554
FXUS61 KPHI 231929
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
329 PM EDT MON JUN 23 2025
SYNOPSIS
HOT HIGH PRESSURE ACROSS THE WESTERN ATLANTIC WILL CONTINUE TO
SETTLE INTO THE APPALACHIAN REGION EARLY THIS WEEK. THIS WILL
RESULT IN THE CONTINUATION OF A SIGNIFICANT HEAT WAVE. THE HIGH
PRESSURE SYSTEM WILL BEGIN TO WEAKEN AND RETREAT TO THE SOUTH BY
THE MIDDLE TO END OF THE WEEK. A COLD FRONT WILL BRING
DECREASING TEMPERATURES ALONG WITH INCREASING CHANCES FOR
SHOWERS AND THUNDERSTORMS TOWARD THE END OF THE WEEK. A WARMING
TREND WILL RESUME OVER THE WEEKEND.
NEAR TERM /THROUGH TUESDAY/
SIGNIFICANT AND DANGEROUS HEAT THROUGH TUESDAY, WITH POTENTIALLY
SOME OF THE HOTTEST TEMPERATURES IN OVER A DECADE IN SOME LOCATIONS.
A STRONG RIDGE OF HIGH HOT AND DRY PRESSURE WILL BUILD ACROSS THE
EASTERN US THROUGH TUESDAY. MID LEVEL HEIGHTS, THICKNESSES, AND 850
MB TEMPERATURES CONTRIBUTING TO THE HEAT WAVE WILL ALL PEAK DURING
THIS TIME FRAME. THE CENTER OF THE RIDGE WILL BE POSITIONED TO OUR
SOUTHWEST, WHICH SHOULD MAXIMIZE HEAT POTENTIAL LOCALLY. AT THE
SURFACE, WINDS WILL BE FROM THE WEST OR NORTHWEST. THIS WILL ADD A
COMPONENT OF DOWNSLOPING INTO THE TEMPERATURE EQUATION, HELPING TO
BOOST TEMPERATURES BY A COUPLE DEGREES. THE PATTERN IS CHECKING A
LOT OF BOXES FOR A SET UP CAPABLE OF PRODUCING FAIRLY WIDESPREAD 100
DEGREE TEMPERATURES IN OUR REGION, PERHAPS ONE OF THE MOST FAVORABLE
PATTERNS IN A FEW YEARS.
FOR TUESDAY, TEMPERATURES LOOK TO BE A BIT WARMER, WITH POTENTIAL
WIDESPREAD TRIPLE DIGITS, THOUGH THE PATTERN WILL FAVOR DEWPOINTS
MIXING OUT REASONABLY WELL INTO THE AFTERNOON HOURS. THIS WILL
RESULT IN LOWER HUMIDITY, BUT HIGHER TEMPERATURES, RESULTING IN HEAT
INDEX VALUES NOT VERY DIFFERENT THAN MONDAY. STILL LOOKING AT 100-
110 HEAT INDICES ACROSS THE BOARD. AGAIN, A SEA-BREEZE MAY TRY TO
GENERATE, BUT LIKELY WON'T GET TOO FAR INLAND. REGARDLESS OF THOSE
DETAILS, IT'S GOING TO CONTINUE TO BE VERY HOT!
WITH OBSERVED HEAT INDICIES APPROACHING 110 DEGREES, EXTREME HEAT
WARNINGS WERE EXPANDED EARLIER TO INCLUDE THE EASTERN SHORE OF
MARYLAND, AND THE REMAINDER OF DELAWARE AND NEW JERSEY OUTSIDE OF
THE COASTAL ZONES FOR THE DELAWARE BEACHES AND JERSEY SHORE WHERE
HEAT ADVISORIES REMAIN IN EFFECT. HEAT ADVISORIES ALSO REMAIN IN
EFFECT FOR CARBON AND MONROE COUNTIES IN THE POCONOS. AROUND THE
DELAWARE VALLEY, LEHIGH VALLEY, AND NORTHERN NEW JERSEY,
TEMPERATURES COULD BE THE HOTTEST OBSERVED IN OVER A DECADE. THERE
WILL BE LITTLE RELIEF OVERNIGHT AS TEMPERATURES TONIGHT ARE EXPECTED
TO BE AROUND 75 TO 80 DEGREES. HEAT TENDS TO HAVE CUMULATIVE EFFECTS
ON THE BODY AND WE ARE CURRENTLY FORECASTING 3 CONSECUTIVE DAYS OF
95+ AND 5-6 DAYS OF 90+ TAKING INTO ACCOUNT TEMPERATURES THIS PAST
WEEKEND. TAKE FREQUENT BREAKS IF OUTSIDE, AND DRINK PLENTY OF
FLUIDS.
SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/
DANGEROUS HEAT WILL CONTINUE ACROSS THE AREA THROUGH WEDNESDAY.
RIDGING ALOFT WILL REMAIN IN PLACE OVER THE AREA TUESDAY NIGHT
AND WEDNESDAY, WITH VERY SLOW HEIGHT FALLS ANTICIPATED DURING
THE DAY WEDNESDAY AS THE RIDGE BEGINS TO BREAK DOWN SOME.
TUESDAY NIGHT WILL REMAIN VERY WARM AND MUGGY, WITH LOW
TEMPERATURES GENERALLY IN THE MID 70S, AND POTENTIALLY FAILING
TO FALL BELOW 80 IN PORTIONS OF THE URBAN CORRIDOR. HIGH
TEMPERATURES ON WEDNESDAY WILL RANGE FROM THE UPPER 80S ACROSS
THE POCONOS AND THE COASTAL STRIP TO THE MID-UPPER 90S
ELSEWHERE. WITH HIGH HUMIDITY REMAINING, HEAT INDICES AT PEAK
HEATING WEDNESDAY WILL LIKELY EXCEED 100 ACROSS MUCH OF EASTERN
PA, INLAND NJ, AND THE DELMARVA, WITH VALUES NEAR 105 POSSIBLE.
WITH THIS IN MIND, AN EXTREME HEAT WARNING WILL REMAIN IN EFFECT
FOR ALL BUT CARBON AND MONROE COUNTIES, AND A HEAT ADVISORY FOR
CARBON AND MONROE, THROUGH 8 PM.
WEDNESDAY EVENING INTO WEDNESDAY NIGHT, THE RIDGE IS EXPECTED
TO CONTINUE TO BREAK DOWN AND SHIFT SOUTH OF THE AREA, WITH A
COLD FRONT BEGINNING TO APPROACH NORTHERN REGIONS. STRENGTHENING
NORTHWEST FLOW ALOFT WILL LEAD TO AN INCREASE IN PROBABILITIES
FOR SHOWERS AND STORMS. POPS ARE EXPECTED TO BE IN THE LOW-END
CHANCE RANGE. WITH STRONG SURFACE HEATING ENHANCING LOW-LEVEL
INSTABILITY, GUSTY WINDS COULD OCCUR WITH ANY STRONGER STORMS,
THOUGH MARGINAL LAPSE RATES AND WEAK WINDS ALOFT SHOULD TEMPER
ANY SEVERE THREAT.
WITH THE ISOLATED SHOWERS AND STORMS, INCREASED CLOUD COVER,
AND THE APPROACHING COLD FRONT, WEDNESDAY NIGHT WILL BE SLIGHTLY
COOLER (THOUGH STILL QUITE WARM). IN GENERAL, LOWS ARE EXPECTED
TO BE NEAR 70 IN THE POCONOS AND ALONG THE COAST, AND IN THE
LOW-MID 70S ELSEWHERE.
LONG TERM /THURSDAY THROUGH MONDAY/
THURSDAY, THE RIDGE WILL CONTINUE TO BECOME FURTHER SUPPRESSED
AND CONTINUE TO SHIFT SOUTH OF THE REGION. NORTHWEST FLOW ALOFT
WILL INTENSIFY SOME, AND THERE ARE SOME INDICATIONS THAT A
SUBTLE SHORTWAVE COULD PASS THROUGH. AT THE SURFACE, THE FRONTAL
BOUNDARY THAT IS EXPECTED TO MOVE INTO THE AREA WEDNESDAY NIGHT
WILL LIKELY SLOW SOME, BEFORE ACCELERATING SOUTHWARD AND
CLEARING THE AREA THURSDAY NIGHT.
SOUTH OF THE COLD FRONT ACROSS PORTIONS OF SOUTHEASTERN PA,
SOUTHERN NJ, AND THE DELMARVA, HIGH TEMPERATURES ON THURSDAY ARE
EXPECTED TO RISE INTO THE LOW 90S. FOR THESE AREAS, IT WILL
ALSO REMAIN HUMID. THEREFORE, IT IS NOT OUT OF THE QUESTION THAT
SOME HEAT HEADLINES COULD NEED TO BE EXTENDED INTO THURSDAY.
NORTH OF THE FRONT, TEMPERATURES WILL GENERALLY BE IN THE MID
80S. ALONG AND SOUTH OF THE BOUNDARY, SCATTERED SHOWERS AND
STORMS WILL BECOME LIKELY DURING THE AFTERNOON AND EVENING
HOURS. SIMILAR TO WEDNESDAY, MARGINAL LAPSE RATES AND WINDS
ALOFT WILL LIMIT SEVERE POTENTIAL, BUT ISOLATED INSTANCES OF
GUSTY WINDS COULD OCCUR WITH THE STRONGER STORMS.
BEHIND THE COLD FRONT, TEMPERATURES ACROSS THE AREA WILL BE
NOTICEABLY COOLER, WITH LOWS THURSDAY NIGHT GENERALLY IN THE
UPPER 60S-LOWER 70S. ON FRIDAY, IT CURRENTLY APPEARS THAT
TEMPERATURES ACROSS EASTERN PA AND NORTHERN NJ WILL BE IN THE
LOW-MID 70S, WITH TEMPERATURES IN THE LOW-MID 80S ACROSS FAR
SOUTHEASTERN PA, SOUTHERN NJ, AND THE DELMARVA.
THE UPPER-AIR PATTERN OVER THE AREA WILL NOT CHANGE MUCH OVER
THE WEEKEND, WITH THE REGION REMAINING ON THE NORTHEASTERN
PERIPHERY OF A RIDGE. A SLOW WARMING TREND IS ANTICIPATED
SATURDAY THROUGH MONDAY, WITH TEMPERATURES LATE THIS WEEKEND
INTO EARLY NEXT WEEK GENERALLY IN THE LOW-MID 70S FOR LOWS AND
NEAR 90 FOR HIGHS. ISOLATED, PRIMARILY DIURNALLY DRIVEN
CONVECTION, WILL BE POSSIBLE EACH DAY.
A MORE ACTIVE WEATHER PATTERN MAY BEGIN TO TAKE SHAPE MONDAY
AND BEYOND, WITH INDICATIONS OF A SLIGHTLY MORE AMPLIFIED UPPER-
AIR PATTERN TAKING SHAPE.
AVIATION /20Z MONDAY THROUGH SATURDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
REST OF TODAY...VFR. W-SW WINDS IN THE AFTERNOON AROUND 5-10
KNOTS EXCEPT AT KACY WHERE S-SE WINDS ARE EXPECTED WITH THE
PASSAGE OF THE SEA BREEZE EARLIER. HIGH CONFIDENCE IN PREVAILING
VFR, MODERATE CONFIDENCE IN HOW FAR INLAND THE SEA BREEZE
PUSHES.
TONIGHT...VFR. WEST/SOUTHWEST WINDS BECOMING WEST/NORTHWEST
AFTER MIDNIGHT, AROUND WINDS 5 KT OR LESS. HIGH CONFIDENCE.
TUESDAY...VFR. WEST-NORTHWEST WINDS AROUND 5-10 KTS. HIGH
CONFIDENCE.
OUTLOOK...
TUESDAY NIGHT... VFR. NO SIGNIFICANT WEATHER.
WEDNESDAY THROUGH SATURDAY...MAINLY VFR. BRIEF PERIODS OF SUB-
VFR WILL BE POSSIBLE DURING THE AFTERNOON AND EVENING HOURS EACH
DAY IN ISOLATED TO WIDELY SCATTERED SHOWERS AND STORMS.
MARINE
NO MARINE HEADLINES EXPECTED THROUGH TUESDAY. WINDS GENERALLY
OUT OF THE SOUTH AROUND 10 KT WITH 2 FOOT SEAS. FAIR WEATHER.
OUTLOOK...
TUESDAY NIGHT THROUGH SATURDAY...NO MARINE HEADLINES EXPECTED.
WINDS REMAIN BELOW 25 KT AND SEAS BELOW 5 FT. PERIODS OF SHOWERS
AND STORMS POSSIBLE EACH DAY BEGINNING WEDNESDAY AFTERNOON, BUT
SIGNIFICANT MARINE IMPACTS ARE NOT ANTICIPATED.
RIP CURRENTS...
FOR MONDAY, W TO NW WINDS OF 5 TO 10 MPH WILL TURN S IN THE
AFTERNOON BEHIND DEVELOPING SEA BREEZES. A WEAK E TO ESE SWELL
AROUND 1 FEET WILL BE OF LITTLE CONSEQUENCE. SINCE WINDS WILL
BE FAIRLY LIGHT AND BREAKING WAVES AROUND 1 FEET, THERE WILL BE
A LOW RISK FOR THE DEVELOPMENT OF DANGEROUS AND LIFE
THREATENING RIP CURRENTS FOR THE JERSEY SHORE AND FOR DELAWARE
BEACHES.
FOR TUESDAY, NW WINDS OF 5 TO 10 MPH TURN S IN THE AFTERNOON
BEHIND DEVELOPING SEA BREEZES. A WEAK E TO ESE SWELL AROUND 1
FEET WILL BE OF LITTLE CONSEQUENCE. WITH LIGHT WINDS AND
BREAKING WAVES AROUND 1 FEET, THERE WILL BE A LOW RISK FOR THE
DEVELOPMENT OF DANGEROUS AND LIFE THREATENING RIP CURRENTS FOR
THE JERSEY SHORE AND FOR DELAWARE BEACHES.
FOR SPECIFIC BEACH FORECASTS, VISIT WEATHER.GOV/BEACH/PHI
TIDES/COASTAL FLOODING
WITH THE NEW MOON APPROACHING ON JUNE 25TH, ASTRONOMICAL TIDES
ARE EXPECTED TO INCREASE. SPOTTY MINOR TIDAL FLOODING IS
ANTICIPATED FOR THE IMMEDIATE COASTLINE AND BACK BAYS AS WELL AS
WITHIN DELAWARE BAY BEGINNING WITH THE HIGH TIDE TONIGHT.
CANNOT RULE OUT THE NEED FOR ADVISORIES LATER THIS WEEK AS ASTRO
TIDES PEAK. NO TIDAL FLOODING IS EXPECTED WITHIN THE TIDAL
DELAWARE RIVER OR CHESAPEAKE BAY.
CLIMATE
NEAR RECORD BREAKING HEAT IS EXPECTED ACROSS THE AREA THROUGH
THE MIDDLE OF THE UPCOMING WEEK. WE ALREADY ARE SETTING RECORDS,
WITH PHILADELPHIA (PHL) TYING THEIR RECORD WARMEST LOW
TEMPERATURE YESTERDAY (JUNE 22ND), AND ATLANTIC CITY AIRPORT
(ACY) SETTING A NEW RECORD WARM LOW. FURTHER RECORDS ARE
EXPECTED TO FALL INTO THE WEEK. BELOW IS A LOOK AT THE LAST 100
DEGREE DAY, DAILY RECORD HIGH MAXIMUM AND MINIMUM TEMPERATURE
FOR ALL OF OUR CLIMATE SITES.
MOST RECENT 100 DEGREE DAY
SITE DATE/TEMPERATURE
ALLENTOWN (ABE) JULY 22, 2011/104
AC AIRPORT (ACY) JULY 21, 2019/100
AC MARINA (55N) JULY 5, 1999/101
GEORGETOWN (GED) JULY 21, 2019/100
MOUNT POCONO (MPO) JULY 3, 1911/103
PHILADELPHIA (PHL) JULY 18, 2012/100
READING (RDG) JUNE 22, 2024/101
TRENTON (TTN) JULY 18, 2012/100
WILMINGTON (ILG) JULY 18, 2012/101
RECORD HIGH TEMPERATURES
JUNE 23
SITE RECORD/YEAR
ALLENTOWN (ABE) 96/2024
AC AIRPORT (ACY) 98/1988 & 2024
AC MARINA (55N) 91/1909
GEORGETOWN (GED) 100/1988
MOUNT POCONO (MPO) 90/1954
PHILADELPHIA (PHL) 98/2024
READING (RDG) 98/2024
TRENTON (TTN) 97/1894
WILMINGTON (ILG) 100/1894
RECORD WARMEST LOW TEMPERATURES
JUNE 23
SITE RECORD/YEAR
ALLENTOWN (ABE) 71/2017 & 2024
AC AIRPORT (ACY) 75/2024
AC MARINA (55N) 74/2010
GEORGETOWN (GED) 76/1988
MOUNT POCONO (MPO) 69/2024
PHILADELPHIA (PHL) 76/1888
READING (RDG) 77/2024
TRENTON (TTN) 74/2017 & 2024
WILMINGTON (ILG) 75/2024
RECORD HIGH TEMPERATURES
JUNE 24
SITE RECORD/YEAR
ALLENTOWN (ABE) 98/1923
AC AIRPORT (ACY) 99/2010
AC MARINA (55N) 95/2002
GEORGETOWN (GED) 97/2010
MOUNT POCONO (MPO) 92/1914
PHILADELPHIA (PHL) 99/1923
READING (RDG) 98/1908 & 1923
TRENTON (TTN) 98/1894
WILMINGTON (ILG) 102/1894
RECORD WARMEST LOW TEMPERATURES
JUNE 24
SITE RECORD/YEAR
ALLENTOWN (ABE) 71/2010
AC AIRPORT (ACY) 72/1951, 2013, 2017 & 2024
AC MARINA (55N) 72/1924, 2002, 2010, 2011, 2013 & 2020
GEORGETOWN (GED) 74/2010
MOUNT POCONO (MPO) 66/1960, 1964 & 2002
PHILADELPHIA (PHL) 75/1909, 1921, 1994 & 2020
READING (RDG) 73/1909, 1994 & 2010
TRENTON (TTN) 76/1894 & 2010
WILMINGTON (ILG) 74/1994
RECORD HIGH TEMPERATURES
JUNE 25
SITE RECORD/YEAR
ALLENTOWN (ABE) 98/1923
AC AIRPORT (ACY) 96/1997
AC MARINA (55N) 95/1952
GEORGETOWN (GED) 96/1952
MOUNT POCONO (MPO) 91/1952
PHILADELPHIA (PHL) 98/1952
READING (RDG) 99/1943
TRENTON (TTN) 99/1997
WILMINGTON (ILG) 98/1894
RECORD WARMEST LOW TEMPERATURES
JUNE 25
SITE RECORD/YEAR
ALLENTOWN (ABE) 74/1923 & 1976
AC AIRPORT (ACY) 80/1950
AC MARINA (55N) 75/1997 & 2002
GEORGETOWN (GED) 75/2019
MOUNT POCONO (MPO) 69/1952
PHILADELPHIA (PHL) 76/1909, 1976 & 2002
READING (RDG) 75/1943 & 1949
TRENTON (TTN) 75/1976
WILMINGTON (ILG) 75/1976
PHI WATCHES/WARNINGS/ADVISORIES
PA...EXTREME HEAT WARNING UNTIL 8 PM EDT WEDNESDAY FOR PAZ060>062-
070-071-101>106.
HEAT ADVISORY UNTIL 8 PM EDT WEDNESDAY FOR PAZ054-055.
NJ...EXTREME HEAT WARNING UNTIL 8 PM EDT WEDNESDAY FOR NJZ001-
007>010-012-013-015>023-027.
HEAT ADVISORY UNTIL 8 PM EDT TUESDAY FOR NJZ014-024>026.
DE...EXTREME HEAT WARNING UNTIL 8 PM EDT WEDNESDAY FOR DEZ001>003.
HEAT ADVISORY UNTIL 8 PM EDT TUESDAY FOR DEZ004.
MD...EXTREME HEAT WARNING UNTIL 8 PM EDT WEDNESDAY FOR MDZ012-015-
019-020.
MARINE...NONE.
SYNOPSIS...COOPER/MJL/STAARMANN
NEAR TERM...AKL/HOEFLICH/STAARMANN
SHORT TERM...COOPER
LONG TERM...COOPER
AVIATION...AKL/COOPER
MARINE...AKL/COOPER
TIDES/COASTAL FLOODING...WFO PHI
CLIMATE...WFO PHI
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