303  
FXUS61 KPHI 190050  
AFDPHI  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ  
850 PM EDT FRI SEP 18 2020  
   
SYNOPSIS
 
 
HIGH PRESSURE CENTERED IN THE WESTERN GREAT LAKES THIS  
AFTERNOON WILL BUILD SLOWLY TO THE EAST. THE AIR MASS IS  
FORECAST TO SETTLE ALONG THE APPALACHIANS EARLY IN THE NEW WEEK.  
THE HIGH SHOULD CONTINUE TO INFLUENCE OUR WEATHER INTO  
THURSDAY. A WEAK COLD FRONT APPROACHING FROM THE NORTHWEST IS  
EXPECTED TO ARRIVE EARLY ON FRIDAY.  
 

 
   
NEAR TERM /UNTIL 6 AM SATURDAY MORNING/
 
 
NO SIGNIFICANT CHANGES WITH THE LATE EVENING UPDATE.  
 
HIGH PRESSURE WILL CONTINUE TO AFFECT OUR WEATHER TONIGHT WITH  
DRY AND COOL AIR ADVECTING ACROSS THE REGION. AS WINDS DECREASE  
SLIGHTLY (THOUGH SPEEDS MAY STAY NEAR 10 MPH THROUGH THE NIGHT),  
AND CLOUDS DECREASE, EXPECT RADIATIONAL COOLING TO BE EFFICIENT  
OVERNIGHT. THEREFORE, LOWERED MIN TEMPERATURE FORECAST TO BE  
CLOSER TO THE COOLER SIDE OF GUIDANCE. ONE POTENTIAL QUESTION  
MARK IS THE COASTAL PLAINS - IF THE LOW AND MID LEVEL CLOUDS ARE  
SLOWER TO MOVE OUT, TEMPERATURES MAY NOT DROP AS MUCH - AT LEAST  
FOR THE FIRST HALF OF THE NIGHT.  
 
EVEN WITH LOWERING MIN T SLIGHTLY, IT STILL LOOKS LIKE FROST  
SHOULD BE LIMITED TO SHELTERED VALLEYS IN CARBON, MONROE, AND  
SUSSEX (NJ) COUNTIES. THEREFORE, WILL CONTINUE TO HOLD OFF ON  
ISSUING A FROST ADVISORY AS IT APPEARS THAT THE AREAS AFFECTED  
WILL BE LIMITED.  
 

 
   
SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/
 
 
HIGH PRESSURE OVER THE GREAT LAKES WILL CONTINUE TO BUILD  
ACROSS THE MIDDLE ATLANTIC. FAIR WEATHER WITH COOL DRY AIR WILL  
REMAIN IN PLACE. MOSTLY SUNNY SKIES ARE EXPECTED WITH  
TEMPERATURES TOPPING OUT MOSTLY IN THE 60S ACROSS THE AREA.  
THESE HIGHS WILL BE ROUGHLY 10 DEGREE BELOW NORMAL FOR MID-  
SEPTEMBER. WINDS WILL BE MOSTLY N TO NE AT 5 TO 10 MPH.  
 

 
   
LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/
 
 
THE WEATHER OVER THE WESTERN NORTH ATLANTIC WILL REMAIN RATHER  
ACTIVE FROM SUNDAY INTO THE EARLY PART OF THE NEW WEEK.  
MEANWHILE, CONDITIONS WILL BE TRANQUIL IN OUR AREA.  
 
HIGH PRESSURE IS FORECAST TO BE CENTERED IN THE SAINT LAWRENCE  
RIVER VALLEY AND VICINITY ON SATURDAY NIGHT AND SUNDAY. THE AIR  
MASS IS EXPECTED TO BUILD SOUTHWARD ALONG THE APPALACHIANS ON  
MONDAY AND TUESDAY, BEFORE DRIFTING EASTWARD ACROSS THE  
CAROLINAS AND OFF THE COAST ON WEDNESDAY AND THURSDAY. THE HIGH  
SHOULD BRING DRY WEATHER TO OUR REGION DURING THE PERIOD.  
 
BELOW NORMAL TEMPERATURES ARE ANTICIPATED FOR SUNDAY, MONDAY  
AND TUESDAY, AS WE WELCOME AUTUMN. PATCHY FROST IS POSSIBLE UP  
NORTH EARLY ON SUNDAY MORNING AND AGAIN EARLY ON MONDAY MORNING.  
THE AIR MASS WILL MODIFY AND TEMPERATURES WILL LIKELY RISE  
ABOVE NORMAL FOR WEDNESDAY AND THURSDAY.  
 
A WEAK COLD FRONT IS FORECAST TO APPROACH FROM THE NORTHWEST ON  
THURSDAY NIGHT AND IT SHOULD PASS THROUGH OUR REGION EARLY ON  
FRIDAY. THE FEATURE IS EXPECTED TO HAVE ONLY LIMITED MOISTURE  
ASSOCIATED WITH IT. TEMPERATURES ON FRIDAY SHOULD RETURN NEAR  
NORMAL.  
 

 
   
AVIATION /01Z SATURDAY THROUGH WEDNESDAY/
 
 
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,  
KILG, KMIV, KACY AND SURROUNDING AREAS.  
 
TONIGHT...VFR CONDITIONS EXPECTED WITH MID LEVEL CLOUDS  
DISSIPATING BY 06Z. WINDS MAY START NORTH NORTHWESTERLY, BUT  
SHOULD EVENTUALLY SHIFT TO NORTH NORTHEASTERLY. SPEEDS OF 10 TO  
15 KT SHOULD DECREASE TO NEAR OR BELOW 10 KT BY 06Z. HIGH  
CONFIDENCE.  
 
SATURDAY...VFR EXPECTED WITH CLEAR SKIES MUCH OF THE DAY.  
NORTHEASTERLY WINDS 5 TO 15 KNOTS. HIGH CONFIDENCE.  
 
OUTLOOK...  
 
SUNDAY...VFR. NORTHEAST WIND 10 TO 15 KNOTS WITH GUSTS AROUND  
20 KNOTS. HIGH CONFIDENCE.  
 
MONDAY...VFR. NORTHEAST WIND AROUND 10 KNOTS. HIGH CONFIDENCE.  
 
TUESDAY...VFR. NORTHWEST WIND AROUND 10 KNOTS. HIGH CONFIDENCE.  
 
WEDNESDAY...VFR. WEST WIND 5 TO 10 KNOTS. HIGH CONFIDENCE.  
 

 
   
MARINE
 
 
FAIR WEATHER TONIGHT AND SATURDAY. SCA FLAGS WILL CONTINUE WITH  
GUSTS AROUND 25 KNOTS AND ENHANCED SEAS ON THE OCEAN. IT'S  
POSSIBLE THAT THE SCA FLAG FOR THE NORTHERN DEL BAY COULD BE  
TAKEN DOWN THIS EVENING IF WIND GUSTS DECREASE LATER ON.  
 
OUTLOOK...  
 
SATURDAY NIGHT AND SUNDAY...A SMALL CRAFT ADVISORY IS IN EFFECT  
FOR OUR OCEAN WATERS AND FOR DELAWARE BAY. A NORTHEAST WIND IS  
FORECAST TO BE 15 TO 25 KNOTS WILL GUSTS AROUND 30 KNOTS. WAVES  
ON OUR OCEAN WATERS WILL LIKELY BUILD TO 6 TO 10 FEET.  
 
SUNDAY NIGHT AND MONDAY...THE SMALL CRAFT ADVISORY WILL LIKELY  
NEED TO BE EXTENDED TO COVER THIS PERIOD AS THE GUSTY NORTHEAST  
WIND AND ROUGH SEAS CONTINUE.  
 
MONDAY NIGHT THROUGH WEDNESDAY...WHILE WIND SPEEDS ARE EXPECTED  
TO FALL BELOW 25 KNOTS, WAVE HEIGHTS ON OUR OCEAN WATERS SHOULD  
BE SLOW TO DROP BELOW 5 FEET. AS A RESULT, A SMALL CRAFT  
ADVISORY MAY BE NEEDED FOR OUR OCEAN WATERS FOR MOST OF THIS  
PERIOD, AS WELL.  
 
RIP CURRENTS...  
 
ROUGH SURF WILL CONTINUE ALONG THE COASTS OF DELAWARE AND NEW  
JERSEY FROM SATURDAY NIGHT INTO TUESDAY AS THE WEATHER PATTERN  
OVER THE WESTERN NORTH ATLANTIC REMAINS ACTIVE. AS A RESULT,  
THERE WILL BE AN ENHANCED RISK FOR THE DEVELOPMENT OF DANGEROUS  
RIP CURRENTS THROUGH THE PERIOD. AT THIS POINT, EXPECT A  
MODERATE RISK FOR THE DEVELOPMENT OF RIP CURRENTS ON SATURDAY,  
THOUGH IF THE WAVES INCREASE HIGHER OR IF LONGER PERIOD SWELLS  
ARRIVE SOONER, IT IS POSSIBLE THAT SOME AREAS COULD HAVE A HIGH  
RISK OF RIP CURRENTS ON SATURDAY. THIS WILL BE REEVALUATED  
EARLY SATURDAY MORNING.  
 

 
   
TIDES/COASTAL FLOODING
 
 
THE NEW MOON OCCURRED ON THURSDAY AND HIGHER THAN NORMAL  
ASTRONOMICAL TIDES WILL CONTINUE FOR THE NEXT COUPLE OF DAYS.  
 
FOR THE ATLANTIC COAST: A CONTINUED NORTH TO NORTHEAST FLOW  
WILL INCREASE THE SURGE ALONG THE ATLANTIC COAST. WITH  
ASTRONOMICAL TIDES RUNNING HIGHER THAN NORMAL DUE TO THE RECENT  
NEW MOON, WE ARE EXPECTING MINOR FLOODING TO OCCUR WITH  
TONIGHT'S AND ESPECIALLY SATURDAY MORNINGS HIGH TIDES. CAN'T  
RULE OUT A FEW SPOTS MAINLY SOUTH OF BARNEGAT BAY GETTING CLOSE  
TO OR JUST TOUCHING MODERATE FLOODING LEVELS WITH THE SATURDAY  
MORNING HIGH TIDE BUT CONFIDENCE REMAINS TOO LOW TO ISSUE ANY  
COASTAL FLOOD WATCH OR WARNING PRODUCTS AT THIS TIME.  
 
FOR THE DELAWARE BAY AND TIDAL DELAWARE RIVER: A NORTH TO  
NORTHEAST WIND IS NOT LIKELY TO INCREASE THE POTENTIAL FOR TIDAL  
FLOODING ALONG THE DELAWARE RIVER. HOWEVER, THE WINDS WILL BE  
BLOWING ACROSS THE DELAWARE BAY AND THIS WILL INCREASE THE RISK  
ALONG THE SOUTHERN BAY SHORES OF DELAWARE, WHERE WE EXPECT MINOR  
TIDAL FLOODING TO OCCUR WITH TONIGHT'S AND SATURDAY MORNING'S  
HIGH TIDES.  
 
FOR THE NORTHEAST CHESAPEAKE BAY: WE DO NO EXPECT ANY COASTAL  
FLOODING TO OCCUR ALONG THE CHESAPEAKE BAY AS THE NORTH TO  
NORTHEAST WIND DIRECTION IS NOT IDEAL FOR TIDAL FLOODING.  
 

 
   
PHI WATCHES/WARNINGS/ADVISORIES
 
 
PA...NONE.  
NJ...COASTAL FLOOD ADVISORY UNTIL 2 PM EDT SATURDAY FOR NJZ013-014-  
020-022>027.  
COASTAL FLOOD ADVISORY FROM 8 AM TO 2 PM EDT SATURDAY FOR  
NJZ012.  
DE...COASTAL FLOOD ADVISORY UNTIL 2 PM EDT SATURDAY FOR DEZ002>004.  
MD...NONE.  
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT SUNDAY FOR ANZ430-431-  
450>455.  
 

 
 

 
SYNOPSIS...IOVINO  
NEAR TERM...JOHNSON/O'HARA  
SHORT TERM...O'HARA  
LONG TERM...IOVINO  
AVIATION...IOVINO/JOHNSON/O'HARA  
MARINE...IOVINO/JOHNSON/O'HARA  
TIDES/COASTAL FLOODING...WFO PHI  
 
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