Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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401
FXUS61 KPHI 210737
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
337 AM EDT THU MAY 21 2015

.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL TRACK SOUTH AND EAST OF OUR REGION LATE
TODAY AND TONIGHT, THEN A COLD FRONT CROSSES OUR AREA LATER FRIDAY.
HIGH PRESSURE BUILDS IN SATURDAY BUT THEN SHIFTS OFFSHORE SATURDAY
NIGHT AND SUNDAY. THE NEXT COLD FRONT DROPS INTO OUR AREA SUNDAY
NIGHT INTO MONDAY, THEN AS LOW PRESSURE TRACKS FROM THE PLAINS TO
THE GREAT LAKES REGION THE FRONT LIFTS BACK NORTH AS A WARM FRONT
LATE MONDAY INTO TUESDAY. A COLD FRONT IS FORECAST TO REMAIN WELL TO
OUR WEST DURING WEDNESDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
TODAY...HPC QPF AND 00Z/21 MODEL CONSENSUS HAS THE NORTHERN EDGE
OF THE MEASURABLE RAIN TODAY NEAR I-95. THIS 330AM FORECAST THEN
TAKES INTO ACCOUNT THE HRRR AS WELL AS THE NARRE THROUGH THIS
MORNING. CONFIDENCE ON TEMPS/POPS IS BELOW AVERAGE FROM SE PA
ACROSS CENTRAL NJ WHERE GREATEST UNCERTAINTY EXISTS (KPHL-KTTN).

NO RAIN IS EXPECTED IN NE PA AND NNJ TODAY.

LIGHT WIND WILL BE N-NE THIS MORNING THEN THIS AFTN BECOMES LIGHT
SOUTH IN THE NORTH AND REMAINING E-NE ACROSS ACROSS THE SOUTH.

WARMEST TEMPS MAY BE IN NNJ TODAY WHERE NO RAIN IS FCST.

FCST BASED ON A GENERAL 50 50 BLEND OF 00Z/21 NAM/GFS MOS.

CAUSE OF THE RAIN AND CLOUD COVER: INSTABILITY BURST WITH SLY FLOW
WAA AHEAD OF A RELATIVELY STRONG 500MB SHORT WAVE MOVING ESEWD
FROM THE MIDWEST THIS MORNING AND ARRIVING IN THE UPPER OHIO
VALLEY THIS EVENING.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
LEFTOVER RAIN ALONG THE COAST AND A CHANCE OF A PERIOD OF RAIN
ELSEWHERE EARLY, THEN CLEARING TOWARD DAWN AS THE RELATIVELY STRONG
500MB SHORT WAVE SEEN AS AN -80M 12 HR HFC PASSES THROUGH E PA
REACHING LI BY DAYBREAK FRIDAY.

PATCHY FOG POSSIBLE TOWARD DAWN IF IT CLEARS FAST ENOUGH AND IT
REMAINS DECOUPLED THROUGH THE NIGHT.

LIGHT WIND TREND W-NW OVERNIGHT.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
THE SYNOPTIC SETUP IS COMPRISED OF A CLOSED LOW ACROSS EASTERN
CANADA THAT SHIFTS EASTWARD FRIDAY AND OVER THE WEEKEND AS ENERGY
STARTS TO EJECT INTO THE CENTRAL AND SOUTHERN PLAINS. THE LATTER
WILL TEND TO BUILD A RIDGE FROM NEAR FLORIDA NORTHWESTWARD TOWARD
THE MIDWEST SATURDAY INTO MONDAY. THE RIDGE THEN STRENGTHENS SOME AS
IT SHIFTS EASTWARD MONDAY AND TUESDAY, HOWEVER IT SHOULD FLATTEN
SOME ON ITS NORTHERN SIDE. THE MAIN FEATURE OF INTEREST IS A COLD
FRONT THAT DROPS DOWN LATE SUNDAY INTO MONDAY, BUT THEN IT LIFTS
BACK NORTH AS A WARM FRONT AS THE RIDGE BUILDS. IT LOOKS TO TURN
RATHER WARM TO EVEN HOT NEXT WEEK AS THE UPPER-LEVEL RIDGE IS IN
PLACE. WE USED A MODEL BLEND FOR FRIDAY THROUGH SUNDAY, THEN THE 00Z
WPC GUIDANCE WITH CONTINUITY THEREAFTER. SOME TWEAKS WERE THEN MADE
FOLLOWING ADDITIONAL COLLABORATION WITH OUR NEIGHBORING OFFICES.

FOR FRIDAY AND SATURDAY...THE CLOSED LOW TO OUR NORTH IS FORECAST TO
BE SHIFTING EASTWARD DURING THIS TIME FRAME AS ENERGY EJECTS INTO
THE CENTRAL AND SOUTHERN PLAINS. THIS WILL TAKE SURFACE LOW PRESSURE
INTO THE CANADIAN MARITIMES FRIDAY AND A COLD FRONT THROUGH OUR AREA
LATE IN THE DAY. WHILE THERE IS SOME INCREASE IN MOISTURE AHEAD OF
THE FRONT AND ALSO SOME LOWER LEVEL INSTABILITY FORECAST, THE DEEP
WESTERLY FLOW SHOULD TEND TO LIMIT THE CONVERGENCE. WHILE SOME
ISOLATED SHOWERS CANNOT BE RULED OUT, WE OPTED TO KEEP THE FORECAST
FRIDAY DRY ATTM. THE PRESSURE GRADIENT TIGHTENS WITH BREEZY
CONDITIONS DURING FRIDAY, THEN THIS GRADUALLY RELAXES LATER FRIDAY
NIGHT AND SATURDAY AS SURFACE HIGH PRESSURE MOVES IN. A MUCH DRIER
AIRMASS FOLLOWS THE FRONT, AND THIS WILL SET THE STAGE FOR A CHILLY
FRIDAY NIGHT AND EARLY SATURDAY. THERE COULD BE SOME FROST FORMATION
EARLY SATURDAY MORNING ACROSS PORTIONS OF THE NORTHERN ZONES,
PENDING WE DECOUPLE. FOR NOW, WE INCLUDED A PATCHY FROST MENTION.
HIGH PRESSURE THEN BEGINS TO SHIFT OFFSHORE SATURDAY NIGHT AS
RIDGING BUILDS TO OUR WEST.

FOR SUNDAY AND MONDAY...A RIDGE TO OUR WEST WILL GRADUALLY BUILD
EASTWARD. SOME ENERGY SLIDING SOUTHEASTWARD ACROSS NEW ENGLAND WILL
DROP A COLD FRONT INTO OUR AREA SUNDAY NIGHT AND MONDAY. THIS
FEATURE GENERALLY LOOKS TO BE ON THE WEAK SIDE, AND THERE IS SOME
GUIDANCE THAT HOLDS THIS FRONT FARTHER TO THE NORTH IN THE FORM OF A
WARM FRONT. THE FRONT DOES NOT LOOK TO STAY IN PLACE LONG AS THE
BUILDING RIDGE ALOFT ALONG WITH SURFACE HIGH PRESSURE TO OUR EAST
WILL HELP REINFORCE A SOUTHWESTERLY FLOW. THEREFORE THE BOUNDARY
SHOULD MOVE NORTH AS A WARM FRONT DURING MONDAY AND MONDAY NIGHT.
THERE MAY BE SOME CONVECTION RIDING ALONG OR NEAR THIS FRONT,
HOWEVER THIS MAY NOT BE UNTIL LATE MONDAY AS THE RIDGE AXIS MOVES
ACROSS. A WARMER AIRMASS SHOULD OVERSPREAD THE AREA ESPECIALLY
MONDAY AS AN EXPANDING WARM SECTOR MOVES NORTH, AND SOME INCREASE IN
THE DEW POINTS WILL ALSO OCCUR.

FOR TUESDAY AND WEDNESDAY...WE SHOULD BE IN THE WARM SECTOR DURING
THIS TIME FRAME AS A SHORT WAVE ALOFT AND SURFACE LOW TRACKS TO OUR
NORTH, WHICH WILL FLATTEN THE RIDGE SOME. WHILE THE SURFACE COLD
FRONT IS CURRENTLY FORECAST TO STAY TO OUR WEST, SOME CONVECTION
CANNOT BE RULED OUT AS THERE ARE SOME INDICATIONS OF A LEE SIDE
TROUGH DEVELOPING IN THE PRESENCE OF A WARM TO HOT AIRMASS ALONG
WITH AN INCREASE IN THE HUMIDITY. SOME PLACES HAVE A GOOD CHC OF
REACHING 90 DEGREES EACH AFTERNOON.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

THROUGH 12Z...VFR. AREAS OF CIGS AOA 20000 FT LOWER TO NEAR 10000
FT AT 12Z. WIND NNW BECOMING NNE WITH GUSTS 10-15 KT FROM THE I-95
CORRIDOR EASTWARD INCLUDING KPHL GROUP OF TAFS.

AFTER 12Z TODAY...VFR CIGS. LIGHT RAIN IS FORECAST TO SPREAD INTO
OUR REGION FROM THE WEST AND SOUTHWEST AROUND 1500Z. THE RAIN IS
EXPECTED TO REMAIN SOUTH OF KRDG AND KABE. A PERIOD OF LIGHT RAIN
IS ANTICIPATED FOR KILG, KPHL, KPNE AND KTTN DURING THE AFTN WITH
THE CATEGORICAL RAIN PROBABILITY RESTRICTED TO KILG. CONDITIONS
SHOULD REMAIN IN THE VFR CATEGORY AT THOSE LOCATIONS WITH CEILINGS
STAYING ABOVE 3000 FEET AND VISIBILITY VALUES STAYING ABOVE 5
MILES.

THE RAIN IS FORECAST TO HAVE A GREATER IMPACT ON KMIV AND KACY
THAN ON OUR TAF SITES TO THE NORTH. CONDITIONS MAY DROP TO MVFR AT
KMIV AND KACY THIS THURSDAY AFTERNOON.

AFTER THIS MORNINGS LIGHT NE WIND TO START, A LIGHT SOUTHWEST
WIND MAY DEVELOP AT KRDG, KABE, KTTN, KPNE, KPHL AND KILG DURING
MIDDAY. THE WIND MAY REMAIN VARIABLE AT KMIV AND KACY OR IT COULD
RESETTLE INTO THE NORTHEAST OR EAST DURING THE AFTERNOON HOURS AT
THOSE LOCATIONS.

TONIGHT...MOSTLY VFR CIGS; ALTHOUGH, SOME LINGERING RAIN/SHWRS
MAY MEAN SOME SUB-VFR THROUGH THE FIRST PART OF THE NIGHT MAINLY
FROM AROUND KMIV/KACY AND SOUTH. LIGHT WIND TREND W-NW OVERNIGHT.

OUTLOOK...
FRIDAY...VFR OVERALL. A COLD FRONT MOVES THROUGH LATER IN THE DAY
WITH PERHAPS AN ISOLATED BRIEF SHOWER. WEST WINDS BECOMING NORTHWEST
AND GUSTING UP TO 25 KNOTS MAINLY DURING THE AFTERNOON AND EVENING,
THEN DIMINISHING.

SATURDAY...VFR. NORTHWEST WINDS AROUND 10 KNOTS.

SUNDAY...VFR. SOUTHWEST WINDS 10 TO 15 KNOTS, THEN TENDING TO BECOME
LIGHT AND VARIABLE AT NIGHT AS A FRONT DROPS NEAR OR INTO THE AREA.

MONDAY...MAINLY VFR. LIGHT AND VARIABLE WINDS BECOMING SOUTHWEST
AROUND 10 KNOTS. A FEW SHOWERS AND THUNDERSTORMS ARE POSSIBLE
ESPECIALLY IN THE AFTERNOON.

&&

.MARINE...
SAFE BOATING WEEK CONTINUES THROUGH FRIDAY MORNING.

THERE IS A NEW USCG SAFETY APP THAT SHOULD BE OF VALUE TO
MARINERS AND WAS JUST UNVEILED THIS WEEK:

HTTP:/WWW.USCG.MIL/MOBILE

THIS APP PROVIDES ADDITIONAL SAFE BOATING RESOURCES FOR MOBILE DEVICE
USERS. WHEN LOCATION ENABLED, USERS CAN RECEIVE THE LATEST WEATHER
REPORTS FROM THE CLOSEST NOAA BUOY AS WELL AS REPORT THE LOCATION
OF A HAZARD ON THE WATER. IT FEATURES AN EMERGENCY ASSISTANCE
BUTTON, WHICH CAN CALL THE CLOSEST CG COMMAND CENTER.

THE FORECAST:

ISSUING SCA FOR THE DE BAY ATLC WATERS TONIGHT. NCAROLINA LOW
INTENSIFIES IN ITS DEPARTURE AND SHOULD DEVELOP MARGINAL 5 FT
HAZARDOUS SEAS AND A FEW SCA GUSTS AROUND 25 KT OVERNIGHT NEAR
44009.

OTHERWISE NO MARINE HEADLINE ANTICIPATED THROUGH TONIGHT.

NORTHERLY WINDS EARLY TODAY TEND NORTHEAST NORTHEAST-EAST BY
DAYBREAK THEN ONSHORE SOUTHEAST THIS AFTERNOON. WINDS EVENTUALLY BECOMING
NORTHWEST EVERYWHERE LATER THIS THURSDAY NIGHT.

OUTLOOK...
FRIDAY...A COLD FRONT MOVES THROUGH THE AREA LATE IN THE DAY AND THE
EVENING AS LOW PRESSURE MOVES AWAY, WITH A NORTHWEST WIND IN ITS
WAKE. PRIOR TO THIS, SOME GUSTS TO NEAR 25 KNOTS SHOULD LINGER
ACROSS THE FAR SOUTHERN COASTAL WATERS EARLY. THE FORECAST SOUNDINGS
SHOW BETTER MIXING MOSTLY NEARSHORE DURING THE DAY, THEN EXPANDING
TO OFFSHORE AT NIGHT AS COLDER AIR MOVES IN AND THEREFORE A SMALL
CRAFT ADVISORY MAY BE NEEDED FOR LATER FRIDAY NIGHT.

SATURDAY AND SUNDAY...NORTHWEST WIND GUSTS TO 25 KNOTS MAY OCCUR TO
START SATURDAY, OTHERWISE THE CONDITIONS SHOULD BE BELOW ADVISORY
CRITERIA.

MONDAY...A SOUTHWESTERLY FLOW IS ANTICIPATED TO INCREASE SOME,
HOWEVER THE CONDITIONS OVERALL SHOULD BE BELOW ADVISORY CRITERIA.
SOME SHOWERS AND THUNDERSTORMS ARE POSSIBLE.

&&

.FIRE WEATHER...
FOR FRIDAY AFTERNOON, THERE MAY BE THE RISK FOR ENHANCED WILDFIRE
SPREAD AS WEST-NORTHWEST WINDS GUST TO 20-25 MPH AT TIMES. IN
ADDITION, THIS WILL COMBINE WITH RELATIVE HUMIDITY VALUES DROPPING
TO AROUND 30 PERCENT IN SOME AREAS ALONG WITH DRY FINE FUELS. THIS
WILL DEPEND ON HOW MUCH WETTING OCCURS LATER TODAY ESPECIALLY ACROSS
THE SOUTHERN AREAS.

&&

.RIP CURRENTS...
SST`S ABOVE NORMAL AND JUST OFF THE COAST SSTS WELL ABOVE NORMAL
BY ALMOST 3C. THIS IS NOT GOOD ONCE IT TURNS HOT AND BEACHES ARE
UNGUARDED, SWIMMERS MAY TAKE CHANCES AT UNGUARDED LOCATIONS. BE
SMART ABOUT ANY SWIMMING EARLY THIS SEASON. ATLANTIC COASTAL WATER
TEMPS ARE WARMING --UPPER 50S TO MID 60S.

RIP CURRENT AWARENESS WEEK FOR MT HOLLY IS JUNE 7-13 WITH PSAS
VIA PUBLIC INFORMATION STATEMENTS, SOCIAL MEDIA, NOAA WEATHER
RADIO AND ANY MEDIA INTERVIEWS DESIRED (CONTACT OFFICE).

FOR RIP CURRENTS: DESPITE ANTICIPATED PROJECTIONS OF LOW OR
MODERATE RISK THROUGH THE MEMORIAL DAY WEEKEND, EARLY SEASON
FATALITIES OCCUR WHEN SWIMMING AT UNGUARDED TIMES/LOCATIONS.
WEAKER SWIMMERS OR SWIMMING IN AREAS WHERE RIP CURRENTS ARE
STRONGER (JETTIES) CAN QUICKLY BECOME LIFE THREATENING. WHEN
TRAINED LIFEGUARDS ARE NOT NEARBY, TIMELY RESCUE IS MUCH LESS
LIKELY. LETS GET THROUGH THE MONTH OF MAY WITH ALL SWIMMERS SAFE!
SWIM IN THE PRESENCE OF LIFE GUARDS! THANK YOU.

&&

.CLIMATE...
**TOP 10 WARMEST MAY CONTINUES LIKELY IN PORTIONS OF THE FORECAST
 AREA**

THE FIRST 19 DAYS OF MAY IN OUR FORECAST AREA WERE AVERAGING WITHIN
ABOUT 1/2 DEGREE OF 7 DEGREES ABOVE NORMAL.

BASED ON THE ENSEMBLE AND A FORECAST THAT IS DETERMINISTICALLY
CONSERVATIVE INCLUDING OUR 330 PM MAY 20 PROJECTIONS THROUGH THE
27TH AND THEN THE 00Z/21 CONSERVATIVE FTPRHA THEREAFTER THROUGH
THE 31ST...EASILY OUTLOOKS A TOP 10 WARMEST MAY ON RECORD.

FOR PHILADELPHIA...PERIOD OF RECORD BACK TO 1874. PROJECTING AN
AVG TEMP OF 68.7 TO 69.3 OR AROUND 5 DEGREES ABOVE NORMAL AND AT
THE LEAST, 3RD WARMEST ON RECORD. WARMEST WAS 70.8 IN 1991. THEN
69.2 2004.

FOR ALLENTOWN...POR TO 1922. YESTERDAY WE WERE PROJECTING 65.0 OR
5.1 DEGREES ABOVE NORMAL AND 8TH WARMEST ON RECORD. WARMEST WAS
67.2 IN 1991.

POSTED BECAUSE WE`RE EXPECTING OUR FIRST 90 IN PHILADELPHIA BY THE
MIDDLE OF NEXT WEEK.

NORMAL FIRST DATE OF 90 OR HIGHER.

PHILADELPHIA MAY 29
ALLENTOWN MAY 30
WILMINGTON JUNE 4
ATLANTIC CITY JUNE 11.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 8 AM EDT
     FRIDAY FOR ANZ455.

&&

$$
SYNOPSIS...GORSE
NEAR TERM...DRAG
SHORT TERM...DRAG
LONG TERM...GORSE
AVIATION...DRAG/GORSE
MARINE...DRAG/GORSE
FIRE WEATHER...GORSE
RIP CURRENTS...DRAG
CLIMATE...DRAG



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