311
FXUS61 KCTP 202210
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
610 PM EDT WED MAY 20 2026
WHAT HAS CHANGED
* RISK FOR SEVERE STORMS HAS ENDED ACROSS THE CWA AS OF EARLY
THIS EVENING.
* REITERATING BEARISH TREND FOR MAX TEMPS FRIDAY AND SATURDAY
KEY MESSAGES
1) PERIODS OF LIGHT RAIN/SHOWERS OVER CENTRAL AND SOUTHERN PA
TONIGHT ALONG AND JUST TO THE NORTH OF A SLOW MOVING COLD FRONT.
2) MAJOR COOLDOWN TO CLOSE OUT THE WEEK AND START MEMORIAL DAY
WEEKEND WITH WIDESPREAD SOAKING RAINFALL OVER 1 INCH FRIDAY AND
SATURDAY
DISCUSSION
KEY MESSAGE 1: PERIODS OF LIGHT RAIN/SHOWERS OVER CENTRAL AND
SOUTHERN PA TONIGHT ALONG AND JUST TO THE NORTH OF A SLOW MOVING
COLD FRONT.
SURFACE COLD FRONT WAS ALONG A LINE FROM KJST TO KSEG AND KMPO
AT 2100Z. THIS BOUNDARY WILL SINK SLOWLY TO THE SOUTH OVERNIGHT
BUT A FEW WEAK UPPER LEVEL WAVES RIPPLING NE UP THE OHIO RIVER
VALLEY AND ACRS PA WILL PROVIDE PERIODS OF UVVEL AND OCCASIONAL
-RA/SHRA ACROSS MAINLY THE SOUTHERN 2/3RDS OF THE STATE.
ADDITIONAL RAINFALL THROUGH 12Z WILL BE LESS THAN 0.10 OF AN
INCH NEAR THE I-80 CORRIDOR AND 0.10 TO 0.25 OF AN INCH ACROSS
THE PORTION OF THE STATE NEAR AND TO THE SOUTH OF RT 22.
TEMPS WILL COOL OFF SIGNIFICANTLY WITH EARLY MORNING LOWS
RANGING FROM THE LOW TO MID 40S ACROSS THE NORTHERN MOUNTAINS TO
BETWEEN 50-55F THROUGHOUT THE CENTRAL AND SOUTHERN VALLEYS.
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KEY MESSAGE 2:
MAJOR COOLDOWN TO CLOSE OUT THE WEEK AND START MEMORIAL DAY
WEEKEND WITH WIDESPREAD SOAKING RAINFALL OVER 1 INCH 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 LSV. 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 (CAD) EVENT HEADING
INTO MEMORIAL DAY WEEKEND.
INCREASING CAD SIGNAL STRENGTH ENHANCED BY MODERATELY STRONG
EAST/SOUTHEAST LOW LEVEL FLOW AND SOAKING RAINFALL HAS PROMPTED
A CONSIDERABLE BEARISH/LOWER ADJUSTMENT TO MAX TEMPS FRIDAY AND
SATURDAY. IN FACT, HIGHS ON SATURDAY ARE NEAR DAILY RECORD LOWS
AT SEVERAL LOCATIONS (MINI/MAX). GUIDANCE MAY BE TOO OPTIMISTIC
IN REBOUNDING TEMPS SUNDAY INTO MONDAY, BUT OPTED TO KEEP
BASELINE NBM FOR NOW. THAT SAID, THE TREND WILL BE TO MODERATE
WARMER WITH STEADIER RAIN GIVING WAY TO MORE SHOWERY CONDITIONS
FOR THE UNOFFICIAL START OF SUMMER.
NBM/WPC QPF CONTINUES TO SHOW WIDESPREAD 48HR RAINFALL TOTALS
IN THE 1-2 INCH RANGE FRIDAY-SATURDAY. THE COOL/STABLE AIR WILL
CAP RATES WITH LONGER DURATION HELPING TO MITIGATE FLOODING
RISK IN MOST AREAS. THE FORECAST RAINFALL IS MUCH NEEDED OVER
THE FAR SOUTH CENTRAL/SOUTHEASTERN COUNTIES WHO REMAIN UNDER
D1-D2 MODERATE TO SEVERE DROUGHT CONDITIONS.
AVIATION /21Z WEDNESDAY THROUGH MONDAY/
WIDESPREAD SHOWERS AND THUNDERSTORMS ARE ONGOING ACROSS CENTRAL
PA. BETWEEN NOW AND AROUND 00Z THURSDAY IS THE BEST CHANCE FOR
CONVECTIVE RESTRICTIONS TO IMPACT SOUTHERN SITES. THESE INCLUDE
HEAVY RAIN, BRIEF CONVECTIVE WIND GUSTS, LIGHTNING, AND
VISIBILITY DROPS. THE IMMEDIATE CONVECTIVE IMPACTS ARE AT AOO
WITH MDT AND LNS EXPERIENCING THUNDER LIKELY AROUND AND AFTER
20Z. MVFR RESTRICTIONS DUE TO CONVECTION ARE LIKELY WITH BRIEF
IFR POSSIBLE AS WELL.
TRAILING RAIN SHOWERS ARE EXPECTED DURING THE OVERNIGHT WITH
MVFR CEILINGS POSSIBLE AT JST AND AOO, WILL ASSESS POSSIBILITY
OF IFR IN SUBSEQUENT TAF PACKAGES. THESE SHOWERS WILL ALSO
IMPACT MDT AND LNS BUT VFR, BORDERLINE MVFR, CEILINGS EXPECTED.
THESE SHOWERS MAY IMPACT UNV AND IPT BUT CONFIDENCE IS LOWER AT
THESE SITES WITH MOSTLY VFR EXPECTED TO PREVAIL THROUGH THE TAF
PERIOD.
SOUTHEASTERN SITES THURSDAY MORNING INTO THE EARLY AFTERNOON ARE
LIKELY TO SEE DETERIORATING CONDITIONS DUE TO LOWING CLOUD DECKS
AND POSSIBLE RAIN SHOWERS. MVFR IS EXPECTED IN THE MORNING WITH
IFR NOT OUT OF THE QUESTION IN THE LATER MORNING.
OUTLOOK...
FRI...RESTRICTIONS LIKELY WITH RAIN MOVING IN FROM SOUTH TO
NORTH, LASTING INTO FRI NIGHT.
SAT-SUN-MON...RESTRICTIONS LIKELY WITH RAIN.
CTP WATCHES/WARNINGS/ADVISORIES
NONE.
WHAT HAS CHANGED...LAMBERT/
KEY MESSAGES...LAMBERT
DISCUSSION...LAMBERT/STEINBUGL/BOWEN
AVIATION...TEARE/LAMBRECH
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