Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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423
FXUS61 KPHI 050910
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
410 AM EST FRI FEB 5 2016

.SYNOPSIS...
LOW PRESSURE WILL MOVE ALONG A NEARBY OFFSHORE FRONT EARLY TODAY
BEFORE TRACKING NORTHEAST AND AWAY FROM OUR AREA THIS AFTERNOON.
HIGH PRESSURE TO OUR SOUTHWEST WILL GRADUALLY BUILD INTO OUR REGION
TONIGHT AND SATURDAY, FOLLOWED BY A WEAK COLD FRONT PASSING THROUGH
EARLY SUNDAY. A STRONG OCEAN STORM IS FORECAST TO TRACK WELL
OFFSHORE LATE SUNDAY INTO MONDAY, WITH ANOTHER LOW PRESSURE SYSTEM
POSSIBLY DEVELOPING OFF THE MID-ATLANTIC COAST MONDAY NIGHT INTO
TUESDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A COASTAL LOW WAS DEVELOPING OFF THE MID-ATLANTIC COAST EARLY THIS
MORNING. SIMILAR TO THE LOW FROM THE BLIZZARD ALMOST TWO WEEKS
AGO...THIS SYSTEM WILL TRACK ALONG THE STRONG SST GRADIENT JUST TO
THE WEST OF THE GULF STREAM. THERE IS LESS COLD AIR AVAILABLE WITH
THIS CURRENT SYSTEM AND IT WILL BE CONSIDERABLY WEAKER...SO IMPACTS
WILL NOT BE COMPARABLE.

KDIX/KDOX DUAL POL RADAR, METAR REPORTS AND QUICK OBSERVATION
OUTSIDE THE OFFICE HAS SHOWN THAT RA HAS MIXED WITH AND IN SOME
AREAS CHANGED OVER TO SNOW ALONG THE I-95 CORRIDOR. IT`S STILL
RAINING CLOSER TO THE COAST BUT THE TRANSITION TO SNOW IS EXPECTED
TO OCCUR FROM WEST TO EAST THRU 6 AM. THE HOURLY POP AND WX GRIDS
FROM LAST EVENING APPEAR TO BE VERIFYING WELL SO FAR. THE FORECAST
UPDATE MADE EARLY THIS MORNING DOES NOT CONTAIN SIGNIFICANT CHANGES.

DESPITE TEMPS BEING SO WARM LAST NIGHT AND A GOOD AMOUNT OF RAIN AT
THE ONSET LAST NIGHT, WERE STILL EXPECTING ADVISORY LEVEL SNOWFALL
FROM ABOUT THE I-95 CORRIDOR TO THE COAST. STRONG DYNAMICAL COOLING
COINCIDING WITH HEAVIER PRECIP RATES WILL YIELD SNOWFALL RATES OF
AROUND AN INCH AN HOUR JUST IN TIME FOR THE MORNING COMMUTE. THE
BULK OF THE ACCUMULATING SNOW IS EXPECTED TO FALL BETWEEN 4-9 AM FOR
THE I-95 CORRIDOR AND BETWEEN 5 AND 10 AM FARTHER EAST TOWARD THE NJ
AND DE COAST. THIS COINCIDES WITH RUSH HOUR, SO PLEASE GIVE YOURSELF
CONSIDERABLY EXTRA TIME TO GET TO YOUR DESTINATION. EVEN CONSIDER
DELAYING YOUR TRAVEL (IF POSSIBLE) AS SECONDARY ROADS, BRIDGES AND
OVERPASSES THAT BECOME SNOW COVERED DURING RUSH HOUR WILL ADVERSELY
IMPACT TRAVEL. NO CHANGES WERE MADE TO WINTER WEATHER ADVISORIES.

SNOWFALL TOTALS REMAIN SIMILAR TO THE PREVIOUS FORECAST ALTHOUGH
THEY WERE LOWERED SLIGHTLY JUST WEST OF I-95 DUE TO A SHARP PRECIP
GRADIENT. SIMILAR TO LAST EVENING, THE SIMULATED SNOWFALL FROM THE
LATEST 05Z HRRRX USING A VARIABLE DENSITY IS ALMOST IDENTICAL TO OUR
SNOWFALL FORECAST. THIS FORECAST PARAMETER FROM THE HRRRX PERFORMED
EXTREMELY WELL WITH THE BLIZZARD TWO WEEKS AGO ALTHOUGH THE SETUPS
FOR THESE TWO EVENTS ARE VASTLY DIFFERENT. NOTE THE PARAMETER FROM
THE HRRR/HRRRX OR ANY OTHER MODELS THAT ASSUMES A 10:1 SNOW RATIO
FOR THIS EVENT WILL BE OVERDONE AS IT DOESN`T TAKE INTO ACCOUNT
THERMAL PROFILES THAT ALTER THE MICROPHYSICS, MIXING AND MELTING AT
THE SURFACE (WHICH ALL ARE IMPORTANT FACTORS IN THIS EVENT). THE
HEAVIEST SNOWFALL AMOUNTS (3-4 INCHES) ARE EXPECTED IN SOUTHERN AND
CENTRAL NJ.

THE SNOW WILL END FROM WEST TO EAST THIS MORNING AS THE LOW MOVES
TOWARD CAPE COD BUT IT MAY LINGER THRU MIDDAY ALONG THE NJ COAST.

MAX TEMPS ARE HIGHEST (MID 40S) IN EASTERN MD AND EASTERN PA
(EXCLUDING THE POCONOS) WHERE THERE WILL BE LITTLE TO NO SNOW COVER
AND CLEARING WILL OCCUR THIS MORNING. MAX TEMPS ARE CLOSER TO 40F IN
SNOWIER PARTS OF NJ AND ONLY IN THE 30S AT HIGHER ELEVATIONS IN THE
POCONOS AND NW NJ.

NLY WINDS WILL INCREASE THIS MORNING AS THE LOW DEEPENS TO OUR EAST.
WIND GUSTS OF 25 TO 30 MPH ARE EXPECTED.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/...
THE COASTAL STORM WILL CONTINUE TO DEEPEN TONIGHT AS IT MOVES
NORTHEASTWARD TOWARD THE CANADIAN MARITIMES. MEANWHILE, HIGH
PRESSURE OVER THE MIDWEST AND MID SOUTH AT THE END OF THE DAY WILL
BUILD EASTWARD TOWARD THE MID-ATLANTIC REGION TONIGHT.

THE GUSTY NW WINDS WILL DIMINISH AFTER SUNSET AS THE PRESSURE
GRADIENT RELAXES. EXPECT A LOT OF THE SNOW THE MELT THIS AFTERNOON
BUT THERE SHOULD BE ENOUGH OF A SNOWPACK LEFTOVER IN CENTRAL AND
SOUTHERN NJ TO CONTRIBUTE TO THE RADIATIONAL COOLING.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
AN OVERALL ACTIVE PATTERN LOOKS TO BE IN PLACE THROUGH THE LONG TERM
PERIOD. SATURDAY, HOWEVER, IS EXPECTED TO BE ON THE QUIET SIDE WITH
SURFACE HIGH PRESSURE STRETCHING ACROSS THE REGION. SOME CLOUDS MAY
ADVANCE INTO OUR AREA FROM THE NORTHWEST AS THE DAY WEARS ON
SATURDAY, WITH AN UPPER LEVEL TROUGH EXTENDING OVER THE NORTHEAST
STATES. IN FACT, BY EARLY SUNDAY A WEAK COLD FRONT MAY PASS OVER OR
JUST TO OUR NORTH, BUT WE HAVE KEPT A DRY FORECAST THROUGH SUNDAY AS
THERE LOOKS TO BE LIMITED MOISTURE ASSOCIATED WITH THIS BOUNDARY.
ALSO OF NOTE FOR LATE SUNDAY, MODEL GUIDANCE CONTINUES TO DEVELOP A
STRONG SURFACE LOW PRESSURE OFF OF THE SOUTHEASTERN SEABOARD WHICH
INTENSIFIES AS IT PROGRESSES OUT TO SEA THROUGH MONDAY. LITTLE OR NO
IMPACT IS STILL EXPECTED FOR OUR REGION FROM THIS SYSTEM, EXCEPT
PERHAPS SOME INCREASING CLOUDINESS, ESPECIALLY OVER THE SOUTHERN
HALF OF OUR CWA. DAYTIME MAXIMUM TEMPERATURES SATURDAY AND SUNDAY
ARE EXPECTED TO REACH INTO THE 40S FOR MOST OF THE REGION, EXCEPT
SOME HIGHS MAXING OUT IN THE 30S OVER THE HIGHER TERRAIN OF OUR
NORTHWEST ZONES.

THE MONDAY/TUESDAY TIMEFRAME CONTINUES TO SHOW A LARGE, PRONOUNCED
TROUGH SETTLING DOWN ACROSS THE EASTERN UNITED STATES, WITH A
SURFACE LOW MOVING ACROSS THE GREAT LAKES MONDAY. BOTH THE GFS AND
ECMWF CONTINUE TO INDICATE A TRANSFER OF ENERGY EASTWARD THAT
ULTIMATELY RESULTS IN LOW PRESSURE DEVELOPING OFF THE MID-ATLANTIC
COAST MONDAY NIGHT INTO TUESDAY. WHILE THERE ARE THESE SIMILARITIES
IN MODEL SOLUTIONS, THERE CONTINUE TO BE DIFFERENCES IN TRACK AND
INTENSITY OF THE POTENTIAL COASTAL LOW PRESSURE AND ITS RESULTING
IMPACTS OF RAIN/SNOW/WIND TO OUR REGION. IT DOES LOOK, HOWEVER, WITH
THE OVERALL PATTERN AND STRONG DIGGING TROUGH THAT COLDER AIR WILL
BE RETURNING TO THE REGION EARLY NEXT WEEK. WITH THE CONTINUED
UNCERTAINTY IN THE FORECAST DETAILS AT THIS EXTENDED RANGE, WE
LEANED TOWARD A SUPERBLEND/WPC GUIDANCE APPROACH WITH REGARDS TO
TEMPS, WINDS, AND POPS THROUGH MONDAY AND TUESDAY.

INTO WEDNESDAY AND THURSDAY OF NEXT WEEK, THE PRONOUNCED UPPER-LEVEL
TROUGH WILL BE PASSING OVER THE NORTHEAST TO MID-ATLANTIC. THE
POTENTIAL COASTAL STORM WILL HAVE EXITED BY THIS TIME, BUT AN
OVERALL CYCLONIC FLOW WILL RESULT IN COLDER AIR AND PERHAPS SOME
SCATTERED SNOW SHOWERS FOR WEDNESDAY. NOT MUCH DIFFERENCE IN THE
OVERALL PATTERN FOR THURSDAY, BUT HIGH PRESSURE TO THE SOUTHWEST MAY
BEGIN TO BUILD TOWARD THE REGION.

&&

.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

RA IS STARTING TO MIX WITH AND CHANGE OVER TO SN JUST BEFORE 08Z IN
THE I-95 TERMINALS. EXPECT THIS PTYPE TRANSITION TO OCCUR AT MIV AND
ACY BY 10Z. MVFR VSBYS AND CIGS WILL LOWER TO IFR AFTER IT BECOMES
ALL SN. LIFR EXPECTED WITH MODERATE TO HEAVY SN AT TIMES BETWEEN
ABOUT 09Z-14Z AT THE I-95 TERMINALS AND 10Z-16Z FARTHER EAST TOWARD
ACY. FARTHER WEST AT RDG AND ABE, THE IMPACT WILL BE MINOR AS THE
STEADIER/HEAVIER SN WILL REMAIN TO THE EAST. FORECAST KEEPS
RESTRICTIONS AT MVFR FOR A BRIEF PERIOD BETWEEN 09Z-12Z.

CONDITIONS WILL IMPROVE FROM WEST TO EAST LATER THIS MORNING. VFR
FOR THIS AFTERNOON AND TONIGHT.

NLY WINDS WILL CONTINUE TO INCREASE THIS MORNING TO 10-20 KT WITH
GUSTS AROUND 25 KT. THE WINDS WILL SUBSIDE AFTER 21Z AND BECOME
LIGHT (UNDER 10 KT) AFTER 00Z.

OUTLOOK...
SATURDAY AND SUNDAY...MAINLY VFR CONDITIONS ARE EXPECTED.

MONDAY AND TUESDAY...CONDITIONS ARE EXPECTED TO LOWER AS THE DAY
WEARS ON MONDAY DUE TO LOW PRESSURE DEVELOPING OFF THE MID-ATLANTIC
COAST. IN ADDITION TO POSSIBLE LOWER CIGS DEVELOPING, LOWER VSBYS
MAY ALSO OCCUR IN RAIN/SNOW, LASTING FROM LATE-DAY MONDAY THROUGH
TUESDAY.

&&

.MARINE...
THE GALE WARNING WAS EXTENDED THRU 4 PM FOR THE ATLANTIC COASTAL
WATERS. NLY WINDS HAVE INCREASED STEADILY OVERNIGHT IN RESPONSE TO A
DEVELOPING COASTAL LOW OFF THE NC COAST. EXPECT GALE FORCE WIND
GUSTS OF AROUND 35 KT TO REACH OUR ZONES STARTING AROUND 5 AM AND
CONTINUE THRU MID AFTERNOON. THE WINDS WILL BE SLIGHTLY LOWER IN THE
DE BAY BUT STILL GUST TO AROUND 30 KT TODAY.

THE PRESSURE GRADIENT AND WIND FIELD WILL WEAKEN LATE THIS AFTERNOON
BUT STILL BE IN SCA LEVELS IN OUR ATLANTIC COASTAL ZONES THRU THE
EVENING. NO MARINE HEADLINES ANTICIPATED FOR THE OVERNIGHT.

OUTLOOK...
SATURDAY...SUB-ADVISORY CONDITIONS ARE EXPECTED.

SUNDAY AND MONDAY...WINDS AND SEAS LOOK TO REMAIN BELOW ADVISORY
CRITERIA FOR MUCH OF SUNDAY, BUT THERE IS SOME POTENTIAL FOR STRONG
OFFSHORE LOW PRESSURE TO PASS SOUTHEAST OF OUR WATERS SUNDAY NIGHT
INTO MONDAY, WHICH COULD ENHANCE SEAS AND WIND GUSTS TO SCA LEVELS.

MONDAY NIGHT THROUGH TUESDAY...ANOTHER COASTAL STORM MAY DEVELOP
DURING THIS TIMEFRAME OFF THE MID-ATLANTIC COAST. THIS COULD RESULT
IN SCA OR EVEN GALE FORCE WINDS GUSTS AND BUILDING SEAS.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR
     PAZ070-071-101>106.
NJ...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR
     NJZ008>010-012-015>019.
     WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR NJZ013-014-
     020>027.
DE...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR
     DEZ001.
     WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR DEZ002>004.
MD...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR
     MDZ008-012.
     WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR MDZ015-019-
     020.
MARINE...GALE WARNING UNTIL 4 PM EST THIS AFTERNOON FOR ANZ450>455.
     SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR ANZ430-
     431.

&&

$$
SYNOPSIS...KLINE
NEAR TERM...KLEIN
SHORT TERM...KLEIN
LONG TERM...KLINE
AVIATION...KLEIN/KLINE
MARINE...KLEIN/KLINE



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