Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KPHI 191436
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1036 AM EDT SUN OCT 19 2014

.SYNOPSIS...
HIGH PRESSURE LOCATED OVER THE OHIO VALLEY EARLY TODAY WILL MOVE
EAST AND CREST OVER THE MIDDLE ATLANTIC REGION MONDAY. THE HIGH WILL
THEN MOVE OFFSHORE MONDAY NIGHT AS LOW PRESSURE APPROACHES FROM THE
GREAT LAKES. THIS LOW WILL MOVE SLOWLY ACROSS THE AREA DURING THE
MIDDLE OF THE WEEK BEFORE MOVING AWAY THURSDAY AND FRIDAY. MORE HIGH
PRESSURE WILL BUILD IN FOR NEXT WEEKEND.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
NOT TOO MUCH CHANGE WITH THIS UPDATE IN TERMS OF PUBLIC PRODUCTS.
ADJUSTED THE WINDS UP A BIT MORE AND ADJUSTED THE SKY COVER
SLIGHTLY TO INCLUDE MORE BREAKS EARLY ON. THE KATABATIC FLOW IS
STARTING TO ERODE THE STRATOCU, SO NO BIG CHANGES TO SKY COVERAGE.

OTHERWISE, THE WRF-NMMB INITIALIZATION LOOKED BETTER AT 500MB
WHILE A COMPROMISE OF BOTH THE WRF AND GFS WORKED BEST AT 850MB
AND 925MB.

IF ANYONE WONDERED WHERE OCTOBER WENT, ITS BACK TODAY. IT WILL
FEATURE A BLUSTERY FALL FEEL TO IT. ONE SHORT WAVE DOWN AND ONE TO
GO THIS MORNING AS THE LONG WAVE TROF CLEARS OUR CWA. CLOUDINESS
ASSOCIATED WITH THE LAST SHORT WAVE IS NOW MOVING ACROSS OUR CWA AND
SHOULD CLEAR THE COAST BY ABOUT 13Z.

THERE IS STILL THE MATTER OF THE NW FLOW OFF OF LAKE ONTARIO.
MESOSCALE MODELS SUGGEST SOME LAKE ENHANCED PCPN MIGHT JUST MAKE IT
INTO OUR POCONO CWA BEFORE DISSIPATING. WE CARRY A CHANCE OF
SPRINKLES/FLURRIES EARLY THERE. AS THE MORNING PROGRESSES, THE FCST
SUBSIDENCE INVERSION LOWERS AND THE CONVECTIVE TEMPS BECOME HARDER
TO REACH. THERE SHOULD BE A PERIOD OF MOSTLY CLOUDY CONDITIONS THIS
MORNING NORTH UNTIL THIS COMES TO FRUITION. LESS CLOUDINESS EXPECTED
ELSEWHERE, ESPECIALLY IN THE SOUTHWEST PART OF OUR CWA. TEMPS HAVE
FOUND A WAY TO OUTDO GUIDANCE AND WHILE LOCAL PROCEDURES SUGGEST
GOING LOWER, WE KEPT CONTINUITY. IT WILL BE BREEZY/BLUSTERY TODAY,
ESPECIALLY DURING THE MID DAY HOURS WHEN MIXING SHOULD BE MAXIMIZED.
PEAK GUSTS BETWEEN 20 AND 30 MPH ARE LIKELY. IF THIS WERE HALLOWEEN,
THE GREAT PUMPKIN WOULD HAVE NO PROBLEM GETTING AIRBORNE.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
FREEZE WARNING AND FROST ADVISORIES HAVE BEEN ISSUED FOR MOST OF OUR
CWA NORTH OF DELMARVA EXCLUDING THE IMMEDIATE PHILADELPHIA AREA.

BASED ON A COMPROMISE OF THE 925MB AND 850MB INITIALIZATION, WE USED
A STRAIGHT STAT GUIDANCE BLEND FOR MINS. WHERE THIS GAVE US
PREDOMINATE MINS OF FREEZING OR LESS IN THE COUNTIES, WE WENT WITH
FREEZE WARNINGS. THE NJ PINE BARRENS FIND A WAY TO RADIATE LIKE THE
BEST OF THEM. HERE WE WENT BELOW STAT GUIDANCE FOR THE FREEZE
WARNING. THE FROST ADVISORY MAINLY SURROUNDS THESE COLDER SPOTS AND
MOST LIKELY TO COME TO FRUITION IN THE MORE RURAL LOW LYING AREAS OF
THOSE COUNTIES INCLUDED. IN DELMARVA, DEW POINTS ARE PREDICTED TO BE
ABOVE CRITICAL LEVELS AND CONFIDENCE TO INCLUDE IS TOO LOW AT THIS
TIME. WE WILL CONTINUE MENTION OF PATCHY FROST IN THE AFD.

WINDS SHOULD DECOUPLE QUICKLY TONIGHT AND TEMPS DROP LIKE A ROCK
DURING THE EVENING. OVERNIGHT A JET STREAK IS PREDICTED TO PASS
ACROSS THE NORTHERN PART OF OUR CWA WITH CIRRUS LEVEL MOISTURE
INCREASING. THERE IS RIDGING PREDICTED ALOFT AND NO PREDICTED OMEGA
AT THE SUB CIRRUS LEVEL. THE COMBINATION LED TO OUR DECISION NORTH
THAT THE CIRRUS MAY NOT BE THICK ENOUGH TO HOLD TEMPS ABOVE
FREEZING.

AS WE MOVE FARTHER SOUTH, THE ENTRANCE REGION TO THAT JET STREAK
ARRIVES LATER AT NIGHT WITH LESS MOISTURE AND LESS TIME TO PREVENT
FROST/FREEZING TEMPS FROM OCCURRING. THIS IS ALSO WHY DELMARVA WILL
BE LOOKED CLOSELY TODAY AS THEY SHOULD HAVE LITTLE CIRRUS OVERNIGHT.
FAR FAR NORTH MIGHT BE SAVED BY THE CIRRUS (CONFIDENCE TOO LOW ABOUT
THAT TO NOT ISSUE A WARNING). BETWEEN THERE SHOULD BE A SWEET SPOT
WHERE DEW POINTS ARE LOW ENOUGH AND THE CIRRUS ARRIVES TOO LATE.
MESOSCALE MODELS SUGGEST THE LEHIGH AND RARITAN VALLEYS.

THIS IS RATHER LATE FOR A FREEZE OR A WIDESPREAD FROST (THERE WAS
SOME FROST INTO THE PHL NW SUBURBS EARLIER THIS MONTH) TO AFFECT OUR
CWA. THE PLUS SIDE IS THAT IF PROTECTIVE MEASURES SUCCEED TONIGHT,
FREEZING OR FROSTY CONDITIONS ARE NOT ON TAP FOR A WHILE.
WE BROUGHT IN OUR MEYER LEMON TREE INDOORS YESTERDAY ANYWAY.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
MONDAY...HIGH PRESSURE WILL BE CRESTING OVER THE AREA DURING THE
MORNING BEFORE MOVING EAST. DRY WEATHER IS EXPECTED...ALTHOUGH
CLOUDS WILL BE INCREASING OVER THE AREA DURING THE DAY. HIGH
TEMPERATURES WILL REMAIN A BIT BELOW NORMAL WITH HIGHS IN THE
LOW/MID 50S NORTH AND MID 50S OT LOW 60S ELSEWHERE.

MON NIGHT THRU TUE NIGHT...LOW PRESSURE AT THE SFC AND A DEEPENING
H5 LOW WILL BE WEST OF THE AREA. THIS WILL BE THE BEGINNING OF A
RATHER EXTENDED PERIOD OF UNSETTLED CONDITIONS ACROSS OUR AREA. THIS
FIRST FEW DAYS WILL BE SHOWERS WITH TEMPERATURES A BIT ABOVE NORMAL.
SLGT CHC POPS MON NIGHT WILL INCREASE TO HIGH CHC/LOW LIKELY POPS BY
TUE NIGHT. HIGHS TUE WILL TOP OUT IN THE LOW/MID 60S NORTH AND
MID/UPPER 60S SOUTH.

WED THRU THU NIGHT...UNSETTLED CONDITIONS CONTINUE WITH THE H5
LOW/TROUGH CROSSING THE AREA WED AND THE SFC LOW JUST AHEAD OF IT.
FREQUENT PERIODS OF CLOUDS AND SHOWERS ARE EXPECTED THROUGH THE
PERIOD. WE HAVE KEPT THE POPS OFFERED BY WPC WHICH ARE MOSTLY HIGH
CHC CATEGORY WED THRU THU...THEN SLGT CHC THU NIGHT. TEMPERATURES
WILL MOSTLY BE BELOW NORMAL WITH HIGHS MOSTLY IN THE 50S.

FRI THRU SAT...HIGH PRESSURE WILL AFFECT THE WEATHER INTO NEXT
WEEKEND. DRY WEATHER IS EXPECTED AT THIS TIME ALONG WITH MILDER
TEMPERATURES. HIGHS ACROSS THE DEL VALLEY AND POINTS SOUTH/EAST WILL
REACH THE LOW 60S FRI/SAT WHILE READINGS ACROSS THE NORTH/WEST WILL
BE IN THE MID 50S TO AROUND 60.

&&

.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
12Z TAFS WILL FEATURE NO BIG CHANGES. WE BUMPED UP WIND GUSTS
SLIGHTLY AND WILL BE ADDING A SOUTHWEST WIND CHANGE GROUP FOR KPHL
FOR MONDAY MORNING.

TODAY...VFR CIGS POSSIBLE AT AIRPORTS MAINLY TO THE NORTH OF
PHILADELPHIA AND INTERSTATE 195 IN NJ. EVEN SOME MVFR CIGS EARLY IN
THE HIGHER TERRAIN. ELSEWHERE MAINLY JUST A SCATTERED DECK OF CU
CLOUDS. NORTHWEST WINDS WILL AVERAGE AROUND 15 KNOTS WITH
GUSTINESS AROUND 25 KNOTS. STAT GUIDANCE IS SUGGESTING THE PEAK
WINDS SHOULD OCCUR BY ABOUT 18Z. CLEARING OR CLEAR SKIES AND
DIMINISHING WINDS TOWARD SUNSET.

SUNDAY NIGHT...VFR WITH LIGHTER NORTHWEST TO WEST WINDS BECOMING
LIGHT AND VARIABLE AT MOST TERMINALS. ANY CLOUDS WILL BE AT CIRRUS
LEVEL AND MORE LIKELY LATER AT NIGHT.

OUTLOOK...
MON AND MON NIGHT...MOSTLY VFR. INCREASING CLOUDS AND PERHAPS A
     FEW SHOWERS MON NIGHT.
TUE THRU THU...UNSETTLED WITH CLOUDS AND FREQUENT SHOWERS. MOSTLY
     VFR BUT OCNL LOWER CONDITIONS EXPECTED IN SHOWERS.

&&

.MARINE...
HAVE ISSUED A SHORT FUSED GALE WARNING THROUGH 3PM FOR THE
DELAWARE BAY AND ADJACENT OCEAN ZONES. STARTING TO SEE WIND GUSTS
AT OR SLIGHTLY BELOW 34 KNOTS THIS MORNING AND DUE TO THE
CONTINUED FUNNELING EFFECT OF THE WINDS DOWN THE BAY, FELT IT WAS
A GOOD IDEA TO HOIST THE FLAGS.

AFTER THE GALES COME DOWN THIS AFTERNOON WE WILL STILL HAVE THE
SMALL CRAFT ADVISORY IN PLACE...THE END TIME FOR THE OCEAN REMAINS
UNCHANGED. IN ALL LOCATIONS, THE GRADIENT WILL WEAKEN DURING THE
EVENING AND OVERNIGHT AND SEAS AND SWELLS ON THE OCEAN SHOULD FALL
BELOW 5 FEET BY MORNING.

OUTLOOK...
MON THRU TUE NIGHT...SUB SCA CONDITIONS. SHOWERS POSSIBLE TUE/TUE
NIGHT. WED THRU FRIDAY...SCA CONDITIONS DEVELOPING WED AND LASTING
INTO FRI.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...FREEZE WARNING FROM 3 AM TO 8 AM EDT MONDAY FOR PAZ054-055-061-
     062.
     FROST ADVISORY FROM 2 AM TO 8 AM EDT MONDAY FOR PAZ060-101>106.
NJ...FREEZE WARNING FROM 3 AM TO 8 AM EDT MONDAY FOR NJZ001-007>010.
     FREEZE WARNING FROM 4 AM TO 8 AM EDT MONDAY FOR NJZ020>022-027.
     FROST ADVISORY FROM 2 AM TO 8 AM EDT MONDAY FOR NJZ012-013-
     015>019-023.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ450>453.
     GALE WARNING UNTIL 3 PM EDT THIS AFTERNOON FOR ANZ430-431-454-
     455.

&&

$$
SYNOPSIS...O`HARA
NEAR TERM...GIGI/HEAVENER
SHORT TERM...GIGI
LONG TERM...O`HARA
AVIATION...GIGI/O`HARA
MARINE...GIGI/HEAVENER/O`HARA






USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.