218
FXUS61 KPHI 170534
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
134 AM EDT THU SEP 17 2026
WHAT HAS CHANGED
AVIATION SECTION UPDATED FOR THE 06Z TAFS.
KEY MESSAGES
1. HIGH PRESSURE ALONG THE EASTERN SEABOARD MOVES OUT TO SEA AS
A COLD FRONT APPROACHES FROM THE WEST.
2. SCATTERED SHOWERS AND A FEW STORMS ARE POSSIBLE THURSDAY
NIGHT AS A COLD FRONT MOVES THROUGH THE REGION.
3. A STRETCH OF UNSETTLED WEATHER WILL BEGIN SATURDAY NIGHT
INTO SUNDAY, CONTINUING INTO THE FIRST HALF OF NEXT WEEK.
MONITORING THE POTENTIAL FOR HEAVY RAIN.
DISCUSSION
KEY MESSAGE 1...HIGH PRESSURE ALONG THE EASTERN SEABOARD MOVES
OUT TO SEA AS A COLD FRONT APPROACHES FROM THE WEST.
HIGH PRESSURE ALONG THE EASTERN SEABOARD MOVES OUT TO SEA
TONIGHT. MEANWHILE, A COLD FRONT MOVING THROUGH THE OHIO VALLEY
CONTINUES TO TRACK EAST. SOUTHERLY FLOW DEVELOPS TONIGHT AND
THEN INCREASES ON THURSDAY. A WARM AND HUMID DAY, AT LEAST BY
MID-SEPTEMBER STANDARDS, SETS UP ON THURSDAY WITH HIGHS IN THE
LOW TO MID 80S AND SURFACE DEW POINTS IN THE MID TO UPPER 60S.
SOME SHOWERS, PERHAPS A THUNDERSTORM, MAY MOVE INTO THE SOUTHERN
POCONOS, LEHIGH VALLEY, AND FAR NORTHWEST NEW JERSEY STARTING
AROUND MIDDAY AND INTO THE LATE AFTERNOON.
KEY MESSAGE 2...SCATTERED SHOWERS AND A FEW STORMS ARE POSSIBLE
THURSDAY NIGHT AS A COLD FRONT MOVES THROUGH THE REGION.
THE AFOREMENTIONED COLD FRONT WILL TRACK FROM NORTHWEST TO
SOUTHEAST ACROSS THE REGION THURSDAY NIGHT, CLEARING THE REGION
BY FRIDAY MORNING. AS IT DOES SO, ISOLATED TO SCATTERED SHOWERS
AND PERHAPS A FEW STORMS WILL BE POSSIBLE ACROSS MOST OF THE
AREA. HOWEVER, SHOWER AND STORM ACTIVITY ASSOCIATED WITH THIS
FRONT WILL BE OUTRUNNING INSTABILITY AS IT TRACKS INTO THE AREA,
WITH A NOCTURNAL INVERSION DEVELOPING AND ONLY MODEST ELEVATED
INSTABILITY REMAINING. SOME LOCALLY HEAVY RAINFALL CAN'T BE
ENTIRELY RULED OUT GIVEN PWATS OF 1.5 TO 2 INCHES, BUT COVERAGE
LOOKS LIMITED AND THE FRONT LOOKS PROGRESSIVE ENOUGH THAT HYDRO
CONCERNS ARE NOT ANTICIPATED. SEVERE WEATHER IS NOT ANTICIPATED.
THE FRONT WILL USHER IN A DRIER AIRMASS FOR FRIDAY, BUT
TEMPERATURES WILL ONLY COOL BY A COUPLE OF DEGREES RELATIVE TO
THURSDAY.
KEY MESSAGE 3...A STRETCH OF UNSETTLED WEATHER WILL BEGIN
SATURDAY NIGHT INTO SUNDAY, CONTINUING INTO THE FIRST HALF OF
NEXT WEEK. MONITORING THE POTENTIAL FOR HEAVY RAIN.
AS WE HEAD INTO THE WEEKEND, MID-LEVEL RIDGING THAT HAS BEEN
CENTERED OVER PORTIONS OF THE SOUTHEAST AND MID-ATLANTIC WILL
SLOWLY BEGIN TO RETROGRADE SOUTHWESTWARD TOWARDS THE GULF COAST.
ENHANCED NORTHWESTERLY FLOW ALOFT WILL THEN OVERSPREAD THE
REGION BEGINNING THIS WEEKEND AS MULTIPLE DISTURBANCES PASS TO
THE NORTH OVER PORTIONS OF ONTARIO AND QUEBEC. AT THE SURFACE,
HIGH PRESSURE CENTERED NORTH OF THE REGION WILL SHIFT EASTWARD
AND OFFSHORE SATURDAY AS A LOW PRESSURE SYSTEM TRACKS OUT OF THE
OHIO VALLEY AND GREAT LAKES REGION TOWARDS THE AREA. AN
ASSOCIATED WARM FRONT LOOKS TO MOVE THROUGH THE AREA SUNDAY
MORNING, WITH A COLD FRONT PASSING THROUGH THE AREA BY MONDAY.
AT THIS TIME, THIS FRONT LOOKS LIKELY TO STALL JUST SOUTH OF THE
REGION THROUGH THE MIDDLE OF NEXT WEEK.
SATURDAY SHOULD BE A DRY AND SEASONABLE DAY WITH TEMPERATURES
GENERALLY TOPPING OUT IN THE 70S TO NEAR 80. BEGINNING SATURDAY
NIGHT, CHANCES FOR SHOWERS AND STORMS WILL BEGIN TO INCREASE
ACROSS THE AREA AS THE LOW PRESSURE AND ASSOCIATED FRONTAL
BOUNDARIES BEGIN THEIR APPROACH TO THE REGION. SUNDAY INTO
SUNDAY NIGHT, SCATTERED TO NUMEROUS SHOWERS AND STORMS ARE
EXPECTED ACROSS THE REGION. IT CURRENTLY APPEARS THAT
INSTABILITY WILL BE MODEST AT BEST LIMITING ANY SEVERE THREAT.
HOWEVER, PWATS LOOK TO BE NEAR 2 INCHES WITH DEEPLY SATURATED
VERTICAL COLUMNS. GIVEN THIS, AT LEAST A LIMITED HYDRO THREAT
COULD EVOLVE. CURRENTLY, WPC HAS PLACED FAR NORTHWESTERN
PORTIONS OF OUR EASTERN PA COUNTIES IN A MARGINAL RISK (1 OF 4)
EXCESSIVE RAINFALL OUTLOOK FOR SATURDAY NIGHT, WITH THAT RISK
EXPANDING ACROSS THE ENTIRE AREA SUNDAY.
ONCE THE FRONT CLEARS THE REGION SUNDAY NIGHT OR MONDAY,
UNCERTAINTY INCREASES SUBSTANTIALLY. GUIDANCE AGREES THAT THE
FRONTAL BOUNDARY WILL STALL TO THE SOUTH OF THE REGION WITH A
FEW WAVES OF LOW PRESSURE RIDING ALONG IT. SHOULD THE BOUNDARY
STALL JUST SOUTH OF THE REGION OR EVEN OVER SOUTHERN PARTS OF
THE AREA, SCATTERED SHOWER AND STORM CHANCES WILL LIKELY
CONTINUE THROUGH MID-WEEK. IF IT STALLS FARTHER SOUTH, IT MAY
NOT BE QUITE AS UNSETTLED ACROSS OUR REGION. FOR NOW, MOST OF
THE REGION HAS POPS RANGING FROM 30-50% MONDAY THROUGH
WEDNESDAY.
HIGHER CONFIDENCE EXISTS IN NEAR OR SLIGHTLY BELOW NORMAL
TEMPERATURES ACROSS THE REGION FOR THE EARLY PARTS OF NEXT WEEK
NORTH OF THE FRONT.
AVIATION /06Z THURSDAY THROUGH MONDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
REST OF TONIGHT (THROUGH 12Z)...VFR. A FEW LIGHT SHRA MAY
IMPACT KRDG/KABE, BUT IMPACTS NOT EXPECTED. WINDS 5 KTS OR LESS
FAVORING A SOUTHERLY DIRECTION. HIGH CONFIDENCE IN PREVAILING
CONDITIONS.
THURSDAY...OVERALL, VFR. CHANCE (30% OR LESS) OF A SHOWER OR
STORM IMPACTING RDG/ABE IN THE AFTERNOON. AN ISOLATED
THUNDERSTORM CANNOT BE RULED OUT, BUT WILL NOT BE MENTIONED IN
THE TAFS AT THIS TIME. SOUTH TO SOUTHWEST WINDS 5 TO 10 KT.
HIGH CONFIDENCE IN PREVAILING CONDITIONS.
THURSDAY NIGHT...PREVAILING VFR. BRIEF RESTRICTIONS WILL BE
POSSIBLE IN ISOLATED TO SCATTERED SHOWERS AND STORMS. MVFR
CEILINGS POSSIBLE AT RDG/ABE BY 06Z, BUT LOW CONFIDENCE ON THIS.
OUTLOOK...
FRIDAY THROUGH SATURDAY...VFR. NO SIGNIFICANT WEATHER.
SATURDAY NIGHT THROUGH MONDAY...SCATTERED TO NUMEROUS SHOWERS
AND STORMS WILL LIKELY LEAD TO SUB-VFR CONDITIONS AT TIMES.
MARINE
NO MARINE HAZARDS THROUGH THURSDAY WITH WINDS OUT OF THE
SOUTH/SOUTHWEST AROUND 5 TO 15 KT AND SEAS 2 TO 3 FEET.
OUTLOOK...
THURSDAY NIGHT THROUGH SUNDAY NIGHT...NO MARINE HAZARDS
CURRENTLY ANTICIPATED WITH WINDS UNDER 25 KT AND SEAS UNDER 5
FEET.
MONDAY...ADVISORY CONDITIONS ARE POSSIBLE. EAST-NORTHEAST WINDS
WILL INCREASE TO 15-20 KT WITH GUSTS 25-30 KT. SEAS 4-6 FEET.
RIP CURRENTS...
THURSDAY...SOUTHERLY FLOW INCREASES SOME, BUT BREAKING WAVES OF
1-2 FEET WITH A 6-8 SECOND PERIOD REMAIN FORECAST. THEREFORE, A
LOW RISK FOR THE DEVELOPMENT OF DANGEROUS RIP CURRENTS ARE
FORECAST AT ALL NEW JERSEY AND DELAWARE BEACHES.
FRIDAY...WINDS TURN OFFSHORE, PREDOMINATELY OUT OF THE NORTH-
NORTHWEST. BREAKING WAVES OF 1-2 FEET WITH A 6-8 SECOND PERIOD
ARE EXPECTED TO CONTINUE THOUGH, RESULTING IN A LOW RISK FOR THE
DEVELOPMENT OF DANGEROUS RIP CURRENTS AT ALL NEW JERSEY AND
DELAWARE BEACHES.
FOR SPECIFIC BEACH FORECASTS, VISIT WEATHER.GOV/BEACH/PHI
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
DISCUSSION...COOPER/MPS
AVIATION...COOPER/MJL/MPS/STAARMANN
MARINE...AKL/COOPER/MPS
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