Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 151947
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
347 PM EDT WED APR 15 2015

.SYNOPSIS...
HIGH PRESSURE WILL BUILD ACROSS THE NORTHEAST TONIGHT INTO THURSDAY.
THE HIGH WILL BUILD OFFSHORE AND TO SEA THURSDAY NIGHT INTO FRIDAY.
A COUPLE OF LOW PRESSURE SYSTEMS ARE FORECAST TO CROSS SOUTHERN
CANADA FRIDAY AND SATURDAY. THIS FIRST IS EXPECTED TO PULL A COLD
FRONT ACROSS THE AREA FRIDAY, THEN THE SECOND IS EXPECTED TO PUSH A
COLD FRONT ACROSS THE AREA SATURDAY. HIGH PRESSURE MAY BRIEFLY
AFFECT THE NORTHEAST SATURDAY NIGHT INTO EARLY SUNDAY, BEFORE A
COMPLEX WEATHER SYSTEM MOVES INTO THE GREAT LAKES AND NORTHEAST
EARLY NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
HIGH PRESSURE LOCATED IN SOUTHEAST CANADA WILL CONTINUE TO RESULT IN
MOSTLY CLEAR SKIES TONIGHT. WINDS WILL DECREASE THIS EVENING WITH
THE LOSS OF DAYTIME HEATING AND MIXING. A RED FLAG WARNING WILL
STILL CONTINUE FOR THE NEXT FEW HOURS UNTIL WIND GUSTS DECREASE. THE
LOWER WINDS WILL ALLOW TEMPERATURES TO FALL FAIRLY QUICKLY THIS
EVENING. HOWEVER, THE AIRMASS ASSOCIATED WITH THE HIGH PRESSURE IS
NOT EXTREMELY CHILLY AND WILL LIMIT HOW FALL TEMPERATURES CAN DROP
TONIGHT. THE COLDEST READINGS WILL BE ACROSS NORTHERN NJ AND THE
POCONOS IN THE MID 30`S WHERE THE FORECAST DOES ALLOW FOR THE MOST
EFFICIENT RADIATIONAL COOLING AND IS COOLER THAN MOST STAT GUIDANCE.
THE GROWING SEASON HAS NOT YET STARTED AT THOSE LOCATIONS. RURAL
AREAS IN EASTERN PA AND THE PINE BARRENS IN SOUTHEAST NJ MAY ALSO
SEE LOWS IN THE UPPER 30`S, JUST A FEW DEGREES TO WARM FOR FROST
CONCERNS ATTM. LOWS WILL BE IN THE LOW TO MID 40`S OUTSIDE OF THESE
AREAS. ANY RECOVERY IN RH VALUES WILL POSSIBLY BE A BIT SLOWER THAN
WHAT THE CURRENT MET/MAV SUGGEST.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
HIGH PRESSURE OFFSHORE OF ATLANTIC CANADA WILL ALLOW FOR A CHANGE THE
WIND DIRECTION FROM NORTHEASTERLY TO SOUTHEASTERLY BY THE AFTERNOON
THURSDAY. OVERALL, IT LOOKS LIKE ANOTHER MOSTLY SUNNY DAY WITH AN
INCREASE IN MID AND HIGH LEVEL CLOUDS LATE AHEAD OF THE NEXT SYSTEM.
WINDS SHOULD STAY UNDER 10-15 MPH FOR THE MOST PART WITH SOME GUSTS
AROUND 15 MPH. THE CHANGE IN WIND DIRECTION WILL ALLOW FOR HIGHER
DEWPOINTS THAN WHAT WE SAW TODAY BUT THE MOISTURE ADVECTION IS
LIKELY TO FAST ON THE MET AND MAV GUIDANCE SETS. ABUNDANT SUNSHINE
WILL ALLOW FOR EFFICIENT WARMING WELL INTO THE 60`S FOR MOST,
SUPPORTED BY 925 MB TEMPS AROUND 8C. MODELED TWO METER TEMPERATURES
LOOK TO COOL HERE.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
TWO LOW PRESSURE SYSTEMS ARE FORECAST TO BE SLIDING ACROSS SOUTHERN
CANADA FRIDAY AND AGAIN SATURDAY. A FRONT ASSOCIATED WITH THE FIRST
LOW PRESSURE SYSTEM IS EXPECTED TO CROSS THE AREA DURING THE DAY
FRIDAY. THERE COULD BE SOME PRECIPITATION START OVERNIGHT THURSDAY
JUST AHEAD OF THE FRONTAL BOUNDARY AS MOISTURE INCREASES AND LIFT IS
ENHANCED WITH THE PASSAGE OF A SHORT WAVE/VORTICITY IMPULSE. MODELS
KEEP PRECIPITATION CHANCES ACROSS THE AREA THROUGH THE FRIDAY AS THE
FRONT PASSES ACROSS THE AREA.

THE SECOND OF THE LOWS IS FORECAST TO BRING A COLD FRONT ACROSS THE
AREA SATURDAY. MODEL GUIDANCE IS INDICATING THIS FRONTAL PASSAGE WILL
BE DRY, SO WE WILL KEEP THE FORECAST DRY SATURDAY.

BRIEF HIGH PRESSURE MAY BRIEFLY BUILD ACROSS THE NORTHEAST SATURDAY
NIGHT INTO THE EARLY PART OF SUNDAY AS THE FRONTAL BOUNDARY STALLS
TO OUR SOUTH. THIS SHOULD KEEP THE WEATHER DRY SATURDAY NIGHT INTO
EARLY SUNDAY.

HOWEVER, THIS DRY WEATHER IS NOT EXPECTED TO LAST LONG AS A COMPLEX
WEATHER SYSTEM IS BEING DEPICTED BY THE GFS AND ECMWF FOR EARLY NEXT
WEEK. THE GUIDANCE IS SHOWING SEVERAL LOW PRESSURE SYSTEMS TO OUR
WEST, ONE ACROSS SOUTHERN CANADA, ONE ACROSS THE DEEP SOUTH, AND ONE
ACROSS THE CENTRAL PLAINS, EVENTUALLY MOVING INTO THE GREAT LAKES
AREA BY SUNDAY NIGHT/EARLY MONDAY AND MERGING INTO ONE LARGE LOW
PRESSURE. THE FRONTAL BOUNDARY TO OUR SOUTH IS EXPECTED TO LIFT BACK
NORTHWARD ACROSS OUR AREA MONDAY INTO MONDAY NIGHT, WHILE ANOTHER
COASTAL LOW MAY DEVELOP ALONG THE FRONT AS IT LIFTS ACROSS THE AREA.
THIS IS EXPECTED TO LEAD TO AN EXTENDED PERIOD OF PRECIPITATION
STARTING AS EARLY AS THE LATTER PART OF SUNDAY AND CONTINUING INTO
MONDAY NIGHT. THE FRONT AND COASTAL LOW WILL SLOWLY LIFT TO OUR NORTH
THROUGH TUESDAY, SO SHOWERS COULD LINGER INTO THE DAY TUESDAY.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD. HIGH CIRRUS
CLOUDS ARE POSSIBLE THROUGH TONIGHT WITH A FEW MID LEVEL CLOUDS ON
THURSDAY. NORTHERLY WIND GUSTS WILL DIMINISH THIS EVENING WITH THE
LOSS OF DAYTIME HEATING. WINDS ARE EXPECTED TO GRADUALLY SHIFT TO
EAST NORTHEASTERLY OVERNIGHT TONIGHT UNDER 10 KNOTS THEN TO EASTERLY
IN THE MORNING FROM 8-10 KNOTS. THE WINDS WILL THEN SHIFT
SOUTHEASTERLY BY THURSDAY AFTERNOON.

OUTLOOK...

THURSDAY NIGHT-FRIDAY...MVFR CONDITIONS POSSIBLE WITH SCATTERED SHOWERS.

FRIDAY NIGHT-SUNDAY..GENERAL VFR CONDITIONS.

SUNDAY NIGHT-MONDAY...CONDITIONS LOWERING TO MVFR OR IFR WITH
RAIN EXPECTED.

&&

.MARINE...
SEAS WILL REMAIN AROUND THREE FEET THROUGH THURSDAY WITH MAXIMUM
WIND GUSTS AROUND 20 KNOTS EARLY THIS EVENING THEN AGAIN THURSDAY
AFTERNOON. THE WINDS WILL SHIFT FROM NORTHERLY TONIGHT TO EASTERLY
BY THURSDAY MORNING THEN SOUTHEASTERLY BY THE AFTERNOON. NO SCA
HEADLINE.

OUTLOOK...
THURSDAY NIGHT-SATURDAY NIGHT...SUB-SMALL CRAFT ADVISORY
CONDITIONS EXPECTED. FRONTAL PASSAGES EXPECTED FRIDAY AND
SATURDAY.

SUNDAY-MONDAY...WINDS MAY APPROACH SMALL CRAFT ADVISORY LEVELS
SUNDAY NIGHT INTO MONDAY, BUT SEAS ARE EXPECTED TO BUILD TO 5
FEET OR MORE OVERNIGHT SUNDAY AND CONTINUE INTO MONDAY.

&&

.FIRE WEATHER...
MINIMUM RELATIVE HUMIDITY VALUES NEAR OR BELOW 20 PERCENT WILL BE
PRESENT INTO THE EARLY EVENING.  MUCH OF DELMARVA AND FAR SOUTHERN
NJ HAD RAIN TOTALS NEAR OR ABOVE 1 INCH YESTERDAY, LEADING TO HIGHER
FUEL MOISTURES. FOR THE REST OF THE REGION HOWEVER, THE LIGHT RAIN
YESTERDAY DID NOT HAVE MADE A SIGNIFICANT IMPACT ACROSS
CENTRAL/NORTHERN NJ AND EASTERN PA ON FUEL MOISTURE AND DRYING OF
THE FUEL MOISTURE WILL CONTINUE INTO THIS EVENING.

AS FOR WINDS, GUSTS AROUND 25 MPH WILL CONTINUE INTO THE FIRST HOUR
OR TWO OF THE EVENING BEFORE QUICKLY DECREASING. WE WILL CONTINUE A
RED FLAG WARNING FOR EASTERN PA, NORTHERN/CENTRAL NJ UNTIL 7 PM DUE
TO A COMBINATION OF LOW MOISTURE IN FINE FUELS, LOW RH 20% OR LOWER
AND WIND GUSTS AROUND 25 MPH.

FOR THURSDAY, THE RELATIVE HUMIDITY VALUES ARE FORECAST TO DROP TO
25-35 PERCENT IN THE AFTERNOON MAINLY FOR NEW JERSEY /AWAY FROM THE
COAST/ AND EASTERN PENNSYLVANIA. TOP WIND GUSTS LOOK TO BE AROUND OR
JUST ABOVE 15 MPH IN THE AFTERNOON. THESE VALUES ARE SHORT OF
MEETING RED FLAG CRITERIA BUT WITH DRY FINE FUELS AN ELEVATED FIRE
RISK STILL MAY STILL BE PRESENTED

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...RED FLAG WARNING UNTIL 7 PM EDT THIS EVENING FOR PAZ054-055-
     060>062-070-071-101>106.
NJ...RED FLAG WARNING UNTIL 7 PM EDT THIS EVENING FOR NJZ001-
     007>010-012>015.
DE...NONE.
MD...NONE.
MARINE...NONE.

&&

$$

SYNOPSIS...ROBERTSON
NEAR TERM...GAINES
SHORT TERM...GAINES
LONG TERM...ROBERTSON
AVIATION...GAINES/ROBERTSON
MARINE...GAINES/ROBERTSON
FIRE WEATHER...GAINES


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