NWS Philadelphia/Mount Holly wrote its last area forecast discussion before the first event at Oct 15, 9:16 AM EST, 4 hours 44 minutes earlier.
Area forecast discussion, Oct 15, 9:16 AM EST, 4 hours 44 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1016 AM EDT THU OCT 15 2009
.SYNOPSIS...
LOW PRESSURE IS FORECAST TO DEVELOP OFF THE SOUTHEAST U.S. COAST
THIS MORNING AND INTENSIFY AS IT MOVES NORTHEASTWARD ALONG THE COAST
THIS AFTERNOON AND TONIGHT. THE LOW WILL MOVE NORTHEAST OF OUR AREA
OVERNIGHT AND FRIDAY. ANOTHER COASTAL LOW PRESSURE SYSTEM IS
EXPECTED TO AFFECT OUR AREA DURING THE WEEKEND. HIGH PRESSURE WILL
BUILD GRADUALLY ACROSS THE MID ATLANTIC REGION EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
BIG CHANGES ARE COMING TO OUR AREA TODAY AS A COASTAL LOW...A
NOR/EASTER...INTENSIFIES ON ITS NORTH-NORTHEASTWARD TREK TODAY.
LOTS OF EFFECTS FOR OUR AREA ARE ON TAP...INCLUDING WIND...
RAIN...SNOW FAR NORTH...AND POSSIBLE COASTAL FLOODING. SEE ALL THE
APPROPRIATE ASSOCIATED PRODUCTS WHICH HAVE BEEN ISSUED.
FIRST...PRECIPITATION OVER THE NORTH: THE NAM SEEMED TO INITIALIZE
TOO COOL WITH THE 00Z RUN. SURFACE TEMPERATURES AND THERMAL
PROFILES WERE TUNED MORE TO GFS MODEL OUTPUT FOR A SOLUTION, OR,
IN A FEW INSTANCES A SLIGHT HEDGE TOWARD THE NAM WAS USED.
1000-850 THICKNESSES AROUND 1300 METERS...OR BETWEEN 1300 AND
1305...SHOWED MORE CONSISTENCY BETWEEN THE NAM AND THE GFS THIS
MORNING, BUT OVERALL THE NAM WAS SLIGHTLY COOLER, AND PERHAPS A
BIT TOO COOL. EVEN SO, EVAPORATIVE COOLING IS EXPECTED TO TURN
RAIN TO WET SNOW OVER THE HIGHER ELEVATIONS...ESSENTIALLY ABOVE
1000 FEET...LATER THIS AFTERNOON AND TONIGHT, AND PERHAPS INTO
FRIDAY AS WELL AS THE STORM STARTS TO PULL AWAY. WITH EXPECTED
QPF OF A QUARTER TO A HALF INCH, THE FIRST GUESS OF 1 TO 4 INCHES
WAS CONTINUED. WITH THESE AMOUNTS, MAINLY OVER THE HIGHER
ELEVATIONS OF CARBON AND MONROE IN PENNSYLVANIA AND SUSSEX IN NEW JERSEY,
A WINTER WEATHER ADVISORY WAS ISSUED FOR THIS MORNING THROUGH FRIDAY
MORNING.
SECOND...WINDS WILL BE A CONCERN NEAR THE COAST WITH THE
DEVELOPING STRONG GRADIENT. WINDS WILL BEGIN TO RAMP UP LATER
THIS AFTERNOON AS THE STORM NEARS OUR LATITUDE. GFS AND NAM 925
HPA WINDS WERE BOTH A BIT LESS THAN YESTERDAY...BUT STILL SHOWED
45 KNOTS AT TIMES ALONG THE COAST. THE GRADIENT SEEMED TO BE
TIGHTEST OVER CENTRAL PORTIONS OF OUR AREA...SO A WIND ADVISORY WAS
CONTINUED FOR THE NEXT TIER OF ZONES INLAND, AND EXTENDED TO THE
FAR SOUTH AND FAR NORTH COASTAL STRIP ZONES. IN BETWEEN, THE HIGH
WIND WATCH WAS UPGRADED TO A HIGH WIND WARNING. THE REASONING USED
WAS THAT, IF WINDS CAN STRETCH A COUPLE MORE KNOTS, THEN WED BE
IN WARNING TERRITORY. ALSO, WITH LEAVES STILL ON TREES, THERE
WILL BE A LOT OF WIND LOADING, SO ANY DOWNED TREES AND LIMBS ARE
MORE LIKELY ALONG THE SOUTHERN AND CENTRAL NEW JERSEY COASTAL
ZONES.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
THE TONIGHT PERIOD WILL BE THE TIME OF MOST CONCERN FOR THE
WEATHER, WITH WIDESPREAD PRECIPITATION, WINDS EAST, POSSIBLE
COASTAL FLOODING, AND SNOW NORTH. AGAIN, GFS OUTPUT WAS PREFERRED.
SEE DETAILS IN THE PRECEDING SECTION.
THIS FIRST STORM WILL BE MOVING OFF TO THE NORTHEAST LATER FRIDAY
INTO FRIDAY NIGHT. PRECIPITATION WILL BECOME LIGHTER AND MORE
INTERMITTENT BUT IS NOT FORECAST TO END COMPLETELY, AS YET
ANOTHER COASTAL LOW WILL BEGIN TO DEVELOP AND IS EXPECTED TO
AFFECT OUR AREA MAINLY IN THE LONG TERM PERIOD.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
THE BEGINNING OF THIS PERIOD LOOKS TO START OFF RATHER ACTIVE AS IT
CONTINUES FROM THE SHORT TERM. A LARGE UPPER-LEVEL TROUGH IS
FORECAST TO CONTINUE TO AMPLIFY ACROSS THE EAST. A STRONG PACIFIC
JET IS FORECAST TO BE MOVING THROUGH THE PACIFIC NORTHWEST AND
SOUTHWESTERN CANADA WITH A DOWNSTREAM RIDGE BUILDING. THIS FORCES
THE EASTERN INCOMING TROUGH TO AMPLIFY SOME MORE. AS THIS OCCURS,
SHORT WAVE ENERGY MOVING THROUGH THE TROUGH ALONG WITH A STRONG
UPPER-LEVEL JET AND TIGHTENING BAROCLINICITY OFF THE MID ATLANTIC
COAST SHOULD ALLOW ANOTHER COASTAL STORM TO DEVELOP. THIS MOSTLY
APPEARS TO BE SEPARATE ENERGY FROM THE SHORT TERM SINCE THE
UPPER-LEVEL TROUGH WILL BE TRENDING MUCH MORE AMPLIFIED OVER THE
WEEKEND. THE TIMING AND EXTENT OF THE PRECIPITATION IS IN QUESTION
OVER THE WEEKEND GIVEN THE VARYING MODEL GUIDANCE AND EVEN ENSEMBLE
MEMBERS. WE TRENDED TOWARD HPC GUIDANCE /WHICH WENT MORE TOWARD THE
ECMWF ENSEMBLE MEAN/, ALTHOUGH DID BLEND IN SOME OF CONTINUITY GIVEN
THE UNCERTAINTY.
THE FIRST PIECE OF ENERGY LOOKS TO MOVE AWAY EARLY SATURDAY,
HOWEVER A SURFACE TROUGH MAY BE IN PLACE TO KEEP SOME
PRECIPITATION AROUND. THE NEXT COASTAL LOW IS THEN FORECAST TO
ORGANIZE AND STRENGTHEN AS IT MOVES NORTH AND NORTHEASTWARD
SATURDAY INTO SUNDAY. BASED ON THE HPC PRESSURES/FRONTS GRAPHICS,
THIS SYSTEM PULLS AWAY BY EARLY MONDAY MORNING AS HIGH PRESSURE
BUILDS TOWARD OUR AREA FROM THE OHIO VALLEY. THE GFS IS MUCH
SLOWER IN MOVING THIS SYSTEM OUT AS THE UPPER-LEVEL TROUGH TURNS
INTO A MORE PRONOUNCED CLOSED LOW. THE ECMWF IS NOT AS CLOSED OFF
AND LOOKS FARTHER EAST AND SLOWER WITH THE SURFACE LOW
STRENGTHENING SUNDAY NIGHT INTO MONDAY. FOR NOW, A BLENDED
APPROACH WAS USED WITH THE POPS UTILIZING MOSTLY EVEN WEIGHTING OF
CONTINUITY AND HPC GUIDANCE. THIS KEPT POPS NO HIGHER THAN LIKELY
AT THIS TIME. BASED ON SOME FORECAST SOUNDINGS, WE WENT WITH A
RAIN/SNOW MIX FOR THE FAR NORTHWEST ZONES. THIS COULD END UP
BEING MORE ELEVATION DEPENDENT, UNLESS THE PRECIPITATION IS HEAVY
ENOUGH WHERE IT COOLS THE ENTIRE COLUMN ENOUGH TO ALLOW A COMPLETE
CHANGE TO WET SNOW. THE GFS SOUNDINGS FOR THE POCONOS WOULD
SUGGEST A WET SNOW POTENTIAL SATURDAY MORNING, THEN A WARM SURGE
GETS GOING AROUND 850 MB THROUGH MOST OF SUNDAY. GIVEN THE
UNCERTAINTY, WE WENT WITH A RAIN/SNOW MIX.
HIGH PRESSURE THEN LOOKS TO SETTLE ACROSS OUR AREA DURING THE
EARLY TO MIDDLE PORTION OF NEXT WEEK. A COLD FRONT MAY BE LURKING
TO OUR NORTHWEST ON WEDNESDAY, BUT FOR NOW THE MID LEVEL RIDGE MAY
TEND TO KEEP THAT TO OUR NORTH SO A DRY FORECAST WAS CARRIED.
&&
.AVIATION /14Z THURSDAY THROUGH MONDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
EXCELLENT DETAIL ON THE AVIATION WEATHER PAGE SHOWING FLIGHT
CATEGORIES. OUR TAFS STILL VFR BUT SOME LIGHT RAIN IS MAKING ITS
WAS EAST AND NORTH. GOOD PART NOT REACHING THE GROUND ATTM. AS
MENTIONED LAST EVENING... A CONCERN WITH MIXED PRECIPITATION IN THE
NORTHERN AREAS WITH SOME ICING CONCERNS.
BELOW IS THE FORECAST ICING LEVELS AND RH AT THAT LEVEL..
STA 15/12 15/18 16/00 16/06 16/12 16/18 17/00 17/06 17/12
BOS 02290 02290 02395 02495 02695 02495 02295 02690 02990
LGA 03790 03495 02695 06895 05395 03895 03395 06795 04295
PHL 04290 05695 08795 08495 08395 08195 08295 08595 08195
IPT 02270 01695 01495 01295 01595 01595 01895 01695 01295
AS OF 3 AM HERE IS SOME VWP DOPPLER RADAR PROFILE DATE...
KCCX-SE WIND 20 KT 1,000 FT VEERING AROUND TO SW 15KT AT 7,000 FT
WITH CLDS TOPPING OFF AROUND 14,000 FT.
KDIX-NNE WIND 15 KT FROM 1-4,000 FT BACKING TO SW THEN W 30 KT AT
14,000 FT.
KDOV - NE WIND 20 KT BACK TO SW 20 KT AT 5,000 FT AND WSW 11,000 FT.
TPHL - NE WIND 20 KT TO 2,000 FT BACK TO SOUTH AT 4,000 FT THEN WSW
30 KT AT 12,000 FT.
KAKQ - NE WINDS 15 KT AT 1,000 FT VEERING SE THEN BACKING TO S 15 KT
AT 5,000 FT THEN WSW UP THROUGH 16,000 FT AT 30 KT.
SYSTEM WILL AFFECT ALL TAF SITES AND LIKELY TO BE A 48 HOUR ISSUE.
STRONGEST WINDS WILL BE IN NJ/DE WITH SOME GUSTS APPROACHING 45 KT
PERHAPS AT ACY/MIV. OTHERWISE SOME GUSTS INTO THE 20 TO NEAR 30
RANGE BACK TOWARDS PHL.
OUTLOOK...
MVFR TO IFR CONDITIONS TO CONTINUE THROUGH THE WEEKEND WITH THE
FIRST REAL GOOD SUPER VFR DAYS NOT UNTIL MONDAY AND TUESDAY.
&&
.MARINE...
PRESENT CONDITIONS AT BUOY 44009-WIND FROM 100 DEGREES AT 10-14 KTS.
FORECAST CALLS FOR AT LEAST 12 FT SEAS BY LATE TONIGHT AND GALE
FORCE WINDS. TEXAS TOWER BUOY AT 2 THIS MORNING REPORTING A 100
DEGREE WIND WITH 2 TO 4 KT AND 2 FT SEA. FORECAST IS FOR AT LEAST 13
FT BY 10 AM FRI. BUOYS INSIDE DELAWARE BAY ARE 1 TO 2 FT BUT
EXPECTING NEAR 5 AND 6 FT ACROSS THE LOWER BAY TONIGHT.
WITH THAT SAID...A VERY STORY PERIOD BEGINNING THIS AFTERNOON AS A
COASTAL LOW MOVES NORTH FROM THE CAROLINAS AND NORTHEAST OUT TO SEA
BY FRIDAY AFTERNOON. THIS LOWS CLOSEST POINT OF APPROACH WILL BE
155 MILES SOUTHEAST BY 8 PM FROM FENWICK ISLAND DE THEN 340
MILES EAST BY FRIDAY MORNING. ANOTHER MODEL HAS IT 125 MILES
SOUTHEAST 8 PM AND 450 MILES AWAY FROM 8 AM FRIDAY.
THE CLOSENESS WILL HAVE AN IMPACT ON THE WIND BUT THE TIDE WILL RISE
AS WE CONTINUE WITH AN EXTENDED LONG PERIOD FETCH.
SMALL CRAFT ARE UP AND GALE WATCHES FLYING ALONG THE ENTIRE MID
ATLANTIC REGION. SO IT IS NOT SAFE TO VENTURE TO FAR OFF SHORE AFTER
MID DAY TODAY. FORECAST FROM THE OCEAN PREDICTION CENTER RAISED
GALES FOR THE CANYON AREAS. THE FIRST LOW IS EXPECTED TO BE WELL
OFFSHORE ON FRIDAY BUT A SECONDARY ONE IS GOING TO FORM SOMETIME
SATURDAY AND KEEP THE WIND GRADIENT HIGH ENOUGH TO HAVE AT LEAST
HIGH END SMALL CRAFT ADVISORIES OR GALE WARNINGS IN EFFECT.
THE FORECAST FOR THE DELAWARE 44009 BUOY MAXS OUT AROUND 14 FEET
BUT I WOULDNT BEEN SURPRISED AT ALL TO SEE 20 FEET WITH THE
EXTENDED FETCH...INTO SUNDAY WITH THE NEXT STORM ADDING WAVES ON
TOP WITH NO REAL STRONG HIGH PRESSURE.
NO REAL IMPROVEMENT IN THE PICTURE UNTIL MONDAY AND TUESDAY AS THE
LOWS EXIT THE WESTERN BOUNDARY OF THE ATLANTIC AND HIGH PRESSURE
REACHES THE MID ATLANTIC COAST.
TO SEE THE WIND FIELD AROUND THE DEVELOPING COASTAL LOW GO TO ANY
BUOY PAGE AND BEFORE GOING DOWN TO THE CONDITIONS CLICK ON LATEST
SATELLITE WIND MAP FOR THIS AREA.
&&
.TIDES/COASTAL FLOODING...
THE UPCOMING WEATHER EVENT IS TRULY MARINE IN ALL FACETS WITH
INCREASING GALE FORCE WINDS...BUILDING SEAS AND TIDAL FLOODING. WE
HAVE HAD SOME STRONG STORMS IN OCT PAST FEW YEARS BUT NOTHING STRONGER
THAN HURRICANE WILMA IN 2005 WHEN SHE RODE UP THE EASTERN SEABOARD.
WILMA PRODUCED 22 FT SEAS AT BUOY 44009 A RECORD THAT STANDS FOR
OCTOBER. WE MONITOR THE OFFSHORE WAVE FORECAST SINCE IT IMPACTS
THE COASTLINE AS THE WATER APPROACHES THE COAST AND KEEPS THE BACK
BAYS FROM DRAINING AND BREAKING WAVES ON THE BEACH BRINGING BEACH
EROSION.
REGARDING TIDAL FLOODING, THE EAST TO NORTHEAST FLOW HAS BEGUN TO
STRENGTHEN ENOUGH TO CAUSE A GENERAL INCREASE IN DEPARTURES,
ESPECIALLY SOUTH OF THE NORTHERN NEW JERSEY COASTLINE.
CONSERVATIVE SSE GUIDANCE TAKES ALL SITES ALONG THE COAST AND
DELAWARE BAY TO WITHIN ABOUT A HALF-FOOT OF THE LEVEL NEEDED FOR
MINOR TIDAL FLOODING THIS EVENING, AND IT IS LAGGING ABOUT A HALF-
FOOT BEHIND PRESENT DEPARTURES. WE HAVE ISSUED AN ADVISORY FOR
THIS EVENINGS HIGH TIDE FROM OCEAN COUNTY SOUTH ALONG THE COAST
AND FOR DELAWARE BAY.
OTHERWISE, THE COASTAL FLOOD WATCH REMAINS IN EFFECT AND THAT
COULD BE RAISED TO A WARNING WITHIN THE NEXT 6 TO 8 HOURS. THE
CONCERN IS THAT DEPARTURES STARTING WITH TOMORROWS HIGH TIDES
COULD RUN UP TO 2 FT OR ABOVE AND THAT WOULD PLACE US IN MODERATE
LEVELS. AS MENTIONED, THE BUILDING SEAS, ANY HEAVY RAINFALL AT
TIME OF HIGH TIDE AND THE APPROACHING NEW MOON WILL ALL COMBINE TO
RAISE THE TIDE LEVELS HIGHER.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...WINTER WEATHER ADVISORY UNTIL 8 AM EDT FRIDAY FOR PAZ054-055.
NJ...HIGH WIND WARNING FROM 8 PM THIS EVENING TO 6 AM EDT FRIDAY
FOR NJZ025-026.
COASTAL FLOOD WATCH FROM LATE TONIGHT THROUGH FRIDAY EVENING
FOR NJZ012>014-020>027.
COASTAL FLOOD ADVISORY FROM 5 PM THIS AFTERNOON TO 11 PM EDT
THIS EVENING FOR NJZ020>027.
WIND ADVISORY FROM 5 PM THIS AFTERNOON TO 10 AM EDT FRIDAY FOR
NJZ013-014-020-022-023-027.
HIGH WIND WARNING FROM 5 PM THIS AFTERNOON TO 6 AM EDT FRIDAY
FOR NJZ024.
WINTER WEATHER ADVISORY UNTIL 8 AM EDT FRIDAY FOR NJZ001.
DE...COASTAL FLOOD WATCH FROM LATE TONIGHT THROUGH FRIDAY EVENING
FOR DEZ002>004.
COASTAL FLOOD ADVISORY FROM 5 PM THIS AFTERNOON TO 11 PM EDT
THIS EVENING FOR DEZ002>004.
WIND ADVISORY FROM 5 PM THIS AFTERNOON TO 10 AM EDT FRIDAY FOR
DEZ003-004.
MD...NONE.
MARINE...GALE WARNING UNTIL MIDNIGHT EDT FRIDAY NIGHT FOR ANZ430-431-
450>455.
&&
SYNOPSIS...RPW/
NEAR TERM...HEAVENER/
SHORT TERM...RPW/
LONG TERM...GORSE
AVIATION...EBERWINE
MARINE...EBERWINE
TIDES/COASTAL FLOODING...EBERWINE/DELISI