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Area Forecast Discussion
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000
FXUS61 KOKX 280529
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
1229 AM EST SAT FEB 28 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 THIS MORNING/...
FORECAST BASICALLY ON TRACK - COLD & DRY. HIGH PRESSURE RESULTS
IN A CLEAR SKY AND LIGHT NW SFC FLOW (CALM AT TIMES). THE BOUNDARY
LAYER HAS STARTED TO DECOUPLING (8 AT FOK AND 9 AT DXR AS OF 02Z)
WHICH ALWAYS MAKES DETAILED HOURLY TEMPERATURE FORECASTS VERY
DIFFICULT.

BY MORNING...EXPECTING AROUND ZERO FOR INTERIOR VALLEYS AND THE
PINE BARRENS OF LONG ISLAND. THE CITY AND IMMEDIATE SURROUNDING
AREAS ARE EXPECTED TO DROP TO AROUND 15 F.  

NOT EXPECTING TO REACH THE RECORD LOWS THAT WERE SET LAST YEAR.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SUNDAY/...
NO CHANGES AT THIS TIME. FOR THE LAST DAY OF THE METEOROLOGICAL
WINTER...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 NIGHT THROUGH FRIDAY/...
RAISED POPS SLIGHTLY BASED ON TRENDS IN THE NWP AND MOVE UP THE
START SLIGHTLY. 18Z GFS IS NOW FASTER AND CLOSER TO NAM WITH THE
ONSET OF PCPN LATE SUNDAY - SUGGESTING MORE OF A MID AFTN ONSET.
21Z SREF ALSO NOW SUGGESTING AN EARLIER START.

FROM PREVIOUS...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 /06Z SATURDAY THROUGH WEDNESDAY/...
HIGH PRESSURE BUILDS IN THROUGH TODAY...THEN OVER THE AREA 
TONIGHT.

VFR THROUGH THE TAF PERIOD.

WNW WINDS 10 TO 15 KT WITH OCCASIONAL GUSTS TO 20 KT AT METRO 
TERMINALS... GRADAULLY SUBSIDE TO 10 KT OR LESS AFT 06-08Z. WINDS 
GENERALLY RIGHT OF 310 MAGNETIC THIS MORNING...BACKING TO LEFT OF 
310 MAG AFTER 18-20Z. LIGHT AND VARIABLE WINDS THIS EVENING INTO 
TONIGHT.

.OUTLOOK FOR 06Z SUNDAY THROUGH WEDNESDAY...
.LATE TONIGHT-SUN MORN...VFR.
.SUN AFTN-EARLY MON MORN...MVFR OR LOWER IN -SN CHANGING TO A
WINTRY MIX COAST AND -SN INLAND SUN NIGHT. SE SFC WND G15-20KT
POSSIBLE SUN AFTN.
.MON-TUE MORN...VFR. NW WINDS G15-25KT MON AFTN/EVE.
.TUE AFTN-WED...IFR POSSIBLE IN -SN CHANGING TO A WINTRY MIX TUE
NGT. RA LATE TUE NGT/WED MORN. BECOMING VFR LATE WED. LLWS
POSSIBLE TUE NGT-WED.

&&

.MARINE...
SWELL WILL BE DIMINISHING INTO TONIGHT...AND WITH ALL AREA BUOYS 
REPORTING JUST BELOW 5 FT. WINDS INCREASE SLIGHTLY TONIGHT AS THE
PRESSURE GRADIENT TIGHTENS...BUT STILL BELOW SCA CRITERIA. WINDS
WILL BE OFFSHORE...SO WAVE HEIGHTS SHOULD CONTINUE TO FALL AS THE
SWELL SUBSIDES. BY SAT AFTN...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...
SHORT TERM...JC
LONG TERM...DW
AVIATION...NV
MARINE...JC/DW
HYDROLOGY...JC/DW






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