971
FXUS61 KPHI 241948
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
348 PM EDT SUN MAR 24 2019
SYNOPSIS
A COLD FRONT WILL SETTLE ACROSS THE REGION TONIGHT INTO MONDAY.
A WEAK AREA OF LOW PRESSURE IS THEN EXPECTED TO DEVELOP ALONG THE
FRONT AND TRACK JUST SOUTH OF OUR REGION MONDAY NIGHT INTO
TUESDAY. HIGH PRESSURE THEN BUILDS INTO THE REGION TUESDAY AND
REMAINS IN PLACE THROUGH FRIDAY. THE NEXT COLD FRONT ARRIVES LATER
NEXT WEEKEND.
NEAR TERM /UNTIL 6 AM MONDAY/
CLOUDS WILL CONTINUE TO INCREASE DURING THE OVERNIGHT HOURS AS A
COLD FRONT APPROACHES, THEN CROSSES THE FORECAST AREA, POSITIONING
ITSELF SOUTH OF THE AREA MONDAY MORNING. MOISTURE WITH THIS SYSTEM
IS LIMITED, SO ONLY SCATTERED LIGHT RAIN SHOWERS OR SPRINKLES ARE
EXPECTED WITH THE FRONTAL PASSAGE ITSELF, MAINLY TOWARD MORNING,
ALONG WITH A WIND SHIFT TO THE NORTH.
WITH THE CLOUD COVER AND A WEAK SOUTHERLY FLOW FOR MUCH OF THE
OVERNIGHT PERIOD, LOW TEMPERATURES WILL RANGE FROM THE LOW TO MID
30S IN THE FAR NORTH TO THE MID 40S SOUTH, A GOOD TEN DEGREES WARMER
THAN LAST NIGHT AND 5 TO 10 DEGREES ABOVE NORMAL FOR THIS TIME
OF YEAR.
SHORT TERM /6 AM MONDAY THROUGH 6 PM MONDAY/
LOW PRESSURE FROM THE OHIO AND TENNESSEE RIVER VALLEYS IS EXPECTED
TO MOVE NORTH ALONG THE COLD FRONT POSITIONED JUST TO OUR SOUTH,
BRINGING AN INCREASED CHANCE OF RAIN SHOWERS TO THE SOUTHERN TWO-
THIRDS OF THE FORECAST AREA, MAINLY SOUTH OF THE I-95/I-195
CORRIDOR, LATER MONDAY AFTERNOON AND MONDAY NIGHT. TEMPERATURES WILL
BE WARM ENOUGH FOR PRECIPITATION TO FALL AS ALL RAIN. A WEAK
NORTHEASTERLY FLOW MONDAY MORNING WILL BECOME STRONGER AS THE LOW
APPROACHES THE VA/NC COAST LINE LATER IN THE DAY. EXPECT HIGHS IN
THE LOW 40S NORTH AND MID TO UPPER 50S SOUTH.
LONG TERM /MONDAY NIGHT THROUGH SUNDAY/
MONDAY NIGHT-TUESDAY... A MID-LVL WAVE WILL PASS SOUTH OF THE
AREA OVERNIGHT MONDAY CONCURRENT WITH THE LONGWAVE TROUGH
CENTERED EAST OF HUDSON BAY SAGGING SOUTHWARD OVER THE AREA.
LIFT ASSOCIATED WITH THIS WAVE COMBINED WITH MODEST LOW-LVL
CONVERGENCE WILL SPARK PRECIPITATION OVER THE SOUTHERN PART OF THE
AREA MONDAY NIGHT. PROGGING THE NORTHWARD EXTENT OF THE
PRECIPITATION IS TRICKY AS THE AIRMASS WILL BE RAPIDLY DRYING
FROM N-S MONDAY NIGHT INTO TUESDAY MORNING DUE TO INCREASING NORTHERLY
FLOW RESULTING FROM HIGH PRESSURE BUILDING OVER THE GREAT LAKES
COINCIDENT WITH CYCLOGENESIS TO OUR SE OVER THE ATLANTIC.
LOWER-RESOLUTION GUIDANCE TYPICALLY STRUGGLES WITH THESE LOW-
LVL DRY AIR SETUPS AND THUS LEANED MORE TOWARDS THE NAM/3KM AND
CMC REG FOR POPS THIS PACKAGE AND DIDN'T GO AS FAR NORTH WITH
HIGHER POPS AS THE EC/GFS/FV3 WOULD SUGGEST. THIS ESSENTIALLY
CONFINES LIKELY POPS TO DELMARVA SOUTH OF NEW CASTLE/CECIL
COUNTIES, AND FAR SOUTHERN NJ NEAR CAPE MAY. CAN'T RULE OUT
PRECIPITATION MAKING IT UP TO ABOUT PHILADELPHIA BUT THINK THE
DRY AIR WILL FILTER IN TOO QUICKLY FOR THE NORTHERN HALF OF THE
CWA TO GET ANYTHING MONDAY NIGHT. ALTHOUGH CURRENTLY EXPECT MOST
OF THE PRECIPITATION WILL BE RAIN, CAN'T RULE OUT SOME SNOW
MIXING IN AT THE TAIL END EARLY TUESDAY MORNING (ALTHOUGH THIS
WOULDN'T ACCUMULATE). SNOW POTENTIAL WILL LARGELY DEPEND UPON
HOW LONG PRECIPITATION LINGERS IN THE FACE OF THE DRY AIR
ADVECTION (E.G. THE NAM SOLUTION WOULD BE THE MOST FAVORABLE FOR
SNOW BUT THE NAM IS ALSO THE SLOWEST PIECE OF GUIDANCE).
PRECIPITATION IN THE SOUTH SHOULD END BY OR BEFORE DAYBREAK
TUESDAY AS BOTH THE MID-LVL WAVE AND THE ASSOCIATED SFC LOW MOVE
OUT TO SEA. TUESDAY WILL BE QUIET WITH A DRY AIRMASS IN PLACE,
ALTHOUGH IT WILL BE SOMEWHAT COOL (HIGHS ABOUT 10 DEGREES BELOW
NORMAL), AS CONTINUED COLD ADVECTION PERSISTS AS THE SFC. HIGH
MOVES JUST TO OUR NW.
WEDNESDAY... QUIET AS HIGH PRESSURE MOVES OVERHEAD.
TEMPERATURES WARM A FEW DEGREES BUT ARE STILL A BIT BELOW
NORMAL.
THURSDAY/FRIDAY... THE AFOREMENTIONED HIGH PRESSURE MOVES OUT
TO SEA BY EARLY THURSDAY WITH FLOW TURNING MORE SOUTHERLY. THIS
WILL RESULT IN A NOTABLE WARM UP ON THURSDAY (APART FROM THE
IMMEDIATE COAST WHERE THE WARM UP WILL BE MORE MODERATED) WITH
HIGHS GETTING BACK TO NEAR NORMAL (UPPER 50S, MAYBE EVEN LOW
60S). MOISTURE BEGINS TO INCREASE OVER THE AREA LATE THURSDAY
ALTHOUGH THIS WILL BE MOSTLY CONFINED TO THE MID-LVLS.
THE WARM UP CONTINUES ON FRIDAY AS SOUTHERLY FLOW PREVAILS.
HIGHS SHOULD REACH THE MID TO UPPER 60S IN MOST LOCATIONS APART
FROM THE IMMEDIATE COAST. GIVEN ADDITIONAL MOISTURE ADVECTION
COMBINED WITH INCREASED HEATING, CAN'T RULE OUT A SHOWER OR
THUNDERSTORM ACROSS THE FAR NORTHWEST BUT CONFIDENCE IS LOW AT
THIS POINT
SATURDAY/SUNDAY... GUIDANCE BEGINS TO DIVERGE ON SOLUTIONS FOR
NEXT WEEKEND, AS THE PATTERN LOCALLY WILL DEPEND UPON THE
EVOLUTION OF SHORTWAVE ENERGY OVER THE WESTERN US AND THIS
ENERGY'S INTERACTION WITH A SAGGING LONGWAVE TROUGH OVER
NORTHERN CANADA. THE GENERAL TREND HAS BEEN TO FURTHER AMPLIFY
THE SHORTWAVE & PHASE IT WITH PART OF THE NORTHERN TROUGH BEFORE
MOVING IT THROUGH THE AREA. HOWEVER THE DEGREE OF AMPLIFICATION
WILL LARGELY DICTATE THE SPEED OF THE FEATURE AND ANY
ASSOCIATED FRONTS OR PRECIPITATION AND THIS IS NOT AGREED UPON
AT THIS TIME. CONSEQUENTLY BROADBRUSHED POPS IN THIS PERIOD AS
BOTH PREFRONTAL CONVECTION AND PRECIPITATION ASSOCIATED WITH A
COLD FRONT WOULD BE POSSIBLE.
AVIATION /19Z SUNDAY THROUGH FRIDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
TONIGHT...VFR. INCREASING CLOUDS. SOUTHWEST WINDS 10 TO 15 KNOTS
EARLY, BECOMING VARIABLE 6 KNOTS OR LESS DURING THE LATE EVENING
HOURS.
MONDAY...VFR CEILINGS, BUT MVFR CONDITIONS POSSIBLE BY AFTERNOON,
ESPECIALLY NEAR/SOUTH OF PHL TO MIV AS SHOWERS ASSOCIATED WITH A LOW
PRESSURE SYSTEM MOVE IN FROM THE SOUTHWEST. NORTH TO NORTHEAST WINDS
AROUND 10 KNOTS.OUTLOOK... MONDAY...VFR CEILINGS, HOWEVER A
PERIOD OF MVFR POSSIBLE WITH LIGHT RAIN MAINLY NEAR AND SOUTH OF
ILG TO MIV. ANY RAIN ENDS BY LATE MONDAY NIGHT. NORTH TO
NORTHEAST WINDS 10 KNOTS OR LESS.
OUTLOOK...
MONDAY NIGHT TO TUESDAY MORNING...MVFR CONDITIONS POSSIBLE IN
PRIMARILY RAIN AT PHL AND SOUTHWARD. CONDITIONS IMPROVING NW TO
SE WITH ALL TERMINALS LIKELY VFR BY 12Z TUESDAY. NORTHEAST
WINDS 10-15 KTS (HIGHEST AT ACY).
TUESDAY-FRIDAY VFR CONDITIONS EXPECTED TO PREVAIL. NORTHERLY
WINDS ON TUESDAY BECOME LIGHT AND VARIABLE BY WEDNESDAY,
EVENTUALLY TURNING SOUTHERLY BY THURSDAY.
MARINE
TONIGHT AND MONDAY...HIGH PRESSURE WILL CONTINUE TO INFLUENCE
THE COASTAL WATERS OF NEW JERSEY AND DELAWARE THROUGH A GOOD
PORTION OF THE OVERNIGHT HOURS. HOWEVER, A COLD FRONT WILL BEGIN
MOVING ACROSS THE NORTHERN WATERS AFTER MIDNIGHT, REACHING THE
COASTAL WATERS OF DELAWARE MONDAY MORNING. A SOUTHWEST WIND 10
TO 15 KNOTS WILL DOMINATE PRIOR TO THIS FRONTAL PASSAGE, THEN
VEER TO THE NORTH- NORTHEAST SOON AFTER. 2 TO 3 FOOT WAVES ARE
EXPECTED.
OUTLOOK...
MONDAY NIGHT AND TUESDAY...SCA CONDITIONS EXPECTED TO DEVELOP OVER
SOUTHERN AND CENTRAL ATLANTIC MARINE AREAS WITH NORTHERLY/NORTHEASTERLY
WIND GUSTS UP TO 30 KNOTS AND SEAS INCREASING TO 5-6 FT.
NORTHERN NJ COASTAL WATERS AND DELAWARE BAY WILL BE MORE
MARGINAL HOWEVER THERE WILL BE A WINDOW FOR SCA CONDITIONS
TUESDAY MORNING. NORTHEASTERLY WINDS INCREASE LATER MONDAY
NIGHT AND TUESDAY MORNING WITH GUSTS UP TO 30 KNOTS (ESPECIALLY
ON THE ATLANTIC COASTAL WATERS TO PERHAPS LOWER DELAWARE BAY),
THEN WINDS SHOULD DIMINISH SOME FROM NORTH TO SOUTH LATER
TUESDAY. SEAS WILL ALSO BUILD DUE TO THE INCREASED NORTHEAST
FLOW.
WEDNESDAY THROUGH FRIDAY... SCA SEAS MAY LINGER IN SOUTHERN
OCEAN ZONES WEDNESDAY MORNING HOWEVER AFTER THAT POINT SUB-SCA
CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THE PERIOD.
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 2 AM TO 11 PM EDT TUESDAY FOR ANZ451-
452.
SMALL CRAFT ADVISORY FROM 11 PM MONDAY TO 8 AM EDT WEDNESDAY
FOR ANZ453>455.
SYNOPSIS...MIKETTA
NEAR TERM...MIKETTA
SHORT TERM...MIKETTA
LONG TERM...CARR
AVIATION...CARR/MIKETTA
MARINE...CARR/MIKETTA
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