178  
FXUS61 KPHI 271437  
AFDPHI  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ  
1037 AM EDT FRI MAR 27 2015  
   
SYNOPSIS
 
 
LOW PRESSURE WILL FORM ALONG A COLD FRONT EAST OF THE MID  
ATLANTIC COAST THIS AFTERNOON AND HEAD NORTHEAST OUT TO SEA LATE  
SATURDAY. AT THE SAME TIME. STRONG CANADIAN HIGH PRESSURE IS  
EXPECTED TO BUILD INTO THE REGION THROUGH MONDAY. ANOTHER COLD  
FRONT WILL CROSS THE REGION LATER ON MONDAY. HIGH PRESSURE WILL  
MOVE IN AGAIN FOR TUESDAY AND WEDNESDAY BEFORE ANOTHER LOW  
PRESSURE SYSTEM AFFECTS THE AREA BY THURSDAY.  
 

 
   
NEAR TERM /UNTIL 6 PM THIS EVENING/
 
 
AS OF MID/LATE MORNING RAIN HAS MOSTLY ENDED OVER THE AREA EXCEPT  
FOR SOME SPRINKLES...PROBABLY NOT MEASURABLE. THERE IS MORE RAIN  
TO THE SW OVER VA/MD WHICH WILL LIKELY CLIP DELMAVA AND SRN NJ  
LATER TODAY...AS SUGGESTED BY LATEST RAP AND HRRR GUIDANCE. SKIES  
ARE EXPECTED TO REMAIN CLOUDY OR MOSTLY CLOUDY FOR THE REST OF  
TODAY WITH SW FLOW AT MID/HI LEVELS...ALTHOUGH SMWHT DRIER AIR IS  
COMING IN ON NNW WINDS AT LOW LEVELS.  
 
THE COMBINATION OF LOW-LEVEL COLD ADVECTION AND CLOUDY SKIES WILL  
LIMIT MAX TEMPS THIS AFTERNOON WELL BELOW YESTERDAY'S MILD  
READINGS. THE MAX TEMPS FORECAST GRID WAS ADJUSTED DOWNWARD  
SLIGHTLY ACCORDING TO THE LATEST MAV/MET GUIDANCE.  
 

 
   
SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/
 
 
A SURFACE TROUGH IS FORECAST TO DROP THROUGH OUR AREA FROM THE  
NORTHWEST THIS EVENING. IT WILL USHER A REINFORCING SHOT OF COLD  
DRY AIR INTO OUR REGION. THE TROUGH IS NOT EXPECTED TO BRING ANY  
PRECIPITATION WITH IT. WE ARE FORECASTING VARIABLE CLOUD COVER FOR  
TONIGHT.  
 
A NORTHWEST WIND SHOULD REMAIN AROUND 10 MPH FOR TONIGHT. MINIMUM  
TEMPERATURES ARE ANTICIPATED TO BE MAINLY IN THE 20S IN THE NORTH  
AND IN THE LOWER AND MIDDLE 30S ELSEWHERE.  
 

 
   
LONG TERM /SATURDAY THROUGH THURSDAY/
 
 
THE PD STARTS OUT WITH A LARGE AND ANOMALOUSLY COLD UPR TROF OVER  
THE ERN CONUS ON SAT AND A SFC LOW WELL OFF THE ATLC COAST. STRONG  
HIGH PRES IS LOCATED TO THE W. THERE REMAINS SOME DISAGREEMENT IN  
THE MDLS AS TO PRECIP CHCS ON SAT, BUT BOTH THE GFS AND ECMWF HAVE  
TRENDED LOWER. HOWEVER, WITH THE STRONG TROF AND THE  
AFOREMENTIONED SFC LOW PSBLY CREATING A SFC TROF AND THE STRONG  
NLY TO NWLY FLOW, THERE CUD BE SOME SHWRS/SHSN TRIGGERED ACRS THE  
REGION, SO WILL MAINTAIN LOW POPS. THE BEST CHCS WUD BE CLOSEST TO  
THE CST.  
 
BY SAT NIGHT, THE LOW PULLS FURTHER AWAY AND THE H5 TROF MOVES  
OFF THE CST AS THE HIGH PRES SETTLES TO THE S. THESE FEATURES WILL  
ALLOW FOR A DRY AND COOL DAY.  
 
THE HIGH MOVES FURTHER SE ON MON WHICH ALLOWS FOR LOW PRES TO  
MOVE ACRS SERN CANADA. THE ATTENDANT CDFNT FROM THIS LOW WILL  
CROSS THE REGION LATER MON AND CUD TOUCH OFF A SHOWER, MAINLY OVER  
NRN AREAS. WILL CONTINUE LOW POPS TO ACCOUNT FOR THESE  
POSSIBILITIES.  
 
HIGH PRES THEN BUILDS BACK IN FOR TUE BEFORE ANOTHER WK LOW DIVES  
SEWD FOR TUE NIGHT INTO ERLY WED. THIS LOW LOOKS TO BRING ANOTHER  
ROUND OF LIGHT PRECIP MAINLY TO NRN AREAS.  
 
FINALLY, BY THU A MORE ORGANIZED AREA OF LOW PRES WILL APPROACHED  
THE REGION AND BRING MORE WIDESPREAD RAIN CHCS. MDLS STILL DIFFER  
ON THE TIMING, WHICH CAN BE EXPECTED AT A WEEK OUT.  
 
TEMPS WILL START OUT AS MUCH AS 10-15 DEGREES BELOW NRML ON SAT,  
RISE A BIT ON SUN BUT STILL REMAIN ABOUT 10 DEGREES BELOW NRML  
THEN RETURN TO NR NRML VALUES FOR THE REMAINDER OF THE PD. THERE  
WILL BE A VERY NICE WARM UP ON MON IN ADVANCE OF THE CFP. TEMPS  
MAY BE KNOCKED DOWN A COUPLE OF DEGREES ON TUE BEHIND THE FRONT  
BEFORE CLIMBING AGAIN DURG THE MIDWEEK PD.  
 

 
   
AVIATION /14Z FRIDAY THROUGH TUESDAY/
 
 
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,  
KILG, KMIV, KACY, AND SURROUNDING AREAS.  
 
AS OF MID/LATE MORNING...VFR CONDS ARE NOTED AT ALL OUR TAF SITES  
EXCEPT MIV/ACY. SOME MVFR OR IFR CONDS ARE LIKELY THERE FOR THE  
REST OF TODAY...MAINLY LOWER CIGS...AS SOME LIGHT RAIN MOVES  
ACROSS FROM THE SW. SOME SPRINKLES OR VERY LIGHT RAIN ARE POSSIBLE  
ALONG THE ILG-PHL-TTN CORRIDOR BUT NOT ENOUGH TO AFFECT VFR CONDS.  
 
WINDS TODAY WILL CONTINUE LIGHT NNW...BUT THE CHANCES FOR  
GUSTINESS ARE LOOKING LESS FAVORABLE THAN EARLIER. IF GUSTS DO NOT  
DEVELOP SOON THEY WILL BE REMOVED FROM THE TAFS.  
 
PREVIOUS DISCUSSION...  
DRYING WILL TAKE PLACE TODAY WITH AN IMPROVEMENT SOLIDLY INTO THE  
VFR CATEGORY AFTER THE RAIN ENDS. VFR CONDITIONS ARE FORECAST TO  
CONTINUE INTO TONIGHT.  
 
A NORTHWEST WIND AROUND 10 KNOTS IS ANTICIPATED FOR TODAY AND  
TONIGHT. THE WIND MAY GUST NEAR 20 KNOTS AT TIMES INTO THIS  
EVENING.  
 
OUTLOOK...  
SAT...MAINLY VFR. SOME LWR CONDS IN LOW PROB SHRA/SHSN. MDT  
CONFIDENCE.  
 
SUN - MON...VFR. N WIND VEER TOWARDS THE SW ERLY MON AND BEGIN TO  
GUST IN THE 20 TO 25 KT RANGE MON AFT. CFP MON WITH WSHFT TO WNW  
OR NW. MDT TO HIGH CONFIDENCE.  
 
TUE...VFR. HIGH CONFIDENCE.  
 

 
   
MARINE
 
 
COLD ADVECTION WILL CONTINUE ON THE COASTAL WATERS OF NEW JERSEY  
AND DELAWARE THIS MORNING WITH A REINFORCING SHOT OF COLD AIR  
ARRIVING TONIGHT. THE WIND IS EXPECTED TO REMAIN FROM THE  
NORTHWEST.  
 
THERE MAY BE GUSTS AROUND 25 KNOTS ON OUR OCEAN WATERS THROUGH  
THIS MORNING AND AGAIN LATE TONIGHT. MEANWHILE, WAVE HEIGHTS ARE  
FORECAST TO REMAIN IN THE 5 TO 7 FOOT RANGE TODAY BEFORE FALLING  
TO AROUND 4 FEET FOR TONIGHT. WE WILL KEEP THE SMALL CRAFT  
ADVISORY GOING FOR TODAY AND TONIGHT, EVEN THOUGH CONDITIONS MAY  
DROP BRIEFLY BELOW THE CRITERIA FOR A TIME THIS EVENING.  
 
WE HAVE DISCONTINUED THE SMALL CRAFT ADVISORY FOR DELAWARE BAY.  
HOWEVER, WE WILL BE ISSUING A NEW ONE THAT BEGINS AT MIDNIGHT TO  
ACCOUNT FOR THE WIND GUSTS ASSOCIATED WITH THE NEXT SHOT OF COLD  
AIR THAT ARRIVES TONIGHT.  
 
OUTLOOK...  
SAT...SCA WILL BE CONTINUED INTO SAT AS STRONG N TO NWLY FLOW  
WILL KEEP BOTH WIND AND SEAS ELEVATED.  
 
SAT NIGHT - TUE...POSSIBLE SCA CONDS SAT NIGHT AND AGAIN ON MON,  
WITH SOME MARGINAL GALES EVEN ON SAT NIGHT INTO ERLY SUN. THROUGH  
TUESDAY. THESE LOOK TO BE THE MOST PROBABLE TIMES FOR SCA THOUGH  
THERE CUD BE SOME OTHER MORE MARGINAL EVENTS SUCH AS ON TUE.  
 

 
   
PHI WATCHES/WARNINGS/ADVISORIES
 
 
PA...NONE.  
NJ...NONE.  
DE...NONE.  
MD...NONE.  
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT SATURDAY FOR ANZ450>455.  
SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM EDT  
SATURDAY FOR ANZ430-431.  
 

 
 

 
SYNOPSIS...NIERENBERG  
NEAR TERM...AMC/IOVINO  
SHORT TERM...IOVINO  
LONG TERM...NIERENBERG  
AVIATION...AMC/IOVINO/NIERENBERG  
MARINE...IOVINO/NIERENBERG  
 
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