944
FXUS61 KCTP 061749
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
149 PM EDT SAT SEP 6 2025
SYNOPSIS
* STRONG TO SEVERE STORMS ARE POSSIBLE IN SOUTHEAST PA THIS
AFTERNOON AS A COLD FRONT APPROACHES THE REGION.
* HIGH PRESSURE BUILDS IN FOR SUNDAY THROUGH NEXT WEEK, WITH
ABUNDANT SUNSHINE, MORNING FOG, AND DRY CONDITIONS.
* THE POTENTIAL FOR FROST MOVES BACK INTO THE PICTURE FOR
MONDAY AND TUESDAY MORNINGS ACROSS THE TYPICAL COLD SPOTS IN
NORTHERN PA.
NEAR TERM /THROUGH TONIGHT/
AT 18Z/2PM SATURDAY, A COLD FRONT EXTENDED FROM JUST EAST OF
BEDFORD NORTHEAST TO WILLIAMSPORT COINCIDENT WITH A WEAK LINE OF
SHOWERS, DELINEATING THE WARM MOIST AIRMASS WITH DEWPOINTS INTO
THE UPPER 60S AND 70S TO THE EAST FROM THE COOLDER DRIER
AIRMASS TO THE NORTH AND WEST. THIS BOUNDARY HAS BEEN PARKED
OVER CENTRAL PA THE LAST 48 HOURS OR SO AND WILL FINALLY MOVE
EAST OF THE REGION TONIGHT.
HIGHS TODAY WILL DISPLAY A SIGNIFICANT SPREAD FROM WEST TO
EAST, AND WILL ONLY REACH THE LOW TO MID 60S IN THE
CLOUDY/RAINY/POST FRONTAL AIRMASS OVER NW PA, BUT SHOULD PEAK IN
THE MID 80S AHEAD OF THE FRONT AND BEFORE STORMS ENTER THE
LOWER SUSQUEHANNA VALLEY.
AS THE ONGOING SHOWERS MOVE EASTWARD, THEY WILL ENCOUNTER AN
INCREASINGLY UNSTABLE AIRMASS ENHANCED BY A SURFACE LOW PRESSURE
SYSTEM DRIFTING NORTHEAST ALONG THE BOUNDARY. EFFECTIVE BULK
SHEAR OF 40 TO 50KTS WILL PROVIDE MORE THAN ENOUGH ORGANIZATION
AS STORMS TAP INTO 1000 TO 1500 J/KG OF MLCAPE AS THEY MOVE EAST
OF I-83. THE MAIN LIMITING FACTOR FOR STORMS TODAY WILL BE WEAK
MID- LEVEL LAPSE RATES, BUT A SUFFICIENT PARAMETER SPACE EXISTS
OTHERWISE.
SPC CONTINUES TO PAINT THE SOUTHWESTERN EDGE THE SLIGHT RISK
AREA (AND THREAT FOR LOCALLY SVR TSRA) EXTENDS ACROSS ABOUT 1/2
OF LANCASTER COUNTY AND INTO EXTREME SOUTHEAST YORK COUNTY.
BASED ON THE LATEST CAM TRENDS AND THE AFOREMENTIONED
ENVIRONMENTAL PARAMETERS, A SEVERE THUNDERSTORM WATCH HAS BEEN
HOISTED FOR YORK AND LANCASTER COUNTY UNTIL 8PM. AFTER SUNSET,
STORMS WILL WEAKEN AND THE SEVERE THREAT WILL CEASE. LATEST
GUIDANCE KEEPS RAIN SHOWERS IN LANCASTER COUNTY FOR MUCH OF THE
OVERNIGHT HOURS, BUT RAINFALL AMOUNTS OF 1 TO 1.5 INCHES AT MOST
SHOULD PRECLUDE ANY NOTEWORTHY FLASH FLOOD THREAT.
FARTHER NORTHWEST IN THE WAKE OF THE COLD FRONT, CLOUDS WILL
LIKELY HANG AROUND FOR AWHILE AS THE MOISTURE AT MID-LEVELS IS A
BIT SLOWER TO CLEAR. LAKE EFFECT RAIN SHOWERS WILL RAMP UP
DOWNWIND OF THE LAKE AS WELL THANKS TO WEST-NORTHWEST WINDS
CARRYING COOL AIR OVER THE RELATIVELY WARMER WATERS.
VALLEY FOG IS LIKELY IN THE TYPICAL SPOTS ACROSS THE NORTH AND
WEST ON SUNDAY MORNING IN THE WAKE OF THE FRONT WHERE AIR-WATER
TEMPERATURE DIFFERENCES WILL BE SUFFICIENTLY HIGH TO PROMOTE
DENDRITIC FOG FORMATION. WITH LOWER DEWPOINTS BUILDING IN BEHIND
THE FRONT, LOWS IN THE UPPER 30S COULD BE OBSERVED IN FAR
NORTHWEST PA AND MOST SPOTS WILL FALL INTO THE MID 40S TO UPPER
50S FARTHER SOUTHEAST.
SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/
THE BASE OF AN UPPER TROUGH WILL SWEEP THROUGH THE GREAT LAKES
ON SUNDAY AND LIFT OUT SUNDAY NIGHT AS HIGH PRESSURE BUILDS IN
AT THE SURFACE. 850MB TEMPS IN THE SINGLE DIGITS C WILL PROVIDE
ENOUGH INSTABILITY OVER THE RELATIVELY WARMER LAKE ERIE WATERS
TO PRODUCE SCATTERED LAKE EFFECT RAIN SHOWERS DURING THE DAY ON
SUNDAY. SHOWERS SHOULD PRIMARILY STAY NORTHWEST US-6, BUT A
STRAY SHOWER CANNOT BE RULED OUT AS FAR SOUTHEAST AS THE
I-80/I-99 CORRIDOR.
MOSTLY SUNNY SKIES ARE ON TAP FOR THE REST OF THE COMMONWEALTH
AS TEMPERATURES TREND A BIT BELOW AVERAGE FOR THIS TIME OF YEAR.
A GUSTY WEST WIND AND REFRESHLINGLY LOW HUMIDITY WILL MAKE FOR A
PERFECT FALL DAY.
HIGH PRESSURE WILL MOVE DIRECTLY OVERHEAD ON MONDAY MORNING,
BRINGING HIGH CONFIDENCE IN RIVER VALLEY FOG AND FROST ACROSS
NORTHERN PA. A FEW SPOTS COULD EVEN EXPERIENCE THEIR FIRST
FREEZE OF THE YEAR. FROST ADVISORIES WILL BE NEEDED FOR PORTIONS
OF NORTHERN PA. LOWS ON MONDAY MORNING WILL RANGE FROM NEAR
FREEZING IN MCKEAN COUNTY TO NEAR 50 IN THE LOWER SUSQUEHANNA
VALLEY THANKS TO IDEAL RADIATIONAL COOLING CONDITIONS AND A VERY
DRY AIRMASS (10TH PERCENTILE PWATS FOR THIS TIME OF YEAR).
LONG TERM /MONDAY THROUGH FRIDAY/
THE FALL-LIKE PATTERN WILL CONTINUE THROUGH NEXT WEEK. THE
AIRMASS MOVING OVERHEAD WILL BE THE COOLEST OF THE SEASON SO
FAR. HIGHS IN THE 60S AND 70S WILL PAIR WITH LOWS IN THE 30S TO
50S. FROST CONDITIONS ARE POSSIBLE AGAIN ON TUESDAY MORNING FOR
THE TYPICAL COOL SPOTS IN NORTHWEST PA WITH RIVER VALLEY FOG
CONTINUING EACH MORNING THROUGH THE END OF THE WEEK. ABUNDANT
SUNSHINE AND DRY CONDITIONS ARE FAVORED, WITH TEMPERATURES
GRADUALLY INCREASING EACH DAY THANKS TO A BUILDING RIDGE ALOFT.
AVIATION /18Z SATURDAY THROUGH THURSDAY/
SCATTERED SHOWERS ARE BEGINNING TO DEVELOP OVER THE LOWER
SUSQUEHANNA VALLEY AHEAD OF A COLD FRONT. ADDITIONAL SHOWERS AND
STORMS ARE EXPECTED TO DEVELOP THIS AFTERNOON AND ARE MOST
LIKELY TO IMPACT MDT AND LNS. ANY THUNDERSTORMS WILL BE CAPABLE
OF PRODUCING STRONG WIND GUSTS AND VERY HEAVY RAINFALL. WHILE
SHOWERS WILL BE POSSIBLE NORTH AND WEST OF THOSE SITES AS WELL,
COVERAGE IS EXPECTED TO BE TOO LIMITED TO MENTION IN THE TAFS.
MOST OF THE REGION WILL DRY OUT OVERNIGHT, BUT RAIN WILL LIKELY
CONTINUE AT MDT AND LNS INTO THE MORNING. PATCHY FOG SHOULD
DEVELOP NORTH AND WEST OF UNV, BUT CONFIDENCE ON ANY
RESTRICTIONS AT BFD, JST, AND IPT IS LOW. CLOUD COVER WILL
INCREASE OVER NORTHWEST PA TOWARDS SUNRISE AND LAKE EFFECT RAIN
SHOWERS ARE EXPECTED AT BFD DURING THE DAY ON SUNDAY. THE REST
OF THE REGION WILL BE DRY WITH VFR CONDITIONS.
OUTLOOK...
SUN-MON...CLEARING WITH PRIMARILY VFR CONDITIONS. BREEZY.
TUE-WED...VFR.
CTP WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...BANGHOFF
NEAR TERM...BANGHOFF
SHORT TERM...BANGHOFF
LONG TERM...BANGHOFF
AVIATION...BAUCO
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