740
FXUS61 KPHI 270721
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
321 AM EDT THU AUG 27 2026
WHAT HAS CHANGED
FLOOD WATCH EXPANDED TO INCLUDE THE LEHIGH VALLEY AND BERKS
COUNTY.
UPDATED THE AVIATION SECTION FOR THE 06Z TAFS.
KEY MESSAGES
1. A WARM FRONT ON THURSDAY WILL BRING THE NEXT CHANCE FOR
WIDESPREAD RAIN.
2. A COLD FRONT IS EXPECTED TO FOLLOW CLOSE BEHIND ON FRIDAY.
DISCUSSION
KEY MESSAGE 1...A WARM FRONT TOMORROW WILL BRING THE NEXT
CHANCE FOR WIDESPREAD RAIN.
HIGH PRESSURE MOVES OFFSHORE WITH SOUTHERLY RETURN FLOW BEHIND
A WARM FRONT WILL BRING DEW POINTS INTO THE LOW 70S. SHOWERS AND
THUNDERSTORMS WILL START MOVING INTO WESTERN AREAS BEFORE
DAYBREAK AND CONTINUE THROUGH THE DAY. CAMS PRODUCING SOME
ORGANIZATION TO CONVECTIVE ACTIVITY LARGELY FOCUSED ON THE I-95
URBAN CORRIDOR.
AS FOR THE HAZARDS, THERE IS A SLIGHT (2 OUT OF 4) RISK FOR
EXCESSIVE RAINFALL. PRECIPITABLE WATER VALUES INCREASE TO
PERHAPS AS HIGH AS 150% OF NORMAL FOR THIS TIME OF YEAR.
THE HIRES GUIDANCE SUGGESTS THAT HEAVIEST PRECIPITATION WILL BE
GENERALLY ALONG THE I-95 CORRIDOR AND POINTS NORTHWEST. HIRES
GUIDANCE HAS ALSO POINTED TO AREAS ALONG THE I-78 CORRIDOR
POTENTIALLY SEEING HEAVY RAINFALL AMOUNTS AS WELL. GENERALLY
AROUND 1-2 INCHES OF RAIN WITH LOCALIZED QPF VALUES IN EXCESS OF
3 INCHES. WIDESPREAD FLASH FLOODING STILL SEEMS UNLIKELY, BUT
THE LOCALIZED THREAT REMAINS ELEVATED. THE FLOOD WATCH WAS
EXPANDED TO INCLUDE THE LEHIGH VALLEY AND BERKS COUNTY AND
REMAINS IN EFFECT FOR NORTHERN NJ AND THE I-95 CORRIDOR.
FOR SEVERE HAZARDS, LATEST CAMS AND HREF GUIDANCE SHOW SBCAPE
VALUES REMAINING AROUND 1500-2500 J/KG WITH ENSEMBLE MAXIMUMS
IN EXCESS 3000 J/KG. DEEP LAYER SHEAR FORECASTS REMAIN AROUND
30KT WITH A STRONGLY VEERING PROFILE ALOFT. BOUNDARY LAYER FLOW
IS NOT PARTICULARLY STRONG BUT SURFACE WINDS ARE MORE BACKED
THAN PREVIOUS FORECASTS SO AN ISOLATED TORNADO IS POSSIBLE
PRIMARILY ALONG AND WEST OF I-95. THAT SAID, DAMAGING WIND GUSTS
AND HAIL WILL REMAIN THE GREATEST THREAT. DOMINANT MODE SHOULD
BE MULTICELL CONVECTION BUT A SUPERCELL CAN'T BE RULED OUT
ESPECIALLY WHERE CLOUD BEARING SHEAR IS MAXIMIZED. SPC HAS
EXPANDED THE AREA OF A SLIGHT RISK (2 OUT OF 5) TO NOW INCLUDE
MUCH OF THE AREA.
KEY MESSAGE 2...A COLD FRONT WILL CROSS THE AREA FRIDAY.
THE TIMING OF THIS COLD FRONT WILL BE CRITICAL IN THE RISK FOR
THUNDERSTORM HAZARDS. THERE ARE DIFFERENCES BETWEEN MODELS IN
BOTH THE TIMING, AND IF THIS WILL BE A SINGLE COLD FRONT, OR AN
INITIAL COLD FRONT WITH A REINFORCING SHOT OF COLD AIR ADVECTION
COMING IN BEHIND IT. SATURDAY AND SUNDAY APPEAR TO BE DRY ACROSS
MOST OF THE AREA WITH THE EXCEPTION OF SOUTHERN AREAS SATURDAY
WHERE LOW PROBABILITIES OF SHOWERS AND STORMS WILL EXIST.
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 WITH INCREASING MID AND
HIGH CLOUDS. SHOWERS AND PERHAPS AN EMBEDDED THUNDERSTORM
DEVELOP AFTER 06Z FOR MAINLY THE LEHIGH VALLEY TERMINALS AND WAS
HANDLED WITH VCSH WITH A PROB30 FOR -TSRA. WINDS ARE MORE
SOUTHERLY OVERNIGHT AT AROUND 5 KNOTS.
THURSDAY...MAINLY VFR. LIGHT SOUTH WINDS IN THE MORNING BECOME
MORE OUT OF THE SOUTH-SOUTHWEST AT AROUND 10 KNOTS DURING THE
AFTERNOON WITH GUSTS TO 20 KNOTS FOR KMIV/KACY. FOR THE LEHIGH
VALLEY AND I-95 TERMINALS, SHOWERS AND POTENTIALLY AN EMBEDDED
THUNDERSTORM ARE POSSIBLE IN THE MORNING WHICH WAS HANDLED WITH
VCSH WITH A PROB30 FOR -TSRA. AS THE POTENTIAL FOR SHOWERS AND
THUNDERSTORMS INCREASES FROM MIDDAY INTO THE EVENING, VCTS AND
PROB30 GROUPS FOR TSRA FOR MOST TERMINALS TO ACCOUNT FOR THIS
ACTIVITY.
OUTLOOK...
FRIDAY...PERIODS OF MVFR OR LOWER ARE POSSIBLE IN SHOWERS AND
STORMS.
SATURDAY THROUGH MONDAY...PREVAILING VFR CONDITIONS.
MARINE
NO MARINE HAZARDS EXPECTED. SOUTHERLY WINDS WITH GUSTS NEAR 20
KT POSSIBLE.
OUTLOOK...
THURSDAY NIGHT AND THROUGH SUNDAY...NO MARINE HAZARDS EXPECTED.
RIP CURRENTS...
ON THURSDAY, WINDS REMAIN SOUTHERLY AT 10 TO 15 MPH WITH GUSTS
TO 20 TO 25 MPH. THERE IS AN EAST-SOUTHEASTERLY SWELL WITH A
PERIOD OF 8-9 SECONDS AND BREAKING WAVES AROUND 2-3 FEET. AS A
RESULT, THERE IS A MODERATE RISK FOR THE DEVELOPMENT OF
DANGEROUS AND LIFE THREATENING RIP CURRENTS AT THE JERSEY SHORE
AND A LOW RISK AT DELAWARE BEACHES.
FOR FRIDAY, WINDS IN THE MORNING ARE MORE WESTERLY AT 5 TO 10
MPH BEFORE BECOMING MORE SOUTHWESTERLY IN THE AFTERNOON AT 5 TO
10 MPH. AN EAST-SOUTHEASTERLY SWELL REMAINS WITH A PERIOD OF
6-7 SECONDS WITH BREAKING WAVES AROUND 2-3 FEET. AS A RESULT,
THERE IS A MODERATE RISK FOR THE DEVELOPMENT OF DANGEROUS AND
LIFE THREATENING RIP CURRENTS AT THE JERSEY SHORE AND A LOW RISK
AT DELAWARE BEACHES.
FOR SPECIFIC BEACH FORECASTS, VISIT WEATHER.GOV/BEACH/PHI
PHI WATCHES/WARNINGS/ADVISORIES
PA...FLOOD WATCH FROM NOON EDT TODAY THROUGH LATE TONIGHT FOR
PAZ060>062-070-071-101>106.
NJ...FLOOD WATCH FROM NOON EDT TODAY THROUGH LATE TONIGHT FOR
NJZ001-007>010-012-013-015-017>019.
DE...FLOOD WATCH FROM NOON EDT TODAY THROUGH LATE TONIGHT FOR
DEZ001.
MD...NONE.
MARINE...NONE.
DISCUSSION...WFO PHI
AVIATION...WFO PHI
MARINE...WFO PHI
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