Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 052131
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
431 PM EST THU MAR 5 2015

.SYNOPSIS...
A STORM SYSTEM WILL EXIT TO OUR EAST THIS EVENING, THEN ARCTIC HIGH
PRESSURE BUILDS IN OVERNIGHT AND FRIDAY. THE HIGH WILL THEN SETTLE
TO OUR SOUTH ON SATURDAY. A WEAK LOW PRESSURE SYSTEM WILL TRACK TO
OUR NORTH LATE SUNDAY INTO MONDAY, PULLING A COLD FRONT ACROSS OUR
REGION ON MONDAY. HIGH PRESSURE SHOULD THEN BUILD INTO THE AREA
TUESDAY INTO WEDNESDAY, WITH THE NEXT COLD FRONT SCHEDULED TO ARRIVE
LATER WEDNESDAY INTO THURSDAY.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
FOR THE POCONOS AND NORTHWEST NJ, SNOW HAS ENDED AND THE WINTER
WEATHER ADVISORY HAS BEEN ALLOWED TO EXPIRE. TOTAL ACCUMULATIONS OF
A FEW INCHES OCCURRED WITH A SHARP CUTOFF AS YOU GO NORTH IN THIS
REGION.

FOR THE LEHIGH VALLEY, SNOW WILL BE ENDING BY SUNSET AND A WINTER
STORM WARNING CONTINUES UNTIL 7PM. NUMEROUS REPORTS OF AROUND SIX
INCHES HAVE COME IN WITH LOCALLY HIGHER TOTALS AND THESE HAVE BEEN
REFLECTED IN THE STORM TOTAL WEB MAP.

FOR CENTRAL NEW JERSEY AND THE PHILADELPHIA METRO REGION, A COUPLE
MORE HOURS OF MODERATE, BRIEFLY HEAVY SNOW ARE POSSIBLE BEFORE
ENDING SHORTLY AFTER SUNSET. TOTAL ACCUMULATIONS 6-8, ISOLATED
HIGHER.

IN THE DELMARVA AND SOUTHEAST NEW JERSEY, THE CHANGEOVER WAS SLOW
THIS AFTERNOON AND THIS WILL CUT INTO THE ACCUMULATIONS OF SNOW AND
SLEET. FAVORABLE ISENTROPIC LIFT AND 700MB FRONTOGENETICAL FORCING
ARE TAKING PLACE RESULTING IN HEAVIER BANDING, SO NOT A DRASTIC
REDUCTION IN TOTALS. SUSSEX AND CAPE MAY COUNTIES  MAY HAVE THE
HARDEST TIME REACHING WARNING CRITERIA (4-6 OR SO) WITH AREAS
FURTHER NORTH ENDING UP WITH 6 INCHES OR SO.

FOR ADDITIONAL SNOW MAINLY USED THE RAP AND WPC QPF AS A GUIDELINE
AND TOOK INTO ACCOUNT CURRENT OBS TO MAKE THE SNOW TOTAL FORECASTS
REFERENCED ABOVE.

TEMPERATURES WILL TUMBLE ONCE SKIES CLEAR. THIS SHOULD TAKE PLACE
FAIRLY QUICKLY AFTER THE SNOW ENDS GIVEN A STEEP DROP IN DEW POINTS
AND CONSIDERABLE DRY AIR ADVECTION. RECORD LOWS ARE POSSIBLE,
PLEASE SEE CLIMATE SECTION BELOW. LOW TEMPERATURES TONIGHT ARE
COMPOSED OF MET/MAV AND THE MODELED TWO METER TEMPERATURES FROM
THE GFS WHICH HAS DONE WELL AT NIGHT WITH SNOW COVER.

WIND CHILLS ARE LIKELY TO FALL BELOW ZERO ACROSS MOST OF THE REGION,
WITH THE POCONOS SEEING WIND CHILLS WHICH MAY GET CLOSE TO ADVISORY
THRESHOLD FOR A FEW HOURS. GIVEN THE LIMITED WINDOW AND MARGINAL
VALUES IN TERMS OF AND ADVISORY, WILL JUST CONTINUE MENTION IN THE
HWO.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
SUNNY DAY WITH HIGH PRESSURE BUILDING IN ON FRIDAY BUT STILL
COLD. DID GO A TOUCH WARMER THAN MAV/MET GIVEN THE COOL DAYTIME BIAS
WITH SNOW COVER. OTHER ELEMENTS STRAIGHT MAV/MET. CONTINUED
NORTHWESTERLY WINDS UNDER 10 MPH OR SO.

&&

.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
THE OVERALL SYNOPTIC SETUP IS COMPRISED OF AN UPPER-LEVEL TROUGH
FROM THE MIDWEST TO THE NORTHEAST AND MID ATLANTIC. AS SHORT WAVE
ENERGY MOVES THROUGH THE FLOW, THIS FEATURE SHOULD AMPLIFY A LITTLE
FOR A TIME OR TWO. THIS SHOULD EVENTUALLY WEAKEN AS ENERGY EJECTS
ACROSS THE SOUTHERN PLAINS LATE IN THE WEEKEND AND EARLY NEXT WEEK,
WITH A RIDGE POTENTIALLY BUILDING OFF THE SOUTHEASTERN U.S. COAST.
THIS RESULTS IN THE UPPER-LEVEL FLOW TURNING MORE ZONAL NEXT WEEK.
WE USED A MODEL BLEND FOR FRIDAY NIGHT THROUGH SUNDAY, THEN WENT
WITH THE 12Z WPC GUIDANCE THEREAFTER. WE THEN MADE SOME ADJUSTMENTS
AFTER ADDITIONAL COLLABORATION WITH OUR NEIGHBORING OFFICES.

FOR FRIDAY NIGHT AND SATURDAY...A SHORT WAVE TROUGH LOOKS TO SLIDE
ACROSS THE AREA, HOWEVER A DRY AIRMASS RESULTS IN NO PRECIPITATION.
AT THE SURFACE, HIGH PRESSURE BUILDS OVER THE AREA HOWEVER ITS
CENTER SLIDES TO OUR SOUTH THROUGH SATURDAY. THIS WILL RESULT IN A
GRADUAL RETURN FLOW BEING ESTABLISHED AND AFTER A VERY COLD START
SATURDAY, SOME MODERATION IS EXPECTED IN THE AFTERNOON.

FOR SUNDAY AND MONDAY...A SHORT WAVE IS FORECAST TO TRACK NEAR THE
MIDWEST AND GREAT LAKES SUNDAY, THEN WELL TO OUR NORTH MONDAY. THIS
WILL DRIVE WEAK LOW PRESSURE WELL TO OUR NORTH, HOWEVER A COLD FRONT
IS FORECAST TO MOVE THROUGH DURING MONDAY. IT APPEARS THAT THE
MOISTURE WILL BE LACKING WITH THIS FEATURE AS MUCH OF THE LIFT
OCCURS WELL TO OUR NORTH. THERE COULD BE A SNOW SHOWER THOUGH SUNDAY
NIGHT INTO MONDAY ACROSS THE FAR NORTHWEST. OTHERWISE, THE AIRMASS
IS FORECAST TO CONTINUE TO MODIFY AS THE FLOW COMES MORE FROM THE
WEST AND NOT THE NORTH.

FOR TUESDAY AND WEDNESDAY...HIGH PRESSURE SHOULD SHIFT TO OUR EAST
AS A COLD FRONT MOVES ACROSS THE MIDWEST AND THE GREAT LAKES. LOW
PRESSURE APPEARS TO TRACK WELL TO OUR NORTH ONCE AGAIN, WITH A WARM
FRONT LIFTING MOSTLY TO OUR NORTHWEST. WHILE THE FLOW LOOKS FAIRLY
WEAK, ENOUGH WAA IS EXPECTED TO OCCUR TO ALLOW FOR FURTHER
MODERATION OF THE AIRMASS WITH MANY AREAS GETTING INTO THE LOWER 50S
WEDNESDAY AFTERNOON. THE COLD FRONT SHOULD BE ARRIVING LATE
WEDNESDAY, HOWEVER GIVEN THE TRACK OF THE SURFACE LOW AND SHORT WAVE
ALOFT IT ALSO LOOKS TO BE MOISTURE STARVED.

FOR THURSDAY...A WEAK SURFACE HIGH IS ANTICIPATED TO MOVE ACROSS THE
AREA, WHILE A FRONTAL BOUNDARY IS DRAPED FROM NEAR MAINE TO THE
GREAT LAKES THEN INTO THE CENTRAL PLAINS. THE AIRMASS SHOULD BE MUCH
MILDER WITH AFTERNOON HIGHS GETTING INTO THE 50S. THE OCEAN AND
DELAWARE BAY ARE COLD AND IF THERE IS LIGHT ENOUGH FLOW, THEN A
COOLING AFFECT CAN BE EXPECTED CLOSER TO THE COAST.

&&

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

LIFR AND IFR CONDITIONS WILL LIKELY BE PRESENT AT ALL TAF SITES INTO
THE EVENING WITH ACCUMULATING SNOW. KRDG AND KABE WILL BE FIRST TO
IMPROVE TO VFR BY 00Z 3/6. OTHER TAF SITES WILL FOLLOW WITH AN
IMPROVEMENT TO VFR WITH KACY LAST AROUND 03Z. NORTHERLY WINDS
BETWEEN 10 AND 15 KNOTS ARE EXPECTED AS WELL INTO THE EVENING,
POTENTIALLY LASTING LONGER THAN CURRENT TAFS INDICATE. OVERNIGHT
NORTH TO NORTHWEST WINDS SHOULD SLACKEN SLIGHTLY WITH CONTINUED VFR
CONDITIONS ON FRIDAY.

OUTLOOK...
FRIDAY NIGHT THROUGH SUNDAY...VFR OVERALL. A WEAK SYSTEM MOVING BY
LATER SATURDAY SHOULD RESULT IN MORE CLOUDS, HOWEVER ANY
PRECIPITATION LOOKS TO STAY TO OUR NORTH AND WEST.

MONDAY AND TUESDAY...VFR OVERALL. A WEAK COLD FRONT MOVING THROUGH
MONDAY SHOULD RESULT IN MORE CLOUDS, HOWEVER IT APPEARS THAT IT
MOVES THROUGH DRY.

&&

.MARINE...
WAVES ALONG THE COASTAL WATERS WILL CONTINUE TO REMAIN NEAR OR ABOVE
5 FT. IN ADDITION, WINDS ARE EXPECTED TO INCREASE SLIGHTLY THROUGH
THE EVENING HOURS OUT OF THE NORTH NORTHWEST. THEREFORE THE SMALL
CRAFT ADVISORY CONTINUES ON THE ATLANTIC COASTAL WATERS THROUGH THE
OVERNIGHT HOURS. ON THE BAY, A FEW GUSTS ABOVE 20 KT ARE POSSIBLE,
BUT CONDITIONS SHOULD GENERALLY STAY BELOW SMALL CRAFT ADVISORY
CRITERIA. FOR FRIDAY, WINDS AND SEAS SHOULD REMAIN BELOW SCA
CRITERIA.

OUTLOOK...
FRIDAY NIGHT AND SATURDAY...THE CONDITIONS ARE EXPECTED TO BE
BELOW SMALL CRAFT ADVISORY CRITERIA, HOWEVER THE WINDS WILL
INCREASE SOME FROM THE WEST-SOUTHWEST DURING SATURDAY. THERE IS A
CHC FOR SOME LIGHT FREEZING SPRAY FRIDAY NIGHT AND SATURDAY
MORNING.

SUNDAY THROUGH TUESDAY...WE ARE ANTICIPATING SUB SMALL CRAFT
ADVISORY CONDITIONS AS A WEAK FRONT MOVES THROUGH MAINLY DURING
MONDAY.

&&

.CLIMATE...
WITH A SNOW COVER IN PLACE AND ANOTHER ARCTIC AIRMASS SETTLING
INTO THE REGION AND RADIATIONAL COOLING OCCURRING WE HAVE ANOTHER
CHANCE FOR MORE RECORD LOWS ACROSS THE REGION.

FRIDAY 3/6

RECORD LOWS

ACY 10 1888
PHL 10 1978
ILG 11 1926
ABE 7  1960
TTN 7  1872
GED 10 1978
RDG 7  1978
MPO -5 1909

THE CURRENT FORECAST CURRENTLY HAS MOST LOCATIONS BREAKING THERE
RECORD LOW ON FRIDAY MORNING. THE ONE EXCEPTION WOULD BE MOUNT
POCONO.

SATURDAY 3/7

RECORD LOWS

ACY 10 1890
PHL 9  1960
ILG 11 1960
ABE 1  1960
TTN 7  1890
GED 3  1960
RDG 10 1989
MPO -18 1911

IT APPEARS THAT READING AND ATLANTIC CITY HAVE THE BETTER CHANCE
OF GETTING TO THEIR RECORD LOW SATURDAY MORNING.

RECORD DAILY SNOWFALL FOR THURSDAY MARCH 5

RECORD EVENT REPORTS WILL BE SENT SHORTLY FOR KACY AND KILG AND
THOSE WILL BE UPDATED AT 7 PM TONIGHT. WE MAY NEED OTHERS LATER
THIS EVENING.

KACY 0.3 - 1960
KILG 3.7 - 1981
KABE 7.0 - 1917
KPHL 8.8 - 1981

FWIW...WATER EQUIVALENCE OF TOTAL SNOW DEPTH IN PORTIONS OF
EASTERN PA IS NOW WELL OVER 3 INCHES.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR
     PAZ060>062-070-071-101>106.
NJ...WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR
     NJZ007>010-012>027.
DE...WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR
     DEZ001>004.
MD...WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR MDZ008-
     012-015-019-020.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR ANZ450>455.

&&

$$
SYNOPSIS...GORSE
NEAR TERM...GAINES
SHORT TERM...GAINES
LONG TERM...GORSE
AVIATION...GAINES/GORSE/O`HARA
MARINE...GORSE/JOHNSON/O`HARA
CLIMATE...DRAG 430P



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