177
FXUS61 KPHI 181111
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
711 AM EDT SAT JUL 18 2026
WHAT HAS CHANGED
AVIATION SECTION UPDATED FOR 12Z TAFS.
KEY MESSAGES
1. SMOKE FROM CANADIAN WILDFIRES WILL BE SWEPT AWAY TODAY.
2. WIDESPREAD SEVERE WEATHER AS WELL AS FLASH FLOODING WILL BE
POSSIBLE FOR TODAY INTO TONIGHT. CONDITIONS WILL ALSO BE WARM
AND VERY HUMID.
3. MAINLY FAIR AND DRY WEATHER IS EXPECTED FOR SUNDAY THROUGH
MONDAY BEFORE THE NEXT CHANCE FOR SHOWER AND STORMS RETURNS BY
LATE TUESDAY.
DISCUSSION
KEY MESSAGE 1...SMOKE FROM CANADIAN WILDFIRES WILL BE SWEPT
AWAY TODAY.
SMOKE FROM THE CANADIAN WILDFIRES REMAINS IN THE REGION EARLY
THIS MORNING. HOWEVER, THE DEVELOPING SOUTHERLY FLOW SHOULD
START TO PUSH THE SMOKE OUT BY THIS AFTERNOON INTO THIS
EVENING. EXPECTED CONVECTION (SEE BELOW) MAY ALSO HELP IMPROVE
THINGS.
KEY MESSAGE 2...WIDESPREAD SEVERE WEATHER AS WELL AS FLASH
FLOODING WILL BE POSSIBLE FOR TODAY INTO TONIGHT. CONDITIONS
WILL ALSO BE WARM AND VERY HUMID.
BOTTOM LINE UP FRONT: THERE REMAINS AN ELEVATED THREAT FOR
RELATIVELY WIDESPREAD SEVERE WEATHER AND FLASH FLOODING FOR
TODAY INTO TONIGHT. A FLOOD WATCH REMAINS IN EFFECT FOR A LARGE
PORTION OF THE AREA FROM THE URBAN CORRIDOR NORTHWARD STARTING
AT 10 AM AND CONTINUING UNTIL 2 AM TONIGHT. ALSO, THE STORM
PREDICTION CENTER HAS NOW PLACED THE REGION IN AN ENHANCED RISK
FOR SEVERE WEATHER. THIS MEANS THAT INSTANCES OF SEVERE WEATHER
COULD BE FAIRLY WIDESPREAD ACROSS THE AREA COMPARED TO THE MORE
TYPICAL SCATTERED COVERAGE THAT WE OFTEN SEE. THE GREATEST
THREAT WILL BE FOR DAMAGING WINDS BUT THERE IS ALSO THE THREAT
OF A FEW TORNADOES, AND THE THREAT OF TORNADOES HAS INCREASED A
BIT MORE THIS MORNING, WITH POTENTIAL FOR AN EF2. THE GREATEST
THREAT FOR SEVERE WEATHER LOOKS TO BE BETWEEN NOON AND 10 PM.
GETTING INTO THE WEEDS, LOW PRESSURE WILL BE MOVING INTO
PORTIONS OF EASTERN ONTARIO AND SOUTHERN QUEBEC BY LATE
TODAY. THIS WILL PUSH A WARM FRONT THROUGH THIS MORNING
FOLLOWED BY A COLD FRONT LATER TONIGHT. WE ARE STILL EXPECTING
THERE WILL BE MULTIPLE ROUNDS OF SHOWERS AND STORMS THAT OCCUR.
THE FIRST LOOKS LIKE IT WILL MOVE THROUGH THIS MORNING TO
MIDDAY AND AFFECT AREAS MAINLY NEAR AND ESPECIALLY NORTH OF THE
URBAN CORRIDOR. HEAVY RAINFALL WITH THE POTENTIAL FOR FLASH
FLOODING WILL BE POSSIBLE BUT THE RISK OF SEVERE WEATHER LOOKS
RELATIVELY LOWER COMPARED TO LATER IN THE DAY.
FOLLOWING THIS FIRST ROUND MOST AREAS SHOULD SEE A BREAK OF
SEVERAL HOURS IN THE AFTERNOON. IT IS DURING THIS TIME THAT
TEMPERATURES AND DEW POINTS RAMP UP. GENERALLY EXPECT HIGHS IN
THE 80S WITH HEAT INDICES OF OVER 90 FOR MUCH OF THE AREA WITH
THE POTENTIAL FOR HEAT INDICES TO HIT NEAR 100 TO 105 NEAR AND
SOUTH OF AROUND PHILLY WHERE HIGHS WILL RANGE FROM THE UPPER 80S
TO MID 90S. A HEAT ADVISORY HAS BEEN ISSUED FOR PORTIONS OF THE
EASTERN SHORE OF MARYLAND WHERE 105 OR GREATER HEAT INDICES LOOK
LIKELY. FURTHER NORTH, LINGERING SMOKE AND CLOUD COVER/PRECIP
MAY HOLD TEMPS DOWN JUST ENOUGH TO PREVENT ADVISORY CRITERIA
FROM BEING REACHED.
ML CAPE VALUES LOOK TO REALLY SURGE IN THE AFTERNOON AS WELL
AIDED BY THE VERY HIGH DEW POINTS. CAPE SHOULD MAX OUT AT LEAST
IN THE 1500-2500 RANGE WITH THE POTENTIAL FOR IT TO EVEN GO
3000+ DEPENDING ON HOW WARM WE GET. IN ADDITION, DEEP LAYER
SHEAR LOOKS TO BE 40-50 KNOTS WITH STRONG LOW LEVEL SHEAR AND
TURNING OF THE WINDS AS WELL. THE ANOMALOUSLY HIGH DEW POINTS
EXPECTED WILL ALSO HELP LCL VALUES GET QUITE LOW WITH PWAT
VALUES PROGGED TO SURGE TO OVER 2.2 INCHES. THIS ALL MEANS THAT
THE SECOND ROUND OF STORMS THAT WILL LIKELY ARRIVE DURING THE
LATTER PART OF THE AFTERNOON INTO THE EVENING WILL BE EASILY
CAPABLE OF PRODUCING DAMAGING WINDS AND TORRENTIAL RAINFALL
LEADING TO FLASH FLOODING.
EXPECT CONVECTION TO TAKE THE FORM OF MULTI-CELL CLUSTERS
AND/OR LINE SEGMENTS WITH THE POTENTIAL FOR EMBEDDED SUPERCELLS.
A FEW TORNADOES WILL ALSO BE POSSIBLE. IN FACT THE SPC HAS MUCH
OF THE AREA IN A RELATIVELY RARELY ISSUED FOR THIS AREA 5% RISK
OF TORNADOES, AND HAS HIGHLIGHTED MOST OF OUR FORECAST AREAS
WITH THE POTENTIAL FOR AN EF2 TORNADO.
IN TERMS OF THE HEAVY RAINFALL AND ASSOCIATED FLASH FLOOD
THREAT, THIS LOOKS TO BE HIGHEST FROM NORTHERN DELAWARE TO
NORTHERN PARTS OF SOUTH JERSEY ON NORTHWARD WHERE WE HAVE THE
FLOOD WATCH IN EFFECT. GIVEN THE VERY HIGH PWATS DESCRIBED
ABOVE, STORMS WILL BE CAPABLE OF PRODUCING RAIN AMOUNTS OF 2-3
INCHES WITHIN A PERIOD OF JUST 1-2 HOURS. THE FLOOD THREAT WILL
BE GREATEST FOR URBAN, LOW LYING AREAS, AND AREAS NEAR STREAMS
AND CREEKS. AREAS THAT GET HIT HARD REPEATEDLY BY THE MULTIPLE
ROUNDS OF CONVECTION WILL ALSO BE PARTICULARLY VULNERABLE. AND
IN FACT THERE WILL BE THE POTENTIAL FOR A FINAL ROUND OF
CONVECTION TO MOVE THROUGH LATER THIS EVENING JUST AHEAD OF THE
ACTUAL COLD FRONT.
SHOWERS/STORMS SHOULD FINALLY WIND DOWN HEADING INTO THE
OVERNIGHT PERIOD TONIGHT AS THE COLD FRONT PUSHES THROUGH.
KEY MESSAGE 3...MAINLY FAIR AND DRY WEATHER IS EXPECTED FOR
SUNDAY THROUGH MONDAY BEFORE THE NEXT CHANCE FOR SHOWER AND
STORMS RETURNS BY LATE TUESDAY.
FOLLOWING THE PASSAGE OF A COLD FRONT LATER TONIGHT INTO EARLY
SUNDAY, THE REST OF THE DAY SUNDAY IS SHAPING UP TO FEATURE
SUNSHINE WITH BOTH LOWER TEMPERATURES AND LOWER HUMIDITY LEVELS.
GENERALLY EXPECT HIGHS RANGING FROM THE 70S TO NEAR 80 OVER OUR
NORTHERN ZONES OVER NE PA INTO NW NJ WITH LOW TO MID 80S NEAR
THE URBAN CORRIDOR AND UPPER 80S OVER PORTIONS OF OUR EASTERN MD
SHORE COUNTIES AND SOUTHERN DELAWARE. DEW POINTS WILL BE MUCH
LOWER COMPARED TO SATURDAY SO THE HEAT INDICES WILL BE CLOSE TO
THE ACTUAL AIR TEMPERATURES.
HIGH PRESSURE BUILDS IN TO START THE WEEK MONDAY WITH
TEMPERATURE AND HUMIDITY LEVELS EVEN A BIT LOWER THAN SUNDAY
UNDER MAINLY SUNNY SKIES AND LIGHT WINDS. HOWEVER LOOKING BEYOND
THIS TIME, THE NEXT FRONTAL SYSTEM APPROACHES TUESDAY WITH HEAT
AND HUMIDITY RETURNING AHEAD OF IT AND SHOWERS/STORMS LIKELY BY
LATE DAY INTO TUESDAY NIGHT AS THE SYSTEM MOVES THROUGH. THIS
IS STILL SEVERAL DAYS OUT BUT IT'S WORTH NOTING THAT WPC AND SPC
ARE ALREADY INDICATING THREATS FOR HEAVY RAINFALL AND FLASH
FLOODING AS WELL AS SEVERE STORMS. EXPECT HIGHS TUESDAY
GENERALLY IN THE 80S TO NEAR 90 WITH HEAT INDICES AS HIGH AS THE
MID TO HIGH 90S FROM AROUND THE URBAN CORRIDOR EXTENDING
SOUTHWARD. IT'S POSSIBLE SOME SHOWERS STORMS LINGER INTO
WEDNESDAY BUT THE GENERAL TREND SHOULD BE TOWARDS IMPROVING
CONDITIONS...ESPECIALLY BY LATE DAY.
AVIATION /12Z SATURDAY THROUGH WEDNESDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
TODAY...LOW VSBYS IN FU IMPROVE IN THE MORNING. SEVERAL WAVES
OF SHRA/TSRA THROUGHOUT THE DAY, STARTING IN THE MORNING, WITH
SUB-VFR CONDS. STRONGER TSRA WILL BE CAPABLE OF BRIEF WIND GUSTS
IN EXCESS OF 50 KT. OUTSIDE OF TSRA, WINDS WILL BE OUT OF THE
S-SW 5 TO 10 KT. LOW CONFIDENCE.
TONIGHT...SUB-VFR CONDS IN LINGERING SHRA/TSRA. LOW CONFIDENCE.
OUTLOOK...
SUNDAY THROUGH SUNDAY NIGHT...LINGERING SUB-VFR CONDS AT KACY
SUNDAY MORNING. OTHERWISE, VFR.
MONDAY...VFR.
TUESDAY THROUGH WEDNESDAY...SUB-VFR IN SHRA/TSRA FROM TIME TO
TIME.
MARINE
WINDS SHIFT MORE SOUTH-SOUTHWEST AND INCREASE AHEAD OF A STRONG
COLD FRONT TODAY. A SMALL CRAFT ADVISORY IS IN EFFECT FOR ALL
OCEAN ZONES STARTING AT NOON TODAY AND RUNNING UNTIL MIDNIGHT
TONIGHT FOR OUR SOUTHERN TWO ZONES OFF THE COAST OF DELAWARE
AND ADJACENT TO THE DELAWARE BAY. FARTHER NORTH, THE SCA RUNS
UNTIL 4 AM SUNDAY. EXPECT WINDS GUSTING TO AROUND 30 KNOTS WITH
SEAS GETTING UP TO 5-6 FOOT RANGE. SHOWERS AND THUNDERSTORMS
WILL BECOME INCREASINGLY LIKELY AS WELL.
OUTLOOK...
SUNDAY...SEAS MAY LINGER NEAR SCA LEVELS EARLY IN THE DAY BUT
OTHERWISE THE CONDITIONS SHOULD BE SUB SCA.
MONDAY...FAIR WEATHER EXPECTED WITH WINDS UNDER 25 KNOTS AND SEAS
AROUND 2-3 FEET.
TUESDAY - WEDNESDAY...WINDS AND SEAS LIKELY APPROACH SCA LEVELS
BY LATE DAY TUESDAY AND COULD LINGER INTO WEDNESDAY.
RIP CURRENTS...
FOR TODAY, SOUTH WINDS STRENGTHEN TO AROUND 15-20 MPH (WITH THE
EXCEPTION OF MONMOUTH COUNTY WHERE WINDS WILL BE A BIT
LIGHTER). WINDS WILL HAVE AN ONSHORE COMPONENT FOR CAPE MAY
COUNTY, ATLANTIC COUNTY, AND OCEAN COUNTY IN NJ AND BE MORE
SHORE PARALLEL FOR THE DELAWARE BEACHES AND MONMOUTH COUNTY
BEACHES. ENDED UP GOING A MODERATE RISK FOR RIP CURRENTS WHERE
THE WINDS ARE STRONGEST AND WHERE THERE IS AN ONSHORE COMPONENT
(CAPE MAY, ATLANTIC, OCEAN), WITH A LOW RISK ELSEWHERE (MONMOUTH
AND SUSSEX). BREAKING WAVES START AROUND 1 TO 2 FEET, BUT
GRADUALLY INCREASE THROUGH THE DAY TO AROUND 2 TO 3 FEET. THE
WAVE PERIOD WILL BE AROUND 8 SECONDS. GIVEN LOWER WAVE HEIGHTS
AND A SHORT TO MEDIUM PERIOD, THINKING A HIGH RISK IS NOT
NECESSARY AT THIS TIME.
FOR SUNDAY, WINDS TURN OFFSHORE, BECOMING NORTHWESTERLY UP TO 10
MPH. STILL A MEDIUM PERIOD SWELL WITH WAVE HEIGHTS AROUND 2 FEET
AS WELL. ALL OF THIS WILL RESULT IN A LOW RISK FOR RIP CURRENTS
AT ALL BEACHES.
FOR SPECIFIC BEACH FORECASTS, VISIT WEATHER.GOV/BEACH/PHI
PHI WATCHES/WARNINGS/ADVISORIES
PA...FLOOD WATCH THROUGH LATE TONIGHT FOR PAZ054-055-060>062-070-
071-101>106.
NJ...FLOOD WATCH THROUGH LATE TONIGHT FOR NJZ001-007>010-012>020-
026-027.
DE...FLOOD WATCH THROUGH LATE TONIGHT FOR DEZ001.
MD...HEAT ADVISORY FROM NOON TODAY TO 8 PM EDT THIS EVENING FOR
MDZ015-019-020.
MARINE...SMALL CRAFT ADVISORY FROM NOON TODAY TO 4 AM EDT SUNDAY FOR
ANZ450>453.
SMALL CRAFT ADVISORY FROM NOON TODAY TO MIDNIGHT EDT TONIGHT
FOR ANZ454-455.
DISCUSSION...FITZSIMMONS/HOEFLICH/RCM
AVIATION...MPS/RCM
MARINE...FITZSIMMONS/HOEFLICH/RCM
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page