397
FXUS61 KPHI 190827
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
427 AM EDT SUN APR 19 2026
WHAT HAS CHANGED
THE MARINE DENSE FOG ADVISORY HAS BEEN EXTENDED THROUGH 13Z/9AM
EDT AND EXPANDED FURTHER NORTH AS NEARBY OBSERVATIONS INDICATE
FOG IS PERSISTING AND IT IS UNLIKELY TO DISSIPATE UNTIL THE
FRONT GETS CLOSER.
KEY MESSAGES
1. A STRONG COLD FRONT WILL BRING RAIN SHOWERS TO THE AREA THROUGH
EARLY THIS AFTERNOON.
2. MINOR TIDAL FLOODING (ADVISORY LEVEL) ENDING EARLY THIS MORNING.
3. FREEZE/FROST EARLY THIS WEEK AS MUCH COLDER AIR WILL BE SETTLING
IN, WITH A WIDESPREAD FREEZE POTENTIAL EARLY TUESDAY MORNING. A
RETURN TO ABOVE AVERAGE TEMPERATURES THEN OCCURS LATER THIS WEEK.
DISCUSSION
KEY MESSAGE 1...A STRONG COLD FRONT WILL BRING RAIN SHOWERS TO THE
AREA THROUGH EARLY THIS AFTERNOON.
AS OF 2 AM, THE COLD FRONT REMAINS WEST OF OUR REGION, IN CENTRAL
PA. THAT FRONT IS EXPECTED TO SWEEP THROUGH THE REGION QUICKLY,
MOVING OFF SHORE BY LATE MORNING. COVERAGE OF SHOWERS AHEAD OF THE
FRONT HAS BEEN QUITE LIMITED THUS FAR, BUT STILL EXPECTING COVERAGE
OF SHOWERS TO INCREASE AS IT GETS CLOSER. THAT BEING SAID, OVERALL,
RAIN AMOUNTS ARE STILL EXPECTED TO BE RATHER LIGHT - RANGING FROM A
FEW HUNDREDTHS TO THREE QUARTERS OF AN INCH.
THE RISK FOR OTHER THUNDERSTORM HAZARDS REMAINS QUITE LOW, ALTHOUGH
THANKS TO SOME ELEVATED INSTABILITY, CAN'T RULE OUT AN ISOLATED
THUNDERSTORM.
DUE TO THE STRONG COLD AIR ADVECTION BEHIND THE FRONT, HIGH
TEMPERATURES ARE LIKELY TO OCCUR EARLY IN THE DAY.
KEY MESSAGE 2...MINOR TIDAL FLOODING (ADVISORY LEVEL) ENDING
EARLY THIS MORNING.
THE COASTAL FLOOD ADVISORY CONTINUES EARLY THIS MORNING FOR THE
TIDAL DELAWARE RIVER AS THE HIGH TIDE WORKS ITS WAY NORTHWARD.
THE LOW-LEVEL FLOW WILL BE SWITCHING AROUND TODAY FROM ONSHORE TO
INCREASING FROM AN OFFSHORE DIRECTION. THIS COMBINED WITH MOVING
FARTHER AWAY FROM THE NEW MOON SHOULD LOWER THE TIDE LEVELS WITH A
DECREASING SURGE COMPONENT. AS A RESULT, NO ADDITIONAL ADVISORY
LEVEL COASTAL FLOODING IS EXPECTED AFTER THE ONGOING MINOR TIDAL
FLOODING ENDS EARLY THIS MORNING.
TIDAL FLOODING IS STILL NOT EXPECTED FOR OUR PORTION OF THE EASTERN
SHORE OF CHESAPEAKE BAY.
KEY MESSAGE 3...FREEZE/FROST EARLY THIS WEEK AS MUCH COLDER AIR WILL
BE SETTLING IN, WITH A WIDESPREAD FREEZE POTENTIAL EARLY TUESDAY
MORNING. A RETURN TO ABOVE AVERAGE TEMPERATURES THEN OCCURS LATER
THIS WEEK.
THE BIG CHANGE IS THAT THERE IS INCREASING CONFIDENCE THAT HIGHER
TERRAIN AREAS, PARTICULARLY THE SOUTHERN POCONOS, WILL SEE
TEMPERATURES NEAR OR BELOW FREEZING LATER TONIGHT INTO MONDAY
MORNING. A FREEZE WARNING HAS BEEN ISSUED FOR CARBON AND MONROE
COUNTIES WHERE THERE IS THE HIGHEST CONFIDENCE FOR BELOW FREEZING
TEMPERATURES. FOR SURROUNDING AREAS, PARTICULARLY THE LEHIGH
VALLEY AND NW NJ, IF WINDS DIMINISH QUICK ENOUGH, AND IF CLOUDS
DON'T BUILD IN UNTIL AFTER MIDNIGHT, THERE IS A RISK FOR NEAR
FREEZING TEMPERATURES AND PATCHY FROST DEVELOPMENT. HOWEVER, THE
RISK IN THESE AREAS IS VERY CONDITIONAL ON THE WINDS AND
CLOUDS. THEREFORE, WHILE THERE IS A CHANCE, CONFIDENCE IS TOO
LOW TO ISSUE A FROST ADVISORY AT THIS TIME.
THE CENTER OF COLD SURFACE HIGH PRESSURE WILL THEN SLIDE OVER
OUR REGION DURING MONDAY NIGHT BEFORE GRADUALLY SHIFTING OFFSHORE
DURING TUESDAY. THIS COMBINED WITH A CLEARING SKY, WINDS BECOMING
VERY LIGHT TO CALM AND LOW DEW POINTS WILL RESULT IN EFFICIENT
RADIATIONAL COOLING CONDITIONS MONDAY NIGHT. A WIDESPREAD FREEZE
LOOKS TO OCCUR EARLY TUESDAY MORNING, AND THE FREEZE WATCH HAS
BEEN EXPANDED TO INCLUDE MOST OF OUR AREA. ALL OF OUR COUNTIES
NOW HAVE AN ACTIVE GROWING SEASON DUE TO THE RECENT EXCESSIVE
WARMTH. BLOOMS/VEGETATION HAVE QUICKLY INITIATED AND IN SOME
CASES ARE AHEAD OF SCHEDULE. FRUIT TREES AND OTHER COLD SENSITIVE
PLANTS ALREADY PLANTED ARE THE MOST CONCERN. FROST FORMATION
MIGHT BE SOMEWHAT LIMITED GIVEN A MUCH DRIER LOW-LEVEL AIR MASS
IN PLACE. OUTSIDE OF THE URBAN CITY CENTERS AND AWAY FROM THE
IMMEDIATE COAST, TEMPERATURES ARE EXPECTED TO DROP BELOW
FREEZING. IN SOME CASES, WELL BELOW FREEZING.
HIGH TEMPERATURES BOTH MONDAY AND TUESDAY ARE FORECAST TO BE IN THE
40S AND 50S ACROSS THE REGION, WHICH IS SEVERAL DEGREES BELOW
AVERAGE. A FEW LIGHT RAIN/SNOW OR GRAUPEL SHOWERS ARE POSSIBLE ON
MONDAY AS THE CORE OF THE COLD AIR ALOFT IS OVERHEAD ALONG WITH SOME
MID LEVEL ENERGY SLIDING THROUGH WITH THE TROUGH AXIS. THE AIR MASS
BELOW CLOUD BASE LOOKS RATHER DRY AND THEREFORE ANYTHING THAT
DEVELOPS COULD BE MOSTLY VIRGA OUTSIDE OF THE HIGHER TERRAIN. IT
WILL FEEL MUCH COLDER MONDAY WITH A BREEZE AND THE VERY DRY AIR IN
PLACE. A RETURN, SOUTHERLY, FLOW WILL THEN BECOME ESTABLISHED
TUESDAY AND CONTINUE INTO WEDNESDAY. THIS ALONG WITH AN INCREASE IN
WARM AIR ADVECTION AND RISING HEIGHTS WILL RESULT IN TEMPERATURES
CLIMBING BACK ABOVE AVERAGE WEDNESDAY THROUGH SATURDAY.
AVIATION /08Z SUNDAY THROUGH THURSDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
THROUGH 18Z...EXPECT PROLONGED MVFR AND IFR CONDITIONS TO
CONTINUE. THE MAIN CONTROLLING FACTOR IS CEILINGS, BUT THERE
HAVE BEEN, AND WILL CONTINUE TO BE SOME VISIBILITY RESTRICTIONS
IN BR AND FG, ESPECIALLY AT KACY. WINDS CURRENTLY ARE LESS THAN
10 KT FAVORING AN EASTERLY DIRECTION. AT KMIV AND KACY, LOW
LEVEL WIND SHEAR IS POSSIBLE FOR THE NEXT FEW HOURS AS A LOW
LEVEL SSW JET IS OVERHEAD.
CEILINGS AND VISIBILITY ARE EXPECTED TO IMPROVE, AND WINDS WILL
ABRUPTLY SHIFT TO NORTHWESTERLY BETWEEN 10 AND 15Z AS A COLD
FRONT MOVES THROUGH. WINDS GUSTING UP TO 30 KT ARE POSSIBLE
BEHIND THE FRONT.
AFTER 18Z...LOWER CLOUDS AND RAIN SHOWERS WILL SLIDE EAST OFF
THE COAST, RESULTING IN A RETURN OF VFR CONDITIONS FROM WEST TO
EAST. WINDS WILL REMAIN OUT OF THE NORTHWEST, BUT BEGIN TO
SLOWLY DIMINISH AFTER 21Z. MODERATE CONFIDENCE.
TONIGHT...VFR CONDITIONS EXPECTED. WESTERLY WINDS NEAR OR BELOW
10KT. MODERATE CONFIDENCE.
OUTLOOK...
MONDAY...VFR. A FEW LIGHT/BRIEF SHOWERS OR SPRINKLES POSSIBLE DURING
THE DAY. WEST-NORTHWEST WIND GUSTS TO 20-25 KNOTS, QUICKLY
DIMINISHING AT NIGHT.
TUESDAY...VFR.
WEDNESDAY...AREAS OF SUB-VFR CONDITIONS ARE POSSIBLE AT TIMES DUE TO
SOME SHOWERS.
THURSDAY...VFR.
MARINE
FOG CONTINUES EARLY THIS MORNING. WE HAVE LITTLE IN THE WAY OF
OFFSHORE VISIBILITY OBSERVATIONS, SO UTILIZING COASTAL
VISIBILITY OBSERVATIONS. THERE REMAIN SEVERAL LOCATIONS THAT ARE
REPORTING VISIBILITY AT OR BELOW 1 NM. THE FRONT REMAINS WELL TO
THE WEST, AND DON'T EXPECT MUCH TO CHANGE THE FOG UNTIL THE
FRONT GETS CLOSER. THEREFORE, THE MARINE FOG ADVISORY HAS BEEN
EXTENDED THROUGH 13Z/9AM EDT, AND NOW INCLUDES THE MARINE AREAS
ADJACENT TO MONMOUTH COUNTY NJ.
WINDS WILL SHIFT TO NORTHWESTERLY AND INCREASE QUICKLY BEHIND A
COLD FRONT LATER THIS MORNING. GUIDANCE HAS TRENDED WINDIER NEAR
THE MOUTH OF THE DELAWARE BAY AND DOWNSTREAM, WHICH IS NOT
UNCOMMON IN THESE FLOW REGIMES DUE TO FUNNELING EFFECTS ALONG
THE BAY. THEREFORE, HAVE ISSUED A GALE WARNING FOR THE LOWER
DELAWARE BAY, THE NEAR COASTAL AREAS (OUT TO 20 NM) FROM GREAT
EGG INLET NJ TO FENWICK ISLAND DE, AND THE FARTHER MARINE AREAS
(20 TO 60 NM) FROM CAPE MAY NJ TO FENWICK ISLAND DE.
FOR THE REST OF THE MARINE AREAS, WINDS ARE EXPECTED TO STAY
BETWEEN 25 AND 30 KT DURING THE DAY TIME, SO A SMALL CRAFT
ADVISORY REMAINS IN EFFECT FOR THE REST OF THE DELAWARE BAY AND
NEAR COASTAL AREAS (SCAS ARE NOT ISSUED FOR THE 20 TO 60 NM
MARINE AREAS).
ONCE WINDS DIMINISH BY EARLY THIS EVENING, WINDS AND SEAS ARE
EXPECTED TO REMAIN BELOW SCA CRITERIA THROUGH THE REST OF
TONIGHT.
OUTLOOK...
MONDAY...WIND GUSTS COULD BE AROUND 25 KNOTS FOR A TIME.
TUESDAY THROUGH THURSDAY...THE CONDITIONS ARE ANTICIPATED TO BE
BELOW SMALL CRAFT ADVISORY CRITERIA.
PHI WATCHES/WARNINGS/ADVISORIES
PA...FREEZE WATCH FROM LATE MONDAY NIGHT THROUGH TUESDAY MORNING
FOR PAZ054-055-060>062-070-071-101>106.
COASTAL FLOOD ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR
PAZ070-071-106.
FREEZE WARNING FROM 11 PM THIS EVENING TO 10 AM EDT MONDAY FOR
PAZ054-055.
NJ...FREEZE WATCH FROM LATE MONDAY NIGHT THROUGH TUESDAY MORNING
FOR NJZ001-007>010-012-013-015>023-027.
COASTAL FLOOD ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR
NJZ017>019.
DE...FREEZE WATCH FROM LATE MONDAY NIGHT THROUGH TUESDAY MORNING
FOR DEZ001>003.
MD...FREEZE WATCH FROM LATE MONDAY NIGHT THROUGH TUESDAY MORNING
FOR MDZ012-015-019-020.
MARINE...SMALL CRAFT ADVISORY FROM 8 AM THIS MORNING TO 6 PM EDT THIS
EVENING FOR ANZ430-450>452.
DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR ANZ431-
450>455-480>483-485.
GALE WARNING FROM 8 AM THIS MORNING TO 5 PM EDT THIS AFTERNOON
FOR ANZ431-453>455-485.
DISCUSSION...GORSE/JOHNSON
AVIATION...GORSE/JOHNSON
MARINE...GORSE/JOHNSON
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