Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 072219
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
519 PM EST SUN FEB 7 2016

.SYNOPSIS...
LOW PRESSURE OFF THE SOUTHEASTERN UNITED STATES WILL RAPIDLY
STRENGTHEN AS IT MOVES NORTHEASTWARD TO THE CANADIAN MARITIMES
THROUGH MONDAY NIGHT. ANOTHER LOW PRESSURE SYSTEM IS FORECAST TO
DEVELOP IN ITS WAKE NEAR THE MID-ATLANTIC COAST MONDAY NIGHT INTO
TUESDAY. BEHIND THESE TWO LOWS, ARCTIC HIGH PRESSURE WILL THEN
BUILD INTO THE CENTRAL PORTION OF THE NATION AROUND MIDWEEK AND
WORK ITS WAY TOWARD THE EAST COAST BY THE WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
QUIET WEATHER WILL CONTINUE THROUGH THE EVENING HOURS, BEFORE THE
POSSIBILITY OF SNOWFALL DEVELOPS ALONG COASTAL PORTIONS OF DELAWARE
AND NEW JERSEY. STRONG LOW PRESSURE OFFSHORE OF THE SOUTHEAST STATES
WILL LIFT NORTHEASTWARD, OFFSHORE OF THE EAST COAST TONIGHT INTO
MONDAY MORNING. THE PRECIPITATION SHIELD IS EXPECTED TO EXPAND
SLIGHTLY ON THE WEST SIDE OVERNIGHT INTO MONDAY MORNING AS THE LOW
LIFTS TO THE NORTHEAST. AS OF NOW THE QUESTION FOR OUR AREA IS HOW
FAR WEST. BASED ON RECENT MODEL DIAGNOSTICS AND COLLABORATION, WE
EXPECT THE MAJORITY OF THE PRECIPITATION TO REMAIN RIGHT NEAR THE
COAST AND OFFSHORE, THEN EXTEND TO OUR NORTH AND EAST. THE NAM AND
SREF ARE CURRENTLY THOUGHT TO BE HIGH WITH THEIR AMOUNTS, WHILE A
BLEND OF THE GFS AND ECMWF GIVE A BETTER EXPECTATION OF AMOUNTS.
ANOTHER CONCERN WOULD BE HOW MUCH WOULD ACCUMULATE BASED ON
TEMPERATURES, AS TEMPERATURES AT THE ONSET WILL LIKELY BE ABOVE
FREEZING. SO FOR NOW WE ARE EXPECTING AROUND AN INCH FOR MUCH OF THE
CENTRAL AND SOUTHERN COASTAL AREAS, WITH 1-2 INCHES ACROSS AREAS
FURTHER NORTH INTO NORTHERN OCEAN AND MONMOUTH COUNTIES AND EASTERN
MIDDLESEX. SO WE WILL NOT ISSUE ANY WINTER ADVISORIES AT THIS TIME
AND LET LATER SHIFTS MONITOR FUTURE GUIDANCE AND SEE IF A SHORT
FUSED ADVISORY IS NEEDED.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
ON MONDAY, THE STRONG LOW PRESSURE SYSTEM OFFSHORE WILL CONTINUE TO
LIFT NORTHEASTWARD WELL OFFSHORE OF THE EAST COAST. MEANWHILE, A
WEAKENING BACKDOOR FRONT MAY SAG DOWN INTO OUR NORTHERN AREAS AS
WELL. THERE MAY LIKELY BE SOME SNOWFALL REMAINING ON THE BACKSIDE OF
THE LOW, AND AS THE BACKDOOR FRONT WEAKENS AS IT MOVES SOUTHWARD
INTO OUR AREA, IT COULD HELP ENHANCE SOME LIGHT SNOWFALL ACROSS THE
NORTHERN AREAS. SO THERE WILL REMAIN A CHANCE OF SNOW ACROSS OUR
NORTHEASTERN AREAS THROUGH MUCH OF THE DAY MONDAY. AGAIN, THE
HIGHEST ACCUMULATIONS THROUGH THE PERIOD ARE EXPECTED TO BE OFFSHORE
AND TO OUR NORTHEAST, SO WHILE THERE COULD BE A LIGHT ACCUMULATING
SNOWFALL, WE DO NOT EXPECT ADVISORY LEVEL SNOWS TO BE MET AT THIS
TIME. ESPECIALLY IF SNOWFALL MIXES WITH OR CHANGES OVER TO RAIN.

&&

.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
AN AREA OF LOW PRES IS EXPECTED TO DEVELOP NR THE MID ATLC CST MON
NIGHT. THE GUID IS IN AGREEMENT ON THIS PART. THE DISAGREEMENT
LIES IN THE DETAILS, WHICH ARE IMPORTANT.

YESTERDAY, THE ECMWF, WENT OUT ON ITS OWN, WITH A STRONGER AND
MORE EWD SOLN. IT CONTINUED THAT TREND ON THE OVERNIGHT RUN AND
AGAIN ON TODAY`S RUN. IT HAS A MORE CONSOLIDATED LOW CENTER,
BRINGS THAT CENTER FURTHER AWAY FROM THE CST, AND HAS MUCH LESS
IMPACT ON OUR AREA.

WHILE THE ECMWF`S PERFORMANCE HAS BEEN LESS THAN STELLAR THIS
WINTER, AND IT IS A CLEAR OUTLIER IN THIS CASE. HOWEVER, ITS
OVERALL STATISTICS MEAN IT`S SOLUTION CAN NOT BE TOTALLY IGNORED,
AND STRANGER THINGS HAVE HAPPENED.

THE REST OF THE OTHER MDLS DO BRING A GENLY LIGHT SNOWFALL TO THE
AREA MONDAY NIGHT INTO TUE. PRECIP WILL BEGIN LATER MON AND TEMPS
WILL BE WARM ENOUGH TO SUPPORT RAIN OR SNOW THAT HAS A HARD TIME
ACCUMULATING IN MOST AREAS AND ON MANY SURFACES DURING THE
DAYLIGHT HOURS.

AFTER SUNSET, THE SNOW WOULD START TO ACCUMULATE MORE. THE GUID
ALSO DIFFERS ON THE AREAS THAT WOULD SEE THE MOST QPF AND CHCS OF
HEAVIEST SNOWS. WHILE MOST OF THE SNOW LOOKS TO FALL WOULD BE ON
THE LIGHTER SIDE, EVEN WITH THE JANUARY BLIZZARD, THE MDLS WERE
HAVING TROUBLE DECIPHERING THIS EVEN 12 HOURS BEFOREHAND.

SO FOR NOW, WILL ONLY MAKE INCREMENTAL CHANGES TO THE SNOWFALL
AMOUNTS. ATTM, THIS LOOKS LIKE AN ADVY EVENT OR PSBLY LOW END WRNG
IN SOME AREAS.

ANOTHER COMPLICATING FACTOR IS TEMPS DURG THE DAY ON TUE. TEMPS
WILL BE ABV FREEZING IN MANY AREAS, SO THERE CUD BE A MIX OR
CHANGEOVER TO RAIN, ESPECIALLY IN SRN AND ERN AREAS, AND MUCH
LIKE WE HAD THE OTHER DAY, EVEN WHERE IT SNOWS, IT COULD END UP
ACCUMULATING MAINLY ON GRASSY SFCS AND LESS TRAVELED ROADS DURG
DAYLIGHT HOURS, IF IT IS NOT COMING DOWN HARD.

THINGS SHUD BEGIN TO TAPER OFF TUE NIGHT INTO WED.

THEN, A LARGE AREA OF ARCTIC HIGH PRES WILL MOVE INTO THE CNTRL
CONUS. THIS HIGH WILL GRADUALLY MOVE EWD THRU THE END OF THE WEEK.
EXPECT A GENLY DRY AND BREEZY NWLY FLOW WED THRU SAT. HOWEVER
TEMPS WILL NOT MAKE IT ABV FREEZING FROM THU ON. WITH OVERNIGHT
LOWS IN THE TEENS. NRML LOWS ARE IN THE LOWER 40S NOW. SO WE ARE
LOOKING AT HIGH TEMPS THAT WILL AVERAGE 15 TO 20 DEGREES BELOW
NRML, AND WITH THE DAYS GETTING INCREASINGLY LONGER, THIS IS
INCREASINGLY DIFFICULT TO ACCOMPLISH, ESPECIALLY FOR AN EXTENDD
PD.

&&

.AVIATION /22Z SUNDAY THROUGH FRIDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

VFR CONDITIONS WILL REMAIN ACROSS THE TAF SITES FOR AT LEAST THE
FIRST HALF OF THE OVERNIGHT. HOWEVER, WE EXPECT CLOUDS TO LOWER ON
THE NORTHWESTERN SIDE OF THE STRONG LOW PRESSURE MOVING TO THE
NORTHEAST WELL OFFSHORE OF THE EAST COAST. LOOKING AT THE SOUNDINGS,
MVFR CIGS SHOULD BEGIN AFFECTING ALL AREAS BY AROUND 10-12Z, AND
COULD REMAIN ACROSS THE AREA THROUGH THE DAY MONDAY. ANOTHER CONCERN
WITH THIS SYSTEM WILL BE THE POSSIBILITY OF SNOWFALL. BASED ON
LATEST MODEL DIAGNOSTICS AND COLLABORATION, WE EXPECT SNOWFALL TO
REMAIN ACROSS MOSTLY COASTAL AREAS OF NEW JERSEY AND DELAWARE AND
OFFSHORE. THE MAIN TAF SITES THAT WOULD BE AFFECTED WOULD BE ACY,
WHICH COULD EXPERIENCE IFR CONDITIONS WITH ANY SNOWFALL, IN ADDITION
TO MIV WHICH COULD ALSO EXPERIENCE SOME LIGHTER SNOWFALL AS WELL.

WINDS WILL REMAIN MOSTLY EAST-NORTHEASTERLY AROUND 5-10 KNOTS FOR
THE REST OF TODAY INTO THIS EVENING. WINDS WILL BEGIN INCREASING
OVERNIGHT AS THE LOW LIFTS NORTHWARD, AND LIKELY BECOME GUSTY 20-25
KNOTS BY MONDAY MORNING AND CONTINUE GUSTY THROUGH THE FIRST HALF OF
THE DAY, BEFORE THE GUSTS DROP OFF BY AFTERNOON.


OUTLOOK...
MON NIGHT AND TUE...PRECIP WILL BE ONGOING DURG THIS TIME AND FOR
FOR KPHL, KPNE, KMIV, KACY WILL TRANSITION FROM RAIN OR MIX TO
SNOW MON NIGHT. ELSEWHERE WILL BE SNOW MON NIGHT. PRECIP SHUD BE
LIGHT FOR THE MOST PART BUT THERE CUD BE SOME MDT OR HVY BURSTS.
EXPECT MVFR/IFR CONDS. ON TUE, TEMPS SHUD WARM ENOUGH THAT FOR
KPHL, KPNE, KACY, KMIV SHUD AGAIN SEE A MIX OR CHANGEOVER TO RAIN,
DEPENDING ON HOW WARM TEMPS GET.  LOW TO MDT CONFIDENCE.

WED...SOME LINGERING SHSN, THEN IMPROVING TO VFR. BREEZY WITH W
TO NW WIND GUSTS AROUND 20 KT.  HIGH CONFIDENCE.

THU...VFR AND BREEZY WITH NW WIND GUSTING 25 TO 30 KT. HIGH
CONFIDENCE.

&&

.MARINE...
GALE WARNING REMAINS IN PLACE OVERNIGHT INTO MONDAY AS A STRONG
COASTAL LOW PRESSURE SYSTEM WILL BE LIFTING EAST OF THE WATERS
TONIGHT INTO MONDAY AND THE PRESSURE GRADIENT STRENGTHENS THROUGH
THE NIGHT AS THE LOW LIFTS NORTHWARD. AS WE PROGRESS THROUGH MONDAY
AND THE LOW LIFTS AWAY FROM THE AREA, THE PRESSURE GRADIENT WEAKENS
AND WINDS SHOULD BEGIN TO SUBSIDE INTO SMALL CRAFT ADVISORY LEVELS.

OUTLOOK...
MON NIGHT THROUGH WED...ANOTHER LOW PRESSURE SYS WILL DEVELOP OFF
THE MID-ATLANTIC COAST. AN EXTENDED PERIOD OF SCA CONDITIONS
LIKELY DURING THIS TIME. IT IS PSBL THAT THERE CUD BE SOME GALES,
ESPECIALLY ON WED, BUT CONFIDENCE REMAINS LOW ON THE TRACK AND
STRENGTH OF THE LOW.

THU...SOLID SCA CONDITIONS. NW WINDS BEHIND A CFP, WITH THE BEST
CHC FOR GALES.

&&

.TIDES/COASTAL FLOODING...
***MINOR COASTAL FLOODING IS LIKELY NEAR THE MONDAY MORNING
HIGH TIDE. THERE IS INCREASING POTENTIAL FOR MODERATE COASTAL
FLOODING NEAR THE TUESDAY MORNING HIGH TIDE***

HIGH PRESSURE WILL ANCHOR OVER EASTERN QUEBEC/LABRADOR WHILE LOW
PRESSURE PASSING OFFSHORE WELL TO THE SOUTHEAST UNDERGOES EXPLOSIVE
DEEPENING OVERNIGHT AND THROUGH THE DAY MONDAY. WITH THE
AFOREMENTIONED HIGH REMAINING TO OUR NORTH, A BROAD AREA OF LOW
PRESSURE WILL DEVELOP OFF THE OUTER BANKS MONDAY NIGHT AND PASS
OFFSHORE SOUTHEAST OF OUR REGION DURING THE DAY TUESDAY.

THESE TWO SYSTEMS WILL MAINTAIN AN ONSHORE FLOW ALONG THE COAST THRU
TUESDAY, WITH ONLY A BRIEF PAUSE MONDAY AFTERNOON AND VERY EARLY
MONDAY NIGHT, AS THE PRESSURE GRADIENT RELAXES BETWEEN SYSTEMS.

SETTING THE STAGE, ASTRONOMICAL TIDES WILL BE HIGH EARLY THIS WEEK,
TO DUE TO THE NEW MOON ON MONDAY.

FOR THE MONDAY MORNING HIGH TIDE, WE THINK THE NAM BACKS THE WINDS
TOO MUCH /MORE NORTHERLY/ AS WE APPROACH HIGH TIDE, POSSIBLY DUE TO
AN ISALLOBARIC EFFECT WITH THE DEEPENING OFFSHORE SYSTEM, AND IT WAS
DEEMED AN OUTLIER. WITH HIGH ASTRONOMICAL TIDES AND NORTHEAST WIND
GUSTS QUICKLY RAMPING UP TO GALE FORCE JUST OFFSHORE OVERNIGHT,
WE EXPECT A SURGE OF 1 TO 1.5 FEET. WE HAVE HIGH CONFIDENCE IN
WIDESPREAD MINOR COASTAL FLOODING, ESPECIALLY ALONG THE NORTHERN
NEW JERSEY COAST WHERE POCKETS OF MODERATE FLOODING ARE POSSIBLE,
DUE TO THE PRESENCE OF A GREATER COMPONENT OF ONSHORE FLOW. WE
HAVE ALSO TEMPERED DOWN THE HIGH-BIASED ET AND ESTOFS GUIDANCE DUE
TO A RESIDUAL OF NEARLY 1 FOOT IN SPOTS. A COASTAL FLOOD ADVISORY
HAS BEEN ISSUED FOR THE MONDAY MORNING HIGH TIDE ALONG THE NJ AND
DE OCEANFRONT, AS WELL AS DELAWARE BAY. THERE IS A BIT MORE
UNCERTAINTY ON WHETHER WE REACH THE MINOR THRESHOLD AT REEDY
POINT, WHICH IS LARGELY DEPENDENT ON EKMAN TRANSPORT IN A
NORTHEAST FLOW, BUT WE EXPECT IT TO BE CLOSE NONETHELESS.

A COASTAL FLOOD ADVISORY CONTINUES FOR THE NJ AND DE OCEANFRONT
FOR THE MONDAY EVENING HIGH TIDE, AS MINOR COASTAL FLOODING IS
EXPECTED TO LINGER.

FOR THE TUESDAY MORNING HIGH TIDE, A MORE EASTERLY COMPONENT/LONGER
FETCH TO THE WIND WILL HAVE A GREATER IMPACT ALONG THE ENTIRE COAST,
INCLUDING DELAWARE BAY, AND PORTIONS OF THE TIDAL DELAWARE. WE AGREE
WITH THE STRONGER GFS WINDS, ESPECIALLY GIVEN THE SYNOPTIC SETUP.
THE MAIN UNCERTAINTY IS REGARDING A BROAD LOW PRESSURE/TROUGH MOVING
NORTHEASTWARD ALONG THE COAST, WHICH MAY ALLOW WINDS TO QUICKLY
RELAX NEAR THE TIME OF HIGH TIDE, PARTICULARLY DELMARVA AND FAR
SOUTHERN NJ. NEVERTHELESS, ASIDE FROM A BRIEF LULL IN THE FLOW
MONDAY AFTERNOON AND VERY EARLY MONDAY NIGHT, WE`LL HAVE HAD
NEARLY 48 HOURS DURATION OF ONSHORE FLOW, WHICH WILL MAKE FOR
HIGHER TIDAL DEPARTURES COMPARED TO MONDAY MORNING, IN ADDITION TO
THE ASTRONOMICALLY HIGHER TIDES. IN TERMS OF GUIDANCE, WE SIDED
MORE WITH THE HIGHER ETSS SURGE OF 2 TO 2.5 FEET, EVEN CONSIDERING
THE AFOREMENTIONED RESIDUAL. A COASTAL FLOOD WATCH HAS BEEN ISSUED
FOR THE TUESDAY MORNING HIGH TIDE FOR THE NJ AND DE OCEANFRONT
WITH THE HIGHEST CONFIDENCE IN WIDESPREAD MODERATE COASTAL
FLOODING FOR CENTRAL AND NORTHERN NJ. ELSEWHERE, WIDESPREAD MINOR
COASTAL FLOODING IS ANTICIPATED, PERHAPS UP TO PHILADELPHIA, GIVEN
THE MORE EASTERLY FLOW UP DELAWARE BAY. FOR THESE AREAS, A
COASTAL FLOOD ADVISORY WILL LIKELY BE NEEDED.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...COASTAL FLOOD WATCH FROM LATE MONDAY NIGHT THROUGH TUESDAY
     AFTERNOON FOR NJZ012>014-020>027.
     COASTAL FLOOD ADVISORY FROM 5 AM MONDAY TO 4 AM EST TUESDAY
     FOR NJZ012>014-020>027.
     COASTAL FLOOD ADVISORY FROM 9 AM TO 1 PM EST MONDAY FOR NJZ016.
DE...COASTAL FLOOD WATCH FROM LATE MONDAY NIGHT THROUGH TUESDAY
     AFTERNOON FOR DEZ002>004.
     COASTAL FLOOD ADVISORY FROM 5 AM MONDAY TO 4 AM EST TUESDAY
     FOR DEZ002>004.
     COASTAL FLOOD ADVISORY FROM 9 AM TO 1 PM EST MONDAY FOR DEZ001.
MD...NONE.
MARINE...GALE WARNING UNTIL NOON EST MONDAY FOR ANZ450>455.
     SMALL CRAFT ADVISORY UNTIL 6 AM EST MONDAY FOR ANZ430-431.

&&

$$
SYNOPSIS...NIERENBERG
NEAR TERM...ROBERTSON
SHORT TERM...ROBERTSON
LONG TERM...NIERENBERG
AVIATION...NIERENBERG/ROBERTSON
MARINE...NIERENBERG/ROBERTSON
TIDES/COASTAL FLOODING...FRANCK


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