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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPHI 011423
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
923 AM EST SUN MAR 1 2015

.SYNOPSIS...
HIGH PRESSURE LOCATED OVER OUR REGION EARLY THIS MORNING WILL
DRIFT OUT TO SEA TODAY. A DEVELOPING COLD FRONT IS FORECAST TO
APPROACH FROM THE NORTHWEST AND IT SHOULD PASS THROUGH OUR AREA
EARLY ON MONDAY MORNING. HIGH PRESSURE IS EXPECTED TO FOLLOW FOR
MONDAY AFTERNOON INTO EARLY TUESDAY. LOW PRESSURE IS ANTICIPATED
TO MOVE ACROSS THE GREAT LAKES ON TUESDAY AFTERNOON AND TUESDAY
EVENING, THEN DOWN THE SAINT LAWRENCE RIVER VALLEY FROM LATE
TUESDAY NIGHT INTO WEDNESDAY MORNING. THE LOW IS FORECAST TO PULL
A COLD FRONT SLOWLY THROUGH OUR REGION ON WEDNESDAY. WEAK LOW
PRESSURE IS EXPECTED TO RIDE ALONG THE FRONT ON THURSDAY BEFORE
HIGH PRESSURE BUILDS INTO OUR AREA FROM THE WEST FOR FRIDAY INTO
SATURDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SNOW HAS ARRIVED ACROSS THE WESTERN COUNTIES AND IT WILL CONTINUE
TO OVERSPREAD THE AREA. THE PRECIP ACROSS THE DELMARVA WILL BEGIN
AS SNOW BUT WILL CHANGE TO SLEET SOON AFTER. WE MAY HAVE TO
RECONSIDER P-TYPE QPF AMTS OVER THE DELMARVA FOR POSSIBLE WSW
UPGRADE.

LOW/MID- LEVEL MOISTURE IS INCREASING ACROSS THE AREA, AN AREA OF
ENHANCED LIFT SLIDES ACROSS THE AREA. TEMPERATURES AT THE SURFACE
AND ALOFT WILL BE COLD ENOUGH FOR THE PRECIPITATION TO START OUT
AS SNOW ACROSS THE AREA. HOWEVER, AS WARM AIR ABOVE THE SURFACE
MOVES IN THROUGH THE DAY, PRECIPITATION WILL CHANGE OVER TO SLEET
THEN FREEZING RAIN ACROSS MUCH OF THE AREA. THIS OCCURS WHEN THE
HEAVIEST PRECIPITATION IS EXPECTED TO MOVE INTO THE AREA AS WELL.
WE ARE BECOMING MORE CONCERNED WITH THE POTENTIAL FOR MORE ICE TO
OCCUR ACROSS PORTIONS OF OUR AREA, ESPECIALLY THE I-95/I-295
CORRIDOR. FOR THESE AREAS, ICE AMOUNTS OF 1/4-1/3 OF AN INCH OF
ICE IS POSSIBLE, ALONG WITH AN INCH OR TWO OF SNOW/SLEET.
THEREFORE, WE HAVE UPGRADED THESE AREAS TO A WINTER STORM WARNING
DUE TO THE INCREASED ICE EXPECTATION.

AREAS TO THE SOUTH AND NORTH OF THE WARNING ARE EXPECTED TO GET
UP TO 1/10-2/10 OF AN INCH OF ICE ALONG WITH AN INCH OF SNOW FOR
SOUTHERN AREAS AND 3-4 INCHES FOR NORTHERN AREAS. THE EXCEPTIONS
TO THIS WOULD BE ACROSS FAR SOUTHERN DELAWARE WHERE JUST A FEW
HUNDREDTHS OF AN INCH OF ICE AND A LIGHT DUSTING OF SNOW MAY OCCUR
AND FAR NORTHEAST PENNSYLVANIA AND NORTHWEST NEW JERSEY WHERE THEY
WILL LIKELY REMAIN ALL SNOW AND GET 4-5 INCHES OF SNOW. THE WINTER
WEATHER ADVISORY REMAINS IN PLACE FOR ALL AREAS OUTSIDE OF THE
WINTER STORM WARNING.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
THE WINTER STORM WARNINGS/WINTER WEATHER ADVISORIES REMAIN IN
PLACE ACROSS THE AREA INTO THIS EVENING AS WINTRY PRECIPITATION IS
EXPECTED TO BE ONGOING; THE ONLY CHANGE WAS TO ADJUST THE END TIME
FOR THE SOUTHERN AREAS. AS A DEVELOPING FRONTAL BOUNDARY MOVES
ACROSS THE AREA OVERNIGHT, THE ENHANCED LOW/MID-LEVEL MOISTURE AND
LIFT WILL BE MOVING TO OUR EAST AS WELL. PRECIPITATION IS EXPECTED
TO COME TO AN END FROM WEST TO EAST DURING THE OVERNIGHT HOURS AND
ALL PRECIPITATION SHOULD BE ENDING BETWEEN MIDNIGHT AND DAYBREAK.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
IT CONTINUES TO APPEARS AS THOUGH WE WILL SEE A BREAK IN THE
PRECIPITATION FOR MONDAY INTO EARLY TUESDAY AS HIGH PRESSURE FROM
THE WEST BUILDS ACROSS OUR REGION. A GUSTY NORTHWEST WIND IS
ANTICIPATED FOR MONDAY AND TEMPERATURES SHOULD REMAIN ABOUT 10
DEGREES BELOW NORMAL FOR MONDAY AND MONDAY NIGHT.

HIGH CLOUDS SHOULD BEGIN TO OVERSPREAD OUR REGION FROM THE WEST
AND SOUTHWEST LATE ON MONDAY NIGHT. MID LEVEL CLOUDS ARE FORECAST
TO FOLLOW ON TUESDAY MORNING. PRECIPITATION IS EXPECTED TO ARRIVE
IN OUR REGION FOR TUESDAY AFTERNOON. THE FORECAST TEMPERATURE
PROFILES SUGGEST A MIX OF SNOW AND SLEET AT THE START, EXCEPT
PERHAPS IN OUR FAR SOUTH WHERE THE PRECIPITATION MAY BEGIN AS
RAIN.

STRONG WARM ADVECTION IS EXPECTED TO TAKE PLACE ALOFT FROM
TUESDAY AFTERNOON INTO TUESDAY EVENING. A TRANSITION FROM MIXED
PRECIPITATION TO RAIN WILL LIKELY WORK ITS WAY NORTHWARD THROUGH
OUR REGION. THE PRECIPITATION TYPE IS FORECAST TO BECOME RAIN
ALONG THE INTERSTATE 95 CORRIDOR DURING THE EVENING HOURS. THE MIX
OF SNOW AND ICE SHOULD LINGER INTO THE OVERNIGHT HOURS IN OUR FAR
NORTHERN COUNTIES. HOWEVER, EVEN THE POCONOS AND SUSSEX COUNTY,
NEW JERSEY SHOULD TRANSITION TO RAIN BY DAYBREAK ON WEDNESDAY AS
TEMPERATURES RISE GRADUALLY THROUGHOUT OUR REGION ON TUESDAY
NIGHT.

SNOWFALL TOTALS IN OUR NORTHERN COUNTIES SHOULD BE SOMEWHAT
LIMITED DUE TO THE MIX OF SLEET AND FREEZING RAIN. ICING MAY BE
THE MORE SIGNIFICANT PROBLEM THERE.

THE RAIN MAY BECOME MODERATE TO HEAVY AT TIMES. THE 0000 UTC RUN
OF THE NAM IS BRINGING FROM A HALF INCH TO AN INCH TO OUR REGION
FROM LATE TUESDAY INTO TUESDAY NIGHT. THE 0000 UTC GFS HAS A RANGE
OF AN INCH TO AN INCH AND A HALF. THE 0000 UTC ECMWF IS A BIT
LOWER THAN THE NAM. BEING THE THE GFS HAS BEEN RUNNING HIGH IN ITS
PRECIPITATION FORECASTS OF LATE, WE WILL FAVOR THE NAM/ECMWF
SOLUTION. SNOW MELT ALONG WITH ICE MOVEMENT ON AREA WATERWAYS
COULD COMBINE WITH THE RAINFALL TO CREATE SOME FLOODING ISSUES.
THE POTENTIAL IS ADDRESSED IN THE HYDROLOGY SECTION OF THE
FORECAST DISCUSSION.

A COLD FRONT IS FORECAST TO MOVE SLOWLY THROUGH OUR REGION ON
WEDNESDAY AND ITS PROGRESS MAY BE SLOWED BY A WAVE OF LOW PRESSURE
RIDING ALONG THE BOUNDARY. AS A RESULT, CLOUDS AND PRECIPITATION
MAY LINGER THROUGH WEDNESDAY NIGHT AND INTO THURSDAY, ESPECIALLY
IN OUR SOUTHERN COUNTIES. THERE COULD BE ADDITIONAL MODERATE
RAINFALL ACROSS THE SOUTH ON WEDNESDAY AND THE PRECIPITATION MAY
BEGIN TO CHANGE BACK TO SNOW, MAINLY IN THE NORTH FROM WEDNESDAY
NIGHT INTO THURSDAY.

ANOTHER ARCTIC HIGH IS EXPECTED TO BUILD ACROSS OUR REGION FROM
THE WEST AND NORTHWEST FOR FRIDAY INTO SATURDAY.

&&

.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

TAFS ARE ALL VFR THIS MORNING, BUT THIS WILL CHANGE THROUGH THE
DAY. CLOUDS WILL INCREASE AND THICKEN THROUGH THE MORNING, AND
EVENTUALLY BECOME MVFR AS LIGHT SNOW MOVES INTO THE AREA BY
MIDDAY. AS THE SNOW CONTINUES, CIGS AND VSBYS ARE EXPECTED TO
LOWER TO IFR. PRECIPITATION IS EXPECTED TO CHANGE OVER TO SLEET
THEN FREEZING RAIN BY THIS AFTERNOON AND CONTINUE INTO THE NIGHT.
IFR CONDITIONS WILL PERSIST INTO THE OVERNIGHT, BEFORE POSSIBLY
IMPROVING TO MVFR BY DAYBREAK.

WINDS ARE FAIRLY LIGHT AND VARIABLE THIS MORNING, BUT WILL BECOME
MORE SOUTHEAST-SOUTH THROUGH THE MORNING INTO THE AFTERNOON INTO
THE EVENING. AS A FRONTAL BOUNDARY APPROACHES THEN MOVES THROUGH
THE AREA OVERNIGHT, WINDS WILL BECOME SOUTHWEST-WEST. ALL SPEEDS
ARE EXPECTED TO REMAIN BELOW 10 KNOTS THROUGH TONIGHT, BEFORE
INCREASING TOWARD DAYBREAK MONDAY.

OUTLOOK...

MONDAY...CONDITIONS IMPROVING TO VFR IN THE MORNING.

MONDAY NIGHT...MAINLY VFR.

TUESDAY...CONDITIONS LOWERING TO MVFR AND IFR IN THE AFTERNOON,
AS SNOW AND SLEET BUILD INTO OUR REGION.

TUESDAY NIGHT...MVFR AND IFR CONDITIONS WITH A WINTRY MIX OF
PRECIPITATION CHANGING TO RAIN FROM SOUTH TO NORTH. THE RAIN MAY
BE MODERATE TO HEAVY AT TIMES. LOW LEVEL WIND SHEAR IS POSSIBLE
DUE TO A SOUTHWESTERLY LOW LEVEL JET THAT IS FORECAST TO DEVELOP
OVERHEAD.

WEDNESDAY...MVFR AND IFR CONDITIONS IN RAIN. THE RAIN MAY BE
MODERATE TO HEAVY AT TIMES, ESPECIALLY SOUTH OF KPHL.

WEDNESDAY NIGHT...MVFR AND IFR CONDITIONS IN RAIN, POSSIBLY
MIXING WITH OR CHANGING TO SNOW TO THE NORTH OF KPHL.

THURSDAY...CONDITIONS IMPROVING GRADUALLY TO VFR WITH A LESSING
CHANCE OF PRECIPITATION THROUGH THE DAY.

&&

.MARINE...
SUB-SMALL CRAFT ADVISORY CONDITIONS CONTINUE TODAY ACROSS THE
WATERS AS HIGH PRESSURE PULLS TO OUR EAST. WINDS DO INCREASE AS
THE PRESSURE GRADIENT TIGHTENS BETWEEN THE HIGH AND AN APPROACHING
FRONTAL BOUNDARY. HOWEVER, THEY DO NOT INCREASE TO ADVISORY LEVELS
UNTIL DAYBREAK MONDAY BEHIND THE FRONTAL BOUNDARY.

OUTLOOK..

MONDAY AND MONDAY NIGHT...A SMALL CRAFT ADVISORY IS IN EFFECT DUE
TO THE EXPECTED GUSTY NORTHWEST WIND. LIGHT FREEZING SPRAY IS
POSSIBLE, ESPECIALLY ON MONDAY NIGHT.

TUESDAY...NO MARINE HEADLINES ARE ANTICIPATED.

TUESDAY NIGHT AND WEDNESDAY...A SMALL CRAFT ADVISORY MAY BE
NECESSARY DUE TO A GUSTY SOUTH TO SOUTHWEST WIND.

WEDNESDAY NIGHT AND THURSDAY...NO MARINE HEADLINES ARE
ANTICIPATED.

&&

.HYDROLOGY...
TWO PRECIPITATION EVENTS ARE EXPECTED OVER THE NEXT 5 DAYS, ONE
TODAY INTO TONIGHT AND A SECOND ONE DURING THE MID WEEK PERIOD.

THE INITIAL EVENT LOOKS TO BE ONE WITH A WINTRY MIX OF
PRECIPITATION. THE SECOND EVENT APPEARS TO BE MAINLY RAIN WITH
TEMPERATURES RISING WELL ABOVE FREEZING ON WEDNESDAY. ALTHOUGH THE
SECOND EVENT IS A FEW DAYS AWAY, WE WANT TO HIGHLIGHT THAT SOME
OF THE MODEL GUIDANCE IS SUGGESTING LOCALLY HEAVY RAINFALL.

THE COMBINATION OF A BRIEF WARM-UP ON WEDNESDAY, LOCALLY HEAVY
RAINFALL, MELTING SNOW, A FROZEN GROUND, AND ABOVE NORMAL ICE IN
CREEKS, STREAMS, AND RIVERS COULD LEAD TO INCREASED RUNOFF AND
POSSIBLE FLOODING. WHERE THE DEPTH OF THE SNOWPACK IS GREATEST (IN
NE PA AND N NJ), RAPID SNOWMELT IS NOT EXPECTED SINCE TEMPS WILL
NOT RISE AS SHARPLY AS IN AREAS TO THE SOUTH.

INCREASED FLOW 0N AREA CREEKS, STREAMS, AND RIVERS COULD ALSO
START TO MOVE ICE, AND IN A WORST CASE SCENARIO, CREATE
RESTRICTIONS OR JAMS.

AGAIN, THE SECOND EVENT BRINGING WARMTH AND RAIN IS A FEW DAYS
AWAY AND THINGS CAN CHANGE. CONTINUE TO MONITOR THE FORECAST.
KEEP IN MIND THAT SNOWMELT AND WARMTH BY THEMSELVES TYPICALLY
DO NOT CAUSE FLOODING. THE AMOUNT OF RAIN THAT WE RECEIVE WILL BE
THE DETERMINING FACTOR.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...WINTER WEATHER ADVISORY UNTIL 4 AM EST MONDAY FOR PAZ054-055-
     060>062-105.
     WINTER STORM WARNING UNTIL 4 AM EST MONDAY FOR PAZ070-071-
     101>104-106.
NJ...WINTER WEATHER ADVISORY UNTIL 4 AM EST MONDAY FOR NJZ001-
     007>010.
     WINTER WEATHER ADVISORY UNTIL 1 AM EST MONDAY FOR NJZ014-021-
     022-025-026.
     WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR
     NJZ023-024.
     WINTER STORM WARNING UNTIL 4 AM EST MONDAY FOR NJZ012-013-
     015>020-027.
DE...WINTER WEATHER ADVISORY UNTIL 1 AM EST MONDAY FOR DEZ002.
     WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR
     DEZ003-004.
     WINTER STORM WARNING UNTIL 4 AM EST MONDAY FOR DEZ001.
MD...WINTER WEATHER ADVISORY UNTIL 1 AM EST MONDAY FOR MDZ015.
     WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR
     MDZ019-020.
     WINTER STORM WARNING UNTIL 4 AM EST MONDAY FOR MDZ008-012.
MARINE...SMALL CRAFT ADVISORY FROM 6 AM MONDAY TO 2 AM EST TUESDAY FOR
     ANZ430-431-450>455.

&&

$$
SYNOPSIS...IOVINO
NEAR TERM...ROBERTSON
SHORT TERM...ROBERTSON
LONG TERM...IOVINO
AVIATION...IOVINO/ROBERTSON
MARINE...IOVINO/ROBERTSON
HYDROLOGY...