Area Forecast Discussion
Issued by NWS Upton, NY

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000
FXUS61 KOKX 272059
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
359 PM EST FRI FEB 27 2015

.SYNOPSIS...
HIGH PRESSURE BUILDS INTO THE REGION THROUGH SATURDAY NIGHT.
A FRONTAL SYSTEM WILL MOVE ACROSS THE AREA SUNDAY NIGHT INTO
MONDAY. HIGH PRESSURE WILL THEN BRIEFLY RETURN ON TUESDAY BEFORE
YET ANOTHER FRONTAL SYSTEM IMPACTS THE AREA FOR THE MIDDLE OF NEXT
WEEK. HIGH PRESSURE BUILDS BACK IN FOR THE END OF THE WEEK.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
HIGH PRESSURE RESULTS IN A CLEAR SKY. WINDS BECOME LIGHTER THROUGH
THE NIGHT...AND FOR SOME SUBURBAN AREAS...CALM AT TIMES. THIS ALONG
WITH A DECENT SNOW PACK WILL ALLOW FOR TEMPS TO DROP TO AROUND ZERO
FOR SOME NORTHERN SUBURBS...WITH SINGLE DIGITS FOR MOST OF THE REST
OF THE SUBURBS. THE CITY AND IMMEDIATE SURROUNDING AREAS ARE
EXPECTED TO DROP TO 10-15. BECAUSE WINDS WILL BE FAIRLY LIGHT IN THE
CITY...WIND CHILLS SHOULD REMAIN ABOVE ZERO THROUGH THE NIGHT...SO
NO SPS PLANNED FOR THE CITY.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
SUNNY TO START ON SATURDAY...THEN THERE COULD BE SOME MID-HIGH
CLOUDS FILTERING IN DURING THE AFTERNOON. SUBSIDENCE FROM THE
APPROACHING HIGH PRESSURE CENTER WILL LIMIT THE MIXING HEIGHT BY
ABOUT 25MB VERSUS TODAY...AND WITH A SIMILAR TEMP EXPECTED AT THE
TOP OF THE BOUNDARY LAYER WITH LESS OF A DOWNSLOPE FACTOR...HIGHS
EXPECTED TO BE A FEW DEGREES COOLER THAN TODAY. A NAM/MAV MOS BLEND
MATCHES THIS THINKING. THIS IS ABOUT 15-20 DEGREES COLDER THAN
NORMAL.

ANY CLOUD COVER REMAINING BY EARLY SATURDAY EVENING SHOULD SHIFT OUT
TO THE EAST...THEN A PERIOD OF CLEAR CONDITIONS BEFORE MID-HIGH
CLOUDS BEGIN TO RETURN LATE AT NIGHT. THE LACK OF CAA AND THE LATE
NIGHT CLOUD INCREASE SHOULD PREVENT TEMPS FROM FALLING AS LOW AS
THEY WILL TONIGHT IN SPITE OF MORE WIDESPREAD CALM WINDS.
STILL...LOWS AVERAGING 10-15 DEGREES BELOW NORMAL.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
GLOBAL MODELS CONTINUE TO BE ON BOARD FOR A CHANGE IN THE UPPER AIR
PATTERN WITH THE PERSISTENT HIGH AMPLITUDE RIDGE ACROSS NORTH
AMERICA FINALLY BREAKING DOWN. THIS WILL RESULT IN A SPLIT CONFLUENT
FLOW ACROSS THE EASTERN HALF OF THE COUNTRY. BY MID WEEK...RIDGING
BEGINS TO EXPAND NORTHWARD FROM THE GULF COAST STATES...AND A
DIGGING UPPER TROUGH TRANSLATES EAST FROM THE PLAINS STATES.

THIS WILL RESULT IN AN ACTIVE PATTERN WITH A SERIES OF FRONTAL
SYSTEMS TO IMPACT THE AREA...THE FIRST SUN NIGHT INTO MON...THEN
ANOTHER TUE NIGHT INTO THU. THE LATTER OF WHICH DIFFERS IN THE
SYSTEM PROGRESSION AMONGST THE GLOBAL MODELS. THE 12Z GFS CONTINUES
TO BE ON THE FASTER SIDE OF THE ENVELOPE. PREFERENCE WAS TO TAKE A
MIDDLE ROAD SOLUTION...WHICH IN TIMING WAS CLOSE TO THE GGEM.

THE FIRST SYSTEM IS A FAST MOVING LOW ACROSS THE GREAT LAKES SUN
INTO SUN NIGHT PRECEDED BY STRONG WARM ADVECTION. THE UNCERTAINTY
LIES IN THE PLACEMENT OF THE SFC LOW WHICH THE GFS AND ECMWF TRACK
TO THE NORTH OF THE AREA...WHILE THE NAM WRF AND GGEM HINT AT A WEAK
SECONDARY LOW FORMING TO THE SOUTH SUN NIGHT. THIS MAY MAKE FOR A
CHALLENGING RAIN/SNOW LINE...WHICH RIGHT NOW LOOKS TO BE IN CLOSE
PROXIMITY TO THE LI/NY METRO AFTER MIDNIGHT. THE NAM SOLUTION WOULD
KEEP THE LOW-LEVEL COLD WITH A NLY FLOW AND RESULT IN A PERIOD OF
FREEZING RAIN. RIGHT NOW...LOOKING FOR 2 TO 4 INCHES OF SNOWFALL
ACROSS THE LOWER HUDSON VALLEY AND CT...WITH 1 TO 2 INCHES AND A
LIGHT ICE ACCRETION TO THE SOUTH. CONDITIONS DRY OUT MON MORNING
WITH A GUSTY NW FLOW AND ANOTHER SHOT OF UNSEASONABLY COLD
AIR...ALBEIT WARMER THAN IN RECENT WEEKS.

STRONG HIGH PRESSURE BRIEFLY BUILDS IN TUE WITH ANOTHER FRONTAL
SYSTEM TO BRING OVERRUNNING PCPN TO THE AREA TUE NIGHT INTO WED.
THIS TIME AROUND WARMER HEIGHTS ALOFT AND SW FLOW WILL RESULT IN A
QUICK TRANSITION OVER TO RAIN FROM SOUTH THE NORTH. KEPT CHANCES OF
PCPN IN THE FORECAST THROUGH WED NIGHT DUE TO THE UNCERTAINTY WITH
THE PROGRESSION OF THE SYSTEM. THERE IS THE POSSIBILITY OF A
TRANSITION BACK TO WINTRY PCPN WED NIGHT.

THE WEEK COMES TO AN END ON A COLD...BLUSTERY NOTE...WITH READINGS
WELL BELOW NORMAL AS THE UPPER TROF REESTABLISHES ITSELF ACROSS
EASTERN NORTH AMERICA.

&&

.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
HIGH PRESSURE BUILDS IN FROM THE WEST TONIGHT...THEN OVER THE AREA
ON SATURDAY.

VFR THROUGH THE TAF PERIOD.

N-NW WINDS AROUND 10 KT OR LESS THROUGH THE TAF PERIOD. OCCASIONAL
GUSTS OF 155-20KT POSSIBLE LATE THIS AFTERNOON/EARLY THIS EVENING.

     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: WIND DIRECTION WILL VARY FROM 290-350 TRUE
(300-360 MAGNETIC) INTO THIS EVENING - BUT MAINLY AT OR TO THE RIGHT
OF 300 TRUE. OCCASIONAL GUSTS TO 15-20 KT UNTIL 2Z.

KLGA FCSTER COMMENTS: WIND DIRECTION WILL VARY FROM 310-010 TRUE
(320-020 MAGNETIC) INTO THIS EVENING. OCCASIONAL GUSTS TO 15-20 KT
UNTIL 2Z.

KEWR FCSTER COMMENTS: WIND DIRECTION WILL VARY FROM 280-010 TRUE
(290-020 MAGNETIC) INTO THIS EVENING - BUT MAINLY AT OR TO THE RIGHT
OF 300 TRUE. OCCASIONAL GUSTS TO 15-20 KT  UNTIL 2Z.

KTEB FCSTER COMMENTS: OCCASIONAL GUSTS TO 15-20 KT UNTIL 2Z.

KHPN FCSTER COMMENTS: OCCASIONAL GUSTS TO 15-20 KT UNTIL 2Z.

KISP FCSTER COMMENTS: OCCASIONAL GUSTS TO 15-20 KT UNTIL 2Z.

.OUTLOOK FOR 18Z SATURDAY THROUGH TUESDAY...
.SATURDAY-SUNDAY MORNING...VFR.
.SUNDAY AFTERNOON-MONDAY MORNING...MVFR OR LOWER IN -SN CHANGING
TO A WINTRY MIX S TERMINALS AND -SN N TERMINALS. SE WINDS
G15-20KT POSSIBLE SUNDAY AFTERNOON.
.MONDAY AFTERNOON-TUESDAY MORNING...VFR. NW WINDS G15-25KT
POSSIBLE MONDAY AFTERNOON/EVENING.
.TUESDAY AFTERNOON-WEDNESDAY...MVFR OR LOWER POSSIBLE IN -SN
CHANGING TO A WINTRY MIX TUESDAY NIGHT...THEN RAIN LATER TUESDAY
NIGHT/WEDNESDAY MORNING. BECOMING VFR LATE WEDNESDAY. LLWS
POSSIBLE TUESDAY NIGHT-WEDNESDAY.

&&

.MARINE...
SWELL WILL BE DIMINISHING INTO TONIGHT...AND WITH ALL AREA BUOYS
REPORTING JUST BELOW 5 FT...WILL CANCEL THE SCA WHICH ORIGINALLY
LASTED THROUGH THE REST OF THIS AFTERNOON. WINDS INCREASE A LITTLE
TONIGHT AS THE PRESSURE GRADIENT TIGHTENS...AND THERE COULD EVEN BE
A GUST OR TWO UP TO 25 KT ON THE OCEAN...BUT NOT JUSTIFYING ANOTHER
SCA. WINDS WILL BE OFFSHORE...SO WAVE HEIGHTS SHOULD CONTINUE TO
FALL AS THE SWELL SUBSIDES. BY SAT AFT...WINDS SUBSIDE BELOW 10 KT
AND REMAIN THAT WAY THROUGH SAT NIGHT AS A HIGH PRESSURE CENTER
MOVES OVERHEAD OR NEARBY LATE AT NIGHT.

SEAS BUILD TO SMALL CRAFT LEVELS ON MONDAY...WITH AN INCREASING
SOUTHWEST FLOW IN THE MORNING. NORTHWEST FLOW BEHIND A COLD FRONT
WILL LIKELY PRODUCE GUSTS TO SMALL CRAFT LEVELS ON THE OCEAN WATERS
ON MONDAY.

&&

.HYDROLOGY...
THERE IS THE POTENTIAL FOR A LIGHT TO MODERATE SNOW EVENT LATE
SUNDAY INTO MONDAY MORNING. THIS EVENT WILL HAVE NO IMMEDIATE IMPACT
ON THE HYDROLOGIC SERVICE AREA.

ICE WILL CONTINUE TO DEVELOP ON LOCAL AREA RIVERS AND STREAMS AS
TEMPERATURES REMAIN WELL BELOW AVERAGE.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...JC/DW
NEAR TERM...JC
SHORT TERM...JC
LONG TERM...DW
AVIATION...MALOIT
MARINE...JC/DW
HYDROLOGY...JC/DW






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