Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 202308
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
608 PM EST THU NOV 20 2014

.SYNOPSIS...
A COLD FRONT WILL SHIFT TO OUR EAST TONIGHT, THEN HIGH PRESSURE
FROM THE LOWER OHIO VALLEY WILL BUILD INTO OUR AREA LATER FRIDAY.
THE HIGH WILL MOVE OFFSHORE SATURDAY, THEN A WARM FRONT LIFTS
ACROSS OUR AREA SUNDAY NIGHT AND MONDAY AS A STRONG LOW PRESSURE
SYSTEM TRACKS INTO THE GREAT LAKES REGION. A COLD FRONT IS
FORECAST TO MOVE THROUGH LATER MONDAY NIGHT AND TUESDAY, FOLLOWED
BY HIGH PRESSURE LATE WEDNESDAY AND THURSDAY.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
A COLD FRONT WAS SLOW TO MOVE THROUGH OUR REGION TODAY. TONIGHT
WINDS WILL BE MORE NORTHWESTERLY WITH ANOTHER SHOT OF ARCTIC AIR
ENTERING THE REGION. A DRY AIR MASS WILL CONTINUE TO PREVENT ANY
CHANCES FOR PRECIPITATION. FOR TEMPERATURES, STARTED WITH LAV
GUIDANCE THROUGH THE EVENING SINCE IT HAS A BETTER HANDLE ON
RECENT TEMPERATURE TRENDS. WENT AT OR A TOUCH COOLER IN SPOTS WITH
LOWS, SUSTAINED WINDS ARGUE FOR WARMER LOWS BUT THE DEGREE OF THE
AIR MASS MAY BE UNDERESTIMATED BY STAT GUIDANCE.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
HIGH PRESSURE WILL MOVE FROM THE OHIO VALLEY INTO OUR REGION
THROUGHOUT THE DAY. CONTINUED DRY WITH MOSTLY SUNNY SKIES OUTSIDE
OF THE POCONOS AND NW NJ. NORTHWEST FLOW WILL CONTINUE WITH SOME
MOISTURE OFF THE GREAT LAKES POSSIBLY INTERACTING WITH THE HIGHER
TERRAIN AREAS. MAINTAINING SOME SCATTERED FLURRIES IN THE GRIDS
FOR NW NJ AND THE POCONOS. MODELED TWO METER TEMPERATURES AND
850/925 MB TEMPS ALONG WITH MET AND MAV GUIDANCE SETS SHOW OUR
REGION ONLY HAVING THE POTENTIAL FOR HIGHS IN THE MID 30`S ON
FRIDAY. GIVEN THE STRONG CAA, THAT SEEMS REASONABLE.

&&

.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
THE OVERALL SYNOPTIC SETUP FEATURES A PATTERN CHANGE, WHICH IS A
RESULT OF ENERGY DRIVING ACROSS THE SOUTHWESTERN U.S. FRIDAY NIGHT
WHICH EJECTS INTO THE SOUTHERN PLAINS SATURDAY. THIS WILL ALLOW
DOWNSTREAM RIDGING TO PUSH EASTWARD AS AN UPPER-LEVEL TROUGH LIFTS
OUT OF THE EAST. THE SOUTHERN ENERGY LOOKS TO AMPLIFY AN UPPER-
LEVEL TROUGH ACROSS THE CENTRAL PORTION OF THE NATION EARLY NEXT
WEEK, WITH THE POTENTIAL FOR A DEEP CYCLONE TRACKING UP ACROSS THE
GREAT LAKES REGION. THIS TROUGH EVENTUALLY ARRIVES IN THE EAST
LATE TUESDAY AND WEDNESDAY, ALTHOUGH IT MAY DEAMPLIFY INTO
THURSDAY. WE USED A MODEL BLEND OVERALL FOR FRIDAY NIGHT THROUGH
SUNDAY, THEN THE 12Z WPC GUIDANCE THEREAFTER. SOME ADJUSTMENTS
WERE MADE FOLLOWING ADDITIONAL COLLABORATION WITH OUR SURROUNDING
OFFICES.

FOR FRIDAY NIGHT AND SATURDAY...A PATTERN CHANGE GETS UNDERWAY AS
A STRONG UPPER-LEVEL TROUGH LIFTS OUT OF THE NORTHEAST THROUGH
FRIDAY NIGHT. AS THIS OCCURS, STRONG HIGH PRESSURE AT THE SURFACE
IS FORECAST TO SETTLE NEARLY RIGHT OVER THE MID ATLANTIC FRIDAY
NIGHT BEFORE SHIFTING OFFSHORE DURING SATURDAY. THIS SHOULD RESULT
IN GOOD RADIATIONAL COOLING CONDITIONS FRIDAY NIGHT. AS THE UPPER-
LEVEL TROUGH DEPARTS, THE FLOW IS FORECAST TO START BACKING
ALLOWING WAA TO GET UNDERWAY. THIS RIBBON OF WAA ALONG WITH AN
INCREASE IN THE FLOW JUST TO OUR NORTHWEST ESPECIALLY WILL TEAM UP
WITH A WEAKENING SURFACE FRONTAL BOUNDARY. THIS THERMAL BOUNDARY
IS MORE DEFINED AROUND 850 MB THOUGH AND THERE APPEARS TO BE
ENOUGH LIFT TO GENERATE SOME LIGHT QPF AROUND THE GREAT LAKES.
SOME OF THIS MAY SETTLE SOUTHEASTWARD DURING SATURDAY NIGHT BEFORE
WEAKENING. GIVEN THE WARMING ALOFT, ANY LIGHT QPF THAT CAN GET TO
OUR FAR NORTH/NORTHWEST ZONES COULD BE A LITTLE FREEZING RAIN.
THIS LOOKS LIKE A LOW PROBABILITY ATTM ALONG WITH LOW CONFIDENCE
AND THEREFORE KEPT POPS AT 30 PERCENT OR LESS. THE SOUTHWESTERLY
FLOW ALONG WITH THE WAA WILL ALLOW SOME MODERATION IN THE SURFACE
TEMPERATURES SATURDAY, ALTHOUGH THERE SHOULD ALSO BE HIGH
CLOUDINESS AROUND.

FOR SUNDAY AND MONDAY...AN AMPLIFYING UPPER-LEVEL TROUGH ACROSS
THE PLAINS AND MIDWEST WILL DRIVE A DEEPENING SURFACE LOW INTO THE
GREAT LAKES REGION LATE SUNDAY AND MONDAY. DOWNSTREAM, INCREASING
WAA AND THETA-E ADVECTION WILL COMBINE WITH AN AREA OF LARGE SCALE
LIFT TO PRODUCE SOME RAIN. THIS WILL BE WITH A WARM FRONT LIFTING
NORTH SUNDAY NIGHT AND MONDAY. THIS SHOULD BE AIDED BY AN
INCREASING LOW-LEVEL JET, AND IT IS POSSIBLE THAT SOME CONVECTIVE
ELEMENTS DEVELOP WITHIN THE OVERRUNNING REGIME WITH A WARMER AND
MORE MOIST AIR MASS SURGING NORTHWARD. AS THE DEEPENING SURFACE LOW
TRACKS ACROSS THE GREAT LAKES MONDAY, A COLD FRONT SHOULD ARRIVE
IN OUR AREA LATE. HOWEVER, A DRY SLOT LOOKS TO OVERSPREAD OUR AREA
DURING MONDAY THEREFORE AFTER SOME EARLY RAIN THE CHC OF LINGERING
SHOWERS LOOKS ON THE LOW SIDE. WE CARRIED CATEGORICAL POPS SUNDAY
NIGHT, THEN THESE TAPER DOWN RAPIDLY AROUND DAYBREAK MONDAY. GIVEN
THE STRONG LOW-LEVEL FLOW AND WAA, A SURGE IN THE SURFACE
TEMPERATURES ARE ANTICIPATING WITH SOME AREAS NEARING 70 DEGREES
FOR A TIME DESPITE BEING THE SECOND HALF OF NOVEMBER. THE RECORD
HIGHS FOR MONDAY ARE MAINLY IN THE UPPER 60S TO LOWER 70S, AND IF
WE CAN GET ENOUGH SUNSHINE AND MIX DECENTLY THEN SOME SPOTS COULD
HAVE A SHOT AT THESE RECORDS.

FOR TUESDAY THROUGH THURSDAY...A COLD FRONT IS FORECAST TO BE
SHIFTING GRADUALLY OFFSHORE AND THIS WILL ALLOW CAA TO KICK IN AS
THE UPPER-LEVEL TROUGH ARRIVES. THE ACTUAL TROUGH AXIS LOOKS TO
REMAIN TO OUR WEST, AND THIS COULD SLOW THE FRONT DOWN AS IT EASES
OFFSHORE. SOME SHORT WAVE ENERGY ROUNDING THE BASE OF THE TROUGH
MAY INDUCE A SURFACE LOW ALONG THE FRONT. THIS FEATURE HOWEVER
LOOKS TO TRACK OFFSHORE THOUGH TUESDAY INTO WEDNESDAY. WE MOSTLY
FOLLOWED THE 12Z WPC POPS DURING THIS TIME FRAME.

THERE BECOMES MORE UNCERTAINTY WITH THE UPPER-LEVEL TROUGH MOVING
ACROSS THE EAST, DUE TO WHAT OCCURS ACROSS THE WEST. SOME GUIDANCE
SHOWS A MUCH STRONGER TROUGH DIGGING ACROSS THE EAST LATE
WEDNESDAY AND THURSDAY. AS OF NOW, WE WENT MUCH CLOSER TO THE 12Z
WPC GUIDANCE WHICH FAVORED A BLEND OF CONTINUITY AND THE ECMWF
MEAN FOR WEDNESDAY AND THURSDAY.

&&

.AVIATION /23Z THURSDAY THROUGH TUESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD WITH A MAINLY
CLEAR SKY.

A WEST NORTHWEST WIND TONIGHT SHOULD FAVOR THE 8 TO 12 KNOT
RANGE. THE WIND IS FORECAST TO INCREASE TO 10 TO 15 KNOTS FOR THE
DAYLIGHT HOURS ON FRIDAY WITH GUSTS INTO THE 20S.

OUTLOOK...
FRIDAY NIGHT AND SATURDAY...VFR, WITH SOME INCREASE IN HIGH LEVEL
CLOUDS LATE SATURDAY. NORTHWEST WINDS LESS THAN 10 KNOTS FRIDAY
NIGHT BECOMING SOUTHWEST, THEN SOUTHWEST AROUND 10 KNOTS DURING
THE DAY SATURDAY.

SUNDAY AND MONDAY...VFR FOR AWHILE SUNDAY WITH AN INCREASE IN
CLOUDS, THEN CEILINGS LOWERING TO MVFR /POTENTIALLY IFR/ SUNDAY
NIGHT INTO MONDAY AS A PERIOD OF RAIN MOVES ACROSS THE AREA. THE
CEILINGS MAY IMPROVE TO VFR DURING MONDAY ALTHOUGH A FEW SHOWERS
MAY LINGER. SOUTHWESTERLY WINDS MAY GUST TO AROUND 20 KNOTS EACH
AFTERNOON. A PERIOD OF LOW-LEVEL WIND SHEAR MAY OCCUR SUNDAY NIGHT
INTO MONDAY AS A LOW-LEVEL SOUTHERLY JET AROUND 50 KNOTS MOVES
THROUGH.

TUESDAY...MOSTLY VFR WITH A SHOWER POSSIBLE ESPECIALLY CLOSER TO
THE COAST AS A COLD FRONT SHIFTS OFFSHORE. THE WINDS BECOMING
WEST-SOUTHWEST.

&&

.MARINE...
SEAS WILL CONTINUE TO BE AT OR OVER FIVE FEET THROUGH A GOOD
PORTION OF FRIDAY. ONCE AGAIN THE POTENTIAL IS PRESENT FOR GUSTY
WEST TO NORTHWEST TO INCREASE TONIGHT TO AROUND 35 KNOTS WITH THE
HIGHEST CHANCE FROM 07-11Z. SOME UNCERTAINTY IS PRESENT IN EXACTLY
WHEN THE WINDS WILL START TO SLACKEN OFF BETWEEN 12 AND 16Z
FRIDAY. GIVEN THE UNCERTAINTY WILL ONLY HAVE THE GALE WARNING GO
TO 12Z FRIDAY ATTM.

OUTLOOK...
FRIDAY NIGHT AND SATURDAY...SOME GUSTS NEAR 25 KNOTS FRIDAY
EVENING, THEN GENERALLY THE CONDITIONS ARE ANTICIPATED TO BELOW
SMALL CRAFT ADVISORY CRITERIA. AN INCREASING SOUTHERLY FLOW
HOWEVER MAY ALLOW WIND GUSTS TO NEAR 25 KNOTS SATURDAY NIGHT.

SUNDAY AND MONDAY...A STRONG SOUTH-SOUTHWEST LOW-LEVEL JET IS
FORECAST TO MOVE ACROSS THE AREA SUNDAY NIGHT INTO MONDAY. THIS
WILL BE ASSOCIATED WITH A WARMER AIR MASS THAT IS MOVING IN, WHICH
TENDS TO NOT ALLOW FOR A FAVORABLE MIXING SETUP. THEREFORE, KEPT
GUSTS BELOW GALE CRITERIA. GIVEN THE SOUTHWESTERLY FLOW, DID GO
BELOW WAVEWATCH BY ABOUT A FOOT AS IT TENDS TO OVERDO THE SEAS
WITHIN THIS FLOW REGIME.

TUESDAY...THE WINDS ARE ANTICIPATED TO BE BELOW ADVISORY
CRITERIA, AND THE SEAS SHOULD BE SUBSIDING BELOW 5 FEET.

&&

.TIDES/COASTAL FLOODING...
A STRONG OFFSHORE FLOW WILL DEVELOP OVER THE AREA AS THE COLD
FRONT MOVES OFF THE COAST. THIS FLOW WILL CREATE LOW WATER
CONDITIONS ALONG THE COAST AND ASSOCIATED INLETS TONIGHT THROUGH
FRIDAY AFTERNOON. THERE IS EVEN SOME CONCERN FOR BLOWOUT TIDES
NEAR THE TIME OF LOW TIDE...WHICH TONIGHT OCCURS WITHIN AN HOUR
EITHER SIDE OF MIDNIGHT ALONG THE COAST...AND LATER TONIGHT IN THE
DELAWARE BAY. DBOFS AND CBOFS INDICATE WATER LEVELS GETTING WITHIN
A TENTH OF A FOOT OR SO OF BLOWOUT CONDITIONS (MINUS 1.8 FEET
MLLW), WHILE ETSURGE GUIDANCE IS NOT NEARLY AS AGGRESSIVE. BASED
ON THE FACT THAT ONE MODEL IS JUST BARELY BRINGING US TO BLOWOUT
CONDITIONS AND ANOTHER ISN`T SO CLOSE, WE WILL HOLD OFF ON ANY
STATEMENTS AT THIS POINT IN TIME. WE WILL OBVIOUSLY BE WATCHING
THE SITUATION THIS EVENING AND ISSUE LATER STATEMENTS, IF
NECESSARY.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...GALE WARNING FROM MIDNIGHT TONIGHT TO 7 AM EST FRIDAY FOR
     ANZ431-450>455.
     SMALL CRAFT ADVISORY UNTIL 6 PM EST FRIDAY FOR ANZ430.

&&

$$

SYNOPSIS...GORSE
NEAR TERM...GAINES
SHORT TERM...GAINES
LONG TERM...GORSE
AVIATION...IOVINO/GORSE
MARINE...GAINES/GORSE
TIDES/COASTAL FLOODING...MIKETTA






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