519
FXUS61 KPHI 292301
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
701 PM EDT WED MAR 29 2023
SYNOPSIS
COLD FRONT CROSSES THE REGION TONIGHT. HIGH PRESSURE BUILDS IN FOR
THURSDAY, MOVING OFFSHORE INTO FRIDAY. STRONG LOW PRESSURE MOVES UP
ACROSS THE GREAT LAKES REGION FRIDAY NIGHT INTO SATURDAY, PULLING A
STRONG COLD FRONT ACROSS OUR AREA LATER SATURDAY INTO SATURDAY NIGHT.
HIGH PRESSURE ARRIVES FOR SUNDAY, HOLDING INFLUENCE OVER THE
REGION MONDAY. WEAKENING FRONTAL BOUNDARY APPROACHES THE REGION
THEREAFTER.
NEAR TERM /THROUGH THURSDAY NIGHT/
A COLD FRONT CONTINUES TO WORK ITS WAY THROUGH WESTERN NEW YORK
AND WESTERN PENNSYLVANIA. THERE ARE GUSTY WINDS AND SNOW SHOWERS
ASSOCIATED WITH IT. VISIBILITY AT KOLE DROPPED TO M1/4SM IN +SN
AT 6:35 PM AND THERE WAS A 43 MPH WIND GUST AT KCLE AT 3:51 PM.
THIS FRONT WILL CROSS THE LOCAL AREA BETWEEN 9 PM AND 2 AM, WITH
THE BEST CHANCES FOR SNOW SHOWERS ACROSS THE SOUTHERN POCONOS
AND NORTHERN NEW JERSEY. BY THE TIME THE FRONT GETS HERE, IT
WILL BE AFTER SUNSET, AND TEMPERATURES WILL BEGIN TO DIMINISH.
THIS WILL HELP LIMIT INSTABILITY. IN ADDITION, IT REMAINS QUITE
DRY WITH SURFACE DEW POINTS IN THE 20S AND 30S. IN THE IMMEDIATE
WAKE OF THE COLD FRONT, THERE SHOULD BE A SURGE OF 30 MPH WIND
GUSTS FOR AN HOUR OR SO.
A COATING OF SNOW IS POSSIBLE IN THE HIGHER ELEVATIONS OF CARBON
AND MONROE COUNTIES. OTHERWISE, NORTHWEST WINDS WILL RANGE FROM
10 TO 15 MPH THROUGH DAYBREAK OR SO. OTHERWISE, SOME RAIN
SHOWERS ARE POSSIBLE INTO THE LEHIGH VALLEY AND NORTHERN NEW
JERSEY.
STRONG COLD AIR ADVECTION WILL THEN BE UNDERWAY. LOW
TEMPERATURES TONIGHT WILL RANGE FROM THE LOWER AND MIDDLE 20S
IN THE POCONOS AND IN FAR NORTHERN NEW JERSEY, TO THE MIDDLE 30S
IN CENTRAL AND SOUTHERN DELAWARE AND IN THE ADJACENT COUNTIES
OF EASTERN MARYLAND.
HIGH PRESSURE BUILDS BACK IN THURSDAY, BRINGING CLEAR SKIES WITH A
COOLER AIRMASS. AFTERNOON HIGHS WILL ONLY REACH THE UPPER 30S TO LOW
40S ACROSS HIGHER ELEVATIONS WITH MID 40S TO LOW 50S ACROSS THE
COASTAL PLAIN. HIGH PRESSURE WILL BECOME CENTERED OVERHEAD THURSDAY
NIGHT, POSSIBLY ALLOWING FOR ROBUST RADIATIONAL COOLING TO ENSUE.
OVERNIGHT LOWS ARE EXPECTED IN THE MID 20S TO LOW 30S.
IN REGARDS TO FROST/FREEZE POTENTIAL ACROSS THE DELMARVA...AS IT
CURRENTLY STANDS, SOME PATCHY FROST IS VERY POSSIBLE THURSDAY NIGHT
ACROSS THE DELMARVA WHERE THE GROWING SEASON HAS BEGUN. FURTHERMORE,
IF WINDS REMAIN LIGHT AND DECOUPLE, OVERNIGHT LOWS COULD COOL BELOW
THE CURRENT FORECAST, WHICH WOULD BRING TEMPERATURES BELOW FREEZING
BY A FEW DEGREES ACROSS THE NORTH-CENTRAL DELMARVA WHERE THE GROWING
SEASON HAS BEGUN. RIGHT NOW UNCERTAINTY REMAINS TOO LOW FOR A FREEZE
WATCH, BUT A FROST ADVISORY MAY BE NEEDED.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/
SIGNIFICANT WARM-UP THROUGH SATURDAY. SHOWERS FRIDAY NIGHT AND
SATURDAY MORNING, THEN SOME SHOWERS OR A THUNDERSTORM POSSIBLE
SATURDAY AFTERNOON WITH A STRONG COLD FRONT. STRONG WINDS SATURDAY.
A MORE ZONAL FLOW ALOFT ACROSS OUR REGION FRIDAY WILL GIVE WAY TO A
POTENT CLOSED LOW FROM THE MIDWEST AND GREAT LAKES. THIS TROUGH WILL
SHIFT ACROSS THE NORTHEAST AND MID-ATLANTIC REGIONS DURING SATURDAY
AND WEAKEN SOME. IT WILL DRIVE STRONG SURFACE LOW PRESSURE ACROSS
THE GREAT LAKES TO NORTHERN NEW ENGLAND THROUGH SATURDAY, WITH A
STRONG COLD FRONT CROSSING OUR AREA SATURDAY AFTERNOON AND EVENING.
THE LOW-LEVEL WARM AIR ADVECTION CONTINUES FRIDAY WITH 925 MB
TEMPERATURES INCREASING TO +7C TO +12C. SOUTH TO SOUTHWEST WINDS
WILL ALSO INCREASE THE LOW-LEVEL MOISTURE. HIGH TEMPERATURES ARE
FORECAST TO JUMP INTO THE MID/UPPER 50S TO LOW TO MID 60S ACROSS THE
REGION (STILL COOLER THOUGH IN PARTS OF THE SOUTHERN POCONOS). AS
THE LOW-LEVEL FLOW INCREASES IN CONJUCTION WITH THE WARM AIR
ADVECTION, A WARM FRONT IS FORECAST TO BECOME BETTER ORGANIZED INTO
OUR AREA. SOME ASSOCIATED LIFT MAY RESULT IN SOME AFTERNOON SHOWERS
MAINLY NEAR AND NORTH OF I-78. THE SHOWERS WILL THEN INCREASE
EASTWARD FRIDAY NIGHT AS FORCING FOR ASCENT BECOMES ENHANCED BY A
PASSING SHORTWAVE, AN 850 MB SOUTHWESTERLY JET OF 50-70 KNOTS AND A
BURST OF LOW-LEVEL WARM AIR ADVECTION. A SOUTH TO SOUTHWEST BREEZE
WILL DEVELOP FRIDAY AND BECOME GUSTY, AND A MORE SOUTHERLY COMPONENT
WILL RESULT IN COOLER TEMPERATURES ALONG THE COAST ESPECIALLY NEW
JERSEY. MUCH MILDER FRIDAY NIGHT AS WE BECOME DEEPER INTO THE WARM
SECTOR.
AS WE GO THROUGH SATURDAY, A POTENT UPPER-LEVEL TROUGH ARRIVES AND
STRONG SURFACE LOW PRESSURE WILL TRACK TO OUR NORTHWEST AND NORTH.
ITS STRONG COLD FRONT HOWEVER WILL CROSS OUR REGION DURING THE
AFTERNOON AND EARLY EVENING. A ROBUST AND DEEP SOUTHWESTERLY WIND
FIELD WILL MOVE ACROSS OUR REGION AHEAD OF THE COLD FRONT, WITH 850
MB WINDS FORECAST TO BE 40-70 KNOTS. THE CORE OF THE LOW-LEVEL JET
HOWEVER IS FORECAST TO SHIFT OFFSHORE BY MIDDAY, AND THIS SHOULD
RESULT IN SHOWERS ENDING. THE MODEL FORECAST SOUNDINGS THEN SHOW A
GOOD AMOUNT OF DRYING TAKING PLACE IN THE AFTERNOON WHICH WOULD
RESULT IN AT LEAST PARTIAL CLEARING AHEAD OF THE COLD FRONT. THE
MORE SUNSHINE THAT IS REALIZED THE WARMER IT WILL GET AND ALSO
RESULT IN DEEPER VERTICAL MIXING. THE WARMTH WILL ALSO DETERMINE HOW
MUCH INSTABILITY CAN BE REALIZED. THE MODEL FORECAST SOUNDINGS SHOW
SOME INSTABILITY DEVELOPING IN THE AFTERNOON WHICH COULD RESULT IN
SOME THUNDERSTORMS. THE EXTENT OF THE DRY AIR ABOVE THE SURFACE
HOWEVER MAY LIMIT THE CONVECTIVE DEVELOPMENT. THE QUESTION IS HOW
MUCH FORCING ACCOMPANIES THE COLD FRONT ESPECIALLY FOR CONVECTIVE
DEVELOPMENT. GIVEN THE ROBUST WIND FIELD ALONG WITH STEEP LOW-LEVEL
LAPSE RATES, IF SOME CONVECTION WERE TO DEVELOP THEN LOCALLY
DAMAGING WINDS WOULD BE POSSIBLE.
OUTSIDE OF ANY CONVECTION, IT WILL BE A WINDY DAY AS DEEP MIXING IS
DEPICTED ON THE MODEL FORECAST SOUNDINGS. IF THE GFS SOUNDINGS ARE
CORRECT, WE MAY BE VERY CLOSE TO HIGH WIND WARNING CRITERIA (WIND
GUSTS OF 58+ MPH) FOR SOME AREAS IN THE AFTERNOON. WHILE THIS CANNOT
BE RULED OUT, THE THINKING IS THAT A WIND ADVISORY IS POSSIBLE WITH
PEAK GUSTS MOSTLY IN THE 40-50 MPH RANGE SATURDAY AFTERNOON. IN
ADDITION, THERE COULD BE A BURST OF STRONGER WINDS WITH THE COLD
FRONT AS QUICKLY INCREASING COLD AIR ADVECTION ENHANCES THE DOWNWARD
MOMENTUM TRANSFER FOR A SHORT TIME.
AHEAD OF THE COLD FRONT, THE AIR MASS IS FORECAST TO BE VERY WARM
WITH MUCH OF OUR AREA GETTING INTO THE LOW TO MID 70S. THE CURRENT
RECORD HIGH TEMPERATURES HOWEVER FOR APRIL 1ST ARE IN THE 80S FOR
ALL OF OUR CLIMATE SITES (EXCEPT LOW 70S FOR THE ATLANTIC CITY
MARINA), THEREFORE THESE WOULD BE SAFE. AS THE COLD FRONT MOVES
THROUGH, STRONG COLD AIR ADVECTION OCCURS AND THIS SHOULD KEEP THE
WINDS GUSTY SATURDAY NIGHT ALTHOUGH SOME DECREASE IS EXPECTED
OVERNIGHT. ANY SHOWERS AND/OR THUNDER ARE EXPECTED TO END DURING THE
EARLY EVENING AS MUCH DRIER AND COLDER AIR ADVECTS INTO THE
REGION.
LONG TERM /SUNDAY THROUGH WEDNESDAY/
FEATURES...THE LONG TERM PERIOD WILL LOOK TO START OUT SUNDAY WITH
SURFACE HIGH PRESSURE TO OUR NORTHWEST NEAR THE GREAT LAKES REGION.
WITH TIME, THIS HIGH WILL LOOK TO MIGRATE GENERALLY SOUTHEASTWARD
BEFORE EMERGING OFFSHORE OF THE REGION BY MONDAY. AS THE HIGH
CONTINUES TO PUSH EASTWARD OVER THE ATLANTIC MONDAY AND ONWARDS, IT
IS POSSIBLE THAT A WEAKENING FRONTAL BOUNDARY ASSOCIATED WITH LOW
PRESSURE OVER THE GREAT LAKES REGION WILL BE APPROACHING. AS THIS
FRONTAL BOUNDARY SLOWS DOWN AND POSSIBLY STALLS OVER OUR REGION
DURING THE MONDAY NIGHT TO TUESDAY TIME FRAME, SURFACE LOW PRESSURE
WILL BE DEEPENING OVER THE CENTRAL CONUS WITH FRONTOGENESIS
OCCURRING ALONG WITH IT. WITH MOST ENSEMBLES SUPPORTING THE
CENTRAL CONUS LOW TRACKING NORTHEASTWARDS TOWARDS THE GREAT
LAKES, A WARM FRONT WILL LOOK TO APPROACH THE REGION DURING THE
TUESDAY AND TUESDAY NIGHT TIME FRAME, POSSIBLY PASSING THROUGH
THE REGION COME TUESDAY NIGHT INTO WEDNESDAY.
IMPACTS...EXPECTING HIGH PRESSURE TO DOMINATE OUR REGION SUNDAY AND
MONDAY WITH MAINLY BENIGN CONDITIONS; HAVE NO POPS INCLUDED IN
FORECAST THROUGH THIS TIME FRAME. HOWEVER, IT SHOULD BE MENTIONED
THAT THERE IS SOME GUIDANCE/MODEL SUPPORT FOR SHORTWAVE ENERGY TO
LINGER SUNDAY. THE WEAKENING FRONTAL BOUNDARY APPROACHING THE REGION
MONDAY MAY LOOK TO BRING SOME RAIN TO THE REGION STARTING MONDAY
NIGHT; HAVE INCLUDED SLIGHT CHANCE POPS IN THE FORECAST FOR THIS
TIME FRAME. GUIDANCE INDICATES THIS WEAKENING BOUNDARY MAY STALL
OVER OR NEAR OUR REGION WHILE BEING FLANKED SOUTHWARDS; CANNOT RULE
OUT PRECIPITATION CONTINUING FROM THIS BOUNDARY THROUGH TUESDAY.
HENCE, SLIGHT CHANCE OF POPS CONTINUE TO BE INCLUDED. TUESDAY NIGHT
AND WEDNESDAY, CHANCE POPS ARE INTRODUCED IN ANTICIPATION OF WARM
FRONTAL BOUNDARY APPROACHING THE REGION FROM CENTRAL CONUS LOW
MOVING NORTHEASTWARDS.
TEMPERATURES WILL LIKELY BE BELOW AVERAGE SUNDAY AS COLD AND DRIER
AIR MOVES IN FROM THE NORTHWEST. MAINLY ABOVE AVERAGE TEMPERATURES
CAN BE EXPECTED THEREAFTER, ESPECIALLY FOR TUESDAY AND
WEDNESDAY.
AVIATION /00Z THURSDAY THROUGH MONDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
TONIGHT...MAINLY VFR. THERE IS A CHANCE OF LIGHT RAIN SHOWERS
BETWEEN ABOUT 01Z AND 05Z AROUND KRDG, KABE AND KTTN. SOUTHWEST WIND
5 TO 10 KNOTS, BECOMING NORTHWEST 10 TO 15 KNOTS WITH GUSTS OF 20 TO
25 KNOTS. A COLD FRONTAL PASSAGE AROUND 03Z TO 06Z COULD BRING A
BRIEF PERIOD OF NORTHWESTERLY WIND GUSTS NEAR THE 30 KNOT RANGE.
MEDIUM TO HIGH CONFIDENCE.
THURSDAY...VFR. NW WINDS 5-10 KTS DURING THE DAY, BECOMING CALM AT
NIGHT. HIGH CONFIDENCE.
OUTLOOK...
FRIDAY...VFR WITH INCREASING CLOUDS AND CEILINGS GRADUALLY LOWER IN
THE AFTERNOON, THEN MVFR TO IFR CONDITIONS DEVELOP AT NIGHT WITH
SHOWERS. SOUTHWEST WINDS 10-15 KNOTS WITH GUSTS TO AROUND 25 KNOTS,
DIMINISHING TO MAINLY 10 KNOTS OR LESS AT NIGHT. A PERIOD OF LOW-
LEVEL WIND SHEAR POSSIBLE AT NIGHT. MODERATE CONFIDENCE.
SATURDAY...MVFR/IFR CONDITIONS IN THE MORNING WITH SHOWERS, THEN
MAINLY VFR IN THE AFTERNOON. SOME SHOWERS OR A THUNDERSTORM POSSIBLE
IN THE AFTERNOON TO EARLY EVENING. SOUTHWEST WINDS 15-25 KNOTS WITH
GUSTS 30-40 KNOTS, WITH THE STRONGEST WINDS IN THE AFTERNOON. WINDS
THEN BECOME WEST TO NORTHWEST AT NIGHT AND DIMINISH SOME. LOW
CONFIDENCE.
SUNDAY...VFR WITH PREVAILING NW FLOW AROUND 15 KTS. HIGH CONFIDENCE.
MONDAY...VFR WITH S/SW FLOW PREVAILING AROUND 15 KTS. HIGH
CONFIDENCE.
MARINE
A EASTERLY WIND AROUND 10 KNOTS THIS AFTERNOON WILL BECOME A
SOUTHWEST WIND 10 TO 15 KNOTS THIS EVENING. WE WILL THEN SEE IT
SHIFT TO THE NORTHWEST WITH A COLD FRONTAL PASSAGE AFTER MIDNIGHT.
SUSTAINED WIND SPEEDS ARE ANTICIPATED TO INCREASE TO 20 TO 25 KNOTS
FOR A FEW HOURS IN THE WAKE OF THE FRONT WITH GUSTS AROUND 30 KNOTS.
SEAS BUILD TO 2-4 FT WITH A FEW 5 FT WAVES. AS A RESULT, A SMALL
CRAFT ADVISORY IS IN EFFECT FOR OUR OCEAN WATERS AND FOR DELAWARE
BAY FROM MIDNIGHT UNTIL 8:00 AM THURSDAY.
SUB-SCA CONDITIONS RESUME THURSDAY WITH NW WINDS SUBSIDING TO AROUND
10 KTS BECOMING LIGHT THURSDAY NIGHT. SEAS 2-4 FT DURING THE DAY
DROP TO 1-2 FT AT NIGHT.
OUTLOOK...
FRIDAY...SMALL CRAFT ADVISORY CONDITIONS DEVELOPING AS SOUTH TO
SOUTHWEST WINDS INCREASE AND SEAS BUILD.
SATURDAY...SMALL CRAFT ADVISORY CONDITIONS LIKELY. A PERIOD OF GALE
FORCE WIND GUSTS POSSIBLE SATURDAY INTO SUNDAY, HOWEVER THIS WILL
DEPEND ON THE VERTICAL MIXING AS A VERY WARM AIR MASS OVER THE
CHILLY OCEAN WATERS WILL BE IN PLACE AHEAD OF A STRONG COLD FRONT.
THE GREATEST CHANCE FOR GALE FORCE WIND GUSTS MAY END UP BEING
DURING SATURDAY NIGHT ALONG AND BEHIND THE COLD FRONT.
SUNDAY...SCA CONDITIONS LIKELY.
MONDAY...SCA CONDITIONS POSSIBLE.
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 8 AM EDT
THURSDAY FOR ANZ430-431.
SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 10 AM EDT
THURSDAY FOR ANZ450>455.
SYNOPSIS...OHARA/WUNDERLIN
NEAR TERM...MJL/MPS
SHORT TERM...GORSE
LONG TERM...WUNDERLIN
AVIATION...GORSE/MJL/MPS/WUNDERLIN
MARINE...GORSE/IOVINO/MJL/WUNDERLIN
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