Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 011233
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
833 AM EDT WED JUL 1 2015

.SYNOPSIS...
A WARM FRONT WILL LIFT NORTHEAST OF THE AREA THIS MORNING. A COLD
FRONT FROM THE EASTERN GREAT LAKES SHOULD THEN MOVE THROUGH LATE
TONIGHT. THE COLD FRONT IS EXPECTED TO STALL JUST SOUTH OF OUR
REGION FOR THE REMAINDER OF THE WEEK AS WAVES OF LOW PRESSURE MOVE
ALONG IT. A SECOND COLD FRONT SHOULD ARRIVE SATURDAY NIGHT
FOLLOWED BY WEAK HIGH PRESSURE FOR SUNDAY. A WARM FRONT SHOULD
THEN MOVE THROUGH THE REGION ON MONDAY WITH A COLD FRONT REACHING
THE GREAT LAKES ON TUESDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE HEAVY SHOWERS/THUNDERSTORMS ASSOCIATED WITH A STRONG SHORT
WAVE/VORTICITY IMPULSE MOVING ACROSS THE AREA HAS LIFTED TO OUR
NORTHEAST. THERE WILL REMAIN SOME LIGHT RAIN ACROSS THE AREA THIS
MORNING, BUT THE HEAVY RAIN HAS ENDED, SO WE HAVE CANCELLED THE
FLASH FLOOD WATCH.

AFTER THE MORNING SHOWERS/THUNDERSTORMS MOVE OUT AND END, THE REST
OF THE MORNING INTO THE EARLY AFTERNOON MAY SEE A BREAK IN
PRECIPITATION. HOWEVER, AS THE COLD FRONT APPROACHES LATER IN THE DAY
AND ANOTHER SHORT WAVE/VORTICITY IMPULSE MOVES ACROSS THE AREA,
SCATTERED SHOWERS/THUNDERSTORMS MAY ONCE AGAIN DEVELOP ACROSS THE
AREA, ESPECIALLY THE WESTERN HALF.

HIGHS TODAY ARE A BLEND OF MAV/MET MOS AND MOSGUIDE AND MIXED 925 MB
ECMWF TEMPERATURES.

WINDS DURING THE DAY WILL ALSO GUST AROUND 20-25 MPH.

WE ARE EXPECTED TO PERFORM STORM SURVEYS TODAY AFTER 9 AM IN CHESTER
COUNTY AND THE LEHIGH VALLEY TO INVESTIGATE THE POSSIBILITY OF
TORNADO OCCURRENCES ON TUESDAY.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
THE COLD FRONT WILL MOVE ACROSS THE AREA THIS EVENING, WHILE THE
SHORT WAVE/VORTICITY ALOFT FOLLOWS ALONG. THERE WILL CONTINUE TO BE
THE CHANCE FOR ISOLATED SHOWERS/THUNDERSTORMS THIS EVENING, BEFORE
THEY DIMINISH AND MOVE OUT OF THE AREA AS THE FRONT MOVES EASTWARD.
THE ENTIRE AREA SHOULD BE RAIN FREE BY MIDNIGHT.

LOWS TONIGHT ARE A BLEND OF MAV/MET MOS AND MOSGUIDE.

THE COLD FRONT PUSHES SOUTH OF THE AREA AND STALLS OUT THURSDAY INTO
THURSDAY NIGHT. WHILE THE FRONT WILL BE WELL SOUTH OF THE AREA,
THERE WILL REMAIN SEVERAL SHORT WAVE/VORTICITY IMPULSES SLIDING
ACROSS OUR SOUTHERN AREAS. THE MAJORITY OF THE PRECIPITATION SHOULD
REMAIN TO OUR SOUTH, BUT THERE WILL REMAIN THE POSSIBILITY FOR
SHOWERS/THUNDERSTORMS TO AFFECT SOUTHERN NEW JERSEY AND THE DELMARVA.

HIGHS THURSDAY ARE A BLEND OF MAV/MET MOS AND MOSGUIDE AND MIXED 925
MB ECMWF TEMPERATURES. LOWS THURSDAY NIGHT ARE A BLEND OF MAV/MET
MOS AND MOSGUIDE.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
THE WRF-NMMB LOOKED BETTER AT 500MB AND 850MB WITH AN EQUAL SPLIT
AT 925MB. THIS CASTS SOME DOUBT ON THE GFS SOLUTION FOR THE LONG
TERM. THERE REMAINS BOTH A TIMING AND LATITUDINAL SPLIT WITH THE
MEDIUM RANGE MODELS WITH THE GFS SLOWEST AND FARTHEST NORTH.
THERE APPEARS TO BE SOME FEEDBACK VORTS WITH THE GFS AND THE GEFS
PCPN MEAN IS LOWER THAN THE OP. REGARDLESS ONGOING SVR AND FLOODING
HAS MADE US LEAN HEAVILY ON PMDHMD (ECMWF PREFERENCE) AND WPC FOR
THE LONG TERM.

FRIDAY, WE ARE KEEPING A CHANCE FOR SHOWERS IN THE SOUTHERN HALF OF
OUR CWA. MAX TEMPS HIGHER THAN MEX GUIDANCE, BUT LOWER THAN PREVIOUS
FORECAST.

PRESERVATION OF CONTINUITY WE KEPT A CHANCE OF THUNDERSTORMS IN
FOR INDEPENDENCE DAY. HERE THE ECMWF IS MORE PESSIMISTIC. SUNDAY
CONTINUES TO BE THE CONSENSUS BETTER WEEKEND DAY WITH THE FRONTAL
BOUNDARY PUSHED FARTHER TO THE SOUTH.

THE RETURNING WARM FRONT SHOULD THEN BRING PCPN CHANCES BACK ON
MONDAY AND THE APPROACHING COLD FRONT PROVIDING AN ADDITIONAL CHANCE
COME TUESDAY.

UNCERTAINTY REMAINS HIGHER THAN AVERAGE, BUT TEMPERATURES FAVOR AT
OR COOLER THAN NORMAL THROUGH INDEPENDENCE DAY WITH A RETURN OF MORE
WARMER AND HUMID WEATHER FOR THE BACK END OF THE LONG TERM.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

THE HEAVY SHOWERS/THUNDERSTORMS HAVE LIFTED TO OUR NORTHEAST AND
CONDITIONS HAVE MOSTLY IMPROVED TO VFR. A BRIEF PERIOD OF MVFR FOG
IS POSSIBLE THIS MORNING AROUND AND SHORTLY AFTER SUNRISE.
HOWEVER, AS THE MORNING PROGRESSES, ANY FOG THAT DEVELOPS WILL
BURN OFF AND A RETURN TO VFR IS EXPECTED FOR THE REMAINDER OF THE
DAY.

SOUTH-SOUTHWEST WINDS EARLY THIS MORNING WILL BECOME MORE
SOUTHWESTERLY LATER THIS MORNING INTO THIS AFTERNOON. WINDS WILL
ALSO GUST 15-20 KNOTS THIS AFTERNOON, BEFORE THE GUSTS DROP OFF
AROUND SUNSET AND BECOME MORE WEST-NORTHWEST OVERNIGHT. WINDS MAY
ACTUALLY BECOME LIGHT AND VARIABLE FOR MANY AREAS OVERNIGHT.

VFR CONDITIONS WILL REMAIN FOR THE FIRST PART OF TONIGHT, BUT THERE
IS THE POSSIBILITY THAT SOME LIGHT FOG MAY DEVELOP OVERNIGHT THROUGH
DAYBREAK THURSDAY.

OUTLOOK...
THURSDAY THROUGH SATURDAY...PREDOMINATELY VFR, BUT SOME MVFR OR
IFR CONDITIONS DURING SCATTERED SHOWERS AND THUNDERSTORMS. IMPACT
OUTLOOKED TO BE GREATER FOR SOUTHERN AIRPORTS AND TERMINALS.

SATURDAY NIGHT AND SUNDAY...VFR CONDITIONS EXPECTED.

&&

.MARINE...
A SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS HAS BEEN ISSUED FOR THE
ATLANTIC COASTAL WATERS FOR TODAY INTO TONIGHT. SEAS ARE AROUND 4
FEET EARLY THIS MORNING AND ARE EXPECTED TO INCREASE TO 5 FEET
THROUGH THE DAY. A SMALL CRAFT ADVISORY HAS ALSO BEEN ISSUED FOR
DELAWARE BAY AS WINDS ARE GUSTING AROUND 25 KNOTS THIS MORNING.
WINDS SHOULD DIMINISH LATER THIS MORNING, SO WE WILL RUN THIS ONE
THROUGH 11 AM.

OUTLOOK...
THURSDAY AND THURSDAY NIGHT...WINDS AND SEAS SHOULD REMAIN BELOW SCA
CRITERIA.

FRIDAY THROUGH SATURDAY...SEAS ON THE SOUTHERN OCEAN WATERS MIGHT
REACH SMALL CRAFT ADVISORY LEVELS PENDING THE STRENGTH OF THE LOW
PRESSURE SYSTEM ON THE FRONTAL BOUNDARY. CONFIDENCE IS LESS THAN
AVERAGE.

SUNDAY...SUB SMALL CRAFT ADVISORY CONDITIONS EXPECTED.

&&

.RIP CURRENTS...
BASED ON OUR LOCAL FORECAST APPLICATION USING A 5 FOOT WAVES/7
SECOND PERIOD AND SOUTHWEST WIND AROUND 12 KNOTS, WE WILL CONTINUE
WITH A MODERATE RISK OF RIP CURRENTS FOR NEW JERSEY AND LOW FOR
DELAWARE.

&&

.CLIMATE...
RAINFALL FOR THE MONTH OF JUNE RANKED IN THE TOP 5 OF THE AVAILABLE
RELIABLE HISTORICAL DATABASE.

WILMINGTON #2 12.52. THE WETTEST WAS 13.66 IN 2013 AND THE TOP 4
WETTEST JUNES OCCURRED SINCE 2003. THE PERIOD OF RECORD (POR)
DATES BACK TO 1894.

ALLENTOWN #5 7.59 INCHES. THE WETTEST 10.51 IN 1938. POR TO 1922.
10.51 1938 THREE OF THE WETTEST JUNES OCCURRED SINCE 2003
9.13 2006
8.58 1972
8.30 2003
7.59 2015

ATLANTIC CITY #2 8.36 INCHES. THE WETTEST 8.45 INCHES 1920. POR
1874.

PHILADELPHIA #3 8.88 INCHES. THE WETTEST 10.56 2013, #2 IS 10.06
IN 1938. THREE OF 4 WETTEST JUNES OCCURRED SINCE 2003.


TEMPERATURES FOR THE MONTH OF JUNE IN OUR FORECAST AREA GENERALLY
AVERAGED SLIGHTLY ABOVE NORMAL BUT NOTHING OF SIGNIFICANCE.

&&

.EQUIPMENT...
PCPN MEASURER ERROR AT KPHL, ESTIMATED AMOUNT OF 1.5" ON 6/30
MAY BE ADJUSTED LATER TODAY.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 6 AM EDT
     THURSDAY FOR ANZ450>455.
     SMALL CRAFT ADVISORY UNTIL 11 AM EDT THIS MORNING FOR ANZ430-
     431.

&&

$$
SYNOPSIS...GIGI
NEAR TERM...ROBERTSON
SHORT TERM...ROBERTSON
LONG TERM...GIGI
AVIATION...GIGI/ROBERTSON
MARINE...GIGI/ROBERTSON
RIP CURRENTS...
CLIMATE...833A
EQUIPMENT...


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