON SUNDAY WILL BE ~5 DEGREES WARMER VS.
SATURDAY WITH FCST HIGHS IN THE MID 70S TO LOW 80S. TOTAL
RAINFALL OVER THE WEEKEND RANGES FROM <0.10" IN THE NORTHERN
TIER TO 0.25-0.50" ACROSS SOUTH CENTRAL PA.
---------------------------------------------------------------
KEY MESSAGE 2: SIGNIFICANT, POTENTIALLY DANGEROUS HEAT WAVE TO
START THE MONTH OF JULY
CONFIDENCE AND PREDICTABILITY REMAINS HIGH FOR A LARGE AND
ANOMALOUS UPPER LEVEL RIDGE TO DELIVER A SIGNIFICANT,
POTENTIALLY DANGEROUS HEAT WAVE TO START THE MONTH OF JULY.
WIDESPREAD TEMPERATURES IN THE 90S TO NEAR 100F, COMBINED WITH
HIGH HUMIDITY, WILL RESULT IN FCST MAX HEAT INDICES APPROACHING
OR EXCEEDING 105F. THIS EQUATES TO WIDESPREAD MAJOR TO EXTREME
HEATRISK AND HIGH PROBABILITY OF HEAT WWA HEADLINES. THURSDAY
7/2 LOOKS TO BE THE HOTTEST DAY AT THIS TIME. THE HEAT WAVE
COULD LAST INTO THE JULY 4TH/INDEPENDENCE DAY WEEKEND, ALTHOUGH
RIDGE RIDING SHORTWAVES MAY ACT TO SUPPRESS/WEAKEN THE HEAT DOME
TO SOME EXTENT. OVERNIGHT LOWS WILL ALSO BE QUITE WARM,
BRINGING LITTLE TO NO RELIEF FROM THE HEAT IN THE NIGHTTIME
HOURS.
LATEST QPF TRENDS FAVOR LITTLE TO NO RAIN MONDAY-FRIDAY NEXT
WEEK GIVEN CLOSE PROXIMITY TO THE UPPER RIDGE. HOWEVER, CAN'T
RULE OUT ISOLATED AIRMASS/TERRAIN-DRIVEN DIURNAL CONVECTION OR
POSSIBLE MCS ACTIVITY (THUNDERSTORM COMPLEXES) ON THE NORTHERN
PERIPHERY OF THE RIDGE WITHIN A CLASSIC RING OF FIRE SYNOPTIC
PATTERN. THIS SETUP APPEARS MORE LIKELY TO UNFOLD DURING THE
SECOND HALF OF NEXT WEEK.
AVIATION /18Z SATURDAY THROUGH THURSDAY/
SCATTERED SHOWERS/MIST AND LOW CLOUDS DUE TO BROAD LOW PRESSURE
ACROSS THE OHIO VALLEY AND MID-ATLANTIC WILL TEND TO MAINTAIN
CURRENT FLIGHT RESTRICTIONS THIS AFTERNOON, THOUGH BREAKS IN
CLOUDS MAY PERMIT SLIGHT IMPROVEMENTS BEFORE SUNSET. SCATTERED SHOWERS
ARE EXPECTED FOR THE REMAINDER OF TODAY GIVEN AMPLE MOISTURE
(PWATS AOA 1.5"), ALBEIT WITH LOWER COVERAGE AS BEST MID-LEVEL
MOISTURE PRESSES EASTWARD, WITH HEAVIER SHOWERS POSSIBLE AROUND
(AND MAINLY SOUTH OF) THE MASON-DIXON LINE WHERE SPC
MESOANALYSIS SHOWS MUCAPE >500 J/KG (LIGHTNING POSSIBLE, THOUGH
TALL/NARROW CAPE PROFILE PRIMARILY FAVORS RAINFALL EFFICIENCY
OVER LIGHTNING).
HIGH CONFIDENCE IN REGIONWIDE IFR-LIFR OVERNIGHT GIVEN MOIST
AIR MASS IN PLACE + RECENT RAINFALL AND LIGHT/VARIABLE WINDS,
ESPECIALLY ALONG THE APPALACHIAN MOUNTAINS. LINGERING SHOWERS
AND DRIZZLE ARE POSSIBLE OVERNIGHT, THOUGH SHOWER COVERAGE IS
FAVORED TO INCREASE SUNDAY AFTERNOON WITH DEVELOPMENT OF MODEST
INSTABILITY (MLCAPE UP TO AROUND 500 J/KG). OTHERWISE, WEATHER
CONDITIONS WILL IMPROVE THROUGH SUNDAY MORNING THROUGH DIURNAL
BOUNDARY LAYER MIXING, THOUGH STUBBORN LOW-LEVEL MOISTURE AND
STRATUS MAY TEND TO MAKE IMPROVEMENTS MORE GRADUAL THROUGH THE
MORNING.
OUTLOOK...
MON-THU...AM FOG; OTHERWISE VFR. TRENDING HOTTER WITH ISOLD PM
T-STORMS PSBL. HIGH DENSITY ALTITUDE CONCERNS POSSIBLE.
CTP WATCHES/WARNINGS/ADVISORIES
NONE.
WHAT HAS CHANGED...LAMBERT/STEINBUGL
KEY MESSAGES...LAMBERT/STEINBUGL
DISCUSSION...LAMBERT/STEINBUGL
AVIATION...TEARE
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