National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS61 KPHI 072336
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
636 PM EST FRI MAR 7 2014

.SYNOPSIS...
A COASTAL LOW PRESSURE SYSTEM WILL CONTINUE TO PULL AWAY FROM THE
REGION LATE TONIGHT. A COLD FRONT WILL THEN CROSS THE AREA FROM
THE NORTHWEST LATE ON SATURDAY INTO SUNDAY MORNING ALLOWING FOR A
RETURN OF HIGH PRESSURE FOR THE START OF THE NEW WORK WEEK. THE
HIGH WILL DEPART TO OUR SOUTH ON TUESDAY WHILE A CLIPPER LIKE
SYSTEM NEARS FROM THE WEST-NORTHWEST. THIS IS FOLLOWED BY THE
POTENTIAL FOR ANOTHER COASTAL LOW PRESSURE SYSTEM TO CROSS THE
REGION LATE WEDNESDAY AND THURSDAY.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF EARLY EVENING...A HIGH PRES RIDGE OVER NEW ENGLAND CONTS TO
WEAKEN WHILE LOW PRES IS DEEPENING OFF THE NC COAST. HI LEVEL CLDS
AND MOISTURE AHEAD OF THE ASSOCD UPPER LOW OFF NC COVER MUCH OF
THE FCST AREA WHILE LOW CLOUDS HAVE SPREAD OVER ERN/SRN PARTS OF
THE AREA ON LOW-LVL NELY FLOW. SFC TEMPS ARE IN THE MID TO UPPER
30S FROM THE POCONOS TO NORTHERN DELMARVA. NELY WINDS ARE NOTED
ACROSS THE AREA AND SPEEDS ARE RELATIVELY LIGHT NW BUT STRONGER SE
TOWARDS THE ATLANTIC COAST. RADAR SHOWS SOME VERY LIGHT RAIN OVER
SERN ZONES.

FOR TONIGHT...THE SFC LOW IS FCST TO CONTINUE A GRADUAL DEEPENING
AS IT MOVES NEWD PAST CAPE HAT AND THEN OUT TO SEA. THE PRES
GRADIENT AROUND THE LOW WILL MAINTAIN A GOOD NELY FLOW THIS
EVENING OVER SRN NJ AND DE...THEN WINDS WILL BACK TO THE N AND
DIMINISH SOME AS THE LOW PRES MOVES AWAY FROM THE MID-ATLANTIC
COAST. ASSOCD PRECIP SHOULD STAY WELL S AND E OF PHL...WITH SRN DE
AND EXTREME SE NJ BEING THE ONLY PLACES LIKELY TO SEE ANY
MEASURABLE RAIN...AND EVEN THOSE AMOUNTS SHOULD BE ONLY A FEW
HUNDREDTHS. AT LEAST PARTIAL CLEARING OF THE SKIES IS EXPECTED
OVERNIGHT WHICH SHOULD ALLOW TEMPS TO FALL INTO THE 20S IN MOST
AREAS.

&&

.SHORT TERM /6 AM SATURDAY THROUGH 6 AM SATURDAY/...
SATURDAY LOOKS LIKE A PRETTY GOOD DAY WITH TEMPS CLOSE TO NORMAL
AND CONSIDERABLE SUNSHINE ESPECIALLY IN THE MORNING. WINDS SHOULD
BE RELATIVELY LIGHT W TO NW. WINDS AT 850MB ARE UP TO 40KT OR SO
BUT THERE APPEARS TO BE AN INVERSION ABOVE 950MB THAT WILL LIMIT
DOWNWARD MIXING DURING THE DAY. CLOUDS WILL INCREASE DURING THE
AFTN AS A COLD FRONT MOVES SEWD INTO NRN NJ AND ADJACENT PA. THERE
IS NOT MUCH MOISTURE WITH THE FRONT BUT WE HAVE PUT IN JUST A
SLIGHT CHC FOR -SHRA/-SHSN OVER THE POCONOS FOR LATE IN THE AFTN.

&&

.LONG TERM /SATURDAY THROUGH FRIDAY/...
THE 5-WAVE MODEL GUIDANCE IS SHOWING WEAK TROUGHING, PSEUDO-ZONAL
FLOW, ACROSS THE REGION AT THE START OF THE PERIOD. BY THE MIDDLE
OF NEXT WEEK WE START TO SEE A RETURN TO A RATHER FAMILIAR, AND
FRANKLY UN-WELCOME PATTERN, RIDGING IN THE WEST, TROUGHING IN THE
EAST. THE FEW BLISSFUL DAYS OF AT OR ABOVE AVERAGE TEMPERATURES
COMES TO HALT AND WINTER ONCE AGAIN TAKES GRASP OF THE REGION. THE
SILVER-LINING IN ALL OF THIS, AT LEAST WE GAIN AN EXTRA HOUR OF
DAYLIGHT ON THE CLOCKS IN THE EVENING...WE ACTUALLY ONLY GAIN A
FEW MINUTES OF ACTUAL DAYLIGHT ASTRONOMICALLY.

GENERALLY SPEAKING THE LATEST 12Z INITIALIZATION LOOKS PRETTY
GOOD OFF THE GFS/NAM/GGEM THOUGH THERE ARE MINOR DIFFERENCES IN
THE THERMAL FIELDS THIS MORNING...THE 12Z EC WAS SLIGHTLY BETTER
THAN THE THREE ABOVE. FOR THE MOST PART THE GUIDANCE SEEMS TO BE
TOO COLD ACROSS THE UPPER MID-WEST AND THE NORTHERN PLAINS AND NOT
FAST ENOUGH WITH THE NEXT COLD FRONT ENTERING INTO THE UPPER
PLAINS. THIS WILL CAUSE ISSUES FOR THE TEMPERATURE FORECASTS
THROUGH THE FIRST HALF OF THE LONG TERM PERIOD AS A PARADE OF
CLIPPER LIKE SYSTEMS SHOULD TRAVERSE CLOSE TO OUR REGION BEFORE
THE MORE ESTABLISHED TROUGHING TAKES OVER.

THE FIRST SUCH SYSTEM WILL TRACK WELL TO THE NORTH OF THE REGION
AND PUSH THROUGH A WEAKENING COLD FRONT LATER ON SATURDAY INTO
SUNDAY MORNING. GUIDANCE IS SHOWING THE LOW-LEVEL TEMPERATURES
CRASHING WITH THE ADVANCEMENT OF THE FRONT WHICH WOULD ALLOW FOR
MORE OF A RAIN/SNOW MIXTURE. THE ISSUE WITH THIS SYSTEM WILL BE
THE AMOUNT OR NO ASSOCIATED ICE WITHIN THE CLOUDS. THERE IS VERY
LIMITED, NEARLY NONE, MOISTURE BEING THAT THE SPLIT FLOW IN THE
MID-LEVELS CONTINUES AND WITH THE LITTLE FORCING ITS NOT LIKELY TO
BE A COLD ENOUGH CLOUD PRODUCER. THAT BEING SAID DECIDED TO ADD IN
SOME FREEZING DRIZZLE ACROSS OUR NORTHERN MOST ZONES WITH A
RAIN/SNOW MIX ELSEWHERE.

SUNDAY WILL BE A COLDER DAY WITH A STIFF NORTHWEST WIND AS
TEMPERATURES FALLING BELOW AVERAGE BEHIND THE FRONT. THE GOOD NEWS
IS THERE SHOULD BE PLENTY OF SUNSHINE AROUND TO MAKE IT NOT FEEL
AS BAD. DID SIDE MORE WITH THE WARMER MAVMOS IN THIS CASE GIVEN
THE ABOVE INFORMATION, THOUGH IT MUST BE NOTED THAT THE 2M
TEMPERATURES OFF THE GFS HAVE BEEN UNDER-PERFORMING THE PAST COUPLE
OF WEEKS...AT LEAST.

MONDAY WE WILL RESTART OUR WARMING TREND WITH RIDGING SLIDE TO
OUR SOUTH AND A NICE RETURN FLOW DEVELOPING. LOW-LEVEL
TEMPERATURES JUMP BACK UP ABOVE FREEZING AND WILL REMAIN THAT WAY
THROUGH AT LEAST THE LATER HALF OF TUESDAY, AHEAD OF THE NEXT
NORTHERN STREAM SYSTEM. BOTH MONDAY AND TUESDAY WILL FEATURE DRY
CONDITIONS AND ABOVE AVERAGE TEMPERATURES.

WE THEN TURN OUR ATTENTION TO LATER ON TUESDAY AS WE WATCH HOW
FAST/SLOW ANOTHER FRONTAL BOUNDARY WILL SHIFT THROUGH THE REGION.
GIVEN THE CURRENT SPEED OF THE NORTHERN STREAM WOULD HAVE TO ERR
ON THE SIDE OF A FASTER MOVEMENT OF THE COLD FRONT THUS DROPPING
IT THROUGH OUR REGION ON TUESDAY EVENING. THE NEXT BIG ISSUE
BECOMES HOW THE MID-LEVEL TROUGHING PROGRESSES THROUGH THE MID-
WEST AND INTO THE EASTERN U.S. BY MID-WEEK.

THERE IS RELATIVELY GOOD CONSENSUS FROM THE MID-RANGE MODEL
PACKAGE THROUGH ABOUT TUESDAY, AND THEN WE START TO SEE THE
GFS/GGEM/EC PART WAYS WITH THE SPEED AND DEEPENING OF THE TROUGH.
TO PUT IT SIMPLY, WE ARE WILL BE IN MID-MARCH WITH SPLIT FLOW
STILL ALOFT AND WE NEED A DEEP THERMAL TROUGH TO CHANGE THAT WITH
PHASING OF NORTHERN AND SOUTHERN STREAM SYSTEMS. WE THEN NEED TO
ROBUST WAVE TO DEVELOP ALONG THE FRONTAL BOUNDARY THAT JUST MOVED
THROUGH TO DRAG IN ENOUGH COLD AIR AND THEN SLING THE SOUTHERN
STREAM MOISTURE OVERHEAD. MUCH LIKE THE LAST EVENT, MARCH 2-3,
THERE ARE A LOT OF MOVING PARTS THAT NEED TO FALL IN-LINE FOR MORE
SNOW.

WHAT DOES HAVE SOMEWHAT HIGHER CONFIDENCE IS THE OCCURRENCE OF A
LOW PRESSURE MOVING BY/THROUGH THE REGION WEDNESDAY INTO THURSDAY
PRODUCING PRECIPITATION. THAT BEING SAID WENT WITH A WPC APPROACH
FOR POPS AND RAIN/SNOW MIXTURE FOR THE TIME BEING.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

KRDG AND KABE...VFR THROUGH THE TAF PERIOD. A LIGHT AND VARIABLE
WIND TONIGHT SHOULD BECOME WEST NORTHWEST AROUND 4 TO 8 KNOTS ON
SATURDAY.

KPHL/KPNE/KTTN/KILG...MAINLY MVFR CEILINGS LIFTING TO VFR
CEILINGS AROUND 0300Z TO 0400Z. THE VFR CEILINGS SHOULD CLEAR
AROUND 0700Z TO 0800Z WITH A MAINLY CLEAR SKY THEREAFTER. A NORTH
WIND AROUND 10 KNOTS SHOULD BECOME NORTHWEST OVERNIGHT, THEN WEST
NORTHWEST ON SATURDAY.

KACY AND KMIV...CEILINGS NEAR THE MVFR/IFR BOUNDARY LIFTING
SLOWLY DURING THE NIGHT. THE CLOUDS SHOULD CLEAR AROUND 0900Z TO
1000Z FOLLOWED BY VFR CONDITIONS THROUGH THE BALANCE OF THE TAF
PERIOD. A NORTH WIND AROUND 10 TO 12 KNOTS SHOULD BECOME NORTHWEST
OVERNIGHT THEN WEST NORTHWEST ON SATURDAY.

OUTLOOK...
SATURDAY NIGHT - SUNDAY...MOSTLY VFR. LIGHT RAIN/SNOW SHOWERS
POSSIBLE EARLY SUNDAY MORNING NORTH OF RDG...MAYBE SOME PATCHY
FREEZING DRIZZLE LATE SATURDAY NIGHT.

MONDAY - TUESDAY...VFR.

TUESDAY NIGHT - THURSDAY...MVFR OR LOWER IN SCATTERED SHOWERS.
INCREASING CHANCES FOR MORE RAIN/SNOW WEDNESDAY INTO THURSDAY WITH
SUB-VFR CONDITIONS LIKELY.

&&

.MARINE...
A SFC LOW OFF THE NC COAST IS FCST TO CONTINUE GRADUALLY
DEEPENING AS IT MOVES NEWD AND OUT TO SEA OVERNIGHT. THE SFC PRES
GRADIENT AND ASSOCD WINDS WILL BE STRONGEST OVER THE COASTAL
WATERS OF SRN NJ AND DE...AND SO A GALE WARNING REMAINS IN EFFECT
FOR THAT AREA. THE STRONGEST GUSTS SHOULD OCCUR THIS
EVENING...THEN WINDS WILL DIMINISH OVERNIGHT AND WILL BACK FROM NE
TO N TO NW BY SAT MORN. ELSEWHERE A SCA REMAINS IN EFFECT EXCEPT
FOR UPPER DEL BAY.

THE SUSTAINED NE FLOW HAS CAUSED SEAS TO BUILD TO 10 FT AT BUOY
44009 AND SOME FURTHER INCREASE IS POSSIBLE THIS EVENING. HIGHEST
SEAS DURG THE EVE SHOULD BEGIN TO SUBSIDE OVERNIGHT...BUT WILL
REMAIN ELEVATED THROUGH THE DAY ON SATURDAY. A SCA WILL LIKELY
NEED TO CONT FOR COASTAL WATERS...EVEN AFTER WINDS DIMINISH

OUTLOOK...
SUNDAY - TUESDAY...SUB-SCA CONDITIONS ARE EXPECTED AT THIS TIME.
WINDS BECOME MORE NORTHWESTERLY BEHIND A COLD FRONT ON SUNDAY.

TUESDAY NIGHT - THURSDAY...INCREASING CHANCES FOR A COASTAL LOW
PRESSURE TO NEAR LATER ON WEDNESDAY. SEAS AND WINDS WILL INCREASE
WITH THIS LOW. SCA CONDITIONS LOOKS VERY POSSIBLE.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EST SATURDAY FOR ANZ450>452.
     GALE WARNING UNTIL MIDNIGHT EST TONIGHT FOR ANZ453>455.
     SMALL CRAFT ADVISORY UNTIL 6 AM EST SATURDAY FOR ANZ431.

&&

$$

SYNOPSIS...HEAVENER
NEAR TERM...AMC
SHORT TERM...AMC
LONG TERM...HEAVENER
AVIATION...IOVINO/HEAVENER
MARINE...AMC/HEAVENER