Area Forecast Discussion
Issued by NWS Upton, NY

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000
FXUS61 KOKX 230021
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
721 PM EST THU JAN 22 2015

.SYNOPSIS...
HIGH PRESSURE BUILDS IN THROUGH FRIDAY. IT THEN MOVES OFF THE MID
ATLANTIC COAST FRIDAY NIGHT AS A RAPIDLY DEEPENING LOW EMERGES FROM
THE GULF COAST STATES. THE LOW WILL TRACK TO THE MID ATLANTIC COAST
SATURDAY MORNING...PASSING SOUTH AND EAST OF SOUTHERN NEW ENGLAND
SATURDAY NIGHT. HIGH PRESSURE BRIEFLY BUILDS BEHIND THE DEPARTING LOW SUNDAY.
ANOTHER AREA OF LOW PRESSURE TRACKS TO THE SOUTH MONDAY...AND TRACKS
WELL TO THE EAST TUESDAY. HIGH PRESSURE BUILDS IN FOR THE MID WEEK
PERIOD.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
WEAK NORTHERN STREAM SHORTWAVE MOVES EAST THROUGH THE REGION TONIGHT
WITH HIGH PRESSURE BUILDING IN FROM THE WEST TONIGHT.

FORECAST IS GENERALLY ON TRACK. LOWERED LOWS ON LI AND NYC A FEW
DEGREES AS TEMPS ARE ALREADY DROPPING QUICKLY UNDER CLEAR SKIES
AND LIGHT WINDS.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
MAIN FOCUS WILL BE QUICK MOVING BUT INTENSE LOW PRESSURE AFFECTING
THE REGION LATE FRIDAY NIGHT INTO SATURDAY EVENING.

FRI WILL THE TRANQUIL WITH INCREASING CLOUDS LATE AND NEAR
SEASONABLE TEMPS.

MODELS IN GOOD GENERAL AGREEMENT WITH UPPER LOW OVER THE SW US
SLIDING EAST THROUGH SATURDAY...INTERACTING WITH THE NORTHERN STREAM
ON SATURDAY. SIMILARLY MODELS IN GOOD GENERAL AGREEMENT WITH LOW
PRESSURE DEVELOPING ALONG THE GULF COAST FRIDAY AND THEN QUICKLY
TRACKING NE FRIDAY NIGHT TOWARDS THE MID-ATLANTIC...AND THEN NEAR
THE 40/70 LAT/LON BENCHMARK SATURDAY EVENING.

SOME DIFFERENCES EXIST BETWEEN MODELS IN AMOUNTS OF PHASING BETWEEN
THE NORTHERN AND SOUTHERN STREAM AND RESULTANT SHORTWAVE
INTENSIFICATION AS IT PIVOTS THROUGH OUR REGION...BUT IN GENERAL
LATEST OPERATIONAL RUNS ARE A BIT WEAKER WITH THE UPPER ENERGY AND A
LITTLE BIT MORE PROGRESSIVE. THIS POINTS TO AN INTENSE BUT QUICK
MOVING SYSTEM.

WITH NO HIGH TO THE NORTH OF THE REGION...A MARGINALLY COLD AIRMASS
WILL BE IN PLACE...WITH P-TYPE STRONGLY PREDICATED ON DISTANCE FROM
LOW AND UPPER DYNAMICS AND BANDING. THERMAL PROFILES LOOKS COLD
ENOUGH FOR A START AS SNOW FOR ALL AREAS LATE FRIDAY NIGHT/EARLY
SATURDAY MORNING. BUT AS INTENSIFYING LOW PRESSURE APPROACHES FROM
THE SW SAT MORN/AFT...AN EASTERLY 850 MB JET BEGINS TO WRAP WARM
AIR/MOISTURE AHEAD/AROUND THE LOW ACROSS NYC/NJ METRO AND POINTS
EAST. THE THERMAL PROFILES POINT TO NYC/NJ METRO AND POINTS EAST
OF SNOW EARLY SAT MORN TO WINTRY MIX/RA LATE SAT MORN/SAT AFT AND
THEN POTENTIALLY BACK TO SNOW SAT EVE BEFORE ENDING. WHILE AREAS
FAR NW OF NYC WILL LIKELY BE MAINLY SNOW.

THERMAL PROFILES ARE ONE ISSUE...BUT THE OTHER ISSUE IS BANDING
PLACEMENT AND QPF. BASED ON AN ENSEMBLE OPER MODELS...BEST
DEFORMATION/HEAVY PRECIP BANDING POTENTIAL LOOKS TO BE ACROSS
LI/CT...WITH LIGHTER AMOUNTS TO THE NW. SO ALTHOUGH AREAS WELL NW OF
NYC WILL LIKELY BE MAINLY SNOW...LIGHTER QPF AMOUNTS THERE WILL KEEP
SNOW AMOUNTS LIGHTER. INCREASED MIXING EXPECTED FARTHER S AND SE
TOWARDS NYC/LI/SE CT WITH WARMING ALOFT AND BOUNDARY LAYER WARMING
WHICH WILL KEEP SNOW AMOUNTS LOWER. THE SWEET SPOT FOR BANDING
POTENTIAL AND COLDER THERMAL PROFILE APPEARS TO BE ACROSS INTERIOR
SOUTHERN CONNECTICUT ZONES...WITH THE HIGHEST SIGNIFICANT SNOWFALL
THREAT.

SO OVERALL CONTINUES TO LOOKS LIKE AN ADVISORY LEVEL EVENT FOR MUCH
OF THE REGION...GENERALLY 2 TO 5 INCHES...WITH LOWEST AMOUNTS ACROSS
EASTERN LI. FOR NYC METRO AND COASTAL AREAS...MUCH OF THE SNOW MAY
BE ON THE FRONT END SAT MORNING. THE POTENTIAL FOR 5 TO 7 INCHES
LIES ACROSS INTERIOR PORTIONS OF THE SOUTHERN CT ZONES...WHERE A
WATCH HAS BEEN HOISTED.

IN TERM OF FREEZING RAIN THREAT...ISSALOBARIC RESPONSE FROM THE
RAPIDLY INTENSIFYING LOW SHOULD KEEP WINDS MORE NORTHERLY THROUGH
THE PEAK OF THE STORM...WITH SURFACE TEMPS HOLDING NEAR FREEZING OR
JUST BELOW FOR NYC/NJ METRO...NORTH SHORE OF LI...AND SW/SC CT
DURING THE MORNING AND POSSIBLY INTO EARLY AFTERNOON. SO
POTENTIAL OF UP TO TENTH OF AN INCH OF ICE ACCRETION HERE IN LATE
MORN/AFT. THIS WILL LIKELY BE MIXED WITH SLEET AS WELL.

IN TERMS OF WINDS...NORTHERLY WINDS INCREASE SAT
AFTERNOON...PEAKING IN THE EVENING. GENERALLY 10 TO 20 MPH WITH
GUSTS IN THE 30S. PEAK GUSTS OF 40 MPH POSSIBLE ACROSS EASTERN
LI/SE CT.

ACROSS E LI/SE CT A PERIOD OF JUST HEAVY RAIN LIKELY LATE SAT
MORNING INTO SAT AFT...WITH SOME NUISANCE FLOODING ISSUES.

OTHERWISE...WITH MORE PROGRESSIVE TREND OF THE UPPER TROUGH...MAY
NOT BE LOOKING AT MUCH SNOW ON BACK END LATE SAT AFT/EVE AS COLDER
AIR WORKS IN FOR AREAS THAT EARLIER TRANSITIONED TO RAIN. THIS WILL
HAVE TO BE REFINED...AND MAY NOT COME IN TO CLARITY UNTIL 6 TO 12
HOURS BEFORE THE EVENT.

ANY SNOW COMES TO AND END SAT EVENING...WITH BREEZY AND NEAR
SEASONABLE TEMPS SAT NIGHT.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
BEHIND THE COASTAL STORM...ATTENTION THEN TURNS TOWARD EARLY WEEK
SYSTEM.

VIGOROUS SHORTWAVE BEGINS TO DIVE OUT OF CENTRAL CANADA SUNDAY.
INITIALLY THOUGH THE UPPER FLOW BACKS BEHIND THE DEPARTING
TROUGH/CSTL STORM. AS SUCH...A DRY...SEASONABLY CHILLY AND BREEZY
DAY IS EXPECTED. SUNSHINE IS FORECAST...BUT CLOUDS INCREASE QUICKLY
SUNDAY NIGHT.

THEN...SHORTWAVE TRACKS TOWARD THE MID ATLANTIC COAST SUNDAY NIGHT
AND MONDAY AS SFC LOW PRESSURE PASSES JUST SOUTH. QUESTIONS ARISE
WITH EXACT PLACEMENT OF SFC LOW...STRENGTH AND EVOLUTION OF THIS
UPPER SHORTWAVE...WITH GFS QUITE ROBUST WITH THE STRENGTH OF THIS
OVERALL SYSTEM. LATEST ECMWF SOLUTION IS WEAKER ALOFT...AND
SFC LOW IS SUPPRESSED FURTHER TO THE SOUTH BY MONDAY.

INITIALLY PLENTY OF COLD AIR IS IN PLACE. AS SUCH...ANY
PRECIPITATION THAT WE DO OBSERVE SHOULD BE MAINLY IN THE FORM OF
SNOW. HOWEVER...SOME WARM AIR COULD ADVECT NORTHWARD DURING THE DAY
MONDAY WITH A WINTRY MIX...AGAIN IF GFS IS CORRECT.

ECMWF THOUGH WOULD BE MAINLY SNOW...BUT MOST OF THE PRECIP REMAINS
JUST SOUTH OF THE AREA.

ANY WINTRY MIX CHANGES BACK TO SNOW BEFORE ENDING MONDAY NIGHT.

GIVEN THE UNCERTAINTY...WILL CAP POPS AT HIGH CHANCE AT THIS TIME.

ONCE THE DEEPENING TROUGH MOVES EAST MONDAY NIGHT INTO TUESDAY...SFC
HIGH AND LOW LEVEL RIDGING BUILDS IN FROM THE WEST...AS UPPER TROUGH
SLOWLY DEPARTS. GENERALLY DRY WEATHER SHOULD PREVAIL...BUT NORTHERN
STREAM SHORTWAVES WILL NEED TO BE WATCHED FOR POTENTIAL MINOR PRECIP
EVENTS MID TO LATE WEEK.

NEAR NORMAL TEMPS SUNDAY ARE EXPECTED...THEN WILL LEAN TOWARD NEW
WPC NUMBERS...WHICH ARE SLIGHTLY COLDER THAN GFS MEX GUIDANCE MID
WEEK. COLD AIR WILL ADVECT IN FROM THE NORTH BEHIND THE LOW...WITH A
MODERATING TREND BY THURSDAY.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
HIGH PRESSURE BUILDS IN TONIGHT AND REMAINS ACROSS THE REGION INTO
FRIDAY...MOVING OFFSHORE LATE IN THE DAY.

VFR.

LIGHT NW WIND TO NEAR CALM BECOMES SOUTHWEST LATE IN THE MORNING
INTO THE AFTERNOON FRIDAY...WITH SPEEDS LESS THAN 10 KT.


         NY METRO ENHANCED AVIATION WEATHER SUPPORT...

DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS
CAN BE FOUND AT: HTTP://WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)

KJFK FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.

KLGA FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.

KEWR FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.

KTEB FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.

KHPN FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.

KISP FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.

.OUTLOOK FOR 00Z SATURDAY THROUGH TUESDAY...
.FRIDAY NIGHT-SATURDAY EVENING...VFR AT THE START. SNOW DEVELOPS BY
LATE EVENING WITH CONDITIONS QUICKLY LOWERING TO IFR. TOWARD
SATURDAY MORNING A WINTRY MIX IS LIKELY AT THE NYC AREA
TERMINALS...ACROSS LONG ISLAND AND INTO COASTAL CONNECTICUT. SOME
RAIN IS POSSIBLE ALONG THE COAST SATURDAY AFTERNOON. THE
PRECIPITATION ENDS LATE SATURDAY INTO SATURDAY EVENING.
.SATURDAY NIGHT...IMPROVING TO VFR WITH GUSTY NORTHWEST TO WEST
WIND.
.SUNDAY...VFR.
.SUNDAY NIGHT-MONDAY NIGHT...CONDITIONS LOWERING TO IFR IN SNOW.
.TUESDAY...LINGERING SNOW SHOWERS POSSIBLE...OTHERWISE...IMPROVING
CONDS.

&&

.MARINE...
WINDS PICK UP TONIGHT AS THE PRESSURE GRADIENT INCREASES OVER THE
WATERS. WINDS AT THE TOP OF THE MIXED LAYER AREN`T MUCH STRONGER
THAN THE SURFACE WINDS...SO NOT EXPECTING TO SEE ADVISORY-LEVEL
GUSTS AS HIGH PRESSURE BUILDS IN BEHIND A LOW PRESSURE SYSTEM
STRENGTHENING WELL OUT TO SEA. A WEST FLOW AROUND 10 KT ON FRIDAY
WILL THEN MAINTAIN SUB-ADVISORY CONDITIONS ACROSS ALL WATERS.

ON SATURDAY...COASTAL LOW PRESSURE DEEPENS AS IT PASSES NEAR THE
40N/70W BENCHMARK LATE IN THE DAY...JUST EAST OF THE CSTL WATERS. AT
THIS TIME...MODEL CONSENSUS WOULD SUGGEST A 990-995 HPA LOW EARLY
SATURDAY DEEPENING TO A 975-980 HPA LOW BY EVENING. AS SUCH...THINK
SCA CONDITIONS ARE LIKELY...EXCEPT POSSIBLE GALES OVER THE OCEAN AND
EASTERN WATERS SATURDAY AFTERNOON POSSIBLY INTO SATURDAY NIGHT. WILL
POST GALE WATCH AT THIS TIME FOR SAT AFTERNOON.

WINDS TURN TOWARD THE WEST/NW SAT NIGHT AND SUNDAY...THEN SHIFT
AGAIN TO THE EAST AS ANOTHER AREA OF LOW PRESSURE PASSES TO THE
SOUTH MONDAY. THE WINDS SHIFT BACK TO THE N MONDAY NIGHT AND
TUESDAY AS THE LOW DEPARTS.

OVERALL...ROUGH CONDITIONS ARE LIKELY FOR THE AREA WATERS THROUGH AT
LEAST MONDAY.

&&

.HYDROLOGY...
LOW PRESSURE IMPACTS THE REGION SATURDAY AND SATURDAY NIGHT WITH QPF
UP TO 1 INCH ACROSS FAR EASTERN LI/SE CT...1/2 TO 3/4 ACROSS NYC NJ
METRO SW CT...TO 1/4 INCH OR LESS FOR AREAS FAR NW OF NYC. THIS WILL
FALL AS A MIX OF SNOW...RAIN...AND FREEZING RAIN.

QPF OF UP TO 1/2 INCH LIQUID EQUIVALENT IS POSSIBLE SUNDAY NIGHT
THROUGH MONDAY NIGHT AS A COASTAL LOW PASSES SOUTH OF THE REGION.
THIS EVENT LOOKS TO BE PRIMARILY SNOW AT THIS TIME.

ICE ON THE WALLKILL AND YANTIC RIVERS IS CAUSING MINOR FLUCTUATIONS
IN RIVER LEVELS AT THIS TIME.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...WINTER STORM WATCH FROM SATURDAY MORNING THROUGH SATURDAY
     EVENING FOR CTZ006>008.
NY...NONE.
NJ...NONE.
MARINE...GALE WATCH SATURDAY AFTERNOON FOR ANZ330-340-350-353-355.

&&

$$




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