Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 051531
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1031 AM EST THU MAR 5 2015

.SYNOPSIS...
A COUPLE OF WAVES OF LOW PRESSURE WILL TRACK SOUTHEAST OF THE
REGION TODAY AND THIS EVENING. A HIGH PRESSURE SYSTEM WILL
MOVE INTO THE REGION ON FRIDAY AND THEN SINK TO THE SOUTHEAST ON
SATURDAY. A WEAK CLIPPER TYPE LOW PRESSURE SYSTEM SHOULD PASS
NORTH OF THE AREA ON SATURDAY NIGHT FOLLOWED BRIEFLY BY ANOTHER
HIGH PRESSURE SYSTEM ON SUNDAY. A COLD FRONT SHOULD PASS THROUGH THE
REGION ON MONDAY. ANOTHER HIGH PRESSURE SYSTEM SHOULD THEN BUILD
INTO THE AREA ON TUESDAY AND WEDNESDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SNOW IS IN PROGRESS ACROSS THE REGION WITH AREAS ACROSS SOUTHEAST
NJ AND THE SOUTHERN DELMARVA CHANGING FROM SLEET AND RAIN TO SNOW
IN THE NEXT FEW HOURS. THE BACK EDGE OF THE SNOW IS APPROACHING
THE NORTHWEST PARTS OF THE REGION. CAA WILL CONTINUE TO PUSH INTO
THE REGION BEHIND A COLD FRONT WITH A CONTINUING STREAM OF
OVERRUNNING MOISTURE. TEMPERATURES WILL CONTINUE TO DROP TODAY
ACROSS THE AREA AND ONLY A FEW ADJUSTMENTS WERE MADE WITH THE 9:30
AM UPDATE. PRECIPITATION SHOULD END VERY SLOWLY FROM NORTH TO
SOUTH THIS AFTERNOON. WIND GUSTS AROUND 20 MPH HAVE ALSO BEEN
REPORTED IN SPOTS AND THESE WERE INCREASED WITH THE 9:30 AM
UPDATE.

ONTO SNOW AMOUNTS IN THE ADVISORY AREA A FEW INCHES HAVE ALREADY
FALLEN WITH THE POTENTIAL FOR SOME ADDITIONAL ACCUMULATION WITH
TOTALS STILL LOOKING TO AVERAGE UNDER WARNING CRITERIA.

*WE UPGRADED THE LEHIGH VALLEY AND SURROUDING AREA TO A WINTER
 STORM WARNING WITH A 10:30 AM UPDATE. WE HAVE ALREADY GOTTEN
 REPORTS OF 3-5 INCHES WITH ANOTHER BAND OF MODERATE SNOW MOVING
 INTO THE AREA FOR THE LATE MORNING AREAS. NAM HAS AN ADDITIONAL.1-.25
 QPF WHICH WOULD PUSH TOTALS TO AROUND 6 INCHES OF SNOW.*


FURTHER SOUTH TOWARD THE PHILADELPHIA METRO AREA MODERATE TO
HEAVY SNOW BANDS HAVE SETUP ACROSS THIS REGION WITH REPORTS OF 1
TO AS MUCH AS 2 INCHES PER HOUR FOR SHORT INTERVALS. THE RAP AND
HRRR BOTH INDICATE THAT THESE MESOSCALE BANDS WILL BE SOMEWHAT
PROGRESSIVE BUT CONTINUE THROUGHOUT THE DAY TODAY. THESE BANDS ARE
CAUSED BY SIGNIFICANT FRONTGENETICAL FORCING AND AMPLE ISENTROPIC
LIFT. STORM TOTALS OF 6-8 INCHES STILL LOOK ON TRACK ATTM. ALSO
PLEASE REFER TO MCD 124 FROM THE SPC AND THE SPS WE HAVE IN
EFFECT.

IN THE DELMARVA AND SOUTHEAST NJ, THE 9:30 AM UPDATE SLOWS THE
CHANGEOVER AN HOUR OR SO. HOWEVER STILL DO NOT THINK THIS WILL CUT
INTO TOTALS EXTENSIVELY ATTM. THIS IS DUE TO THE SAME MESOSCALE
BANDING SIGNATURES SINKING FURTHER SOUTH FOR THE AFTERNOON HOURS.
THIS IS PICKED UP WELL BY THE RAP, HRRR AND 06Z 800-600 MB
FRONTGENETICAL FORCING ON THE 06Z NAM FROM EARLIER TODAY.
SNOWFALL MAY ALSO FALL AROUND AN INCH FOR A TIME THIS AFTERNOON
LEADING TO 4-8 INCHES OF SNOW BY EVENING.

ROAD CONDITIONS WILL CONTINUE TO DETERIORATE TODAY WITH THE SNOW,
ALLOW EXTRA TIME IF YOU HAVE TO TRAVEL.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
THE LAST OF THE STEADY SNOWS WILL PASS EAST OF THE FORECAST AREA
THIS EVENING. SKIES WILL BE CLOUDY EARLY THEN THE CLOUDS WILL BREAK
UP FROM N/W TO S/E OVERNIGHT. THE LACK OF CLOUDS LATE AND THE FRESH
SNOW COVER SHOULD PRODUCE COLD TEMPS OVERNIGHT...WITH LOWS IN THE
SINGLE DIGITS AND A FEW SUB-ZERO READINGS FAR NORTH. WIND CHILLS MAY
DROP TO NEAR -12 TO -15 ACROSS MOUNT POCONO...BUT REMAIN MORE LIKE 0
TO -10 ELSEWHERE. WINDS WILL BE MOSTLY NRLY AT 5 TO 10 MPH.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
THE GFS INITIALIZATION LOOKED SLIGHTLY BETTER THERMALLY, BUT IT
WAS A COLD OP RUN IN COMPARISON TO ITS ENSEMBLE MEAN AND OTHER
MODELS. OVERALL AFTER TODAY, THE LONG TERM IS RELATIVELY QUIET
WITH TEMPERATURES RETURNING TO NEAR NORMAL VALUES AND NOT MUCH
PCPN EXPECTED.

A BRIGHT SUNNY DAY IS EXPECTED ON FRIDAY WITH NOT MUCH WIND. THE
ONE CATCH IS THAT TEMPERATURES WILL BE WELL BELOW AVERAGE, EVEN
IF IT WERE STILL JANUARY. MAX TEMPS ARE CLOSE TO THE FULL SUN
MACROS AND THE HIGHER NAM STAT GUIDANCE.

ON FRIDAY NIGHT WE CONTINUED THE IDEA OF GOING EITHER WITH THE LOWER
STAT GUIDANCE IN URBAN AREAS OR BELOW ALL FOR MINS GIVEN WE ARE
EXPECTING RADIATIONAL COOLING CONDITIONS. THERE IS A SHORT WAVE
TROF THAT MIGHT SPILL SOME CLOUDS THROUGH PART OF THE NIGHT, ONLY
REASON WE DID NOT GO EVEN LOWER.

SATURDAY THE AIR MASS RECOVERY WILL START AS A HIGH PRESSURE SYSTEM
REACHES THE COAST. THERE SHOULD BE MORE CLOUDS AROUND ASSOCIATED
WITH THE WAA PHASE OF THE CLIPPER WHICH SHOULD SLOW TEMP RISE A
BIT. WE ARE CLOSER TO NAM STAT GUIDANCE FOR MAX TEMPS AS BY NOW
THE GEFS MEAN IS WARMER THAN THE OP GFS.

ON SATURDAY NIGHT, CONTINUED WITH THE IDEA THAT THE WEAKENING
CLIPPER MIGHT BRING SOME SNOW SHOWERS TO THE NORTHERN PART OF OUR
CWA. PRECIPITATION INTENSITY AS OF NOW APPEARS LIGHT IF THEY MAKE
IT. SUNDAY, THE MODERATION TREND IS EXPECTED TO CONTINUE AS THE
CLIPPER`S DEMISE SHOULD NOT BRING ANY COLDER AIR BACK INTO THE
REGION.

A NORTHERN STREAM COLD FRONT COULD BRING THE CHANCE OF SHOWERS BACK
INTO THE AREA ON MONDAY AND BY THEN IT MIGHT BE WARM ENOUGH FOR THE
PTYPE TO FALL AS RAIN. A SOUTHERN STREAM LOW PRESSURE SYSTEM IS
EXPECTED TO REMAIN SEPARATE WITH ITS PREDICTED PCPN FOR NOW
REMAINING SOUTHEAST OF OUR AREA.

THEN A HIGH PRESSURE SYSTEM ENTERING FROM THE PACIFIC OCEAN
(INSTEAD OF TAKING THE POLAR ROUTE) FOR A CHANGE IS EXPECTED TO
BRING TEMPERATURES CLOSE TO SEASONAL LEVELS FOR TUESDAY AND
WEDNESDAY.

&&

.AVIATION /16Z THURSDAY THROUGH MONDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

CONDITIONS WILL CONTINUE TO DETERIORATE THIS MORNING WITH
CIGS/VSBYS IN THE IFR/LIFR RANGE IN SNOW. THE CHANGE- OVER WILL
OCCUR BY 15Z AT ACY WITH MOST LOCATIONS SEEING SNOW WELL INTO THE
AFTERNOON. SOME LOWER VSBYS AROUND 1/4 MILE COULD BE OBSERVED AS
WELL LOCALLY FOR SHORT INTERVALS, WHICH WERE NOT INCLUDED IN THE
TAFS. ALSO, ISOLATED WIND GUSTS AROUND 20 KNOTS ARE POSSIBLE
TODAY BUT COVERAGE LOOKS LOW ENOUGH NOT TO MENTION IN TAFS ATTM.
IMPROVEMENT TO MVFR IS POSSIBLE AFTER 20Z WITH VFR CONDITIONS
AROUND 00-03Z AS CLOUDS CLEAR. RUNWAY SNOW ACCUMULATION IS
POSSIBLE TO LIKELY TODAY.


OUTLOOK...
FRIDAY THROUGH SATURDAY...PRIMARILY VFR.

SATURDAY NIGHT...SOME MVFR CIGS POSSIBLE, MAINLY NORTH ALONG
WITH A LOW CHANCE OF SNOW SHOWERS.

SUNDAY AND SUNDAY NIGHT...PRIMARILY VFR.

MONDAY...PRIMARILY VFR, LOCALLY MVFR IN SHOWERS.

&&

.MARINE...
WE WILL KEEP THE SCA FLAG FOR TODAY...AND EXTEND THE EXPIRATION TIME
INTO TONIGHT. WINDS AND SEAS WILL INCREASE ACROSS THE WATERS AS CAA
CONTINUES. IT APPEARS THAT GUSTS IN THE 25 TO 30 KNT RANGE ARE
POSSIBLE ACROSS THE OCEAN WATERS AND AROUND 20 KTS ACROSS DEL BAY.
THERE WILL BE RAIN/SNOW EARLY TODAY...THEN SNOW INTO THE AFTERNOON.
FAIR WEATHER EXPECTED TONIGHT.

OUTLOOK...
FRIDAY AND FRIDAY NIGHT...CONDITIONS SHOULD RETURN TO
SUB SMALL CRAFT ADVISORY LEVELS. FREEZING SPRAY IS LIKELY, NOT
CONFIDENT ENOUGH ABOUT MODERATE FREEZING SPRAY OCCURRING ON
FRIDAY MORNING TO ISSUE AN ADVISORY.

SATURDAY THROUGH MONDAY...SUB SMALL CRAFT ADVISORY CONDITIONS
ARE OUTLOOKED TO PREVAIL MAINLY DUE A COMBINATION OF RELATIVELY
WEAK PRESSURE SYSTEMS AND ALSO WHERE THERE WILL BE STRONGER WINDS
ABOVE THE BOUNDARY LEVEL, IT SHOULD BE AT TIMES WHEN THE
AIR TEMPS WILL BE HIGHER THAN THE WATER TEMPS.

&&

.HYDROLOGY...
WITH THE TRANSITION BACK TO SNOW TODAY (IF NOT ALREADY), THE
HYDROLOGICAL CONCERNS AT LEAST IN THE NEAR TERM ARE LESSENING.
WE ARE STILL MONITORING GAGED SITES TO CHECK FOR JAMS.

&&

.CLIMATE...
CLIMATE: WITH A SNOWCOVER IN PLACE AND ANOTHER MODIFIED 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

ASIDE FROM ATLANTIC CITY, MOST LOCATIONS ARE FORECASTED TO BE
SEVERAL DEGREES WARMER THAN THE RECORD LOWS FOR SATURDAY MORNING.

RECORD DAILY SNOWFALL FOR THURSDAY MARCH 5

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

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR
     PAZ060>062-070-071-101>106.
     WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ054-
     055.
NJ...WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR
     NJZ007>010-012>027.
     WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR NJZ001.
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...GIGI
NEAR TERM...GAINES
SHORT TERM...O`HARA
LONG TERM...GIGI
AVIATION...GAINES/GIGI
MARINE...GIGI/O`HARA
HYDROLOGY...
CLIMATE...



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