Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 091820
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
120 PM EST TUE FEB 9 2016

.SYNOPSIS...
A TROUGH OF LOW PRESSURE WILL EXTEND FROM THE MID-ATLANTIC COAST
INTO THE EASTERN GREAT LAKES TODAY. THIS LOW PRESSURE WILL MOVE
NORTHEAST OF THE REGION LATE TONIGHT AND WEDNESDAY. HIGH PRESSURE
WILL WORK EASTWARD THROUGH THE REGION THURSDAY INTO FRIDAY BEFORE
GIVING WAY ANOTHER AREA OF LOW PRESSURE WITH AN ARCTIC COLD
FRONTAL BOUNDARY BY THE END OF THE WEEK. ON SUNDAY, ANOTHER AREA
OF HIGH PRESSURE WILL BUILD SOUTHWARD INTO THE REGION AS LOW
PRESSURE FORMS ACROSS THE SOUTHERN UNITED STATES BY MONDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LIGHT PRECIPITATION CONTINUED TO MOVE NORTH THROUGH DELMARVA INTO
FAR SOUTHEAST PA AND NJ. AS OF 10 AM...LIGHT SNOW WAS OCCURRING
OVER AND POINTS NORTH OF CECIL AND NEW CASTLE COUNTIES WITH LIGHT
RAIN OBSERVED TO THE SOUTH. COMPLEX FORECAST IN TERMS OF PRECIP
TYPE AND INTENSITY WITH A WEAK NORLUN TROUGH ALOFT AND VERY WEAK
WARM AIR ADVECTION AOB 925 MB. THUS PRECIP INTENSITY WILL BE A
SIGNIFICANT FACTOR IN DETERMINING PTYPE. HEAVIER SNOW REMAINS OFF
TO THE WEST IN CENTRAL MD AND NORTHERN VA, ASSOCIATED WITH A MID
LEVEL VORT MAX AND MODEST FRONTOGENETICAL FORCING. THE NAM IS
CAPTURING THE FORCING AND QPF BETTER THAN GFS, WHICH IS TOO
ROBUST.

AS THIS HEAVIER PRECIP PIVOTS IN FROM THE WEST, WE EXPECT SNOW TO
BE MAINTAINED WHERE IT IS FALLING NOW OVER FAR NORTHEAST MD AND
NORTHERN DE, GIVEN THE LOWER DEWPOINTS AND EXPECTED EVAPORATIONAL
COOLING. TO THE SOUTH OF THIS AREA, WET BULB TEMPERATURES ARE TOO
HIGH TO SUPPORT ALL SNOW, SO A WET SNOW AND RAIN MIX IS EXPECTED
WITH LITTLE IF ANY ACCUMULATION RESTRICTED TO GRASSY SURFACES.

THE MAIN CHANGES TO THE FORECAST WERE TO INCREASE SNOWFALL TOTALS
BY 1 TO 2 INCHES OVER THE WINTER STORM WARNING AREA.

HEADLINES REMAIN THE SAME WITH THIS UPDATE.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
SNOW SHOULD GENERALLY MOVE OUT OF THE REGION BY LATE THIS EVENING
EXCEPT ACROSS NORTHEASTERN NJ WHERE IT MAY LINGER THROUGH THE
OVERNIGHT HOURS.

AS THE SURFACE TROUGH LIFTS FURTHER NORTH, WINDS SHOULD SHIFT TO
WESTERLY WHICH SHOULD HELP TO CONTINUE TO DIMINISH THE COASTAL
FLOODING THREAT.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
AN ACTIVE WINTRY PATTERN TO CONTINUE THROUGH THE PRESIDENTS DAY
HOLIDAY.

WEDNESDAY: SNOW ASSOCIATED WITH A TROUGH OF LOW PRESSURE WILL BE
ENDING ACROSS NORTHERN PORTIONS OF THE REGION IN THE MORNING.
HOWEVER, A SOMEWHAT UNSTABLE AIRMASS WILL BE LEFT ACROSS THE REGION
IN THE AFTERNOON HOURS WITH STEEPING LOW LEVEL LAPSE RATES AND TT
MODELED NEAR 50. ENOUGH MOISTURE MAY STILL BE PRESENT TO FORM A FEW
SCATTERED SNOW SHOWERS AND FLURRIES ACROSS THE REGION WITH THE
HIGHER TERRAIN ACROSS EASTERN PA AND NW NJ HELPING TO AID POTENTIAL
DEVELOPMENT. A LOOK AT BUFKIT SOUNDINGS SHOWS THE POTENTIAL FOR A
FAVORABLE MIXING AS WELL WHICH COULD RESULT IN SOME NORTHWEST WIND
GUSTS AROUND 25 MPH IN THE AFTERNOON. HIGH TEMPERATURES WILL LIKELY
STRUGGLE TO WHAT MET AND MAV GUIDANCE HAS DUE TO SOME SNOW COVER AND
THE STRONG CAA PUSH DURING THE DAY.

WEDNESDAY NIGHT THROUGH THURSDAY NIGHT: OUR REGION WILL BE
SITUATED BETWEEN ARCTIC HIGH PRESSURE BUILDING INTO THE MIDWEST
AND THE DEPARTING LOW PRESSURE SYSTEM. THIS PRESSURE GRADIENT WILL
LEAD TO CONTINUED STRONG NORTHWEST WINDS WITH COLD AIR ADVECTION
INTO THE REGION. THE WIND DIRECTION ALSO LOOKS TO SEND MOISTURE OFF
THE GREAT LAKES INTO THE REGION AS WELL. INSTABILITY LOOKS LESS THAN
DURING THE DAY WEDNESDAY BUT LOW LEVEL LAPSE RATES SHOULD STEEPEN
THURSDAY AFTERNOON. THIS WILL RESULT IN THE CHANCES FOR SOME
SCATTERED SNOW SHOWERS AND FLURRIES TO CONTINUE. ANY LIGHT SNOW
ACCUMULATION COULD LEAD TO A FEW SLICK SPOTS AS TEMPERATURES WILL BE
FALLING QUITE A BIT BELOW FREEZING. CLOUDS AND WIND SHOULD KEEP THE
LOW TEMPERATURES UP WEDNESDAY NIGHT, SAY ONLY THE 10`S TO AROUND 20
WITH AFTERNOON HIGHS IN THE 20`S ON THURSDAY. WINDS WILL DECREASE
THURSDAY NIGHT WITH CLEARING SKIES ALLOWING FOR A MORE FAVORABLE
SETUP FOR RADIATIONAL COOLING AS HIGH PRESSURE BUILDS TOWARD THE
REGION. LOW TEMPERATURES WILL LIKELY FALL INTO THE 10`S REGIONWIDE
AND CONTINUED TO NUDGE THEM SLIGHTLY LOWER THAN WHAT MOST GUIDANCE
INDICATES.

FRIDAY AND SATURDAY: HIGH PRESSURE WILL MOVE THROUGH THE REGION ON
FRIDAY. THIS HIGH PRESSURE SYSTEM WILL GIVE WAY TO ANOTHER ARCTIC
COLD FRONT WITH A CLIPPER TYPE LOW PRESSURE SYSTEM ALONG IT. THIS
MOVES THROUGH THE REGION FRIDAY NIGHT AND SATURDAY. MODELING IS
STILL TRYING TO RESOLVE IF THE MORE CLIPPER LIKE LOW PRESSURE WILL
DEVELOP INTO A COASTAL LOW ALONG THE BOUNDARY. RIGHT NOW ABOUT A
THIRD OF ENSEMBLE MEMBERS FROM BOTH THE GFS AND ECMWF SUITES ARE
SHOWING THE POTENTIAL FOR A COASTAL LOW FORMING NEAR OR SOUTHWEST OF
THE REGION. THE OTHER TWO THIRDS OF ENSEMBLE MEMBERS PLUS THE 00Z
CMC, UKMET AND GFS FORM A LOW PRESSURE MUCH FARTHER OFFSHORE. THE
LESS LIKELY COASTAL LOW FORMATION SCENARIO COULD RESULT IN
ANOTHER PERIOD OF ACCUMULATING SNOWFALL FOR THE REGION. HOWEVER,
WITH THE BULK OF MODEL GUIDANCE STAYING FURTHER OFFSHORE WILL JUST
ADD A GENERIC LOW CHANCE OF SNOW SHOWERS TO THE FORECAST FOR
FRIDAY NIGHT AND SATURDAY. EVEN IF THE LOW FORMS OFFSHORE
SATURDAY, IT WILL BE A COLD AND WINDY WITH ANOTHER ROUND OF NW
FLOW SNOW SHOWERS AND FLURRIES WITH THE HIGHEST COVERAGE IN THE
HIGH TERRAIN AREAS IN EASTERN PA AND NW NJ, SIMILAR TO THE MIDDLE
OF THIS WEEK.

SATURDAY NIGHT THROUGH SUNDAY NIGHT: ANOTHER POTENT AREA OF ARCTIC
HIGH PRESSURE WILL BUILD INTO THE REGION WITH THE COLDEST SHOT OF
AIR OF THE SEASON SO FAR. 850 MB LOOK TO DIVE WELL BELOW -20C ACROSS
MOST OF REGION AS CURRENTLY MODELED. AS IN OTHER PERIODS WILL
CONTINUE TO NUDGE TEMPERATURES A COUPLE OF DEGREES COOLER THAN MOST
ENSEMBLE GUIDANCE SETS. STRONG NORTHWEST WINDS IN THE WAKE OF THE
DEPARTING SYSTEM ON SATURDAY WILL LIKELY LEAD TO BELOW ZERO WIND
CHILLS, PUSHING ADVISORY CRITERIA IN SPOTS.

PRESIDENTS DAY: HIGH PRESSURE WILL GRADUALLY MOVE EAST OF THE REGION
AND WILL GIVE WAY TO A STORM SYSTEM THAT IS CURRENTLY MODELED TO
FORM ACROSS THE SOUTHERN UNITED STATES. RIGHT NOW IT APPEARS THAT A
TYPICAL GFS BIAS IS AT WORK FOCUSING STORM DEVELOPMENT IN THE
NORTHERN BRANCH OF THE JET AND BEING TO PROGRESSIVE WITH MOVING THE
TROUGH EASTWARD ACROSS THE COUNTRY. THE ECMWF, UKMET AND CMC SEEM TO
HAVE A BETTER HANDLE OF A BROADER TROUGH WHICH GIVES THE SOUTHERN
BRANCH MORE OF A CHANCE TO BE INVOLVED IN THE PATTERN. THIS ALLOWS
FOR A STRONGER SYSTEM TO FORM ACROSS THE SOUTHERN PLAINS. RIGHT NOW
IT LOOKS LIKE MONDAY WILL START DRY WITH PRECIPITATION CHANCES
MOVING INTO THE REGION BY MONDAY AFTERNOON AND NIGHT. TIMING CAN
ALWAYS CHANGE BY 24 HOURS OR MORE THIS FAR OUT. TEMPERATURES WILL
ALSO REBOUND ON THE BACKSIDE OF THE HIGH PRESSURE SYSTEM. HOWEVER,
GIVEN THIS IS SEVERAL DAYS A LOT OF ENSEMBLE SPREAD IS STILL PRESENT
AND THE VARIOUS FEATURES INVOLVED WILL NOT EVEN SAMPLED BY
OBSERVATIONAL DATA FOR SEVERAL MORE DAYS.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

WIDESPREAD MVFR AND IFR CEILINGS ARE EXPECTED THROUGH MUCH OF THE TAF
PERIOD. THE LOWEST CONDITIONS, INCLUDING VISIBILITY RESTRICTIONS ARE
EXPECTED WITH SNOW BANDS, WHICH ARE LIKELY TO MOVE THROUGH THE TAF
SITES THIS AFTERNOON INTO THE EARLY EVENING HOURS.

AFTER 00Z, SNOW SHOULD BEGIN TO LIFT OUT OF THE AREA FROM SOUTH TO
NORTH, AND WITH IT, EXPECT IMPROVING VISIBILITIES AND EVENTUALLY
(LIKELY NOT UNTIL AFTER 06Z) IMPROVING CEILING CONDITIONS. WINDS ARE
ALSO EXPECTED TO SHIFT FROM NORTHEASTERLY THROUGH THE DAY TO
WESTERLY OR NORTHWESTERLY AFTER 06Z.

OUTLOOK...

WEDNESDAY THROUGH THURSDAY: MAINLY VFR, SOME BRIEF MVFR RESTRICTIONS
IN ISOLATED SNOW SHOWERS AND FLURRIES. NORTHWEST WINDS 15-25 KNOTS
WITH HIGHER GUSTS.

THURSDAY NIGHT AND FRIDAY: VFR.

FRIDAY NIGHT AND SATURDAY: MAINLY VFR, POSSIBLE MVFR RESTRICTIONS
IN SCATTERED SNOW SHOWERS. NORTHWEST WINDS INCREASING SATURDAY
FROM 15-25 KNOTS WITH HIGHER GUSTS.

&&

.MARINE...
SCA CONDITIONS, ESPECIALLY FOR EASTERLY SWELLS ARE EXPECTED TO
CONTINUE THROUGH WEDNESDAY. THERE MAY BE A BIT OF A LULL IN THE
WINDS DURING TONIGHT, BUT A SHIFT TO WESTERLY OR NORTHWESTERLY
WINDS IS EXPECTED TOWARD SUNRISE WEDNESDAY, AND WITH IT, AND
INCREASE IN WIND SPEEDS ONCE AGAIN FOR WEDNESDAY.

OUTLOOK...

THE SCA HAS BEEN EXTENDED TILL 6PM WEDNESDAY BASED ON A HIGH CONFIDENCE
OF NORTHWEST WIND GUSTS NEAR 25 KNOTS OCCURRING THROUGHOUT THE DAY
AND SEAS STAYING AROUND FIVE FEET.

A GALE WATCH MAY POST FOR THURSDAY IN OUR 330 PM FORECAST WITH WEST
NORTHWEST WINDS INCREASING BENEATH STRONG COLD ADVECTION AND DEEPENING
BOUNDARY LAYER TO 850 MB (~5000 FT) FOR MOMENTUM MIXING TRANSFER. FREEZING
SPRAY SHOULD DEVELOP AS WELL.

NORTHWEST GALES ARE LIKELY SATURDAY INTO SUNDAY AS THE COLDEST AIR
OF THE SEASON ARRIVES, POSSIBLY AS COLD AS THE COLDEST PERIOD OF LAST
FEBRUARY. MODERATE TO HEAVY FREEZING SPRAY RATES SHOULD DEVELOP AS
WELL.

&&

.TIDES/COASTAL FLOODING...
STORM TIDE COMPARISON IN MLLW

           FEB 8      FEB 9       MDT FS
SANDY HOOK 8.21-1224Z 8.19-1336Z  7.7
ATLNTC CTY 7.28-1236Z 7.27-1330Z  7.0
CAPE MAY   7.93-1348Z 8.18-1354Z  7.7
LEWES      7.09-1342Z 7.26-1406Z  7.0

THE WARNING FOR THE NJ AND DE COASTS HAS EXPIRED. WE`RE CONSIDERING
A LESSER ADVISORY HEADLINE FOR OUR 330 PM ISSUANCE.

WIDESPREAD MODERATE COASTAL FLOODING OCCURRED DURING THIS MORNING`S
HIGH TIDE ALONG THE DE AND NJ OCEANFRONT WITH SOME LOCATIONS EXPERIENCING
SLIGHTLY GREATER FLOODING COMPARED TO MONDAY MORNING`S HIGH TIDE.
THANKS TO DECREASING ASTRONOMICAL TIDES, AND AN EXPECTED WIND SHIFT,
WE ARE ONLY EXPECTING ADVISORY LEVEL COASTAL FLOODING WITH THE
HIGH TIDE CYCLE THIS EVENING, THOUGH IT COULD GET CLOSE TO
MODERATE FLOODING THRESHOLDS FOR MONMOUTH MIDDLESEX COUNTIES NEAR
RARITAN BAY AND SANDY HOOK.

WIDESPREAD MINOR TO POSSIBLY MODERATE COASTAL FLOODING WAS OCCURRING
IN UPPER DELAWARE BAY WITH THE LOCATIONS ASSOCIATED WITH REEDY
POINT DELAWARE.

FOR THE TIDAL DELAWARE...MINOR COASTAL FLOODING IS EXPECTED AROUND
THE TIME OF HIGH TIDE. TIDAL DEPARTURES WERE DECREASING RAPIDLY
AT REEDY POINT AND PHILADELPHIA. NO COASTAL FLOOD WARNING NEEDED
AT PHILADELPHIA AT THIS TIME.

MINOR COASTAL FLOODING OCCURRED ALONG THE NORTHEASTERN SHORE OF
THE CHESAPEAKE BAY WITH THE HIGH TIDE CYCLE THIS MORNING, AND
MINOR COASTAL FLOODING IS EXPECTED AGAIN DURING THE HIGH TIDE
CYCLE THIS EVENING. THERE WAS SOME RISK THAT MODERATE COASTAL
FLOODING COULD BE REACHED WITH THE EVENING HIGH TIDE, BUT
CONFIDENCE IS LOW, SO WILL CONTINUE WITH THE COASTAL FLOOD
ADVISORY FOR NOW.

THE POTENTIAL FOR BLOWOUT TIDES IS PRESENT FOR THE THURSDAY LOW
TIDAL CYCLES.

&&

.CLIMATE...
NEAR RECORD COLD IS EXPECTED FOR PORTIONS OF OUR AREA SUNDAY
MORNING AND BY FAR THE COLDEST AIR OF THE SEASON SO FAR.

2015-16 SO FAR   RER 14TH

ABE 8......... -1 1979

ACY 10........ -6 1979

PHL 12........ +2 1979

ILG 12........ -4 1979

RDG 10........ -4-1983

TTN 9.........  0 1916

GED 13........  -7 1979

MPO -1........ -12 1970

ADDITIONALLY...THIS WILL BE WIND DRIVEN COLD WITH MANY AREAS
EXPERIENCING WIND CHILL VALUES OF 15 TO 20 BELOW ZERO...POSSIBLY25
BELOW IN THE HILLS AND MOUNTAINS OF NORTHWEST NEW JERSEY AND
NORTHEAST PENNSYLVANIA.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...WINTER WEATHER ADVISORY UNTIL 6 AM EST WEDNESDAY FOR PAZ060-
     061-071-103>106.
     WINTER STORM WARNING UNTIL 6 AM EST WEDNESDAY FOR PAZ070-101-
     102.
     COASTAL FLOOD ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR
     PAZ070-071-106.
NJ...WINTER WEATHER ADVISORY UNTIL 6 AM EST WEDNESDAY FOR
     NJZ008>010-012>027.
     COASTAL FLOOD WARNING UNTIL 3 PM EST THIS AFTERNOON FOR NJZ016.
     COASTAL FLOOD ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR
     NJZ015-017>019.
DE...WINTER WEATHER ADVISORY UNTIL 6 AM EST WEDNESDAY FOR
     DEZ001>004.
     COASTAL FLOOD WARNING UNTIL 3 PM EST THIS AFTERNOON FOR DEZ001.
MD...WINTER WEATHER ADVISORY UNTIL 6 AM EST WEDNESDAY FOR MDZ008-
     012-015-019-020.
     COASTAL FLOOD ADVISORY UNTIL 10 PM EST THIS EVENING FOR MDZ008-
     012-015-019-020.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST WEDNESDAY FOR ANZ450>455.

&&

$$
SYNOPSIS...GAINES
NEAR TERM...FRANCK/JOHNSON
SHORT TERM...JOHNSON
LONG TERM...GAINES
AVIATION...GAINES/JOHNSON
MARINE...DRAG/GAINES/JOHNSON 120P
TIDES/COASTAL FLOODING...120P
CLIMATE...


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