623  
FXUS61 KPHI 300137  
AFDPHI  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ  
937 PM EDT MON AUG 29 2016  
   
SYNOPSIS
 
 
THE COLD FRONT WILL SLOWLY DISSIPATE AS IT DRIFTS SOUTHWARD  
TONIGHT INTO TUESDAY. WEAK HIGH PRESSURE IS FORECAST TO BUILD  
ACROSS NEW YORK AND NEW ENGLAND FROM TONIGHT INTO TUESDAY.  
TROPICAL DEPRESSION EIGHT IS EXPECTED TO PASS WELL TO OUR  
SOUTHEAST ON WEDNESDAY AS A STRONG COLD FRONT APPROACHES FROM THE  
NORTHWEST. THE FRONT IS ANTICIPATED TO PASS THROUGH OUR REGION  
EARLY ON THURSDAY FOLLOWED BY HIGH PRESSURE FOR FRIDAY INTO THE  
UPCOMING HOLIDAY WEEKEND.  
 

 
   
NEAR TERM /UNTIL 6 AM TUESDAY MORNING/
 
 
NO BIG CHANGES TO THE OVERALL FORECAST NEEDED SO FAR TONIGHT AS  
PREVIOUS FORECAST LOOKS ON TRACK. ONLY MINOR HOURLY CHANGES  
NEEDED. PREVIOUS DISCUSSION BELOW.  
 
A WEAK COLD FRONT WILL MOVE FARTHER OFFSHORE TONIGHT WITH HIGH  
PRESSURE BUILDING SOUTHEAST BEHIND THE FRONT INTO THE REGION.  
WINDS WILL BE FROM THE NORTH TONIGHT BEHIND THE COLD FRONT BUT  
WILL BECOME LIGHT AND VARIABLE MOST PLACES OVERNIGHT. WITH MOSTLY  
CLEAR SKIES AND AN EVEN DRIER AIR MASS WORKING INTO THE REGION, IT  
SHOULD BE A FAVORABLE SETUP FOR RADIATIONAL COOLING BUT NOT MUCH  
IN THE WAY OF FOG. GIVEN THE PLAYERS ON THE FIELD TONIGHT, OPTED  
TO GO A COUPLE OF DEGREES COOLER THAN WHAT MOST OF THE MOS  
GUIDANCE HAS TONIGHT, PARTICULARLY THE ECMWF. IN RURAL AREAS  
ACROSS NORTHERN NJ AND PA ALONG WITH THE PINE BARRENS TEMPERATURES  
SHOULD FALL FAIRLY QUICKLY WITH LOWS IN THE 50'S AND LOW 60'S FOR  
MANY. LOWS SHOULD END UP A FEW DEGREES WARMER IN THE URBAN  
CORRIDOR.  
 

 
   
SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/
 
 
TOMORROW, HIGH PRESSURE WILL MOVE EASTWARD THROUGH THE REGION  
ALLOWING FOR ANOTHER SUNNY LATE SUMMER DAY. TEMPERATURES WILL  
REBOUND QUICKLY WITH ANOTHER RUN AT 90 LIKELY FOR PHILLY. WINDS  
WILL LIKELY BE LIGHT AND VARIABLE, UNDER 10 MPH THROUGHOUT MOST OF  
THE DAY AND NOT MUCH POTENTIAL FOR MIXING IS SHOWING UP ON  
SOUNDINGS. WINDS WILL BE MORE OF AN EASTERLY DIRECTION FROM  
PHILADELPHIA TO THE SOUTHEAST RESULTING IN AN ONSHORE FLOW ANOTHER  
RISKY DAY FOR SWIMMING IN THE OCEAN (SEE RIP CURRENT SECTION).  
 

 
   
LONG TERM /TUESDAY NIGHT THROUGH MONDAY/
 
 
THE FORECAST CONTINUES TO KEEP TROPICAL DEPRESSION EIGHT WELL  
ENOUGH TO OUR SOUTHEAST ON WEDNESDAY AS NOT TO IMPACT OUR WEATHER.  
 
A STRONG COLD FRONT IS EXPECTED TO EXTEND FROM SOUTHERN ONTARIO  
TO THE MIDDLE MISSISSIPPI RIVER VALLEY ON WEDNESDAY MORNING. IT  
SHOULD REACH CENTRAL NEW YORK AND WESTERN PENNSYLVANIA LATE IN THE  
DAY. WE WILL CONTINUE TO MENTION A CHANCE OF SHOWERS AND  
THUNDERSTORMS IN OUR NORTHWESTERN COUNTIES FOR WEDNESDAY  
AFTERNOON. THE POTENTIAL FOR SCATTERED SHOWERS AND THUNDERSTORMS  
WILL OVERSPREAD THE REMAINDER OF OUR FORECAST AREA ON WEDNESDAY  
NIGHT.  
 
THE FRONT IS EXPECTED TO WORK ITS WAY THOUGH OUR REGION EARLY ON  
THURSDAY. THE GUIDANCE CONTINUES TO LINGER SHOWERS THROUGH THE  
MORNING HOURS, ESPECIALLY ON THE COASTAL PLAIN. MAXIMUM  
TEMPERATURES ON THURSDAY ARE ANTICIPATED TO BE IN THE 70S IN THE  
ELEVATED TERRAIN OF THE POCONOS AND NORTHWESTERN NEW JERSEY AND IN  
THE LOWER AND MIDDLE 80S ELSEWHERE. DEW POINT READINGS SHOULD DROP  
INTO THE LOWER 60S AND 50S.  
 
HIGH PRESSURE IS FORECAST TO BUILD FROM ONTARIO AND THE GREAT  
LAKES ON THURSDAY TO THE NORTHEASTERN STATES ON SATURDAY BEFORE  
DRIFTING OFF THE COAST. THE AIR MASS WILL BE NOTICEABLY COOLER AND  
LESS HUMID THAN THE ONE THAT IT WILL BE REPLACING.  
 
WE WILL NEED TO KEEP AN EYE ON THE TROPICAL ACTIVITY TO OUR SOUTH  
AND EAST OVER THE WEEKEND.  
 

 
   
AVIATION /00Z TUESDAY THROUGH SATURDAY/
 
 
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,  
KILG, KMIV, KACY AND SURROUNDING AREAS.  
 
VFR THROUGHOUT THE TAF PERIOD WITH SOME SCATTERED MID AND HIGH  
LEVEL CLOUDS FROM TIME TO TIME. NORTH TO NORTHWEST WINDS ACROSS  
THE NORTHERN TWO THIRDS OF THE AREA, AND WESTERLY WINDS ACROSS THE  
SOUTHERN THIRD OF THE AREA WILL BECOME MOSTLY LIGHT AND VARIABLE  
OVERNIGHT. ANY WIND DIRECTION IS EXPECTED TO BECOME NORTHEAST  
OVERNIGHT AND WINDS SHOULD BE 10 KNOTS OR LESS.  
 
WINDS WILL SHIFT TO EAST THEN SOUTHEAST FROM PHILADELPHIA AND  
POINTS SE ON TUESDAY. AREAS NORTHWEST OF PHILADELPHIA SHOULD  
BECOME MORE WEST/NORTHWEST. NOT MUCH FOG EXPECTED OVERNIGHT EXCEPT  
SOME LIGHT FOG POSSIBLE AT MIV TOWARD DAYBREAK.  
 
OUTLOOK...  
TUESDAY NIGHT AND WEDNESDAY MORNING...MAINLY VFR. LATE NIGHT AND  
EARLY MORNING VISIBILITY RESTRICTIONS ARE POSSIBLE.  
 
WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT...MAINLY VFR. HOWEVER,  
THERE IS A CHANCE OF SHOWERS AND THUNDERSTORM.  
 
THURSDAY...MAINLY VFR WITH A CHANCE OF SHOWERS.  
 
THURSDAY NIGHT THROUGH SATURDAY...MAINLY VFR.  
 

 
   
MARINE
 
 
WAVE HEIGHTS CLOSE TO THREE FEET WILL LIKELY BUILD SLOWLY TO  
BETWEEN THREE AND FOUR FEET GIVEN THE ONSHORE FLOW BY TOMORROW.  
WINDS WILL START FROM THE WEST AND NORTHWEST TONIGHT BEFORE  
BECOMING MORE EASTERLY ON TUESDAY, AROUND 10 KNOTS.  
 
OUTLOOK...  
TUESDAY NIGHT THROUGH SATURDAY...NO MARINE HEADLINES ARE  
ANTICIPATED. HOWEVER, LONG PERIOD SWELLS MAY CREATE ROUGH  
CONDITIONS IN AND AROUND THE INLETS ALONG THE COASTS OF NEW JERSEY  
AND DELAWARE.  
 
RIP CURRENTS...  
WITH THE 3-4 FOOT LONG PERIOD SWELLS ACROSS THE OCEAN AND LIGHT  
EASTERLY FLOW EXPECTED, THE RIP CURRENT RISK FOR TUESDAY IS  
CURRENTLY EXPECTED TO BE MODERATE. IF THE ONSHORE EASTERLY WINDS  
INCREASE A BIT MORE THAN FORECASTED OR THE WAVEHEIGHTS ARE  
SLIGHTLY HIGHER THAN FORECASTED CONDITIONS THEN MAY BE FAVORABLE  
FOR A HIGH RISK.  
 
WEDNESDAY: GFS AND TROPICAL MODELED SWELL/PERIOD WAVE GROUPS  
STRONGLY SUGGEST A MODERATE RISK FOR THE FORMATION OF DANGEROUS  
RIP CURRENTS CONTINUES.  
 
IN TERMS OF SAFETY, FOLLOW THE ADVICE OF LOCAL LIFEGUARDS WHO  
WILL BE OBSERVING. THERE MAY BE SOME BEACH CLOSURES, ALL DEPENDENT  
ON THE REALITY THAT DEVELOPS. THIS IS NOT A TIME TO SWIM ON YOUR  
OWN WITHOUT LIFEGUARD PRESENCE. ADDITIONALLY, WADERS ARE CAUTIONED  
NOT TO TURN THEIR BACKS TO THE WAVES WHEN COMING OUT OF THE WATER.  
WAVE KNOCK DOWN CAN RESULT IN UPPER TORSO INJURY  
(DISLOCATIONS/SPINAL CORD INJURIES).  
 
A BEACH HAZARDS STATEMENT WAS ISSUED TO ALERT FOR THE ROUGH SURF  
FOR THIS WEEK INTO THE COMING WEEKEND, THIS IN PART BASED ON NHCS  
OUTLOOK COMPARED WITH THE GFS/EC OPERATIONAL CYCLES.  
 

 
   
CLIMATE
 
 
THIS SECTION IS UP TO DATE THROUGH 435 AM TODAY-MONDAY AUGUST 29.  
TODAY'S DATA HAVE YET TO BE FINALIZED.  
 
A TOP 4 WARMEST AUGUST APPEARS ASSURED MOST OF OUR FORECAST AREA  
WITH RECORD MONTHLY WARMTH LIKELY AT PHL.  
 
A TOP 3 WARMEST JUNE-JULY-AUGUST FOR PHILADELPHIA, ALLENTOWN AND  
POSSIBLY ATLANTIC CITY.  
 
PHILADELPHIA WILL ESTABLISH ITS WARMEST AUGUST ON RECORD (DATING  
BACK TO 1874). MORE THAN 4 DEGREES ABOVE NORMAL.  
 
THIS PHILADELPHIA AUGUST RANKING INCLUDES OUR FORECAST TEMPS (SFT  
SPECIFIC VALUES) THROUGH THE 31ST. THE 30 YEAR NORMAL IS 76.6  
RECORDS DATE BACK TO 1874.  
 
1. ~81.0 2016  
2. 79.9 1980  
3. 79.8 2001 AND 1995  
 
REGARDING WHETHER AUGUST CAN TIE ITS RECORD OF 17 90F DAYS. ITS  
POSSIBLE BUT NOT PROBABLE. FORESEE AN ADDITIONAL 2 TO 3 MORE 90  
DEGREE DAYS TO ADD ONTO THE 13 WE HAVE SO FAR THIS MONTH. THE  
RECORD OF 17 WAS SET IN 1995. THE MEAN FOR THE MONTH IS ONLY 5.  
TUESDAY IS THE POSSIBLE DAY FOR BREAKING A MODEST HEAT WAVE AND  
ELIMINATING A CHANCE AT A RECORD EQUALING 17, 90 DEGREE DAYS IN  
AUGUST.  
 
ALLENTOWN WILL RANK #2 WARMEST AUGUST. RECORDS DATE BACK TO 1922.  
NORMAL IS 71.7 AND WE ARE PROJECTING A POSITIVE DEPARTURE OF  
AROUND 5 DEGREES.  
 
1. 78.2 1980  
 
2. 76.6 2016  
 
3. 76.0 1937  
 
ATLANTIC CITY RECORDS DATE BACK TO 1874. THE AUGUST MONTHLY  
NORMAL IS 74.4 AND WE'RE PROJECTING A POSITIVE DEPARTURE OF NEARLY  
4 DEGREES. AS IT STANDS, ATLANTIC CITY WILL RANK #1 OR #2 WARMEST  
AUGUST WITH VERY LITTLE CHANCE OF SLIPPING TO #3. THE FORECAST AND  
CLIMATE FOR ATLANTIC CITY HAS GREATER VARIABILITY THAN ALLENTOWN  
AND PHILADELPHIA DUE TO PROXIMITY TO WATER ON SEA BREEZE DAYS AND  
NOTABLE RADIATIONAL COOLING ON SOME NIGHTS.  
 
1. 78.2 2016  
 
2. 77.9 2005  
 
3. 77.1 2009  
 
SEASONAL: THIS SUMMER 2016 FOR PHILADELPHIA WILL PROBABLY BE THE  
2ND WARMEST JUNE-JULY-AUGUST (JJA) IN THE PERIOD OF RECORD DATING  
BACK TO 1874.  
 
1. 79.6 2010  
2. 78.8 2016  
3. 78.6 1995  
4. 78.3 1994  
 
ALLENTOWN SEASONAL AVG IS PROJECTING 75.0 OR A RANKING OF AROUND  
#2 IN THE POR.  
 
1 75.3 1949  
 
2 75.0 2016  
 
3 74.6 2005 AND 1980  
 
ATLANTIC CITY SEASONAL AVERAGE IS PROJECTING 75.8...4TH WARMEST  
IN THE POR.  
 
1. 77.5 2010  
 
2. 77.0 2011  
 
3. 75.9 2005  
 
4. 75.8 2016  
 
5. 75.5 2008  
 
90 DEGREE DAYS THROUGH THE 28TH.  
 
SEASON MEAN AUG AUG AUG SEASON  
MEAN RER RER  
 
ABE 33 17 12 4 16-1980 41-1966  
 
ACY 27 10 10 3 11-2010 46-2010  
 
PHL 38 21 14 5 17-1995 55-2010  
 
ILG 32 20 13 5 23-1895 59-1895  
 
RAINFALL: CONSIDERABLE UNCERTAINTY EXISTS REGARDING ADDITIONAL  
RAINFALL IN AUGUST, SO THIS PART OF THE CLIMATE IS STATED WITH  
CAUTION.  
 
PRESUMING NO FURTHER MEASURABLE RAIN THIS MONTH OF AUGUST...THE  
CURRENT ACY VALUE OF 1.10 WOULD RANK THE 6TH DRIEST AUGUST ON  
RECORD, AFTER A 6TH WETTEST JULY.  
 
FOR PHILADELPHIA, THE JUNE-AUGUST SEASONAL TOTAL OF 7.45 INCHES  
IS SO FAR, THE 12TH DRIEST SUMMER...AGAIN THIS PRESUMES NO FURTHER  
MEASURABLE RAIN IN AUGUST.  
 

 
   
PHI WATCHES/WARNINGS/ADVISORIES
 
 
PA...NONE.  
NJ...BEACH HAZARDS STATEMENT THROUGH WEDNESDAY EVENING FOR NJZ014-  
024>026.  
DE...BEACH HAZARDS STATEMENT THROUGH WEDNESDAY EVENING FOR DEZ004.  
MD...NONE.  
MARINE...NONE.  
 

 
 

 
SYNOPSIS...IOVINO  
NEAR TERM...GAINES/ROBERTSON  
SHORT TERM...GAINES  
LONG TERM...IOVINO  
AVIATION...GAINES/IOVINO/ROBERTSON  
MARINE...DRAG/GAINES/IOVINO/ROBERTSON  
CLIMATE...  
 
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