534  
FXUS61 KOKX 250537  
AFDOKX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NEW YORK NY  
137 AM EDT SAT MAR 25 2017  
   
SYNOPSIS
 
 
A COLD FRONT OVER UPSTATE NEW YORK AND CENTRAL NEW ENGLAND  
WILL DRIFT SOUTH OVERNIGHT AND THROUGH THE TRI-STATE REGION ON  
SATURDAY. AN UNSETTLED WEATHER PATTERN CONTINUES SUNDAY INTO THE  
MIDDLE OF NEXT WEEK. COLD FRONT TO OUR SOUTH RETURNS TO THE  
REGION SUNDAY NIGHT INTO MONDAY AND MOVES OFFSHORE MONDAY NIGHT.  
ANOTHER FRONTAL SYSTEM APPROACHES ON TUESDAY AND MOVES ACROSS  
TUESDAY NIGHT INTO WEDNESDAY. HIGH PRESSURE RETURNS THURSDAY  
AHEAD OF THE NEXT FRONT ON FRIDAY.  
 

 
   
NEAR TERM /UNTIL 6 AM THIS MORNING/
 
 
MINOR ADJUSTMENTS MADE TO TEMPERATURE, DEW POINT AND WINDS  
TONIGHT. A FEW LOCATIONS HAVE DECOUPLED FASTER THAN PREVIOUSLY  
FORECAST, ALLOWING TEMPERATURES TO FALL QUICKLY, THOUGH THESE  
SITES HAVE BEEN FLUCTUATING BETWEEN MID 30S AND LOWER 40S AS THE  
WIND BRIEFLY PICKS UP AGAIN AT TIMES.  
 
MID AND HIGH LEVEL CLOUDS WILL REMAIN THROUGH THE OVERNIGHT WITH  
A FEW BREAKS FROM TIME TO TIME. TEMPERATURES VARY DRASTICALLY  
IN THE DIMINISHING SW FLOW, WHICH IS COMMON IN THE EARLY SPRING  
DUE TO THE COLD NEARSHORE WATERS. PARTS OF THE NYC METRO ARE IN  
THE MID AND UPPER 50S, WHILE IN THE SUBURBS TEMPERATURES RANGE  
FROM THE MID 30S TO THE MID 40S. TEMPERATURES WILL FALL SLIGHTLY  
OVERNIGHT AND THEN LEVEL OFF. LOWS WILL AVERAGE 10 TO 15  
DEGREES ABOVE NORMAL DUE TO THE SW FLOW AND CLOUD COVER.  
 

 
   
SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SUNDAY/
 
 
A COLD FRONT OVER SOUTHERN ONTARIO WILL TRACK SOUTH THROUGH THE  
AREA BY LATE SATURDAY MORNING INTO THE AFTERNOON. THE TIMING IS  
PRETTY CONSISTENT BETWEEN THE NAM AND GFS, SO THE NAM WAS USED  
IN THE GRIDS. THIS TRANSLATES INTO FALLING TEMPERATURES ACROSS  
THE NORTHERN HALF OF THE FORECAST AREA BY AFTERNOON, WITH THE  
FALL IN TEMPERATURES LATER IN THE DAY ACROSS NEW JERSEY ZONES.  
 
WATER VAPOR INDICATES A MOISTURE STREAM FROM THE SUBTROPICAL  
PACIFIC INTO THE SOUTHEASTERN UNITED STATES. THIS WILL ALLOW FOR  
SOME DEEPER MOISTURE TO PENETRATE INTO THE REGION DURING THE DAY  
AND THROUGH THE NIGHT. THE UPPER JET WILL BE PASSING FROM  
SOUTHERN CANADA INTO NORTHERN NEW ENGLAND AT THIS TIME,  
PRODUCING SOME BROAD LIFT. WITH THESE FACTORS COMBINING, LIGHT  
RAIN HAS BEEN FORECAST FOR THE AREA MAINLY SATURDAY AFTERNOON  
AND SATURDAY NIGHT. EASTERLY COMPONENT LOW LEVEL FLOW COULD  
ALLOW FOR SOME FOG OR DRIZZLE DEVELOPMENT PARTICULARLY  
OVERNIGHT. PATCHY FOG HAS BEEN MAINTAINED IN THE FORECAST ALONG  
WITH THE LIGHT RAIN AS A RESULT.  
 
THE DOWNSCALED NAM WAS USED FOR TEMPERATURES SATURDAY TO ACCOUNT  
FOR THE COLD FRONTAL PASSAGE. A BLEND OF GUIDANCE WAS USED  
SATURDAY NIGHT.  
 
THERE IS A LOW CHANCE THAT TEMPERATURES APPROACH FREEZING LATE  
SATURDAY NIGHT WHICH COULD RESULT IN SOME POCKETS OF INTERIOR  
ICING. THE PROBABILITY IS LOW AT THIS TIME, SO IT HAS NOT BEEN  
INCLUDED IN THIS FORECAST.  
 

 
   
LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/
 
 
UNSETTLED, PROGRESSIVE WEATHER PATTERN WILL PERSIST FROM SUNDAY  
THROUGH THE UPCOMING WEEK. DETERMINISTIC MODELS AND ENSEMBLES ARE IN  
GENERAL AGREEMENT WITH THE SYNOPTIC SCALE, WITH DIFFERENCES ARISING  
IN THE TIMING AND AMPLITUDE OF SEVERAL SHORTWAVES TO MOVE ACROSS.  
 
BACKDOOR FRONT WILL BE WELL TO THE SOUTH ON SUNDAY WITH HIGH  
PRESSURE BUILDING SOUTH OF OUT OF QUEBEC. WARM AIR OVERRUNNING THE  
STABLE, COOL LAYER AT THE SURFACE WILL KEEP LOW CLOUDS THROUGHOUT  
THE DAY AND THE CHANCE FOR LIGHT RAIN OR DRIZZLE.  
UPPER LEVEL RIDGING WILL BE IN PLACE, SO THERE IS NOT MUCH SUPPORT  
FOR WIDESPREAD PRECIPITATION. TEMPERATURES WILL BE HELD DOWN IN THE  
LOWER AND MIDDLE 40S DUE TO ONSHORE FLOW AND CLOUDY CONDITIONS.  
 
CUTOFF LOW OVER THE CENTRAL STATES ON SUNDAY WILL OPEN AND LIFT  
TOWARDS THE GREAT LAKES SUNDAY NIGHT AND THEN CONTINUE TO DAMPEN OUT  
AS IT MOVES TOWARDS THE REGION ON MONDAY. UPPER RIDGE AXIS GRADUALLY  
MOVES OFFSHORE ALLOWING FOR BETTER LIFT FOR MORE WIDESPREAD  
RAINFALL. POPS INCREASE TO LIKELY FOR MUCH OF THE AREA LATE SUNDAY  
NIGHT INTO MONDAY MORNING WITH CATEGORICAL ACROSS THE NORTH CLOSER  
TO THE SHORTWAVE ENERGY AND BEST LIFT.  
SHORTWAVE AXIS QUICKLY MOVES EAST MONDAY AFTERNOON AND EVENING,  
WHICH WILL TAKE THE LINGERING FRONT TO THE SOUTH AND EAST.  
 
BRIEF RIDGING MOVES ACROSS MONDAY NIGHT WITH ANOTHER SHORTWAVE ON  
ITS HEELS FOR TUESDAY. THIS IS WHERE DETERMINISTIC RUNS AND  
ENSEMBLES BEGIN TO DIVERGE FURTHER AS THE LATEST 12Z ECMWF FLATTENS  
THIS NEXT SHORTWAVE OUT AS IT PASSES WHEREAS THE 12Z GFS AND THE  
GEFS ARE MORE AMPLIFIED, BRINGING A WEAK LOW PRESSURE ACROSS THE  
REGION. HAVE CAPPED POPS OFF IN THE CHANCE RANGE DUE TO THE  
UNCERTAINTY ON THE AMPLITUDE OF THIS WAVE. IN EITHER CASE, MOSTLY  
CLOUDY TO OVERCAST SKIES CONTINUE.  
 
AN AMPLIFYING SHORTWAVE ACROSS SOUTHEAST CANADA SENDS A SHORTWAVE  
ACROSS NEW ENGLAND ON WEDNESDAY, BUT FRONTAL BOUNDARY SHOULD BE WELL  
OFFSHORE AT THIS TIME, SO IMPROVING CONDITIONS ARE EXPECTED. HIGH  
PRESSURE THAN FOLLOWS ON THURSDAY BEFORE ANOTHER FRONTAL SYSTEM  
APPROACHES FOR FRIDAY.  
 
NEAR SEASONABLE TEMPERATURES ARE FORECAST ON MONDAY WITH  
TEMPERATURES RETURNING TO ABOVE NORMAL LEVELS TUESDAY INTO  
WEDNESDAY. SEASONABLE TEMPERATURES ARE CURRENTLY EXPECTED FOR THE  
END OF THE WEEK.  
 

 
   
AVIATION /06Z SATURDAY THROUGH WEDNESDAY/
 
 
A COLD FRONT APPROACHES FROM THE NORTH OVERNIGHT AND PASSES  
SOUTH OF THE TERMINALS THIS MORNING. HIGH PRESSURE THEN BUILDS  
DOWN FROM THE NORTH INTO SATURDAY EVENING.  
 
VFR UNTIL AROUND 17Z, THEN MVFR CONDITIONS DEVELOP IN LIGHT RAIN  
AND FOG. IFR CONDITIONS LIKELY LATE THIS AFTERNOON, WITH PATCHY  
LIFR CONDITIONS POSSIBLE.  
 
S-SW WINDS LESS THAN 10 KT BECOME LIGHT AND VARIABLE TOWARD 12Z  
AS THE FRONT NEARS, THEN WINDS SHIFT TO NE WITH THE COLD FRONT  
PASSAGE, 10 KT OR LESS.  
   
OUTLOOK FOR 06Z SUNDAY THROUGH WEDNESDAY
 
   
SATURDAY NIGHT-MONDAY
 
IFR LIKELY WITH LIFR OR LOWER  
POSSIBLE. PERIODS OF RAIN, DRIZZLE AND FOG.   
MONDAY NIGHT-TUESDAY NIGHT
 
MVFR OR LOWER POSSIBLE.   
WEDNESDAY
 
BECOMING VFR. NW WINDS G15-20KT POSSIBLE IN THE  
AFTERNOON.  
 

 
   
MARINE
 
 
SMALL CRAFT ADVISORY CONDITIONS WILL CONTINUE ON THE OCEAN  
THROUGH SATURDAY DESPITE THE DIMINISHING WINDS. IT IS POSSIBLE  
CONDITIONS REMAIN AT SMALL CRAFT ADVISORY LEVELS ON THE OCEAN  
SATURDAY NIGHT.  
 
MARGINAL SCA WINDS ARE FORECAST ON SUNDAY ON THE OCEAN, BUT SEAS  
WILL LIKELY BE AROUND 5 FT THROUGH THE EVENING. FROM SUNDAY NIGHT  
THROUGH MONDAY NIGHT, SUB-SCA CONDITIONS ARE FORECAST WITH AN  
OVERALL WEAK PRESSURE GRADIENT. SEAS MAY BUILD TO AROUND 5 FT ON  
TUESDAY AS A COLD FRONT PASSES THROUGH. OTHERWISE WINDS AND SEAS  
SHOULD REMAIN BELOW SCA LEVELS INTO WEDNESDAY.  
 

 
   
HYDROLOGY
 
 
LESS THAN A QUARTER INCH OF RAIN IS EXPECTED THROUGH SATURDAY  
NIGHT. UNSETTLED CONDITIONS SUNDAY THROUGH THE MIDDLE OF NEXT  
WEEK WILL BRING PERIODS OF RAIN. HOWEVER, NO HYDROLOGIC CONCERNS  
ARE ANTICIPATED AT THIS TIME.  
 

 
   
OKX WATCHES/WARNINGS/ADVISORIES
 
 
CT...NONE.  
NY...NONE.  
NJ...NONE.  
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ350-  
353-355.  
 

 
 

 
SYNOPSIS...12/DS  
NEAR TERM...12/MD/DW  
SHORT TERM...12  
LONG TERM...DS  
AVIATION...MET  
MARINE...12/DS  
HYDROLOGY...12/DS  
 
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