552
FXUS61 KPHI 110653
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
253 AM EDT FRI SEP 11 2026
WHAT HAS CHANGED
UPDATED DISCUSSION FOR UPCOMING FRONTS BASED ON THE LATEST
GUIDANCE, AND UPDATED AVIATION DISCUSSION.
THERE IS INCREASING CONCERN FOR A HEAVY RAIN/FLASH FLOOD THREAT
WITH SHOWERS AND STORMS LATE SATURDAY INTO SUNDAY.
KEY MESSAGES
1. A COLD FRONT WILL CONTINUE TO DIG SOUTH THROUGH EARLY THIS
MORNING, BRINGING THE POTENTIAL FOR A ROUND OF SHOWERS AND
ISOLATED THUNDERSTORMS.
2. A LOW APPROACHING THE AREA SATURDAY INTO SUNDAY WILL BRING A
WARM FRONT FOLLOWED CLOSE BEHIND BY A COLD FRONT.
3. DURING THE LATER HALF OF NEXT WEEK, A STATIONARY FRONT MAY
SET UP JUST NORTH OF OUR REGION.
DISCUSSION
KEY MESSAGE 1...A COLD FRONT WILL CONTINUE TO DIG SOUTH THROUGH
EARLY THIS MORNING, BRINGING THE POTENTIAL FOR A ROUND OF
SHOWERS AND ISOLATED THUNDERSTORMS.
THE COLD FRONT CONTINUES TO SLIDE SOUTH OVER THE REGION. WE
COULD STILL SEE A ROUND OF SHOWERS AND MAYBE AN ISOLATED
THUNDERSTORM DURING THE PRE-DAWN/DAWN HOURS, BUT GIVEN UPSTREAM
RADAR TRENDS, IT LOOKS AS IF THE MAIN MODE WILL BE LIGHT RAIN
SHOWERS. THERE IS STILL AMPLE LOW LEVEL MOISTURE AS EVIDENCED BY
THE 70+ DEGREE DEW POINTS, BUT LIFT IS MEAGER, AND INSTABILITY
IS QUITE LIMITED, ESPECIALLY THE LATER THIS IS BEFORE SHOWERS
MOVE INTO THE REGION.
FOLLOWING ANY MORNING SHOWERS, FRIDAY WILL SHAPE UP TO BE A NICE
DAY WITH CLOUDS BREAKING LATER IN THE DAY. HIGHS IN THE UPPER
70S TO LOW 80S IN MOST AREAS.
KEY MESSAGE 2...A LOW APPROACHING THE AREA SATURDAY INTO SUNDAY
WILL BRING A WARM FRONT FOLLOWED CLOSE BEHIND BY A COLD FRONT.
ONCE THE COLD FRONT THIS MORNING SLIDES SOUTH OF OUR REGION, OUR
ATTENTION NEXT TURNS TO THE SATURDAY/SUNDAY TIME PERIOD WHEN
FIRST A WARM FRONT WILL LIFT THROUGH THE REGION ON SATURDAY,
FOLLOWED CLOSELY BY A COLD FRONT SATURDAY NIGHT INTO SUNDAY. THE
EXACT EVOLUTION OF THE MID LEVEL SHORT WAVE TROUGH AND SURFACE
LOW OR TROUGH IS STILL UNCERTAIN. REGARDLESS, THERE SHOULD BE
PLENTY OF LIFT, EVEN JUST WITH THE FRONTS, FOR WIDESPREAD
SHOWERS AND THUNDERSTORMS, PARTICULARLY AHEAD OF THE COLD FRONT
SATURDAY NIGHT INTO SUNDAY.
AS FOR THE HAZARDS, THE MAIN THREAT REMAINS HEAVY RAIN AND FLASH
FLOODING. MODEL SOUNDINGS CONTINUE TO INDICATE PRECIPITABLE
WATER VALUES WELL ABOVE THE 90TH PERCENTILE AND EVEN AT OR
EXCEEDING MANY OF THE DAILY MAX VALUES FOR SURROUNDING SOUNDING
LOCATIONS. MODEL SOUNDINGS ALSO SHOW REMARKABLY DEEP WARM CLOUD
LAYERS (FOR MID SEPTEMBER), FURTHER INCREASING THE CONCERN FOR
HEAVY RAIN. THE BIG QUESTIONS AT THIS POINT ARE HOW QUICKLY ARE
THE FRONTS (AND THUS STORMS) GOING TO MOVE THROUGH OUR REGION,
AND WHERE WILL THE AXIS OF HEAVIEST RAIN BE. GIVEN THAT WE'VE
HAD AT THIS POINT A WEEK OF LITTLE RAIN, RIVERS ARE IN PRETTY
GOOD SHAPE IN TERMS OF LOWER WATER LEVELS LIMITING THE CONCERN
FOR RIVER FLOODING. THE BIGGER CONCERN WITH THIS EVENT WILL BE
FLASH FLOODING, PARTICULARLY IF THE HEAVIER RAINS FALL IN OUR
MORE FLASH FLOOD PRONE URBAN AREAS, AND FLOODING ON SMALLER
CREEKS AND STREAMS.
GIVEN THE FORECASTED TIMING OF THIS EVENT, INSTABILITY LOOKS TO
BE QUITE LIMITED. THUS THE THREAT FOR SEVERE THUNDERSTORM
HAZARDS (DAMAGING WINDS, LARGE HAIL, AND TORNADOES) IS VERY
LIMITED.
IN THE WAKE OF THE COLD FRONT ON SUNDAY, DRIER AIR SHOULD START
TO SETTLE IN TO THE AREA. A FEW MODELS ARE DEPICTING A SECONDARY
COLD FRONT MOVING THROUGH THE REGION SUNDAY NIGHT. THAT COULD
BRING SOME ISOLATED SHOWERS TO THE REGION, BUT GIVEN THE DRIER
AIR IN PLACE, THE VAST MAJORITY OF THE REGION SHOULD STAY DRY.
KEY MESSAGE 3...DURING THE LATER HALF OF NEXT WEEK, A
STATIONARY FRONT MAY SET UP JUST NORTH OF OUR REGION.
ONCE WE GET THROUGH THIS WEEKEND, ATTENTION WILL TURN TO
THURSDAY AND FRIDAY OF NEXT WEEK. MODELS ARE DEPICTING A
STATIONARY FRONT SETTING UP NORTH OF OUR REGION. THE NORTHERN
HALF OF OUR REGION ALREADY HAS 40 TO 60% CHANCE FOR SHOWERS AND
STORMS THROUGH THIS PERIOD. HOWEVER, OF BIGGER NOTE, THE PATTERN
HAS SIMILARITIES TO THE MADDOX FRONTAL EVENT HEAVY RAIN PATTERN.
GIVEN HOW IT IS CURRENTLY DEPICTED ON MOST MODELS, EVEN IF THE
SIMILARITIES CONTINUE, THE MAIN AREA OF HEAVY RAIN RAIN WOULD BE
NORTH OF OUR REGION. HOWEVER, IF WE SEE ANY TRENDS OF THE FRONT
SETTING UP FURTHER SOUTH, THAT COULD INCREASE THE RISK FOR HEAVY
RAIN WITHIN OUR REGION.
AVIATION /06Z FRIDAY THROUGH TUESDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
THROUGH TODAY...PREVAILING VFR. WINDS START NORTH/NORTHEASTERLY
AROUND 5 TO 10 KT, EVENTUALLY BECOMING LIGHT AND VARIABLE AFTER
18Z. A SEA- BREEZE MAY DEVELOP RESULTING IN MORE EAST/SOUTHEAST
WINDS AT KACY/KMIV BUT WINDS SHOULD BE RATHER LIGHT.
TONIGHT...VFR. WINDS LIGHT AND VARIABLE AS THEY SLOWLY SETTLE
OUT OF THE SOUTHEAST.
TOMORROW...PREVAILING VFR. SCATTERED SHRA AND TSRA MAY
TEMPORARILY LOWER CONDITIONS TO MVFR OR EVEN IFR, PARTICULARLY
AFTER 18Z, AND PARTICULARLY FOR KILG AND KRDG.
OUTLOOK...
SATURDAY NIGHT THROUGH SUNDAY...PERIODS OF SUB-VFR CONDITIONS
WILL BE POSSIBLE WITH SCATTERED SHOWERS AND STORMS.
SUNDAY NIGHT THROUGH TUESDAY...VFR.
MARINE
WINDS AND SEAS SHOULD STAY BELOW SMALL CRAFT ADVISORY CRITERIA
THROUGH EARLY NEXT WEEK. HOWEVER, GUSTY AND ERRATIC WINDS WILL
BE POSSIBLE IN THE VICINITY OF ANY SHOWERS AND THUNDERSTORMS
PARTICULARLY SATURDAY NIGHT INTO SUNDAY.
RIP CURRENTS...
ON FRIDAY, WINDS TURN MORE NORTHERLY AND WILL BE AROUND 5 TO 10
MPH. BREAKING WAVES DECREASE TO 2 FEET OR LESS. DOMINANT SWELL
WILL BE AROUND 1-2 FEET WITH A PERIOD OF 6 TO 8 SECONDS FROM THE
SOUTHEAST. WITH MORE TRANQUIL CONDITIONS EXPECTED TO CLOSE OUT
THE WEEK, THERE WILL BE A LOW RISK FOR RIP CURRENTS AT ALL
BEACHES.
ON SATURDAY, WINDS TURN MORE ONSHORE, FROM THE ESE TO SE, AROUND
10-15 MPH. BREAKING WAVES REMAIN AROUND 1-2 FEET. THE DOMINANT
SWELL WILL BE AROUND 1 FOOT WITH A PERIOD OF 9 SECONDS FROM THE
SOUTHEAST. GIVEN THE MORE ROBUST ONSHORE FLOW, THERE WILL BE A
MODERATE RISK FOR RIP CURRENTS AT NEW JERSEY BEACHES AND A LOW
RISK FOR RIP CURRENTS AT DELAWARE BEACHES.
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
DISCUSSION...WFO PHI
AVIATION...WFO PHI
MARINE...WFO PHI
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