249
FXUS61 KPHI 062311
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
711 PM EDT MON APR 6 2020
SYNOPSIS
HIGH PRESSURE WILL CONTINUE TO WORK ITS WAY ACROSS THE REGION
THROUGH TUESDAY, BRINGING DRY AND PLEASANT WEATHER AS IT DOES SO. A
WAVE OF LOW PRESSURE WILL RIDE ALONG A WARM FRONT AS IT SLOWLY LIFTS
NORTHWARD INTO OUR REGION WEDNESDAY. A STRONGER SURFACE LOW WILL
TRACK INTO THE GREAT LAKES BY THE END OF THE WEEK, BRINING A COLD
FRONT EASTWARD ACROSS THE MID-ATLANTIC THURSDAY. UNSETTLED WEATHER
LOOKS TO ACCOMPANY THE LOW AS IT SLOWLY LIFTS NORTH AND EAST FRIDAY,
BEFORE HIGH PRESSURE BEGINS TO BUILD TO OUR SOUTH INTO THE WEEKEND.
ANOTHER LOW PRESSURE SYSTEM MAY AFFECT OUR REGION INTO THE START OF
NEXT WEEK.
NEAR TERM /UNTIL 6 AM TUESDAY MORNING/
NO SIGNIFICANT CHANGES IN THE NEAR TERM. THE SEA BREEZE
CONTINUES TO PROGRESS INLAND, BUT IS EXPECTED TO DISSIPATE
WITHIN THE NEXT 3 HOURS.
OTHERWISE, TRANQUIL WEATHER WILL PERSIST OVER THE REGION
OVERNIGHT. CLOUDS WILL BEGIN TO INCREASE FROM SOUTH TO NORTH AS
THE FRONT TO OUR SOUTH BEGINS TO MOVE BACK NORTHWARD AS A WARM
FRONT AHEAD OF THE NEXT SYSTEM. LOWS WILL BE GENERALLY IN THE
LOW TO MID 40S EXCEPT SOME UPPER 30S OVER THE SOUTHERN POCONOS
AND PARTS OF NW NJ.
SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/
THE CLOUDS WILL GENERALLY LOWER AND THICKEN THROUGH TUESDAY MORNING
AS THE NEXT LOW PRESSURE SYSTEM ADVANCES THROUGH THE MIDWEST AND THE
WARM FRONT TO OUR SOUTH CONTINUES TO NUDGE NORTHWARD. ALONG AND
AHEAD OF THIS FRONT, IT'S STILL LOOKING LIKE THERE WILL BE SOME
SHOWERS DEVELOPING BUT THE TIMING HAS BEEN DELAYED SLIGHTLY AND IT
ALSO LOOKS AT THIS POINT LIKE MOST OF THE ACTIVITY SHOULD BE
CONFINED TO SE PA INTO FAR SOUTHERN NJ AND DELMARVA. EXPECT THESE
AREAS TO SEE INCREASING CHANCES FOR SOME SHOWERS AROUND MAINLY
BEYOND THE MIDDAY TIME FRAME. POPS DECREASE TO SLIGHT CHANCE FARTHER
NORTH OVER NE PA INTO NW NJ. ALSO WORTH MENTIONING, THERE COULD EVEN
BE A FEW RUMBLES OF THUNDER LATE DAY BUT MAINLY SOUTH OF THE MASON-
DIXON LINE. HIGHS TUESDAY WILL BE MAINLY IN THE LOW TO MID 60S SO
NOT TOO DIFFERENT THAN TODAY AS THE WARM ADVECTION PATTERN IS
COUNTERACTED BY THE INCREASED CLOUD COVER.
LONG TERM /TUESDAY NIGHT THROUGH MONDAY/
A WEAK WAVE OF LOW PRESSURE WILL RIDE EASTWARD AS A WARM FRONT LIFTS
NORTHWARD FROM VIRGINIA WEDNESDAY, BRINING SCATTERED RAIN SHOWERS TO
THE REGION AS IT DOES SO. FORCING DOESN'T LOOK PARTICULARLY STRONG
WITH ONLY A 100 KT UPPER LEVEL JET, THUS PVA WILL BE THE PRIMARY
FORCING MECHANISM. RAIN SHOULD TAPER OFF BY LATE AFTERNOON OR EARLY
EVENING AS THE DISTURBANCE PUSHES OFFSHORE TO OUR SOUTH AND
EAST. FORECAST MLCAPE VALUES OF 500-1000 J/KG WILL LIKELY RESULT
IN EMBEDDED THUNDERSTORMS. AS WE MOVE INTO RANGE OF SOME OF THE
CAMS, THEY SUGGEST THERE COULD BE A COUPLE ROUNDS OF SHOWERS
AND CONVECTION, WITH A MORE WIDESPREAD ROUND WEDNESDAY, FOLLOWED
BY A LULL AND EVENTUALLY AN ADDITIONAL ROUND OF SHOWERS AND
THUNDERSTORMS WEDNESDAY EVENING. WITH NO SURPRISE, KEPT MENTION
OF THUNDER IN THE GRIDS THROUGH MUCH OF THE DAY WEDNESDAY.
THE WARM FRONT LOOKS TO HANG SOMEWHERE OVER THE REGION, THUS A
TEMPERATURE GRADIENT WILL LIKELY ESTABLISH ITSELF, YIELDING A LITTLE
DIFFICULTY IN THE TEMPERATURE AND DEW POINT FORECAST IN SPATIAL AND
TEMPORAL REGARD. HIGHS WEDNESDAY WILL VERY WELL LIKELY BE THE
WARMEST OF THE WEEK WITH MOST PLACES REACHING NEAR OR ABOVE 70, SO
THAT WILL ATTEMPT TO MAKE UP FOR THE PRECIPITATION.
MOVING INTO THURSDAY, A SURFACE LOW WILL BEGIN TO APPROACH THE
REGION AS IT MOVES ACROSS THE GREAT LAKES INTO SOUTHEASTERN ONTARIO.
THE LOW LOOKS TO QUICKLY OCCLUDE AS BOTH THE EC AND GFS ARE
FORECASTING A CLOSED 500 MB LOW BY THURSDAY AFTERNOON, THUS, AS IS
USUALLY THE CASE WITH SUCH SYSTEMS, A NEW SURFACE LOW WILL FORM NEAR
THE TRIPLE POINT SOMEWHERE OVER THE DELAWARE VALLEY. NOT A TON
OF CONVECTION ALONG THE COLD FRONT AS IT MOVES INTO THE REGION
AS FORECAST, CAPE VALUES INDICATE LESS IMPRESSIVE INSTABILITY
COMPARED TO WEDNESDAY. NOT TO SAY THIS WON'T CHANGE AS WE DRAW
CLOSER, BUT FORE NOW IT IS SUCH. THE NEW LOW WILL THEN SKIRT
NORTHEAST ALONG THE NEW ENGLAND COAST INTO THURSDAY NIGHT INTO
FRIDAY AS A REINFORCING SHORTWAVE DIVES SOUTHWARD ACROSS THE
GREAT LAKES, PUMPING VORTICITY AND REINFORCING JET ENERGY INTO
THE AMPLIFYING SYNOPTIC TROUGH. HIGHS THURSDAY WILL TREND
SLIGHTLY COOLER WITH THE THREAT FOR MORE WIDESPREAD RAIN ALONG
THE COLD FRONT WITH HIGHS STAYING IN THE LOW 60S NORTH TO UPPER
60S SOUTH.
UNSETTLED CONDITIONS FRIDAY AND INTO FRIDAY NIGHT AS THIS
REINFORCING SHORTWAVE PUSHES A SERIES OF SURFACE TROUGHS SOUTH INTO
THE REGION AROUND THE DEEPENING SURFACE LOW TO OUR NORTHEAST. BROAD-
BRUSHED POPS THROUGH SATURDAY MORNING WITH THE GENERAL CHANCE FOR
SCATTERED SHOWERS FOR NOW UNTIL BETTER GUIDANCE COMES INTO PLAY. THE
SHARP COOLING AND STEEP LAPSE RATES SHOULD MEAN THAT ACROSS THE AREA
THURSDAY AND FRIDAY WE'LL BE FAIRLY GUSTY FROM 25-35 KTS POSSIBLE.
WE COULD APPROACH ADVISORY LEVEL WIND GUSTS THURSDAY AFTERNOON,
SO THIS WILL WARRANT CONTINUAL OBSERVATION.
HIGH PRESSURE BUILDS TO OUR SOUTH INTO THE CAROLINAS SATURDAY
AFTERNOON THROUGH SUNDAY AS NORTHWEST FLOW SLOWLY TURNS MORE
SOUTHWESTERLY. COOLER THAN WHAT WE WILL HAVE GROWN ACCUSTOMED TO
THIS WEEKEND WITH HIGHS IN THE MID TO UPPER 50S SATURDAY AND LOW 60S
BY SUNDAY.
LONG RANGE GUIDANCE GOES SOUTH BY EARLY NEXT WEEK, WITH APPRECIABLE
DIFFERENCES BETWEEN THE EC AND GFS MONDAY AS TO THE TIMING OF
ANOTHER SURFACE LOW. THE EC HAS A SOLID SOAKER WITH A SURFACE LOW
MOVING RIGHT UP THE EASTERN APPALACHIANS SUNDAY NIGHT INTO MONDAY
MORNING MORNING, WHEREAS THE GFS KEEPS THE LOW WELL TO OUR WEST
UNTIL LATE MONDAY AS A SURFACE LOW TRACKS ACROSS THE CAROLINAS. AS
SUCH, POOR CONFIDENCE IN POPS AT THIS TIME WITH ONLY A BROAD GENERAL
MENTION OF SHOWERS.
AVIATION /23Z MONDAY THROUGH SATURDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
THROUGH TONIGHT...VFR CONDITIONS ARE EXPECTED, ALTHOUGH MID AND
HIGH LEVEL CLOUDS ARE EXPECTED TO INCREASE AFTER 06Z. NORTHERLY
AND NORTHWESTERLY WINDS ARE EXPECTED TO DIMINISH SOON AND MAY
BECOME LIGHT AND VARIABLE OVERNIGHT. HIGH CONFIDENCE.
TUESDAY...CLOUDS LOWERING AND THICKENING WITH LOW VFR TO HIGH END
MVFR CIGS LIKELY BY THE AFTERNOON ALONG WITH A DEVELOPING CHANCE OF
SHOWERS. MEDIUM CONFIDENCE.
OUTLOOK...
WEDNESDAY...SUB-VFR CONDITIONS LIKELY, ESPECIALLY IN THE EARLY
MORNING AND LATE AFTERNOON WITH SEVERAL ROUNDS OF SHOWERS AND
THUNDERSTORMS. SOUTHWESTERLY WINDS TURNING NORTHWESTERLY FROM 5 TO
10 KNOTS WITH GUSTS TO 15 KNOTS. HIGHER GUSTS POSSIBLE IN
THUNDERSTORMS. LOW CONFIDENCE.
THURSDAY...VFR INITIALLY WITH DETERIORATION TO MVFR INTO THE LATE
MORNING AND AFTERNOON AS RAIN MOVES INTO THE REGION AHEAD OF A COLD
FRONT. SOUTHEASTERLY WIND TURNING SOUTHWESTERLY THEN WESTERLY INTO
THE AFTERNOON. WINDS INCREASING TO 15 TO 20 KNOTS WITH GUSTS FROM 25
TO 30 KNOTS POSSIBLE BY THE LATE AFTERNOON. MEDIUM CONFIDENCE.
FRIDAY...GENERALLY VFR WITH WESTERLY WINDS FROM 15 TO 20 KNOTS
WITH GUSTS FROM 25 TO 30 KNOTS. A FEW MVFR RESTRICTIONS POSSIBLE
WITH WIDELY SCATTERED SHOWERS. MEDIUM CONFIDENCE.
SATURDAY...VFR WITH WESTERLY WINDS FROM 5 TO 10 KNOTS AND GUSTS FROM
15 TO 20 KNOTS. MEDIUM CONFIDENCE.
MARINE
CONDITIONS ARE EXPECTED TO REMAIN BELOW SCA LEVELS THROUGH TUESDAY.
WINDS BECOMING SW AROUND 5-10 KNOTS TONIGHT AND INCREASING TO 10-15
KNOTS TUESDAY. SEAS MAINLY 3 TO 4 FEET THROUGH THE PERIOD.
OUTLOOK...
WEDNESDAY...SUB-SCA CONDITIONS EXPECTED WITH NORTHWESTERLY WINDS
FROM 10 TO 15 KNOTS WITH GUSTS TO 20 KNOTS. SEAS FROM 1 TO 3
FEET.
THURSDAY...SCA CONDITIONS POSSIBLE WITH SOUTHEASTERLY WINDS TURNING
SOUTHWESTERLY FROM 15 TO 20 KNOTS AND GUSTS UP TO 25 KNOTS. SEAS
RANGING FROM 2 TO 4 FEET.
FRIDAY...SCA CONDITIONS LIKELY WITH WESTERLY WINDS FROM 20 TO 25
KNOTS WITH THE POSSIBILITY FOR GALE FORCE GUSTS ON THE ATLANTIC.
SEAS FROM 2 TO 4 FEET.
SATURDAY...SCA CONDITIONS MAY LINGER INTO EARLY SATURDAY MORNING,
OTHERWISE, WINDS REMAIN BELOW ADVISORY CRITERIA THROUGH THE DAYTIME
HOURS FROM 15 TO 20 KNOTS. SEAS LOWERING TO 1 TO 3 FEET.
TIDES/COASTAL FLOODING
AS WE APPROACH THE FULL MOON TOMORROW, ASTRONOMICAL HIGH TIDES WILL
BE RUNNING HIGH FOR THE NEXT FEW DAYS. WE DON'T HAVE MUCH ON SHORE
FLOW THROUGH THE NEXT FEW DAYS, BUT GIVEN THE CURRENT ASTRONOMICAL
HIGH TIDES, EVEN WEAK ONSHORE FLOW COULD PRODUCE MINOR COASTAL
FLOODING. AT THIS POINT, WE ARE EXPECTING SPOTTY MINOR FLOODING FOR
MOST HIGH TIDE CYCLES UNTIL WE GET TO WEDNESDAY EVENING. FOR THE
WEDNESDAY EVENING/NIGHT HIGH TIDE, WE ARE CURRENTLY FORECASTING
WIDESPREAD MINOR FLOODING FOR THE ATLANTIC OCEANFRONT AND THE
DELAWARE BAY. HOWEVER, THIS WILL BE HIGHLY DEPENDENT ON THE TIMING
OF A COLD FRONT ON WEDNESDAY. CURRENTLY WE ARE FORECASTING THE FRONT
TO CROSS OFF SHORE LATE IN THE DAY, THUS WINDS WON'T SHIFT TO
OFFSHORE UNTIL JUST BEFORE THE HIGH TIDE, HAVING LITTLE TO NO IMPACT
TO DECREASE WATER LEVELS. HOWEVER, IF THE FRONT ARRIVES EARLIER IN
THE DAY, THE INCREASED PERIOD OF OFFSHORE FLOW AHEAD OF THE HIGH
TIDE COULD LEAD TO LOWER WATER LEVELS AT HIGH TIDE. WE WILL CONTINUE
TO MONITOR THIS OVER THE NEXT FEW DAYS.
ON THE TIDAL PORTIONS OF THE DELAWARE RIVER, THERE COULD BE SPOTTY
MINOR TIDAL FLOODING FOR THE NEXT FEW HIGH TIDE CYCLES, BUT THE
CHANCE FOR WIDESPREAD MINOR FLOODING IS LOW.
AT THIS POINT, TIDAL FLOODING IS NOT EXPECTED ALONG THE NORTHEASTERN
CHESAPEAKE BAY.
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
SYNOPSIS...DAVIS
NEAR TERM...FITZSIMMONS/JOHNSON
SHORT TERM...FITZSIMMONS
LONG TERM...DAVIS
AVIATION...DAVIS/FITZSIMMONS/JOHNSON
MARINE...DAVIS/FITZSIMMONS
TIDES/COASTAL FLOODING...JOHNSON
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