National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS61 KPHI 220141
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
941 PM EDT TUE MAY 21 2013

.SYNOPSIS...
HIGH PRESSURE WILL REMAIN OFF THE SOUTHEASTERN UNITED STATES
COAST THROUGH THURSDAY. AN AREA OF LOW PRESSURE WILL MOVE FROM THE
SOUTHERN PLAINS TO SOUTHEASTERN CANADA THROUGH THURSDAY AND BRING
A COLD FRONT THROUGH THE REGION LATE THURSDAY INTO FRIDAY. HIGH
PRESSURE WILL THEN BUILD IN FROM THE WEST FOR THE HOLIDAY WEEKEND
THIS HIGH WILL THEN GRADUALLY MOVE OFFSHORE THROUGH TUESDAY.

&&

.NEAR TERM /UNTIL 8 AM WEDNESDAY MORNING/...
930 PM: CUT BACK FURTHER ON SHOWERS NW PTN OF THE FA TONIGHT. FOG
IS IN THE COUNTRYSIDE FCST BUT NOT NECESSARILY THE URBAN CENTERS
(FOGGER TOOL I THINK IS BETTER THAN THE CONSERVATIVE CROSSOVER).
HOWEVER SREF PROBS EVEN LOWER VSBY TO LESS THAN 1 MI IN THE CITY
BY 09Z.

SO MO CLEAR SKIES GIVE WAY TO LOW OVERCAST LATE. THERE IS A SMALL
CHANCE THAT CONVECTION IN NW PA AND S NYS AT 01Z WILL DEVELOP ESEWD
AND GRAZE THE POCONOS 05Z-08 BUT FOR NOW... MODEL SIGNALS ARE DRY
FOR THIS EVENING AND WITHOUT CU...ITS DIFFICULT TO HAVE A SHOWER.

WARM AND HUMID WITH TEMPS MUCH ABOVE NORMAL FOR THIS TIME OF
YEAR...AND MORE TYPICAL OF A MID SUMMER NIGHT.

&&

.SHORT TERM /8 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
WEDNESDAY WILL HAVE WEATHER SIMILAR TO TODAY. PLENTY OF CLOUDS/FOG IN
THE MORNING AND A CHC FOR SHOWERS/TSTMS DURING THE AFTERNOON...MAINLY
E PA. ITS POSSIBLE THERE WILL BE ISOLATED SHOWERS IN THE DE VALLEY
DURING MIDDAY BUT FOR THE MOST PART CONVECTION SHOULD BE MID OR
LATE AFTN...IF ANY WITHIN OUR CWA.

SPC HAS PLACED THE SLGT RISK FOR TSTMS TO THE WEST OF OUR AREA...SO
WE WILL WATCH FOR THE UPDATE EARLY WEDNESDAY MORNING. HIGHS WILL BE
VERY WARM AGAIN WED WITH TEMPS IN THE MID TO UPPER 80S IN MOST AREAS
(EXCEPT ALONG THE SHORE...WHERE READINGS IN THE UPPER 70S TO LOW
80S MAY OCCUR). THERE IS STILL A SMALL CHANCE THE TEMP NUDGES 90F
VCNTY OF KRDG OR KABE OR NEAR KSMQ IN THE AFTN WHERE THE HOTTEST
TEMPS SHOULD OCCUR...AGAIN PRESUMING NO CONVECTION IN THE 14Z-20Z
TIME FRAME.

CLOUD COVER WILL PROBABLY VERY SLOW TO THIN OVER SE NJ AND S DE ON
WEDNESDAY...POSSIBLY NOT CLEARING OFF TIL MID AFTN.

SW WIND G TO 15 MPH WED AFTN.

 &&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
THE AREA OF HIGH PRESSURE WILL REMAIN OFF THE ATLC CST WED NIGHT
AND THU AND SWLY FLOW WILL CONTINUE WHICH WILL KEEP WARM WX OVER
THE AREA. HOWEVER, BY THU, AN AREA OF LOW PRESSURE WILL MOVE INTO
SERN CANADA. THE CDFNT ASSOCD WITH THIS LOW WILL CROSS THE REGION
THU NIGHT. THIS PD LOOKS TO TO BE THE WETTEST WITH SHOWERS, TSTMS
AND PSBLY SOME HEAVY RAIN. ITS A BIT TOO EARLY TO BE CERTAIN ABOUT
ANY SEVER WX POTENTIAL. IT WILL BE DEPENDENT ON DAYTIME HEATING
AND OTHER FACTORS. HOWEVER, IT COULD BE MITIGATED BY THE FACT THAT
THE FRONT WILL BE COMING THROUGH AFTER SUNSET. THE 21/12Z GFS IS
THE SLOWEST MDL CLEARING THINGS OUT ON FRI AND TRIES TO DEVELOP A
WAVE ALG THE FRONT. NONE OF THE OTHER MDLS HAVE THIS FEATURE, SO
AM NOT INCLINED TO GO ALONG FOR NOW. FRI, ESPECIALLY LATER FRI,
SHOULD SEE IMPROVING WX AND BY SAT A LARGE AREA OF HIGH PRESSURE
WILL PUSH INTO THE MIDWEST FROM CANADA WAND WILL SLOWLY SLIDE EWD
THRU THE HOLIDAY WEEKEND.

THE PGRAD BETWEEN THE BUILDING HIGH AND THE DEPARTING LOW OVER THE
CANADIAN MARITIMES WILL KEEP A DECENT NWLY FLOW OVER THE AREA ON
SAT, WITH WEAKENING FLOW AS THE HIGH MOVES IN ON SUN. SO, AT THIS
POINT, THE WEEKEND LOOKS PREDOMINANTLY DRY, ALBEIT COOL FOR LATE
MAY AND WITH A BRISK NW WIND, IT WILL FEEL COOLER ON SAT.

TEMPS LOOK TO BE WARMEST ON THU, WITH TEMPS AROUND 80 OR INTO THE
80S. THEN BEHIND THE FRONT MOST LOCATIONS WILL BE AROUND 70 OR
INTO THE LOWER 70S FOR THE REMAINDER OF THE PD. SAT LOOKS TO BE
THE COOLEST DAYS, WITH MANY LOCATIONS HOVERING IN THE MID/UPPER 60S.

&&


.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

TONIGHT...VFR CIRRUS THIS EVENING. LIGHT SSW WIND. CONDITIONS
LIKELY TO BECOME IFR OR LIFR IN ST/FOG AFTER 07Z.

WED...AFTER A PROBABLE IFR CONDITION START AT 12Z...A SLOW RETURN TO
VFR BY MID OR LATE MORNING WITH SCT-BKN CLOUDS AOA 3500 FT IN THE
AFTN AND A SHOWER OR TSTM POSSIBLE DURING THE AFTERNOON...MAINLY
VCNTY KRDG OR KABE. SW WIND GUST TO 15 KT IN THE AFTN.

THE IFR CIGS MAY BE VERY SLOW TO LIFT VCNTY KMIV AND KACY NOT LIFTING
TO MVFR CIGS TIL MIDDAY WED AND CLEARING AROUND MID AFTN.

THERE IS A SMALL CHANCE FOR A SHOWER IN THE DE VALLEY VCNTY KPNE/KPHL
AROUND 15-16Z WED PER LONG RANGE RUC-RAP BUT AN UNLIKELY OCCURRENCE.

FEELING IS THE MODELS HAVE A SLIGHT WET BIAS AND ARE OVERDOING CONVECTIVE
POTENTIAL IN THIS SW FLOW SUMMERLIKE SCENARIO IN OUR CWA.


OUTLOOK...
WED NIGHT THROUGH THU NIGHT...MAINLY VFR. MVFR, POSSIBLY IFR,
CONDITIONS POSSIBLE IN ANY SHOWERS AND THUNDERSTORMS OR PDS OF
HEAVY RAIN. WIND WILL SHIFT FROM SW TO NW BEHIND CFP LATE WED
NIGHT/EARLY THU MRNG. HIGH CONFIDENCE ON THE OVERALL DETAILS. LOW
CONFIDENCE ON THE FACT THAT ALL SITES WILL SEE MVFR/IFR AND
TIMING.

FRI...MAINLY VFR WITH A CHANCE OF SHOWERS MAINLY IN THE MORNING.
HIGH CONFIDENCE.

SAT-SUN...VFR CONDITIONS EXPECTED. A BRISK NW WIND ON SAT OF 15-20
KT.  HIGH CONFIDENCE.

&&

.MARINE...
GUIDANCE RUNNING A SOLID 1 FOOT OR MORE TOO HIGH RECENTLY DUE TO
WAA OVER COOLER WATER.

CONDITIONS SHOULD REMAIN SUB-SCA TONIGHT AND APPROACH SCA LATER
WEDNESDAY. WINDS WILL INCREASE WED...BUT WITH THE WARMER AIR AND
COOLER SEAS...THE WINDS/WAVE GUIDANCE WILL PROBABLY BE TOO HIGH.
WE OPT TO KEEP THE SEAS AT 3 TO 4 FT FOR WED AND HOLD THE WINDS
BELOW SCA FLAG LEVELS. A FEW G 20-25 ARE NOT OUT OF THE QUESTION
LATER WED. SCAT SHOWERS/TSTMS EXPECTED WED.

OUTLOOK...
HIGH PRESSURE ANCHORED OFF THE SOUTHEASTERN UNITED STATES COAST WILL
BRING A PROLONGED SOUTH TO SOUTHWEST FLOW FOR WED NIGHT THROUGH
THU. AS THIS FLOW STRENGTHENS WITH A CDFNT APPROACHING FROM THE W
ON THU, WINDS AND SEAS WILL GRADUALLY INCREASE. THEREFORE, SEAS
AND WIND COULD BE AOA SCA CRITERIA BY THE START OF THE OUTLOOK PD. A
SMALL CRAFT ADVISORY MAY BE NEEDED FOR THIS PD ON THE OCEAN FRONT.
HOWEVER, WITH VERY WARM AIR OVER THE RELATIVELY COOL OCEAN AND
WAVE WATCH OVERDOING HEIGHTS OF LATE, HAVE DECIDED NOT TO POST
ANYTHING ATTM. THERE WILL ALSO BE SOME SHWRS/TSTMS WED NIGHT INTO
THU ALG AND AHEAD OF THE CFP.

THE COLD FRONT WILL CROSS THE AREA WATERS LATE THURSDAY INTO FRIDAY.
BOTH WINDS AND SEAS WILL START TO SUBSIDE AND SHOULD FALL BELOW
SCA CRITERIA. WINDS AND SEAS SHOULD REMAIN BELOW CRITERIA THROUGH
THE HOLIDAY WEEKEND AS HIGH PRESSURE BUILDS ACROSS THE REGION.

&&

.CLIMATE...
KNOWING THE FIRST 20 DAYS OF MAY TEMPERATURES HAVE AVERAGED ALMOST
SPOT-ON NORMAL FOR ALMOST EVERY CLIMATE SITE IN OUR AREA...WE
PROJECTED THE REMAINDER OF THE MONTH FOR KPHL. WE USED THE KPHL
MAX/MINS FOR THE NEXT 7 DAYS, AND THEN THE FTPRHA PHL 2M MAX/MIN
TEMPS BEYOND THRU THE 31ST.

THE PROJECTED MONTHLY AVG TEMPS IS IN THE NORMAL RANGE...SLIGHTLY ABOVE
BUT WITHIN 1/2 DEG OF NORMAL.

WE DISCUSS TEMPERATURES TONIGHT SINCE WE`RE COMING INTO THE MEMORIAL DAY
WEEKEND WHICH WILL BE COOL AND LESS FAVORABLE FOR OCEAN SWIMMING BUT
GUIDANCE IS SHOWING INCREASING CHANCES FOR A WARMER THAN NORMAL
PATTERN DEVELOPING HERE BETWEEN ROUGHLY THE 30TH OF MAY WELL INTO
THE FIRST WEEK OF JUNE.

SST`S ARE ALREADY GENERALLY SEVERAL DEGREES ABOVE NORMAL. IF WE
ADVANCE INTO A HOT SPELL BY THE END OF NEXT WEEK...WE DO NOT WANT
A REPEAT OF LAST YEAR WHEN HOT WEATHER...WARMER THAN NORMAL WATERS AND
SEEMINGLY BENIGN OCEAN SWELLS ENCOURAGED SWIMMERS TO TAKE UNNECESSARY
RISKS AT EARLY SEASON "UNGUARDED" BEACHES WITH RIP CURRENT RELATED
DROWNINGS. THE DANGERS OF RIP CURRENTS ARE WORTHY OF A FEW MINUTES
OF DINNER TABLE DISCUSSION...ESPECIALLY SINCE THERE IS ACCESS TO
THE BEACHES FOR MILLIONS OF SWIMMERS OVER INTERIOR SECTIONS OF OUR
AREA WHO MAY BE LESS EXPERIENCED WITH THE DANGERS OF OCEAN SWIMMING.

THE CHANCES OF DROWNING AT A LIFE GUARDED BEACH IS 1 IN 18 MILLION.

RIP CURRENT AWARENESS WEEK IS JUNE 2 THROUGH 8.

&&

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

&&

$$
SYNOPSIS...NIERENBERG
NEAR TERM...DRAG  940
SHORT TERM...DRAG/O`HARA 940
LONG TERM...NIERENBERG
AVIATION...DRAG/NIERENBERG 940
MARINE...DRAG/NIERENBERG/O`HARA 940
CLIMATE...940