794
FXUS61 KPHI 131951
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
251 PM EST WED NOV 13 2024
SYNOPSIS
HIGH PRESSURE OVER THE AREA LIFT TO THE NORTHEAST BY THURSDAY
NIGHT. LOW PRESSURE DEVELOPS OVER THE MID-ATLANTIC ON THURSDAY
AND MOVES OFFSHORE THURSDAY NIGHT THROUGH FRIDAY. HIGH PRESSURE
RETURNS FOR THE WEEKEND. A WEAK FRONTAL SYSTEM PASSES THROUGH
THE REGION ON MONDAY, FOLLOWED BY A RETURN TO HIGH PRESSURE FOR
THE MIDDLE OF NEXT WEEK.
NEAR TERM /THROUGH THURSDAY/
A NARROWING MID TO UPPER LEVEL RIDGE WILL CROSS OUR AREA LATER
TONIGHT BEFORE WEAKENING DURING THURSDAY. SOME BLOCKING SETS UP
ON THE SYNOPTIC SCALE THROUGH THURSDAY, WITH CHILLY AIR
REMAINING IN PLACE.
AN APPROACHING UPPER-LEVEL TROUGH SHOULD CLOSE OFF WHILE
ANOTHER CLOSED LOW RETROGRADES, SLIDES NORTHWEST OR WEST, TO
NEAR NOVA SCOTIA CANADA THROUGH THURSDAY. BOTH OF THESE SUPPORT
SURFACE LOW PRESSURES WITH THE FIRST DEVELOPING OFF THE
SOUTHEAST VIRGINIA/NORTH CAROLINA COAST WHILE THE LATTER PUTS
LOW PRESSURE CLOSER TO THE NOVA SCOTIA AREA. GIVEN THE
RETROGRADING TO OUR NORTHEAST, SURFACE HIGH PRESSURE WHILE IT
WEAKENS OVER OUR AREA DOES STILL REMAIN OVERHEAD FOR MUCH OF OUR
REGION. WHILE WE NEED THE RAIN, THIS PATTERN OFFERS DECREASING
CHANCES DUE TO THE INCOMING SYSTEM HITTING A BRICK WALL AND
BEING DEFLECTED TO OUR SOUTH.
REGARDING MORE OF THE DETAILS, STRONG SURFACE HIGH PRESSURE
CENTERED WELL TO OUR NORTH THIS AFTERNOON AND TONIGHT WILL SHIFT
NORTHWARD AND WEAKEN WITH TIME DURING THURSDAY. THIS WILL
RESULT IN LIGHT TO NEAR CALM WINDS TONIGHT AND WITH A VERY DRY
AIR MASS THE TEMPERATURES WILL DROP QUICKLY THIS EVENING. SOME
CIRRUS WILL CONTINUE TO CREST THE RIDGE AXIS AS IT CROSSES OUR
AREA, HOWEVER THIS SHOULD NOT SIGNIFICANTLY IMPACT THE
RADIATIONAL COOLING FOR MOST OF TONIGHT. AS A RESULT, MANY AREAS
ARE FORECAST TO DROP BELOW FREEZING ONCE AGAIN OVERNIGHT. IT
WILL BE THE WARMEST ALONG THE COAST DUE TO A CONTINUED
NORTHEASTERLY WIND.
AS WE GO THROUGH THURSDAY, CLOUDS WILL QUICKLY INCREASE/THICKEN
WITH THIS INITIALLY BEING HIGH TO MID LEVEL CLOUDS AND THEN
SOME LOWER CLOUDS SHOULD ALSO DEVELOP WITHIN THE EASTERLY LOW-
LEVEL FLOW. THE AIR MASS WILL BE UNDERGOING SOME MOISTENING AND
THIS LOOKS TO BE THE MOST PRONOUNCED ACROSS OUR SOUTHERN ZONES
WHERE SURFACE HIGH PRESSURE WEAKENS THE MOST (DRIEST ACROSS
NORTHERN NEW JERSEY INTO NORTHEAST PENNSYLVANIA). WHILE SOME
SPRINKLES OR A FEW LIGHT SHOWERS CANNOT BE RULED OUT ACROSS OUR
EASTERN MARYLAND SHORE ZONES NORTH TO WESTERN CHESTER AND FAR
WESTERN BERKS COUNTIES LATE IN THE AFTERNOON, IT LOOKS LIKE THE
DRY AIR WILL WIN OUT OVERALL AND THEREFORE LOWERED THE POPS SOME
MORE FOR THE LATE AFTERNOON HOURS. THE INCREASED CLOUDINESS
WILL RESULT IN ANOTHER CHILLY DAY WITH HIGHS ONLY IN THE 40S TO
LOWER 50S WITH A MOSTLY LIGHT NORTHEAST OR EAST BREEZE.
SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/
HIGH PRESSURE WILL BE CENTERED OVER EASTERN CANADA WITH THE
BASE OF THE HIGH DOWN THROUGH NEW JERSEY. A CLOSED H5 LOW WILL
MOVE THROUGH THE OHIO AND TENNESSEE VALLEYS AND SURFACE HIGH
PRESSURE OUT AHEAD OF IT WILL BE SHUNTED SOUTH TOWARDS THE MID-
ATLANTIC AND SOUTHEAST THURSDAY NIGHT THROUGH FRIDAY MORNING.
BEST CHANCES FOR RAIN WILL BE OVER DELMARVA WHERE LIKELY TO
CATEGORICAL POPS ARE FORECAST, BUT THERE MAY BE SOME SHOWERS UP
TO THE SOUTHERN POCONOS. GENERALLY 1/10 TO 1/4 INCH QPF POSSIBLE
FOR DELMARVA, BUT ONLY A FEW HUNDREDTHS TO LESS THAN 1/10 INCH
QPF POSSIBLE ELSEWHERE. THERE MAY EVEN BE A FEW WET SNOWFLAKES
IN THE SOUTHERN POCONOS.
LOW PRESSURE DEPARTS ON FRIDAY. CANADIAN HIGH PRESSURE BUILDS DOWN
INTO THE GREAT LAKES. A MILDER AIRMASS SPREADS INTO THE REGION
FRIDAY AND SATURDAY, WITH HIGHS IN THE UPPER 50S FRIDAY AND THEN IN
THE LOWER 60S ON SATURDAY. A DRIER AIRMASS ALSO SPREADS INTO THE
REGION WITH SURFACE DEW POINTS GENERALLY IN THE 20S TO LOW 30S. A
BRISK NORTHWEST FLOW DEVELOPS ON SATURDAY.
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
HIGH PRESSURE OVER THE OHIO VALLEY SATURDAY NIGHT WILL SLIDE
OFF THE MID-ATLANTIC AND SOUTHEAST COASTS SUNDAY, AND THIS HIGH
WILL REMAIN OFF THE SOUTHEAST COAST. SEASONABLY CHILLY SATURDAY
NIGHT, AND THEN MILD ON SUNDAY WITH HIGHS IN THE LOW 60S.
A WEAK FRONTAL SYSTEM WILL PASS THROUGH THE REGION LATE SUNDAY
NIGHT THROUGH MONDAY MORNING. ALTHOUGH NBM SHOWING THIS WILL
PASS THROUGH DRY, CONSALL GUIDANCE SHOWING SLIGHT CHANCE TO LOW
CHANCE POPS. 12Z/13 GFS DOES HAVE SOME STRONG SHORTWAVE ENERGY
WITH ITS PASSAGE, AND DOES HAVE A WETTING RAIN WITH ITS PASSAGE.
ALTHOUGH IT SEEMS TO BE AN OUTLIER, WILL GO AHEAD AND CARRY
SLIGHT CHANCE POPS FROM AFTER MIDNIGHT SUNDAY NIGHT THROUGH
AROUND DAYBREAK MONDAY MORNING. BASED ON RECENT TRENDS, HOWEVER,
IF THERE IS ANY QPF THAT FALLS, IT WILL LIKELY BE MINIMAL AT
BEST.
HIGH PRESSURE BUILDS IN FROM THE WEST ON MONDAY AND MOVES OFF
THE MID-ATLANTIC COAST ON TUESDAY. ANOTHER WEAKENING FRONTAL
SYSTEM WILL PASS THROUGH THE REGION TUESDAY NIGHT THROUGH
WEDNESDAY. WILL CARRY SLIGHT CHANCE POPS FOR NOW.
A, RELATIVELY SPEAKING, WARM AIRMASS SPREADS INTO THE REGION
MONDAY WITH HIGHS IN THE MID TO UPPER 60S. THESE HIGHS ARE 10+
DEGREES ABOVE NORMAL FOR THIS TIME OF YEAR. STILL MILD, BUT
SEVERAL DEGREE COOLER ON TUESDAY AND WEDNESDAY. THE AIRMASS WILL
BE DRY, BUT NOT OVERLY SO, AS DEW POINTS LOOK TO GENERALLY BE
IN THE UPPER 30S TO LOW 40S.
AVIATION /20Z WEDNESDAY THROUGH MONDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
REST OF THIS AFTERNOON...VFR. NORTH TO NORTHEAST WINDS LESS
THAN 10 KNOTS. MODERATE CONFIDENCE
TONIGHT...VFR, WITH INCREASING MAINLY HIGH CLOUDS ESPECIALLLY
OVERNIGHT. NORTHEAST WINDS AROUND 5 KNOTS TO LOCALLY LIGHT AND
VARIABLE. MODERATE CONFIDENCE.
THURSDAY...VFR CEILINGS. NORTHEAST TO EAST-NORTHEAST WINDS 5-10
KNOTS. MODERATE CONFIDENCE.
OUTLOOK...
THURSDAY NIGHT...OVERALL, VFR, BUT CANNOT RULE OUT SOME MVFR
CIGS IN LIGHT SHRA. BEST CHANCES FOR SHRA KRDG-KPHL-KILG.
FRIDAY THROUGH SATURDAY...VFR. NW WINDS WITH GUSTS UP TO 25 KT
EXPECTED ON SATURDAY.
SUNDAY THROUGH MONDAY...GENERALLY VFR, BUT SOME BRIEF MVFR CIGS
POSSIBLE FROM 06Z-12Z MONDAY IN LIGHT SHRA.
MARINE
A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR MOST OF THE NEW
JERSEY AND DELAWARE ATLANTIC COASTAL WATERS THROUGH AT LEAST
THURSDAY MOSTLY DUE TO ELEVATED SEAS. THE NORTH TO NORTHEASTERLY
WIND GUSTS SHOULD BE UNDER 25 KNOTS, HOWEVER THIS FLOW WILL
KEEP THE SEA HEIGHTS ELEVATED. THE CONDITIONS ARE ANTICIPATED TO
STAY BELOW SMALL CRAFT ADVISORY CRITERIA ON DELAWARE BAY
THROUGH THURSDAY.
OUTLOOK...
THURSDAY NIGHT...SCA REMAINS IN EFFECT FOR THE NJ OCEAN WATERS
SOUTH OF MANASQUAN INLET FOR SEAS AROUND 5 FEET. SUB-SCA
CONDITIONS ELSEWHERE.
FRIDAY...THE SCA MAY HAVE TO BE EXTENDED THROUGH FRIDAY AS SEAS
WILL REMAIN AROUND 5 FEET.
FRIDAY NIGHT THROUGH SATURDAY...SCA CONDITIONS EXPECTED. FOR NW
WINDS GUSTING 25 TO 30 KT AND SEAS 4 TO 6 FEET.
SUNDAY THROUGH MONDAY...SUB-SCA CONDITIONS EXPECTED.
FIRE WEATHER
NORTH TO NORTHEAST WINDS NEAR 10 MPH THIS AFTERNOON BEFORE
DIMINISHING TOWARD EARLY EVENING. A VERY DRY AIRMASS IS IN PLACE
WITH MINIMUM RH VALUES BETWEEN 20-40 PERCENT (HIGHEST ALONG THE
COAST AND IN SOUTHERN DELAWARE). WHILE THE WINDS ARE MUCH
LIGHTER COMPARED TO YESTERDAY, THE CONDITIONS CONTINUE TO BE
VERY DRY AND THEREFORE A SPECIAL WEATHER STATEMENT CONTINUES
INTO EARLY THIS EVENING FOR OUR DELMARVA ZONES AND ALSO FOR NEW
JERSEY BASED ON FEEDBACK FROM OUR STATE FIRE PARTNERS. THE RH
VALUES ARE FORECAST TO RECOVER TONIGHT QUICKLY AS TEMPERATURES
DROP QUICKLY THIS EVENING.
FOR THURSDAY, THE LOW-LEVEL MOISTURE INCREASES ESPECIALLY
ACROSS SOUTHERN NEW JERSEY, DELMARVA INTO SOUTHEASTERN
PENNSYLVANIA AS A SYSTEM APPROACHES FROM THE WEST. MINIMUM RHS
ARE FORECAST TO GENERALLY BETWEEN 35-60 PERCENT (LOWEST ACROSS
NORTHERN NEW JERSEY) AND LIGHT NORTHEAST TO EAST-NORTHEAST
WINDS. GIVEN THIS, NOT EXPECTING ANY CONCERNS REGARDING WILDFIRE
SPREAD.
A WEAK SYSTEM WILL PASS SOUTH OF THE REGION THURSDAY NIGHT,
POSSIBLY RESULTING IN A WETTING RAIN FOR PORTIONS OF DELMARVA
WITH 1/10 TO 1/4 INCH QPF FOR THE EASTERN SHORES OF MARYLAND AND
DELAWARE. LESS THAN 1/10 INCH QPF LIKELY ELSEWHERE.
HIGH PRESSURE RETURNS FOR THE END OF THE WEEK AND WEEKEND.
FRIDAY WILL FEATURE NORTHWEST WINDS 10 TO 15 MPH WITH GUSTS UP
TO 20 MPH AND MINRH VALUES 25 TO 45 PERCENT.
STRONGER WINDS WITH LOWER HUMIDITY VALUES ON SATURDAY WITH
NORTHWEST WINDS 15 TO 20 MPH WITH GUSTS UP TO 25 MPH AND MINRH
VALUES 25 TO 30 PERCENT. SUNDAY WILL ONCE AGAIN FEATURE MINRH
VALUES 25 TO 35 PERCENT WITH NORTHWEST WINDS 10 TO 15 MPH WITH
GUSTS UP TO 20 MPH.
TIDES/COASTAL FLOODING
CONFIDENCE HAS INCREASED THAT A COMBINATION OF PERSISTENT SHORE
PARALLEL WINDS AND INCREASING ASTRONOMICAL TIDES WITH A FULL
MOON ON FRIDAY LOOK TO LEAD TO COASTAL FLOODING FOR THE BACK
HALF OF THE WEEK. WIDESPREAD MINOR TIDAL FLOODING IS EXPECTED
ALONG THE ATLANTIC OCEAN COASTS OF NEW JERSEY AND DELAWARE AND
THE ASSOCIATED BACKBAYS AS WELL AS WITHIN DELAWARE BAY BEGINNING
WITH THE THURSDAY MORNING HIGH TIDE. THE THREAT FOR MODERATE
TIDAL FLOODING HAS DECREASED BUT MADE NO CHANGE TO THE COASTAL
FLOOD WATCH FOR NOW AS THE POTENTIAL STILL REMAINS. HOWEVER,
THINKING THAT THIS IS MORE OF A HIGH-END MINOR EVENT.
BY THURSDAY AND INTO FRIDAY, TIDAL PILING INTO THE LOWER DELAWARE
BAY LOOKS TO RESULT IN MINOR TIDAL FLOODING OCCURING FURTHER
NORTH, ALONG THE SHORES OF THE UPPER DELAWARE BAY AS WELL AS THE
TIDAL DELAWARE RIVER.
COASTAL FLOODING IS NOT EXPECTED TO OCCUR ALONG THE CHESAPEAKE
BAY IN THE EASTERN SHORE OF MARYLAND.
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...COASTAL FLOOD WATCH FROM LATE TONIGHT THROUGH FRIDAY MORNING
FOR NJZ012>014-020-022>027.
DE...COASTAL FLOOD WATCH FROM LATE TONIGHT THROUGH FRIDAY MORNING
FOR DEZ002>004.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR ANZ451>455.
SYNOPSIS...MPS
NEAR TERM...GORSE
SHORT TERM...MPS
LONG TERM...MPS
AVIATION...GORSE/MPS
MARINE...GORSE/MPS
FIRE WEATHER...
TIDES/COASTAL FLOODING...
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