069
FXUS61 KCTP 280020
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
820 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 /00Z SUNDAY THROUGH THURSDAY/
WINDS HAVE STARTED TO DECREASE SLIGHTLY ACROSS THE FORECAST
AREA THIS EVENING, WHICH WILL PROMOTE FAIRLY EXPANSIVE LOW CLOUD
AND/OR FOG FORMATION ACROSS CENTRAL PENNSYLVANIA. BASED ON THE
12Z HREF 25TH/50TH PERCENTILE MEMBERS OUTLINE ALL AIRFIELDS
OUTSIDE OF IPT WITH IFR-TO-LIFR CONDITIONS. MAIN REASON FOR
LEANING TOWARDS THESE MEMBERS REMAINS TO BE AMPLE LOW-LEVEL
MOISTURE CURRENTLY IN PLACE ACROSS THE ENTIRE REGION AND BASED
ON RAINFALL THAT HAS OCCURRED ACROSS THE AREA EARLIER. RECENT
GLAMP GUIDANCE HONES ONTO THIS TREND, THUS MODERATE-TO-HIGH
(60-80%) CONFIDENCE IN THESE CONDITIONS WITH TIMING BEING THE
MAIN UNCERTAINTY AT THIS TIME. GLAMP GUIDANCE REMAINS FAIRLY
SPARSE IN MENTIONS AT IPT; HOWEVER, HAVE INCLUDED LOWER CEILINGS
DUE TO CURRENT DEW POINT DEPRESSIONS ~6F AND HEAVIEST RAINFALL
ALONG THE I-80 CORRIDOR BUT SLIGHTLY LOWER (~40-60%) CONFIDENCE.
FOG/LOW CLOUD BEGIN TO MIX OUT FAIRLY QUICKLY AFTER SUNRISE ON
SUNDAY, WITH THE BULK OF IFR/LIFR MENTIONS OUT BY 15Z SUNDAY
WITH LIGHT WINDS BELOW 10 KNOTS. MAIN CONCERN IN THE LATER HALF
OF THE TAF PACKAGE WILL BE SOME POTENTIAL FOR SHRA/TSRA ACROSS
MAINLY THE SOUTHERN HALF OF THE FORECAST AREA AFTER 18Z. THE 00Z
TAFS GO AGAINST GLAMP GUIDANCE TO INCLUDE SOME MENTIONS AT ALL
AIRFIELDS OUTSIDE OF BFD/IPT WITH LOW-TO-MODERATE (30-50%)
CONFIDENCE GIVEN THE SCATTERED NATURE EXPECTED OF SHRA/TSRA. THE
MOST RECENT HREF 1-HR LIGHTNING GUIDANCE DOES INDICATE LOWER
(LESS THAN 30%) PROBABILITIES FOR TSRA, SO HAVE KEPT MENTIONS
OUT AT THIS TIME.
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...BEATY
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