337
FXUS61 KPHI 130038
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
838 PM EDT MON APR 12 2021
SYNOPSIS
LOW PRESSURE LOCATED OFF THE MIDDLE ATLANTIC COAST THIS
AFTERNOON WILL CONTINUE TO DRIFT FARTHER OUT TO SEA. WEAK HIGH
PRESSURE IS FORECAST TO INFLUENCE OUR WEATHER ON TUESDAY.
ANOTHER AREA OF LOW PRESSURE IS EXPECTED TO DEVELOP IN NORTH
CAROLINA ON WEDNESDAY BEFORE PASSING OFF THE VIRGINIA COAST ON
WEDNESDAY NIGHT. THE SYSTEM IS ANTICIPATED TO MOVE SLOWLY
NORTHEASTWARD ON THURSDAY AND FRIDAY. HIGH PRESSURE IS EXPECTED
TO BUILD INTO OUR REGION FROM THE NORTHWEST AND NORTH DURING THE
WEEKEND. WEAK LOW PRESSURE OR A COLD FRONT MAY FOLLOW FOR
SUNDAY NIGHT INTO MONDAY.
NEAR TERM /THROUGH TUESDAY/
THE BROAD SCALE BLOCKING PATTERN CONTINUES ACROSS THE CONUS
THROUGH TUESDAY. A CLOSED UPPER LOW LOCATED TO OUR NORTHWEST IS
EXPECTED TO OPEN AND EJECT EASTWARD ACROSS THE MID-ATLANTIC
TONIGHT WITH A LARGER AND STRONGER CLOSED UPPER LOW MOVING FROM
THE NORTHERN PLAINS TOWARD THE GREAT LAKES DURING THE DAY
TUESDAY. AT THE SURFACE, A BROAD AND STRUNG OUT AREA OF LOW
PRESSURE EXTENDS FROM THE GREAT LAKES REGION AND TO THE
SOUTHEAST ACROSS THE WESTERN ATLANTIC. HIGH PRESSURE CENTERED
WELL NORTHEAST OF THE REGION CONTINUES TO RIDGE DOWN INTO OUR
AREA.
THE SURFACE RIDGING WILL CONTINUE FEEDING IN THE COOL AND DAMP
AIR WE'VE HAD IN PLACE FOR THE PAST 24 HOURS OR SO, AND AS SUCH
TEMPERATURES ARE FORECAST TO REMAIN LARGELY STEADY IN THE 40S
THROUGH THE OVERNIGHT PERIOD. A NOTABLE NORTHEASTERLY BREEZE
WILL PERSIST AS WELL UNDER THE LOW STRATUS DECK. AS THE UPPER
LOW EJECTS OVER THE REGION TONIGHT, ANOTHER ROUND OF
SHOWERS/DRIZZLE IS FORECAST OVERNIGHT ACROSS MUCH OF THE AREA,
MAINLY BETWEEN ABOUT MIDNIGHT AND 6 AM.
AS THE OPENING UPPER LOW DEPARTS TUESDAY MORNING ALONG WITH THE
REGRESSION OF THE SURFACE RIDGING, WE SHOULD SEE CONSIDERABLE
CLEARING DURING THE MORNING HOURS FROM EAST TO WEST.
TEMPERATURES WILL ALSO RISE TO NEAR NORMAL VALUES, WITH FORECAST
HIGHS IN THE LOW TO MID 60S AWAY FROM THE COASTS. EXPECT
NORTHERLY WINDS AROUND 5-10 MPH DURING THE DAY AS WELL.
SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/
THE AXIS OF A MID LEVEL RIDGE IS FORECAST TO PASS OVERHEAD ON
TUESDAY NIGHT, BEFORE DRIFTING TO OUR EAST ON WEDNESDAY. WE ARE
ANTICIPATING AN INCREASE IN CLOUD COVER ON TUESDAY NIGHT WITH
LIGHT RAIN ARRIVING FROM THE WEST ON WEDNESDAY, AHEAD OF OUR
NEXT WEATHER SYSTEM.
A SHORT WAVE TROUGH TRAVELING IN THE WESTERLY MID LEVEL FLOW IS
EXPECTED TO PASS OVER THE SOUTHEASTERN STATES ON WEDNESDAY AND
WEDNESDAY EVENING. A SURFACE LOW IS FORECAST TO DEVELOP IN NORTH
CAROLINA ON WEDNESDAY BEFORE MOVING OFF THE VIRGINIA COAST ON
WEDNESDAY NIGHT. THE LOW SHOULD THEN DRIFT NORTHEASTWARD OVER
THE WATERS OFF MARYLAND, DELAWARE AND SOUTHERN NEW JERSEY ON
THURSDAY.
WE ARE EXPECTING AN INCREASING CHANCE OF RAIN FROM WEDNESDAY
NIGHT INTO THURSDAY. WHILE SOME MODERATE TO HEAVY RAIN IS
POSSIBLE IN SPOTS, IT IS DIFFICULT TO PINPOINT EXACTLY WHICH
AREAS ARE MOST LIKELY TO RECEIVE IT. THE SAME IS TRUE WITH THE
POTENTIAL FOR LOCALIZED THUNDER.
A LIGHT SOUTHWEST WIND ON WEDNESDAY IS FORECAST TO BECOME EAST
TO NORTH GENERALLY AROUND 10 TO 15 MPH ON THURSDAY AS THE LOW
DRIFTS OUT TO SEA. HIGHS ARE EXPECTED TO FAVOR THE 60S ON
WEDNESDAY, AND THE 50S ON THURSDAY DUE TO THE CHILLY ONSHORE
FLOW.
LONG TERM /THURSDAY NIGHT THROUGH MONDAY/
A MID LEVEL LOW APPROACHING SLOWLY FROM THE GREAT LAKES IS
EXPECTED TO PASS OVERHEAD FROM LATE THURSDAY NIGHT INTO FRIDAY
MORNING. THE FEATURE WILL CONTINUE TO BRING A CHANCE OF SHOWERS
TO OUR REGION. THERE MAY BE ENOUGH COLD AIR IN THE ELEVATED
TERRAIN OF THE POCONOS TO RESULT IN SOME LATE SEASON SNOW FLAKES
AT THAT TIME.
THE MID LEVEL LOW IS ANTICIPATED TO MOVE OUT TO SEA OVER THE
WEEKEND. DRY AIR IS FORECAST TO BUILD INTO OUR REGION FROM THE
NORTHWEST AND NORTH FOR FRIDAY NIGHT AND SATURDAY.
THE SURFACE HIGH SHOULD PASS OFF THE COAST AND BEGIN TO MOVE
OUT OVER THE WESTERN NORTH ATLANTIC ON SUNDAY. WE MAY SEE SOME
SHOWERS IN THE RETURN FLOW ON THE BACK SIDE OF THE HIGH ON
SUNDAY AFTERNOON. A MID LEVEL TROUGH IS EXPECTED TO APPROACH
FROM THE WEST ON SUNDAY NIGHT AND MONDAY.
TEMPERATURES WILL LIKELY REMAIN BELOW NORMAL FOR FRIDAY DUE TO
THE MID LEVEL LOW. READINGS ARE FORECAST TO RETURN NEAR NORMAL
FOR THE WEEKEND AND FOR MONDAY.
AVIATION /01Z TUESDAY THROUGH SATURDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
TONIGHT...INITIALLY MVFR, WITH IFR CEILINGS DEVELOPING AFTER
ABOUT 02-03Z. THERE IS SOME POSSIBILITY THAT THE WESTERN SITES
WILL STAY MVFR BUT CONFIDENCE IN THIS IS LOW. SOME COMBINATION
OF LIGHT RAIN SHOWERS AND/OR DRIZZLE/MIST WILL BE POSSIBLE IN
THE 03-09Z TIME FRAME. THE IFR CEILINGS SHOULD BECOME MVFR
AROUND 09Z. WINDS NORTHEASTERLY AROUND 5 KTS. MODERATE
CONFIDENCE.
TUESDAY...INITIALLY MVFR CEILINGS SHOULD SCATTER OUT IN THE
14-16Z TIME FRAME WITH VFR CONDITIONS THEN PREVAILING THE
REMAINDER OF THE DAY. INITIALLY NORTHEASTERLY WINDS AROUND 5-10
KTS WILL BECOME MORE NORTHERLY 5-10KTS AFTER 15Z. MODERATE
CONFIDENCE.
OUTLOOK...
WEDNESDAY...MAINLY VFR. A CHANCE OF SHOWERS IN THE AFTERNOON.
SOUTHWEST WIND 5 TO 10 KNOTS. MEDIUM TO HIGH CONFIDENCE.
THURSDAY...IFR/MVFR WITH RAIN LIKELY. EAST TO NORTH WIND
INCREASING TO 10 TO 15 KNOTS WITH GUSTS AROUND 20 KNOTS. MEDIUM
CONFIDENCE.
FRIDAY...MVFR/VFR WITH A CHANCE OF SHOWERS. NORTHWEST WIND 10
TO 15 KNOTS WITH GUSTS OF 20 TO 25 KNOTS. MEDIUM CONFIDENCE.
SATURDAY...MAINLY VFR. NORTHWEST WIND 10 TO 15 KNOTS. MEDIUM
CONFIDENCE.
MARINE
A SMALL CRAFT ADVISORY WILL REMAIN IN EFFECT THROUGH TONIGHT
AND THROUGH MUCH OF TUESDAY MORNING ACROSS THE OCEAN WATERS.
SEAS OF 3-6 FEET AREA FORECAST TONIGHT, WHICH WILL GRADUALLY
SUBSIDE TOMORROW MORNING TO BELOW 5 FEET INTO THE AFTERNOON.
WINDS NORTHEASTERLY AROUND 15-20 KTS WITH GUSTS UP TO 25 KTS
ACROSS THE OCEAN WATERS. THE WINDS WILL ALSO GRADUALLY DIMINISH
THROUGHOUT THE DAY TUESDAY AS WELL AND BECOME MORE NORTHERLY.
OUTLOOK...
WEDNESDAY...NO MARINE HEADLINES ARE ANTICIPATED.
THURSDAY...EAST TO NORTH WIND INCREASING TO 15 TO 20 KNOTS WITH
GUSTS AROUND 25 KNOTS.
FRIDAY...NORTHWEST WIND 15 TO 20 KNOTS WITH GUSTS OF 25 TO 30
KNOTS.
SATURDAY...NO MARINE HEADLINES ARE ANTICIPATED.
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EDT TUESDAY FOR ANZ451>455.
SMALL CRAFT ADVISORY UNTIL 11 AM EDT TUESDAY FOR ANZ450.
SYNOPSIS...IOVINO
NEAR TERM...STAARMANN
SHORT TERM...IOVINO
LONG TERM...IOVINO
AVIATION...CARR/IOVINO/STAARMANN
MARINE...IOVINO/STAARMANN
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