114
FXUS61 KPHI 091829
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
229 PM EDT SAT MAY 9 2026
WHAT HAS CHANGED
MINOR ADJUSTMENTS TO THE TIMING OF THE STORMS TODAY - HIGHEST
RISK IS NOW THROUGH EARLY THIS EVENING.
THERE IS AN INCREASING RISK FOR PATCHY FOG OVERNIGHT INTO SUNDAY
MORNING.
KEY MESSAGES
1. WIDESPREAD SHOWERS AND A FEW STORMS ARE EXPECTED TODAY. THERE IS
A MARGINAL (1 OUT OF 5) RISK THAT A FEW STORMS COULD BE STRONG
TO SEVERE.
2. FOG IS POSSIBLE ACROSS THE REGION OVERNIGHT INTO SUNDAY
MORNING.
3. SEVERAL OPPORTUNITIES FOR MUCH NEEDED RAINFALL FROM LATE
SUNDAY THROUGH NEXT WEEK.
DISCUSSION
KEY MESSAGE 1...WIDESPREAD SHOWERS AND A FEW STORMS ARE
EXPECTED TODAY. THERE IS A MARGINAL (1 OUT OF 5) RISK THAT A FEW
STORMS COULD BE STRONG TO SEVERE.
THE WEAK AND DIFFUSE WARM FRONT HAS MADE IT THROUGH MUCH OF OUR
REGION AS OF MID DAY SATURDAY. THAT BEING SAID, THE HIGHEST RISK
FOR SEVERE STORMS STILL APPEARS TO BE PRIMARILY OVER THE COASTAL
PLAINS OF SOUTH JERSEY AND DELMARVA THAT SAW SOME CLEARING
EARLIER TODAY AND THUS HAS HAD TEMPERATURES INCREASE AS HIGH AS
THE MID 70S.
AS OF 2 PM, WE ARE STARTING TO SEE SCATTERED SHOWERS DEVELOP.
SO FAR, ONLY ONE STORM HAS HAD ANY LIGHTNING ACTIVITY WITH IT
(IN CENTRAL JERSEY), BUT WITH STILL A FEW MORE HOURS OF DIURNAL
HEATING, WOULD EXPECT SOME MORE SHOWERS TO DEVELOP INTO
THUNDERSTORMS.
INTERESTINGLY, MUCH OF THE SHOWER AND STORM ACTIVITY APPEARS TO
BE INITIATING OFF A WEAK BOUNDARY (I SUSPECT IT IS AN OUTFLOW
BOUNDARY FROM THE MORNING RAIN SHOWERS), THAT LIES TO THE
SOUTHEAST OF THE I-95 CORRIDOR. NORTH AND WEST OF THIS BOUNDARY,
WINDS HAVE SHIFTED IN SOME AREAS OUT OF THE NORTHWEST, WHICH
COULD SLIGHTLY LIMIT THE INSTABILITY IN THESE AREAS.
NO SIGNIFICANT CHANGES IN THE OVERALL NATURE OF THE SEVERE
THREAT. EVEN IN THE COASTAL PLAINS, CAPE VALUES ARE LIKELY TO BE
NEAR OR JUST ABOVE 500 J/KG. SO OVERALL NOT A LOT OF
INSTABILITY. HOWEVER, WINDS ALOFT WILL BE FAIRLY STRONG,
LEADING TO 0-6 KM SHEAR VALUES AROUND 40-45 KT. THE PRIMARY
HAZARD OF CONCERN IS STRONG WINDS, BUT SMALL HAIL IS ALSO
POSSIBLE.
ALL-TOLD, QPF FROM THIS EVENT LOOKS FAIRLY LIGHT, GENERALLY
LESS THAN ONE QUARTER INCH, THOUGH HIGHER AMOUNTS WILL BE
POSSIBLE IN ANY THUNDERSTORMS. SHOWERS AND STORMS LOOK TO EXIT
THE AREA BY LATE EVENING.
KEY MESSAGE 2...FOG IS POSSIBLE ACROSS THE REGION OVERNIGHT
INTO SUNDAY MORNING.
WITH LIGHT WINDS TONIGHT AND SOME RESIDUAL GROUND MOISTURE FROM
RAIN TODAY, THE DEVELOPMENT OF FOG IS LIKELY. MANY OF THE MODEL
SOUNDINGS DEPICT FOG, ESPECIALLY NORTHWEST OF THE I-95 CORRIDOR.
HAVE INCLUDED A MENTION OF PATCHY FOG ACROSS THE AREA.
RIGHT NOW, THE RISK FOR DENSE FOG OR WIDESPREAD FOG IS
RELATIVELY LOW. HOWEVER, IF CLOUDS CLEAR OUT EARLIER THAN
CURRENTLY FORECAST, OR IF WINDS DROP OFF EARLIER, THAT WOULD
INCREASE THE RISK FOR THOSE THREATS.
KEY MESSAGE 3...SEVERAL OPPORTUNITIES FOR MUCH NEEDED RAINFALL
FROM LATE SUNDAY THROUGH NEXT WEEK.
AN UPPER-LEVEL TROUGH IS FORECAST TO DOMINATE ACROSS MUCH OF THE
EAST TO END THIS WEEKEND AND CONTINUE RIGHT THROUGH NEXT WEEK. SOME
GUIDANCE IS MUCH MORE POTENT WITH THE TROUGH AMPLIFICATION LATER
NEXT WEEK WITH A CLOSED LOW DEVELOPING IN THE VICINITY OF THE MID-
ATLANTIC AND THEN MOVING OFF TO THE NORTHEAST. THIS UPPER-LEVEL
PATTERN WILL KEEP THE EXTENDED PORTION OF THE FORECAST UNSETTLED.
OUR FIRST SYSTEM BRINGS A COLD FRONT THROUGH THE AREA TOMORROW NIGHT
INTO MONDAY MORNING. RAIN SHOWERS START TO DEVELOP TOMORROW
AFTERNOON INTO THE EVENING WITH SOME ISOLATED THUNDERSTORMS POSSIBLE
GIVEN SOME INSTABILITY PRESENT. OVERNIGHT SUNDAY INTO MONDAY
MORNING, SOME GUIDANCE SHOWS MORE A STRATIFORM BAND OF RAIN
DEVELOPING AHEAD OF THE FRONT WITH THE BEST COVERAGE BEING NEAR AND
SOUTHEAST OF THE I-95 CORRIDOR. AN ISOLATED THUNDERSTORM WILL REMAIN
POSSIBLE INTO EARLY TOMORROW NIGHT AS INSTABILITY DECREASES INTO THE
OVERNIGHT. BEHIND THE FRONT, WE TREND DRIER INTO MONDAY
AFTERNOON.
AFTER A BRIEF DRY PERIOD LATE MONDAY INTO TUESDAY, THE ACTIVE
WEATHER PATTERN LOOKS TO RELOAD AS ANOTHER UPPER-LEVEL TROUGH
QUICKLY REPLACES THE FIRST ONE ACROSS MUCH OF THE EAST. THIS FEATURE
MAY BECOME CLOSED OFF IN THE VICINITY OF THE MID-ATLANTIC WEDNESDAY
THROUGH FRIDAY. BEYOND FRIDAY, SOME GUIDANCE MOVES THE CLOSED OFF
UPPER LOW OFF TO THE NORTHEAST INTO SATURDAY.
AS THE PATTERN TURNS UNSETTLED AGAIN, RAIN SHOWERS DEVELOP AND
INCREASE IN COVERAGE LATE TUESDAY NIGHT INTO WEDNESDAY WITH A
SURFACE LOW ADVANCING INTO THE REGION. THESE SHOWERS CONTINUE
THROUGH WEDNESDAY NIGHT. IN TERMS OF ANY ISOLATED THUNDERSTORMS,
THIS WILL BE DEPENDENT ON HOW MUCH INSTABILITY IS PRESENT. FOR
THURSDAY INTO FRIDAY, IF THE UPPER TROUGH CLOSES OFF AND WE GET A
SURFACE LOW OFF THE COAST OF THE MID-ATLANTIC, THEN THIS WOULD LEAD
TO MORE SHOWERS ACROSS THE AREA AND LOWER TEMPERATURES DUE TO THE
ONSHORE FLOW. UNCERTAINTY REMAINS FOR THE END OF THE WEEK AS WE GET
TOWARDS THE END OF THE EXTENDED FORECAST PERIOD.
AVIATION /18Z SATURDAY THROUGH THURSDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS...
THROUGH 00Z...PREVAILING VFR. ISOLATED TSRA IS POSSIBLE. THE
HIGHEST RISK FOR TSRA DIRECTLY AFFECTING A TAF SITE IS AT KMIV
AND KACY. FOR KPHL, KPNE, KTTN, AND KILG, THERE IS A RISK FOR
TSRA IN THE VICINITY, PRIMARILY TO THE SOUTH AND EAST, BUT THE
RISK DIRECTLY OVER THE TAF SITE IS RELATIVELY LOW. MVFR OR
LOWER VISIBILITIES ARE POSSIBLE IN ANY HEAVIER SHOWERS OR
STORMS. SOUTH-SOUTHWEST WINDS 10-15 KT, WITH SOME GUSTS AROUND
20 KT. MODERATE CONFIDENCE.
TONIGHT...STORMS SHOULD CLEAR OUT BY OR JUST AFTER 00Z, LEAVING
VFR CONDITIONS TO START THE OVERNIGHT PERIOD. THERE IS AN
INCREASING RISK FOR FOG OVERNIGHT, PARTICULARLY AFTER 06Z.
THERE IS SOME RISK ACROSS THE REGION, BUT THE HIGHEST RISK FOR
IFR AND EVEN LIFR CONDITIONS IS AT KRDG AND KABE AT THIS POINT.
WINDS QUICKLY DIMINISHING TO LIGHT AND VARIABLE BY 01-03Z WITH
CALM PERIODS LIKELY OVERNIGHT. MODERATE CONFIDENCE OVERALL, LOW
CONFIDENCE IN THE EXTENT OF RESTRICTIONS FROM LOW STRATUS OR
FOG.
SUNDAY...ONCE ANY MORNING FOG CLEARS OUT BY 15Z, PREVAILING VFR
CONDITIONS LIKELY. 20 TO 40% CHANCE FOR SHRA AND TSRA AFTER
18Z. IF ANY SHRA OR TSRA MOVE OVER A TAF SITE, CEILINGS AND
VISIBILITIES COULD BRIEFLY DROP TO MVFR. WINDS OUT OF THE WEST
NEAR OR BELOW 10KT THROUGH MUCH OF THE DAY. MODERATE CONFIDENCE
IN THE OVERALL PATTERN, LOW CONFIDENCE IN ANY ONE TAF SITE BEING
DIRECTLY AFFECTED BY SHRA OR TSRA.
OUTLOOK...
SUNDAY NIGHT THROUGH MONDAY...A PERIOD OF SUB-VFR CONDITIONS
PROBABLE SUNDAY NIGHT INTO MONDAY MORNING WITH SHOWERS. A FEW
THUNDERSTORMS POSSIBLE INTO EARLY SUNDAY NIGHT. CONDITIONS SHOULD
IMPROVE THROUGH THE DAY MONDAY.
TUESDAY...VFR.
WEDNESDAY THROUGH THURSDAY...SUB-VFR CONDITIONS POSSIBLE ALONG WITH
SHOWERS.
MARINE
A SMALL CRAFT ADVISORY IS REMAINS IN EFFECT FOR ALL NJ AND DE
ATLANTIC COASTAL WATERS AND THE LOWER DELAWARE BAY AND CONTINUE
THROUGH 12 AM SUNDAY. SOUTH WINDS 15-20 KT WITH GUSTS AROUND 25
KT ARE EXPECTED THROUGH THIS EVENING. SEAS ARE EXPECTED TO BE
3-5 FEET. IN ADDITION, SHOWERS AND A FEW STORMS COULD CONTRIBUTE
TO HAZARDOUS MARINE CONDITIONS. OVERNIGHT, WINDS AND SEAS ARE
EXPECTED TO SUBSIDE BELOW SCA LEVELS AND CONTINUE THROUGH THE
DAY ON SUNDAY.
OUTLOOK...
MONDAY...A BRIEF PERIOD OF SMALL CRAFT ADVISORY CONDITIONS POSSIBLE.
TUESDAY...THE CONDITIONS ARE ANTICIPATED TO BE BELOW SMALL CRAFT
ADVISORY CRITERIA.
WEDNESDAY...A PERIOD OF SMALL CRAFT ADVISORY CONDITIONS POSSIBLE.
THURSDAY...THE CONDITIONS ARE ANTICIPATED TO BE BELOW SMALL CRAFT
ADVISORY CRITERIA.
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ431-
450>455.
DISCUSSION...COOPER/GORSE/GUZZO/JOHNSON
AVIATION...COOPER/GORSE/GUZZO/JOHNSON
MARINE...COOPER/GORSE/GUZZO/JOHNSON
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page