Area Forecast Discussion
Issued by NWS Upton, NY

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000
FXUS61 KOKX 200438
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
1238 AM EDT MON OCT 20 2014

.SYNOPSIS...
HIGH PRESSURE BUILDS TO THE SOUTH THIS MORNING...THEN OFF THE MID
ATLANTIC COAST LATER TODAY. LOW PRESSURE WILL THEN APPROACH FROM
THE GREAT LAKES TONIGHT. SECONDARY LOW PRESSURE DEVELOPS NEAR THE
MID-ATLANTIC COAST BY LATE TUESDAY...THEN SLOWLY MEANDERS TO THE
GULF OF MAINE BY FRIDAY MORNING...THEN TO THE CANADIAN MARITIME
PROVINCES BY SATURDAY MORNING. A COLD FRONT APPROACHES FROM THE
NORTHWEST SATURDAY...THEN CROSSES THE AREA SATURDAY NIGHT. HIGH
PRESSURE BUILDS IN FROM SOUTH CENTRAL CANADA SUNDAY.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
MEAN TROF RESIDES ACROSS THE EASTERN U.S. AS IT ONCE AGAIN WILL
RELOAD WITH SHORT WAVE ENERGY ACROSS THE UPPER MIDWEST...CARVING
OUT ANOTHER AMPLIFIED TROF ACROSS THE GREAT LAKES AND OHIO VALLEY
STATES BY TONIGHT. PRIOR TO THAT TIME...RIDGING BOTH ALOFT AND
AT THE SFC MOVES INTO THE AREA THIS MORNING. WINDS WILL DIMINISH
WITH THE APPROACH OF THE HIGH.

THE COMBINATION OF A LIGHT W/NW FLOW LATE...MAINLY CLEAR
SKIES...AND A DRY AIR MASS WILL ALLOW INTERIOR LOCATIONS TO DROP
TO AROUND FREEZING AND MOST OTHER LOCATIONS OUTSIDE OF METRO NY
INTO THE UPPER 30S. FREEZE WARNINGS AND FROST ADVISORIES REMAIN UP
FOR MOST LOCATIONS WITH THE EXCEPTION OF NYC METRO AND WESTERN LI.
THE AVERAGE FIRST AUTUMN FREEZE IS OCTOBER 21 FOR THE
INTERIOR...SO THIS RIGHT ON TIME FROM A CLIMATOLOGICAL
PERSPECTIVE. MOST LOCATIONS WILL BE ABOUT 5 TO 10 DEGREES BELOW
NORMAL. THE MAIN FORECAST CHALLENGE THOUGH REMAINS THE AMOUNT OF
HIGH CLOUDS PRECLUDING SFC HEAT TO RADIATE...AND THE AIR MASS
PERHAPS BEING JUST DRY ENOUGH TO LIMIT FROST FORMATION.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/...
HIGH PRESSURE WILL MOVE OFF THE MID ATLANTIC COAST TODAY WITH A
RETURN SW FLOW...WHILE LOW PRESSURE DROPS SE ACROSS THE GREAT
LAKES. THERE IS SOME UNCERTAINTY WITH THE OPAQUENESS OF THE MID AND
HIGH LEVEL CLOUDS AND THE AMOUNT OF SUN FILTERING THROUGH.
CONDITIONS WILL LIKELY START OFF PARTLY TO MOSTLY SUNNY...BUT
BECOME MOSTLY CLOUDY LATE AS MID LEVEL CLOUDS FILTER IN FROM THE
WEST. HIGHS WILL BE A TOUCH WARMER WITH A SW FLOW...BUT A
SUBSIDENCE INVERSION WILL INHIBIT DEEP MIXING...WITH HIGH ONLY IN
THE MID AND UPPER 50S.

FOR TONIGHT...WEAK LIFT AND DEEPENING MOISTURE MAY RESULT IN SOME
SHOWER ACTIVITY AFTER MIDNIGHT. RAINFALL AMOUNTS WILL BE LIGHT.
HEIGHTS BEGIN TO FALL LATE AT NIGHT IN RESPONSE TO THE APPROACHING
LONGWAVE TROF TO THE WEST.

LOWS WILL BE CONSIDERABLY WARMER DUE TO THE CLOUD COVER AND SW
FLOW...WITH MOST LOCATIONS 45 TO 50.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
MODELS START OUT IN SOLID AGREEMENT ON OVERALL PATTERN...AND MOST
DETAILS ON TUESDAY...BUT THEN BEGIN TO DIVERGE LATTER IN THE
WEEK...ESPECIALLY ON THE HANDLING OF SYSTEMS TO THE WEST OF THE
CUTOFF LOW THAT EXITS TO OUR NORTHEAST LATE THIS WEEK. USED A BLEND
OF ALL AVAILABLE GUIDANCE THROUGH FRIDAY NIGHT...THEN LEANED TOWARDS
THE ECMWF FOR SATURDAY THROUGH SUNDAY. I USED THIS BLEND LATE IN THE
PERIOD DUE TO THE ECMWF BETTER RUN TO RUN CONSISTENCY...THE GEFS
ENSEMBLES SUPPORTING A LESS PROGRESSIVE PATTERN...ESPECIALLY WITH
REGARDS TO THE LARGE AMPLITUDE RIDGE TO OUR WEST...AND BETTER
HISTORICAL VERIFICATION OF THE ECMWF IN THIS TIME FRAME.

THE WEATHER WILL BE UNSETTLED FROM TUESDAY INTO AT LEAST FRIDAY AS A
CUTOFF LOW INITIALLY TRACKS TO OUR S...THEN MEANDERS NEAR US DURING
THE MIDDLE OF THE WEEK...THEN SLOWLY LIFTS TO THE NORTHEAST TO THE
CANADIAN MARITIMES BY THE WEEKEND. HOWEVER...WITH THE CUTOFF LOW SO
CLOSE TO THE REGION...WOULD NOT EXPECT CONTINUOUS PRECIPITATION
DURING THIS TIME FRAME. ISENTROPIC LIFT OF ANY SIGNIFICANCE APPEARS
TO HOLD OFF UNTIL TUESDAY NIGHT...SO ONLY FORECASTING A CHANCE OF
SHOWERS ON TUESDAY - EXCEPT LIKELY W 1/3 OF CWA CLOSER TO CLOSED
LOW. THEN HAVE RAIN LIKELY TUESDAY NIGHT-WEDNESDAY IN RESPONSE TO
DECENT ISENTROPIC LIFT - ULTIMATELY WILL LIKELY END UP BEING PERIODS
OF RAIN IN THIS TIME FRAME...LINGERING LIKELY POPS INTO WEDNESDAY
NIGHT AS BEST ISENTROPIC LIFT TRANSITIONS EAST WITH FORECAST TRACK
OF SURFACE LOW. HAVE LIKELY POPS ON THURSDAY ACROSS NORTHERN ZONE IN
RESPONSE TO LIKELY LOCATION OF DEFORMATION AXIS AS CLOSED LOW BEGINS
TO LIFT TO THE NE. THEN LINGER CHANCE POPS INTO FRIDAY AS THE LOW
LIFTS FARTHER NE.

FOR NOW GOING DRY FRIDAY NIGHT-SUNDAY...AS APPEARS WILL BE LIMITED
LOW LEVEL MOISTURE AVAILABLE FOR PASSING COLD FRONT/NORTHERN STREAM
TROUGH TO ACT ON SATURDAY NIGHT...WITH WEAK RIDGING AHEAD OF THE
TROUGH. SHOULD THEN HAVE A DRY NW FLOW ON THE BACKSIDE OF THE
TROUGH.

FOR HIGHS ON TUESDAY USED A BLEND OF MAV/MET/ECS GUIDANCE WITH NAM
2-METER TEMPERATURES AND A MIX DOWN FROM 925-875 HPA PER BUFKIT
SOUNDINGS. EXPECT HIGHS TO BE NEAR TO SLIGHTLY ABOVE NORMAL. A BLEND
OF MAV AND MET GUIDANCE WITH NAM 2-METER TEMPERATURES WAS USED FOR
LOWS TUESDAY NIGHT WITH READINGS FORECAST TO BE 5 TO 10 DEGREES
ABOVE NORMAL. ON WEDNESDAY A BLEND OF MEX/MEN/EKD/ECE/ECM/WPC
GUIDANCE WITH NAM 2-METER TEMPERATURES AND A MIX DOWN FROM 950 HPA
PER BUFKIT SOUNDINGS WAS USED FOR HIGHS. EXPECT VALUES TO BE AROUND
5 DEGREES BELOW NORMAL.

FROM WEDNESDAY NIGHT THROUGH SUNDAY A BLEND OF
MEX/MEN/EKD/ECE/ECM/WPC GUIDANCE WAS USED FOR TEMPERATURES. LOWS
WILL RUN SLIGHTLY ABOVE NORMAL IN THIS TIME FRAME...AND AFTER
SLIGHTLY BELOW NORMAL HIGHS ON THURSDAY...HIGHS WILL RUN NEAR TO
SLIGHTLY ABOVE NORMAL AS WELL FRIDAY THROUGH SUNDAY.

IT SHOULD BE NOTED THAT HIGHS ON SUNDAY COULD END UP BEING SOME 5-10
DEGREES COLDER THAN FORECAST IF THE ECMWF VERIFIES - IN RESPONSE TO
SHALLOW LOW LEVEL COLD ADVECTION BEHIND THE COLD FRONT.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE OVER THE TERMINALS REMAINS THROUGH THE OVERNIGHT
AND THEN MOVES OFF THE MID ATLANTIC COAST MONDAY MORNING. LOW
PRESSURE APPROACHES FROM THE NORTHWEST MONDAY AFTERNOON WITH A
WARM FRONT MOVING THROUGH LATE IN THE DAY.

VFR. THERE COULD BE SOME SPRINKLES WEST OF THE TERMINALS LATE IN
THE DAY.

NORTHWEST WIND LESS THAN 10 KT BACKS TO WEST OVERNIGHT. THE WIND
CONTINUES TO BACK TO THE SOUTHWEST MONDAY MORNING AND THEN WILL BE
NEARLY SOUTHERLY LATE IN THE AFTERNOON. SPEEDS INCREASE TO AROUND
10 KT DURING THE DAY.

.OUTLOOK FOR 00Z TUESDAY THROUGH FRIDAY...
.MONDAY NIGHT THROUGH THURSDAY...MVFR OR LOWER CONDS IN RAIN. BEST
CHANCES TUESDAY THROUGH WEDNESDAY.
.FRIDAY...IMPROVING CONDS. NW WINDS 15-20 KT WITH 20-25 KT GUSTS.

&&

.MARINE...
AS WINDS DIMINISH...CONDITIONS WILL IMPROVE ACROSS THE WATERS
EARLY THIS MORNING. HIGH PRESSURE BUILDS IN FROM THE WEST WITH A
DIMINISHING NW FLOW...AND SWELLS FROM DISTANT HURRICANE GONZALO
CONTINUE TO DIMINISH. HIGH PRESSURE WILL THEN PASS OFF THE MID
ATLANTIC COAST TODAY WITH A RETURN SW FLOW. CONDITIONS ARE FORECAST
TO REMAIN BELOW SCA CRITERIA THROUGH THE DAY AND INTO TONIGHT.

SUB-SMALL CRAFT CONDITIONS ARE MOST LIKELY ON ALL WATERS TUESDAY
THROUGH FRIDAY. WIND GUSTS SHOULD BE AROUND 20 KT FROM WEDNESDAY
INTO THURSDAY NIGHT...AND COULD POSSIBLY REACH 25 KT MAINLY ON THE
COASTAL OCEAN WATERS IN THIS TIME FRAME. ALSO...SEAS ON THE COASTAL
OCEAN WATERS EAST OF MORICHES INLET COULD REACH 5 FT ON
WEDNESDAY...AND POSSIBLY ON THE REMAINDER OF THE COASTAL OCEAN
WATERS FROM WEDNESDAY NIGHT INTO THURSDAY NIGHT.

FOR NOW THERE IS TOO MUCH UNCERTAINTY TO FORECAST SMALL CRAFT
CONDITIONS DURING THE MIDDLE OF THE WEEK..EXCEPT FOR THE SCA LEVEL
SEAS EAST OF MORICHES INLET ON WEDNESDAY.

&&

.HYDROLOGY...
THERE IS THE POTENTIAL FOR AROUND AN INCH OF RAIN FROM TUESDAY INTO
THURSDAY. BECAUSE THIS WILL BE SPREAD OVER AROUND 48 HOURS...THERE
DOES NOT APPEAR TO BE AN SIGNIFICANT HYDROLOGIC IMPACT EXPECTED AT
THIS TIME.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...FROST ADVISORY UNTIL 8 AM EDT THIS MORNING FOR CTZ009>012.
     FREEZE WARNING UNTIL 8 AM EDT THIS MORNING FOR CTZ005>008.
NY...FROST ADVISORY UNTIL 8 AM EDT THIS MORNING FOR NYZ069-070-
     079>081.
     FREEZE WARNING UNTIL 8 AM EDT THIS MORNING FOR NYZ067-068.
NJ...FROST ADVISORY UNTIL 8 AM EDT THIS MORNING FOR NJZ004-103-105-
     107.
     FREEZE WARNING UNTIL 8 AM EDT THIS MORNING FOR NJZ002.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EDT EARLY THIS MORNING FOR
     ANZ350-353.

&&

$$
SYNOPSIS...MALOIT/DW
NEAR TERM...JM/DW/PW
SHORT TERM...DW
LONG TERM...MALOIT
AVIATION...MET
MARINE...MALOIT/DW/PW
HYDROLOGY...MALOIT/DW







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