870  
FXUS61 KPHI 300751  
AFDPHI  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ  
351 AM EDT SAT AUG 30 2014  
   
SYNOPSIS
 
 
HIGH PRESSURE CENTERED OFF THE NEW ENGLAND COAST WILL CONTINUE TO  
MOVE EAST TODAY AND TONIGHT. MEANWHILE...A WARM FRONT IS EXPECTED  
TO LIFT NORTH LATE SATURDAY, THEN BECOME NEARLY STATIONARY NEAR  
THE CANADIAN BORDER SUNDAY THROUGH TUESDAY. A COLD FRONT IS THEN  
EXPECTED TO MOVE ACROSS THE AREA TUESDAY NIGHT AND EARLY  
WEDNESDAY, FOLLOWED BY HIGH PRESSURE FOR THE REMAINDER OF THE  
WEEK.  

 
   
NEAR TERM /UNTIL 6 PM THIS EVENING/
 
 
OUR WEATHER WILL BE IN TRANSITION TODAY AS AN UPPER-LEVEL RIDGE  
SLIDES ACROSS AND THEN SHIFTS TO OUR EAST. AS THIS OCCURS, SURFACE  
HIGH PRESSURE WILL CONTINUE TO RETREAT TO THE NORTHEAST. THIS OPENS  
THE DOOR FOR A SOUTHERLY FLOW THAT WILL BRING IN MORE MOISTURE.  
 
THE MODEL GUIDANCE SHOWS WAA OCCURRING THROUGH THE DAY, HOWEVER  
THERE IS A MORE NOTED INCREASE TOWARD LATE AFTERNOON. THIS ALSO  
OCCURS AS AN INCREASE IN THE MOISTURE ARRIVES, WHICH IS SEEN IN THE  
THETA-E FIELDS. THIS INCREASE IN MOISTURE WILL ALLOW THE SURFACE DEW  
POINTS TO INCREASE, ALTHOUGH THIS PROCESS DURING THE DAYLIGHT HOURS  
WILL PROBABLY BE GRADUAL FOR MUCH OF THE AREA. THE MOISTURE INCREASE  
SHOULD ALSO RESULT IN MORE CLOUDINESS THROUGH THE DAY WITH CUMULUS  
DEVELOPMENT BELOW SOME MID TO HIGH LEVEL CLOUDS ON THE WESTERN FLANK  
OF THE DEPARTING RIDGE. THIS INCREASE IN MOISTURE WITHIN THE  
SOUTHERLY FLOW IS ALREADY EVIDENT EARLY THIS MORNING WITH AREAS OF  
CLOUDINESS TRYING TO EXPAND NORTH-NORTHEASTWARD FROM VIRGINIA AND  
MARYLAND. THERE ARE ALSO SOME LOW CLOUDS ACROSS NORTHEASTERN  
PENNSYLVANIA DUE TO SOME WEAK UPSLOPE FLOW COMBINED WITH BOUNDARY  
LAYER COOLING. AT LEAST SOME FORECAST SOUNDINGS INDICATE A CAP IN  
PLACE AS WARMING OCCURS ALOFT DURING THE DAY, HOWEVER MOISTURE NEAR  
THE BASE OF THE CAP SHOULD HELP FOCUS SOME ADDITIONAL CLOUD  
DEVELOPMENT.  
 
LOW PRESSURE TRACKING ACROSS THE GREAT LAKES REGION AHEAD OF AN  
UPPER-LEVEL TROUGH WILL HELP ASSIST IN WAA DOWNSTREAM, WHICH WILL  
ORGANIZE A WARM FRONT TO OUR SOUTHWEST. IN ADDITION, CONVECTIVE  
DEVELOPMENT IS EXPECTED TO OUR WEST WITHIN THE DEVELOPING WARM  
SECTOR AND NEAR A PRE-FRONTAL TROUGH. HOWEVER, THE LIFT WITH THESE  
FEATURES ARE EXPECTED TO REMAIN TO OUR WEST AND THEREFORE TODAY WAS  
KEPT DRY.  
 
AS FOR HIGH TEMPERATURES, WE USED A BLEND OF THE NAM/GFS MOS THEN  
MADE A LITTLE BIT OF AN UPWARD ADJUSTMENT FOR SOME INLAND AREAS  
GIVEN THE WAA. WE ARE NOT ANTICIPATING TO OBTAIN DEEP MIXING AND THE  
SURFACE FLOW LOOKS MOSTLY FROM THE SOUTH OR SOUTHEAST. THIS WOULD  
TEND TO KEEP TEMPERATURES FROM INCREASING DRAMATICALLY, ALTHOUGH IT  
SHOULD BE WARMER THAN YESTERDAY WITH SOME ADDED HUMIDITY AS WELL.  

 
   
SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/
 
 
HIGH PRESSURE AT THE SURFACE WILL BE SITUATED TO OUR EAST ALLOWING A  
SOUTHERLY FLOW TO BE MAINTAINED. OUR REGION WILL BECOME INCREASINGLY  
MORE ON THE NORTHWESTERN FLANK OF THE UPPER-LEVEL RIDGE, AND THE  
PASSAGE OF A WARM FRONT WILL ALLOW MUCH MORE HUMID AIR TO OVERSPREAD  
THE REGION. WE SHOULD SEE A DECENT INCREASE IN THE SURFACE DEW  
POINTS IN THE EVENING AS ANY MIXING DIMINISHES. WHILE WE STILL  
MAINTAIN SOME WAA THROUGH THE NIGHT, THIS GENERALLY TURNS WEAK. WE  
DO MAINTAIN SOME MOISTURE ADVECTION THOUGH, AND THIS COMBINED WITH A  
WARMER BOUNDARY LAYER MAY LEAD TO AREAS OF STRATUS AND EVEN SOME  
FOG.  
 
THE MAIN SHORT WAVE TROUGH THAT IS FORECAST TO BE AMPLIFYING ACROSS  
THE GREAT LAKES IS FORECAST TO HANG BACK FAIRLY FAR TO OUR WEST.  
THERE DOES APPEAR TO BE SOME LEAD SHORT WAVES TRACKING NORTHEASTWARD  
ALONG THE PERIPHERY OF THE UPPER-LEVEL RIDGE. THE FORECAST SOUNDINGS  
DO SHOW SOME INCREASE IN THE INSTABILITY TONIGHT, HOWEVER THERE MAY  
NOT BE MUCH FORCING. THERE COULD BE SOME WEAKENING SHOWERS/THUNDER  
APPROACHING OUR NORTHWEST ZONES THIS EVENING BEFORE THEY DISSIPATE,  
THEN PERHAPS SOME ADDITIONAL ACTIVITY MAY TRY AND ARRIVE ACROSS OUR  
WESTERN ZONES TOWARD DAYBREAK. THE LATTER MAY BE ASSOCIATED WITH AN  
EMBEDDED SHORT WAVE TRACKING AROUND THE RIDGE. OVERALL, WE THINK THE  
GREATER CHC WOULD BE TO OUR WEST CLOSER TO THE SHORT WAVE TROUGH AND  
ITS ASSOCIATED LIFT. THEREFORE ATTM, WE WERE SLOW TO INCREASE THE  
POPS TOWARD MORNING ACROSS THE WESTERN ZONES. OTHERWISE, AN INCREASE  
IN CLOUDS ESPECIALLY LATE WITH SOME STRATUS DEVELOPMENT AND PERHAPS  
PATCHY FOG. WE ARE NOT ALL THAT CERTAIN HOW MUCH FOG DEVELOPS GIVEN  
THE AIRMASS IS STILL UNDERGOING MOISTENING, THEREFORE WE DID NOT  
INCLUDE FOG ATTM.  
 
AS FOR LOW TEMPERATURES, WE WENT WITH AN INITIAL EVEN BLEND OF THE  
NAM/GFS MOS THEN MADE SOME MAINLY MINOR TWEAKS.  

 
   
LONG TERM /SUNDAY THROUGH FRIDAY/
 
 
MID-LEVEL RIDGING OVER THE EASTERN U.S. NEAR THE BEGINNING OF THE  
LONG TERM PERIOD GRADUALLY BECOMES ZONAL TOWARD THE END OF THE  
PERIOD WHICH TRANSLATES INTO ABOVE NORMAL TEMPERATURES FOR MUCH OF  
THE PERIOD.  
 
SUNDAY - TUESDAY...A NEARLY STATIONARY FRONTAL BOUNDARY TO OUR NORTH  
AND A SOUTHWESTERLY FLOW BOTH AT THE SURFACE AND ALOFT WILL PUMP IN  
WARM AND MOIST AIR OVER OUR REGION THROUGH THE PERIOD, BRINGING A  
CHANCE OF SHOWERS AND THUNDERSTORMS EACH DAY. THE BEST CHANCE FOR  
SHOWERS AND THUNDERSTORMS WILL BE SUNDAY NIGHT INTO MONDAY.  
DEWPOINTS WILL RISE INTO THE 70S ACROSS THE REGION WHICH WILL BE  
INDICATIVE OF HIGHER THAN NORMAL PRECIPITABLE WATER  
VALUES...POSSIBLY OVER TWO INCHES. GIVEN THE DRY CONDITIONS OF LATE,  
ANY FLOODING THAT DOES DEVELOP WOULD MOST LIKELY BE URBAN AND POOR  
DRAINAGE TYPE FLOODING. WITH TEMPERATURES A GOOD TEN DEGREES ABOVE  
NORMAL, AND DEWPOINT TEMPERATURES IN THE 70S, IT WILL FEEL LIKE THE  
DOG DAYS OF SUMMER.  
 
WEDNESDAY...LOW PRESSURE SYSTEM WELL TO THE NORTH OF THE REGION  
SENDS A SOMEWHAT STRONGER COLD FRONT THROUGH OUR AREA. THEN  
CONDITIONS WILL DRY OUT BEHIND THIS FRONT AS HIGH PRESSURE BUILDS IN  
FROM THE WEST DURING THE DAY. DEWPOINTS ARE EXPECTED TO DROP IN TO  
THE MID 60S, AND TEMPERATURES SHOULD DROP A FEW DEGREES TOO,  
ALTHOUGH THEY ARE STILL EXPECTED TO BE ABOVE NORMAL FOR THIS TIME OF  
YEAR.  
 
THURSDAY - FRIDAY...HIGH PRESSURE CONTINUES TO BUILD BACK INTO OUR  
REGION WITH ZONAL FLOW ALOFT, AND WE SHOULD BE DRY BOTH DAYS.  
TEMPERATURES MAY DROP A DEGREE OR TWO COMPARED TO WEDNESDAY, BUT  
STILL SHOULD BE A LITTLE ABOVE NORMAL.  

 
   
AVIATION /08Z SATURDAY THROUGH WEDNESDAY/
 
 
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,  
KMIV, KACY AND SURROUNDING AREAS.  
 
TODAY...LOCALIZED EARLY MORNING GROUND FOG, OTHERWISE VFR WITH  
SCATTERED TO BROKEN BASES AROUND 5000 FEET. SOME STRATUS EARLY THIS  
MORNING MAINLY NORTH OF KABE. SOUTHERLY WINDS INCREASING TO AROUND  
10 KNOTS.  
 
TONIGHT...VFR FOR AWHILE, HOWEVER AN INCREASE IN MOISTURE SHOULD  
RESULT IN AREAS OF STRATUS AND/OR FOG TOWARD MORNING.  
SOUTH-SOUTHWEST WINDS 5 KNOTS OR LESS.  
 
OUTLOOK...  
 
SUNDAY...VFR EARLY. THEN MVFR POSSIBLE IN SCATTERED SHOWERS AND  
THUNDERSTORMS...ESPECIALLY NORTH AND WEST OF PHL. MDT CONFIDENCE.  
 
SUNDAY NIGHT INTO MONDAY...IFR CONDITIONS POSSIBLE WITH SHOWERS AND  
THUNDERSTORMS. CONDITIONS IMPROVING TO VFR LATER MONDAY. LOW TO  
MDT CONFIDENCE ON PRECIP COVERAGE.  
 
MONDAY NIGHT AND TUESDAY...GENERALLY VFR CONDITIONS EXPECTED.  
 
TUESDAY NIGHT INTO WEDNESDAY...MVFR CONDITIONS POSSIBLE IN SCATTERED  
SHOWERS AND THUNDERSTORMS. LOW TO MDT CONFIDENCE.  
 
LATE WEDNESDAY AND THURSDAY...VFR. MDT CONFIDENCE.  

 
   
MARINE
 
 
HIGH PRESSURE WILL CONTINUE TO SHIFT TO OUR NORTHEAST AND EAST  
THROUGH TONIGHT. THIS WILL PRODUCE A SOUTHEAST TO SOUTH FLOW AS A  
WARM FRONT LIFTS NORTH OF THE AREA BY LATE TONIGHT. WHILE THE FLOW  
IS MAINLY ON THE LIGHT SIDE, SOME NEARSHORE ENHANCEMENT COULD OCCUR  
DURING PEAK HEATING. WHILE THE MOISTURE IS FORECAST TO INCREASE WITH  
AN UPTICK IN THE SURFACE DEW POINTS, THE WATER IS ON THE WARM SIDE  
THEREFORE WE MAY NOT HAVE MUCH FOG DEVELOPMENT. OVERALL, THE  
CONDITIONS ARE ANTICIPATED TO REMAIN BELOW SMALL CRAFT ADVISORY  
CRITERIA THROUGH TONIGHT.  
 
OUTLOOK...  
SUNDAY...SUB SCA.  
 
SUNDAY NIGHT AND MONDAY...SCA CONDITIONS POSSIBLE AS SEAS BUILD TO AROUND  
5 FEET. SUB-SCA CONDITIONS EXPECTED AGAIN LATER MONDAY INTO  
TUESDAY. A COLD FRONT WILL APPROACH LATE TUESDAY EVENTUALLY  
CROSSING ON WEDNESDAY. SEAS WILL INCREASE BUT ARE EXPECTED TO  
REMAIN BELOW BELOW SCA.  

 
   
RIP CURRENTS
 
 
TEMPERATURES WILL BE ABOVE NORMAL..AT TIMES MUCH ABOVE NORMAL..  
THIS SUNDAY ONWARD THROUGH NEXT FRIDAY. THIS COMBINED WITH WATER  
TEMPERATURES GENERALLY IN THE 70S WILL MAKE IT FAVORABLE FOR  
BEACHGOERS TO SWIM. ALL GOOD! AS LONG AS THEY SWIM IN THE LIFEGUARDED  
AREAS.  
 
WHY? BECAUSE THERE IS ABOUT A 1 IN 18 MILLION CHANCE OF BECOMING  
A RIP CURRENT CASUALTY UNDER THE WATCHFUL EYES OF THE LIFE  
GUARDS....MUCH BETTER ODDS THAN IF YOU SWIM ON YOUR OWN WHERE  
RESCUE POTENTIAL IS NOT AS TIMELY.  
 
THIS SUMMER 4 HAVE DIED ALONG THE NJ SHORES DUE TO RIP CURRENTS  
AND WHAT WAS COMMON TO ALL...THEY SWAM WHERE LIFEGUARDS WERE NOT  
PRESENT...AND/OR AFTER THE HOURS THEY WERE ON DUTY.  
 
THE FAMILIES/FRIENDS WERE UNABLE TO RESCUE THE VICTIMS. MANY OF  
US DO NOT REALIZE HOW POWERFUL THE OCEAN IS...AND ITS NOT THE SAME  
SWIMMING IN THE POOL. THAT AND THE FACT THAT MANY OF US OVERESTIMATE  
WHAT WE CAN DO IN THE WATER/SWIMMING SKILL, CAN LEAVE A POTENTIAL  
VICTIM IN A LIFE THREATENING SITUATION.  
 
SWIM SAFE AND THE BEST WAY TO DO THAT IS SWIM IN THE PRESENCE OF  
LIFEGUARDS WHILE ENJOYING THIS FINE LABOR DAY WEEKEND WEATHER.  

 
   
PHI WATCHES/WARNINGS/ADVISORIES
 
 
PA...NONE.  
NJ...NONE.  
DE...NONE.  
MD...NONE.  
MARINE...NONE.  
 

 
 

 
SYNOPSIS...MIKETTA  
NEAR TERM...GORSE  
SHORT TERM...GORSE  
LONG TERM...MIKETTA  
AVIATION...GORSE/MIKETTA  
MARINE...GORSE/MIKETTA  
RIP CURRENTS...DRAG  
 
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