Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 231434 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 934 AM EST FRI JAN 23 2015 .SYNOPSIS...
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HIGH PRESSURE BRIEFLY BUILDS OVERHEAD TODAY BEFORE MOVING OFF THE MID ATLANTIC COAST TONIGHT. A RAPIDLY DEEPENING COASTAL MOVES ALONG THE MID ATLANTIC COAST SATURDAY MORNING...PASSING SOUTH AND EAST OF SOUTHERN NEW ENGLAND SATURDAY NIGHT. HIGH PRESSURE BRIEFLY BUILDS IN 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.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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A SEASONABLY COOL AND MOSTLY SUNNY DAY IS IN STORE AS HIGH PRESSURE BRIEFLY BUILDS OVER THE REGION. STRATUS DECK OVER CENTRAL NY/PA MAY CREEP INTO AREAS FAR NW OF NYC THIS MORNING INTO EARLY AFTERNOON. OTHERWISE...HIGH CLOUDS WILL BEGIN STREAMING NORTHWARD LATE IN THE DAY AHEAD OF THE DEVELOPING LOW PRESSURE SYSTEM NEAR THE SOUTHEAST COAST. A BLEND OF MAV/MET GUIDANCE WAS USED FOR HIGHS...GIVING READINGS IN THE MIDDLE AND UPPER 30S.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
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THE MAIN FOCUS DURING THIS PERIOD WILL BE ON A QUICK MOVING AND RAPIDLY DEEPENING LOW PRESSURE SYSTEM AFFECTING THE REGION LATE FRIDAY NIGHT INTO SATURDAY EVENING. MODELS CONTINUE TO COME INTO BETTER AGREEMENT ON THE TIMING...TRACK...AND INTENSITY OF THE LOW. THIS LOW IS MAINLY BEING DRIVEN BY THE SOUTHERN STREAM AND WILL HAVE A SUBTROPICAL MOISTURE FEED. MODELS HAVE ALSO COME INTO BETTER AGREEMENT WITH DEPICTING SOME PHASING OF THE NORTHERN STREAM AS IT PIVOTS THROUGH OUR REGION. HOWEVER...THE UPPER LEVEL ENERGY IS A ELONGATED AND OVERALL FLOW IS PROGRESSIVE PREVENTING A QUICKER PHASE AND A DEEPER LOW AT OUR LATITUDE. THE SYSTEM WILL BE MOVING QUICKLY TO THE NORTHEAST JUST INSIDE OR OVER THE BENCHMARK SATURDAY AFTERNOON...THEN QUICKLY RACING NNE INTO THE CANADIAN MARITIMES SATURDAY NIGHT. ALL OF THE ABOVE POINTS TO AN INTENSE BUT QUICK MOVING SYSTEM. A MARGINALLY COLD AIR MASS WILL BE IN PLACE DUE TO NO COLD HIGH TO THE NORTH. MOISTURE AND DEEP LIFT QUICKLY MOVE OVER THE REGION FROM SOUTH TO NORTH LATE FRIDAY NIGHT INTO EARLY SATURDAY MORNING. THE LOWER AND MID LEVELS OF THE ATMOSPHERE WILL INITIALLY BE DRY...BUT QUICKLY MOISTEN. WET BULBING AT THE ONSET WILL COOL THERMAL PROFILES AND ALLOW THE PRECIPITATION TO BEGIN AS ALL SNOW ACROSS THE REGION. THE SNOW COULD COME DOWN BRIEFLY MODERATE TO HEAVY AT TIMES EARLY SATURDAY MORNING. WARMER AIR ALOFT WILL QUICKLY MOVE IN AROUND THE 900 TO 850 HPA LEVELS AND ALLOW THE SNOW TO MIX WITH SLEET AND/OR FREEZING RAIN AROUND DAYBREAK ACROSS LONG ISLAND...NYC/NJ METRO...AND COASTAL CT. THIS WARM NOSE WILL THEN SLOWLY PUSH INTO THE INTERIOR BY MID TO LATE MORNING BRINGING A WINTRY MIX. CLOSER TO THE COAST...TEMPERATURES WILL LIKELY RISE JUST ABOVE FREEZING FOR PLAIN RAIN MID TO LATE SATURDAY MORNING. MOST CLOSELY FOLLOWED NAM12 THERMAL PROFILES FOR THIS EVENT. WITH ALL OF THIS IN MIND...HAVE ISSUED AN ADVISORY BEGINNING AT 05Z SAT FOR ALL ZONES EXCEPT NE AND SE SUFFOLK AND SOUTHERN NEW LONDON. GENERALLY LOOKING AT 2 TO 5 INCHES OF SNOW...HIGHEST AMOUNTS ACROSS INTERIOR NE NJ...LOWER HUDSON VALLEY AND SOUTHERN CONNECTICUT. THE WINTER STORM WATCH WAS CONVERTED TO AN ADVISORY ACROSS INTERIOR S CT. IN TERMS OF FREEZING RAIN...LIGHT ICING IS POSSIBLE NEAR THE COAST...BUT SURFACE TEMPERATURES SHOULD RISE JUST ABOVE FREEZING TO PREVENT SIGNIFICANT ICING. ONE TO TWO TENTHS OF AN INCH OF ICE ACCRETION IS POSSIBLE ACROSS INTERIOR NE NJ...SOUTHERN CT...AND THE LOWER HUDSON VALLEY. WILL NEED TO MONITOR SURFACE TEMPERATURE TRENDS SATURDAY MORNING SINCE THE ISALLOBARIC RESPONSE TO THE DEEPENING LOW WILL KEEP WINDS MORE NORTHERLY DURING THE DAY. IN TERMS OF WINDS...NORTHERLY WINDS INCREASE SAT AFTERNOON...PEAKING IN THE AFTERNOON AND EVENING. GENERALLY 10 TO 20 MPH WITH GUSTS IN THE 30S. A PEAK GUST TO 40 MPH IS POSSIBLE ACROSS EASTERN LI/SE CT. WITH THE QUICK MOVING SYSTEM...PRECIPITATION WILL BEGIN TAPERING OFF LATE SATURDAY AFTERNOON INTO THE EVENING. COULD SEE SOME SNOW ON THE BACKSIDE AS THERMAL PROFILES COOL WHEN THE LOW DEPARTS.
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&& .LONG TERM /SUNDAY THROUGH THURSDAY/... ATTENTION SHIFTS TO A STRONG CLIPPER LOW THAT DIVES INTO THE OHIO VALLEY ON SUNDAY AND THEN OFF THE MID ATLANTIC COAST ON MONDAY. GLOBAL MODELS IN RECENT DAYS HAVE BEEN AT ODDS WITH THE PROGRESSION AND WHERE EXACTLY THE UPPER LOW CLOSES OFF OVER THE MID ATLANTIC STATES. THE GFS FOR SEVERAL CYCLES DEVELOPED A STRONG SECONDARY LOW CLOSER AND FARTHER NORTH ALONG THE COAST ON MONDAY...WITH THE POTENTIAL FOR SIGNIFICANT SNOW AND STRONG WINDS ACROSS THE TRI-STATE AREA. THE REST OF THE GLOBAL MODEL SUITE HAS THE LOW SUPPRESSED FARTHER TO THE SOUTH AND MORE PROGRESSIVE...WITH ONLY A LIGHT SNOWFALL EVENT ON MONDAY. THE 00Z GFS HAS JOINED THE CONSENSUS. THAT BEING THE CASE...THE UPSTREAM ENERGY IS STILL IN THE N PAC AND WILL BE COMING ONSHORE WESTERN CANADA TODAY. THUS...WHILE IT SEEMS LESS LIKELY FOR SIGNIFICANT WINTER STORM EARLY NEXT WEEK...THE SYSTEM STILL BEARS CLOSE WATCHING. FOR NOW...LOOKING FOR A LIGHT SNOWFALL EVENT LATE SUNDAY NIGHT INTO MONDAY. COASTAL LOCATIONS HAVE THE BEST CHANCE OF SEEING THE SNOW. WHAT DOES SEEM MORE CERTAIN...IS THAT WITH A HIGHLY AMPLIFIED TROF SWINGING ACROSS THE AREA THROUGH THE FIRST HALF OF NEXT WEEK...IT WILL BE UNSEASONABLY COLD AND BLUSTERY ON THE BACKSIDE OF THE STORM. EXPECT A GRADUAL MODIFICATION IN TEMPS TOWARD THE END OF THE WEEK. DRY CONDITIONS ARE ON TAP BEHIND THE EARLY WEEK STORM. && .AVIATION /15Z FRIDAY THROUGH TUESDAY/...
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...HIGH IMPACT AVIATION WINTER EVENT TONIGHT INTO SATURDAY... GENERALLY QUIET CONDS TODAY. NW WINDS 10 KT OR LESS WILL BECOME LGT/VRB EARLY THIS AFTERNOON...AND THEN WILL BECOME SW AT 10 KT OR LESS AS HIGH PRES BUILDS OVER THE AREA...AND THEN MOVES OFFSHORE. COASTAL LOW APPROACHES FROM THE SOUTH TONIGHT. VFR WILL QUICKLY DETERIORATE TO IFR AND BELOW LATE TONIGHT AND THROUGH EARLY SATURDAY MORNING WITH MOST OF THE ACCUMULATING SNOW. PRECIP TRANSITIONS TO A WINTRY MIX...INCLUDING FREEZING RAIN AND SLEET...DURING THE DAY SATURDAY BEFORE TAPERING OFF SATURDAY EVENING. WITH THE APPROACH OF THE LOW...WINDS WILL BECOME VARIABLE AGAIN OVERNIGHT BEFORE TRANSITIONING TO A MORE NORTHERLY FLOW. FORECAST RUNWAY SNOW ACCUMULATIONS... LGA...JFK...EWR...TEB...3-4 INCHES. HPN...SWF...BDR...4-6 INCHES. ISP...GON...1-3 INCHES. FORECAST ICE ACCUMULATIONS... COASTAL TERMINALS...A GLAZE. HPN...SWF...UP TO AROUND A TENTH OF AN INCH. ...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: HIGH CONFIDENCE IN CATEGORY FORECAST THROUGH TODAY. MODERATE CONFIDENCE IN WIND FORECAST THROUGH TODAY. TIMING OF SOUTHWEST SWITCH IN WINDS COULD BE OFF BY 1-2 HRS. KLGA FCSTER COMMENTS: HIGH CONFIDENCE IN CATEGORY FORECAST THROUGH TODAY. MODERATE CONFIDENCE IN WIND FORECAST THROUGH TODAY. TIMING OF SOUTHWEST SWITCH IN WINDS COULD BE OFF BY 1-2 HRS. KEWR FCSTER COMMENTS: HIGH CONFIDENCE IN CATEGORY FORECAST THROUGH TODAY. MODERATE CONFIDENCE IN WIND FORECAST THROUGH TODAY. TIMING OF SOUTHWEST SWITCH IN WINDS COULD BE OFF BY 1-2 HRS. THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD. KTEB FCSTER COMMENTS: HIGH CONFIDENCE IN CATEGORY FORECAST THROUGH TODAY. MODERATE CONFIDENCE IN WIND FORECAST THROUGH TODAY. TIMING OF SOUTHWEST SWITCH IN WINDS COULD BE OFF BY 1-2 HRS. KHPN FCSTER COMMENTS: HIGH CONFIDENCE IN CATEGORY FORECAST THROUGH TODAY. MODERATE CONFIDENCE IN WIND FORECAST THROUGH TODAY. TIMING OF SOUTHWEST SWITCH IN WINDS COULD BE OFF BY 1-2 HRS. KISP FCSTER COMMENTS: HIGH CONFIDENCE IN CATEGORY FORECAST THROUGH TODAY. MODERATE CONFIDENCE IN WIND FORECAST THROUGH TODAY. TIMING OF SOUTHWEST SWITCH IN WINDS COULD BE OFF BY 1-2 HRS. .OUTLOOK FOR 12Z SATURDAY THROUGH TUESDAY... .SATURDAY-SATURDAY EVENING...WINTRY MIX TRANSITION FROM SOUTH TO NORTH. SOME RAIN IS POSSIBLE ALONG THE COAST OF EASTERN LONG ISLAND FOR THE AFTERNOON. THE PRECIPITATION TAPERS OFF SATURDAY EVENING. IFR TO LIFR. VLIFR POSSIBLE EARLY. .SATURDAY NIGHT...IMPROVING TO VFR WITH GUSTY NORTHWEST TO WEST WIND. .SUNDAY...VFR. .SUNDAY NIGHT-MONDAY NIGHT...CONDITIONS LOWERING TO IFR IN SNOW. .TUESDAY...MAINLY VFR.
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&& .MARINE... INITIALLY...CONDITIONS WILL BE BELOW SCA WITH HIGH PRESSURE IN CONTROL. HOWEVER...THE HIGH MOVES OFFSHORE TONIGHT INTO SATURDAY...GIVING WAY TO APPROACHING LOW PRESSURE. THE PRESSURE GRADIENT WILL INCREASE AND THE APPROACHING LOW WILL ALSO BRING HIGHER SEAS. SCA CONDITIONS ARE FORECAST FOR SATURDAY AND SATURDAY NIGHT. THESE MAY LINGER INTO SUNDAY ESPECIALLY WITH OCEAN SEAS DUE TO RESIDUAL SWELL. OTHERWISE...THE PRESSURE GRADIENT WILL BE DECREASING RATHER RAPIDLY AS THE LOW ACCELERATES WELL UP INTO THE CANADIAN MARITIMES. WINDS WILL RESPOND BY FALLING BELOW SCA THRESHOLDS SUNDAY OUTSIDE OF A FEW OCCASIONAL GUSTS ON THE OCEAN TO 25 KT. WINDS AND SEAS BRIEFLY SUBSIDE SUN INTO SUN NIGHT ON THE BACKSIDE OF AN INTENSE AREA OF LOW PRESSURE LIFTING NORTH ACROSS THE CANADIAN MARITIMES. A DEEPENING CLIPPER LOW MOVES OF THE MID ATLANTIC COAST ON MON WITH A POTENTIAL GALE ACROSS THE WATERS MON INTO MON NIGHT. WINDS AND SEAS GRADUALLY SUBSIDE TUE INTO WED WITH HIGH PRESSURE BUILDING IN FROM THE WEST. && .HYDROLOGY... LOW PRESSURE IMPACTS THE REGION SATURDAY AND SATURDAY NIGHT WITH QPF UP TO 1 INCH ACROSS NYC/LI/SE CT...1/2 TO 3/4 ACROSS NE NJ AND SW CT...TO 1/4 INCH OR LESS FOR AREAS FAR NW OF NYC. THIS WILL FALL AS A MIX OF SNOW...SLEET...FREEZING RAIN...AND RAIN. QPF OF UP TO 1/4 INCH LIQUID EQUIVALENT IS POSSIBLE LATE 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 WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM EST SATURDAY FOR CTZ005>011. NY...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM EST SATURDAY FOR NYZ067>075-078-080-176>179. NJ...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM EST SATURDAY FOR NJZ002-004-006-103>108. MARINE...SMALL CRAFT ADVISORY FROM 6 AM SATURDAY TO 6 AM EST SUNDAY FOR ANZ330-335-338-340-345-350-353-355. && $$ SYNOPSIS...DS/DW NEAR TERM...DS SHORT TERM...DS LONG TERM...DW AVIATION...JM MARINE...JM/DW HYDROLOGY...DS/DW

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