400
FXUS61 KPHI 022312
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
712 PM EDT SAT MAY 2 2026
WHAT HAS CHANGED
AVIATION SECTION UPDATED. SOME ADJUSTMENTS MADE TO KEY MESSAGES
ONE AND TWO.
KEY MESSAGES
1. FREEZE LIKELY IN THE SOUTHERN POCONOS TONIGHT WITH AREAS OF
FROST ACROSS THE FAR NORTHWESTERN SUBURBS OF PHILLY, THE LEHIGH
VALLEY TO NORTHWEST NEW JERSEY.
2. LIMITED FIRE WEATHER CONDITIONS ON SUNDAY.
3. A SERIES OF SYSTEMS ON WEDNESDAY AND THURSDAY LIKELY BRINGS
THE NEXT WIDESPREAD RAINFALL.
DISCUSSION
KEY MESSAGE 1...FREEZE LIKELY IN THE SOUTHERN POCONOS TONIGHT WITH
AREAS OF FROST ACROSS THE FAR NORTHWESTERN SUBURBS OF PHILLY, THE
LEHIGH VALLEY TO NORTHWEST NEW JERSEY.
LOW PRESSURE WILL CONTINUE TO MOVE FARTHER AWAY ACROSS THE
WESTERN ATLANTIC THIS EVENING, AND SURFACE HIGH PRESSURE BUILDS
OVER THE TENNESSEE VALLEY AND GULF COAST STATES. MEANWHILE, AN
UPPER TROUGH REMAINS OVER THE NORTHEAST. THIS ALLOWS FOR A
NORTHWEST FLOW OVER THE AREA WITH COLD AIR ADVECTION. LOWS WILL
DROP INTO THE 30S AND LOW 40S WITH TEMPERATURES AS LOW AS THE
UPPER 20S IN THE SOUTHERN POCONOS. A FREEZE WARNING IS IN
EFFECT FOR CARBON AND MONROE COUNTIES TONIGHT, WITH A FROST
ADVISORY ACROSS ADJACENT AREAS INCLUDING THE FAR NORTHWESTERN
SUBURBS OF PHILLY TO NORTHWEST NEW JERSEY. IT IS A LITTLE
UNCERTAIN IN THE FROST ADVISORY AS CLOUDS MAY LINGER GIVEN
MOSTLY THE INCOMING UPPER TROUGH AND THEN THE WINDS MAY REMAIN
UP ENOUGH THROUGH THE NIGHT. MORE CONFIDENT ABOUT THE FREEZE
WARNING IN THE POCONOS WHERE COLD AIR ADVECTION SHOULD BE MORE
EFFECTIVE AT GETTING THE PLATEAU DOWN TO FREEZING OR BELOW.
VALLEYS THERE ARE MORE QUESTIONABLE.
KEY MESSAGE 2...LIMITED FIRE WEATHER CONDITIONS ON SUNDAY.
LOW PRESSURE WELL OFFSHORE AND INCOMING HIGH PRESSURE WILL RESULT
IN A TIGHT PRESSURE GRADIENT SETTING UP FOR SUNDAY. NORTHWEST
WINDS WILL INCREASE TO 15-20 MPH WITH GUSTS 20-30 MPH FROM ABOUT
LATE MORNING AND CONTINUING DURING THE AFTERNOON.
WITH BREEZY AND DRY NORTHWEST WINDS, COMBINED WITH DEEP MIXING
SETTING UP (TAPPING INTO VERY DRY AIR ALOFT), MINIMUM RH VALUES
WILL FALL INTO THE 25-35 PERCENT RANGE SUNDAY AFTERNOON.
BASED ON COLLABORATION WITH STATE FIRE WEATHER PARTNERS THOUGH,
FUEL MOISTURES REMAIN DAMP WITH THE RAINFALL OVER THE LAST FEW
DAYS ALONG WITH THE GREEN UP ACROSS MOST OF THE REGION. THEREFORE,
NO STATEMENTS WILL BE ISSUED AT THIS TIME.
KEY MESSAGE 3...A SERIES OF SYSTEMS ON WEDNESDAY AND THURSDAY
LIKELY BRINGS THE NEXT WIDESPREAD RAINFALL.
AS HIGH PRESSURE SHIFTS FURTHER AWAY ON TUESDAY, A LOW PASSING
WELL TO THE NORTH MAY BRING A FEW SHOWERS LATE TUESDAY INTO
TUESDAY NIGHT FOR AREAS NORTHWEST OF THE I-95 CORRIDOR. A COLD
FRONT THEN APPROACHES FROM THE WEST ON WEDNESDAY AND WILL STALL
OUT OVER THE AREA. A POTENTIALLY MORE DYNAMIC AREA OF LOW
PRESSURE DEVELOPS OVER THE SOUTHEAST AND CUTS INLAND TO OUR WEST
ON THURSDAY. THIS WILL RESULT IN WIDESPREAD RAINFALL OVER THOSE
TWO DAYS.
THE LATEST GUIDANCE HAS THE BULK OF THE PRECIPITATION FALLING
WITH THAT SECOND SYSTEM SLIDING THROUGH THURSDAY THOUGH THE
LATEST GUIDANCE HAS THE SYSTEM MOVING THROUGH FASTER. AS A
RESULT THE PEAK POPS (70-90%) COME A LITTLE BIT EARLIER (LATE
WEDNESDAY NIGHT/EARLY THURSDAY THROUGH THURSDAY EVENING).
TIMING OF THE PEAK ACTIVITY AND THE FRONT WILL PLAY KEY ROLES
IN THE POTENTIAL FOR ANY STRONG TO SEVERE THUNDERSTORMS. IF THE
PEAK OF THE RAINFALL COMES THURSDAY MORNING, THAT MAY INHIBIT
THE ABILITY FOR THE LOW-LEVELS OF THE ATMOSPHERE TO BECOME
UNSTABLE ENOUGH FOR STRONGER STORMS IN THE AFTERNOON BEFORE THE
FRONT ARRIVES. HOWEVER, IT IS STILL MUCH TOO EARLY TO HAVE ANY
LEVEL OF CERTAINTY ON THIS TIMING SO WE WILL HAVE TO CONTINUE TO
WATCH THIS PERIOD OVER THE NEXT COUPLE OF DAYS.
THE NBM PROBABILITY OF TOTAL RAINFALL FROM THOSE TWO SYSTEMS IS
ABOUT 40-70% FOR 1 INCH OR MORE FROM PHILADELPHIA ON NORTH AND
ABOUT 20-40% SOUTH OF PHILADELPHIA. WITH HOW DRY WE HAVE BEEN,
FLOODING CONCERNS APPEAR TO BE MINIMAL, WHICH MEANS THESE
SYSTEMS SHOULD LARGELY BE BENEFICIAL RAINFALL FOR THE AREA.
AVIATION /00Z SUNDAY THROUGH THURSDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
TONIGHT...VFR CEILINGS SHOULD MOSTLY BECOME SCATTERED TO FEW
OVERNIGHT. NORTHWEST WINDS AROUND 10 KNOTS, DIMINISHING TO 5
KNOTS OR LESS FOR A TIME. MODERATE CONFIDENCE.
SUNDAY...VFR CLOUD BASES INCREASE. NORTHWEST WINDS 10-15 KNOTS
WITH GUSTS 20-25 KNOTS. MODERATE CONFIDENCE.
OUTLOOK...
SUNDAY NIGHT THROUGH MONDAY NIGHT...VFR.
TUESDAY THROUGH TUESDAY NIGHT...VFR. SOUTHWESTERLY WIND GUSTS
20-25 KNOTS.
WEDNESDAY...PRIMARILY VFR. SOME SHOWERS MOVE IN FOR THE
AFTERNOON AND EVENING WHICH COULD RESULT IN SOME RESTRICTIONS.
SOUTH/SOUTHWEST WIND GUSTS 20-25 KNOTS.
THURSDAY...SUB-VFR CONDITIONS POSSIBLE WITH SHOWERS.
SOUTH/SOUTHWEST WIND GUSTS 20-25 KNOTS.
MARINE
SUB-SMALL CRAFT ADVISORY CONDITIONS TONIGHT INTO SUNDAY. NORTHWEST
WIND GUSTS TO AROUND 20 KNOTS BY LATER TONIGHT AND ON SUNDAY.
OUTLOOK...
SUNDAY...NO MARINE HEADLINES EXPECTED. CANNOT RULE OUT A BRIEF
PERIOD OF WIND GUSTS AROUND 20-25 KNOTS BUT THE POTENTIAL FOR
WIDESPREAD SCA CONDITIONS IS LOW (10% CHANCE OR LESS).
SUNDAY NIGHT...NO MARINE HEADLINES EXPECTED.
MONDAY...SCA CONDITIONS POSSIBLE (30-40% CHANCE) AS SEAS BEGIN
TO BUILD NEAR 5 FEET WITH WIND GUSTS AROUND 20-25 KNOTS.
TUESDAY THROUGH THURSDAY...SCA CONDITIONS EXPECTED (90-100%
CONFIDENCE). WIND GUSTS OUT OF THE SOUTH AROUND 20-30 KT. GALE
CONDITIONS POSSIBLE (30-40% CHANCE) ON TUESDAY NIGHT. SEAS OF 4
TO 7 FEET ANTICIPATED.
PHI WATCHES/WARNINGS/ADVISORIES
PA...FROST ADVISORY FROM 11 PM THIS EVENING TO 9 AM EDT SUNDAY FOR
PAZ060>062-101-103-105.
FREEZE WARNING FROM 11 PM THIS EVENING TO 9 AM EDT SUNDAY FOR
PAZ054-055.
NJ...FROST ADVISORY FROM 11 PM THIS EVENING TO 9 AM EDT SUNDAY FOR
NJZ001-007>009.
DE...NONE.
MD...NONE.
MARINE...NONE.
DISCUSSION...AKL/GORSE/RCM
AVIATION...AKL/GORSE/RCM
MARINE...AKL/GORSE/RCM
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page