Area Forecast Discussion
Issued by NWS Upton, NY

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869 FXUS61 KOKX 070240 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 940 PM EST SAT FEB 6 2016 .SYNOPSIS... HIGH PRESSURE SLOWLY RETREATS TO THE NORTHEAST THROUGH SUNDAY. INTENSIFYING LOW PRESSURE ALONG THE SOUTHEAST US COAST WILL TRACK NORTHEAST...MOVING SOUTHEAST OF THE REGION SUNDAY NIGHT INTO MONDAY. AN ACTIVE WINTER PATTERN WILL CONTINUE THROUGH MUCH OF NEXT WEEK AS SEVERAL WAVES OF LOW PRESSURE MAY IMPACT THE REGION. HIGH PRESSURE MAY RETURN AT THE END OF THE WEEK. && .NEAR TERM /THROUGH SUNDAY/... A NORTHERN STREAM TROUGH PASSES WELL TO THE NORTH TONIGHT. MAIN IMPACT WILL BE SOME MAINLY THIN CIRRUS CROSSING THE AREA...WITH A MAINLY CLEAR SKY EXPECTED AS A RESULT. AS WINDS CONTINUE TO DIMINISH THIS EVENING...SHOULD END UP WITH DECENT RADIATIONAL COOLING CONDITIONS AFTER MIDNIGHT. STILL APPEAR ON TRACK FOR LOWS TO FALL WELL INTO THE TEENS INLAND AND LOWER AND MIDDLE 20S FOR MOST OTHER LOCATIONS...WITH SOME LOW 30S POSSIBLE IN THE NYC METRO. FOR SUNDAY...A MOSTLY SUNNY SKY CONDITION WITH JUST SOME HIGH CLOUDS AND WEAK WARM AIR ADVECTION ON SW WINDS WILL HELP TEMPS RISE CLOSE TO SEASONAL NORMS. && .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY/... SPLIT FLOW WITH MODEL IN GENERAL AGREEMENT WITH A CLOSED UPPER LOW OFF THE SE US COAST SUN EVENING PIVOTING NE SUN NIGHT TO SE OF THE 40/70 BENCHMARK MONDAY MORNING. MEANWHILE A SECOND LARGER CLOSED LOW DEVELOPING LOW DIGS INTO THE EASTERN 1/2 OF THE COUNTRY THROUGH THE GREAT LAKES SUNDAY NIGHT INTO MONDAY. THE INTERACTION BETWEEN THESE TWO SYSTEMS CONTINUES TO RESULT IN SUBTLE DIFFERENCES (150 MILE SPREAD) IN TRACK OF AN INTENSIFYING LOW PRESSURE SYSTEM AS IT MOVES FROM OFF THE NC COAST SUN EVENING AND THEN SE OF THE 40/70 LAT/LON BENCHMARK ON MONDAY. THIS IS ACCENTUATING DIFFERENCES IN THE WESTERN EXTENT OF THE DEFORMATION BANDING AND PRECIPITATION SHIELD...WITH SNOWFALL VARYING ANYWHERE FROM A TRACE TO INCH FROM W TO E (GFS/ECMWF)...OR TRACE TO 2 INCHES WEST TO 2 TO 4 INCHES EAST (GEM/NAM). OVERALL...A SLIGHT EASTWARD AND DRIER TREND HAS BEEN NOTED WITH THE 12Z GUIDANCE VERSUS 00Z. IN TERMS OF ENSEMBLES...WESTERN LYING 15Z SREF MEAN IS HOLDING FIRM WITH AROUND 1/2 TO 1 INCH QPF ACROSS THE REGION WITH MEAN LYING IN THE MIDDLE OF A TRI- MODAL PATTERN. MEANWHILE 12Z GEFS HAS MEAN OF .05 TO .1 INCH QPF AREAWIDE...WHICH IS BETWEEN THE STRONG CLUSTERING AROUND THE OPERATIONAL GFS OF ONLY A FEW HUNDREDTHS OF AN INCH AREA WIDE...TO A HANDFUL OF MEMBERS WITH 1/4 TO 1/2 INCH QPF. 00Z AND 12Z SBU ENSEMBLE SENSITIVITY INDICATING ENSEMBLE SPREAD IS ON THE NW SIDE OF THE GEFS/ECMWF/CMC ENSEMBLE MEANS FOR THE LOW TRACK...WITH SENSITIVITY LYING IN THE STRENGTH AND INTERACTION OF THE AFORE MENTIONED UPPER LOWS. THIS NW SPREAD PATTERN...HAS MANY TIMES FAVORED WESTERN MOST SOLUTIONS OR WESTWARD TREND IN LOW PRESSURE TRACK. BASED ON THE ABOVE...HESITANT TO MAKE MANY CHANGES TO THE CURRENT FORECAST...PARTICULARLY TOWARDS THE DRIER DETERMINISTIC TREND. A BLEND OF DETERMINISTIC AND ENSEMBLE QPF PROBABILITIES INDICATING INCREASING LIKELIHOOD FOR LIGHT PRECIPITATION TO DEVELOP LATE SUNDAY NIGHT INTO MONDAY MORNING EAST OF NYC AND HUDSON RIVER. LOWER PROBABILITIES FOR MEASURABLE PRECIPITATION WEST OF THE NYC METRO AND HUDSON RIVER. PRECIPITATION SHOULD MAINLY BE IN THE FORM OF SNOW...BUT MAY INITIALLY START AS A MIX WITH RAIN ACROSS EASTERN LONG ISLAND DUE TO WARM BOUNDARY LAYER. WILL CONTINUE WITH A GOING FORECAST FOR LATE SUNDAY NIGHT THROUGH MONDAY WITH... A LIKELY SCENARIO OF A DUSTING TO COUPLE INCHES ACROSS NYC METRO AND POINTS WEST AND 2 TO 4 INCHES TOWARDS EASTERN LONG ISLAND AND SE CT. A CHANCE SCENARIO FOR A WESTWARD SHIFT...AND DOUBLING OF THESE AMOUNTS. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... CONFIDENCE THIS PERIOD IS LOW AS MODELS AND ENSEMBLES HAVE NOT COME INTO BETTER AGREEMENT WITH A POTENTIALLY ACTIVE WINTER PATTERN FOR THE MIDDLE OF NEXT WEEK. INTENSE OFFSHORE LOW WILL CONTINUE MOVING FURTHER NE AWAY FROM COAST MONDAY NIGHT. RIGHT BEHIND THIS SYSTEM IS THE CONTINUATION OF A VERY ANOMALOUS PATTERN. BASED ON THE 12Z GEFS...THE WESTERN NORTH AMERICA RIDGING HEIGHT ANOMALIES ARE BETWEEN 2 AND 3 SD ABOVE NORMAL. THE LONGWAVE TROUGH DIGGING INTO THE EASTERN STATES IS BETWEEN 3 AND 4 SD BELOW NORMAL. THIS TYPE OF PATTERN IS USUALLY CAUSE FOR CONCERN AND MODELS AND ENSEMBLES ARE SHOWING QUITE A LARGE SPREAD WITH IMPORTANT FEATURES AT THE SURFACE AND ALOFT. SOME OF THIS COULD BE WITH HOW THEY HANDLE THE FIRST LOW THAT MOVES AWAY FROM THE COAST MONDAY NIGHT. MONDAY NIGHT INTO TUESDAY NIGHT...A VERY ENERGETIC LONGWAVE TROUGH SETS UP OVER THE EASTERN STATES. A PARENT LOW IS PROGGED TO MOVE ACROSS THE LAKES...TRANSFERRING SOMEWHERE NEAR THE MIDDLE ATLANTIC COAST. THIS NEW WAVE OF LOW PRESSURE WILL THEN MOVE ENE AWAY FROM THE COAST TO SOMEWHERE IN THE VICINITY OF OF THE 40/70 BENCHMARK. THERE IS A GENERAL AGREEMENT WITH THIS AMONG THE DETERMINISTIC MODELS...BUT THEY VARY IN HOW PRECIPITATION IS GENERATED DUE TO PLACEMENT OF UPPER LEVEL ENERGY AND AMPLITUDE OF THE UPPER LEVEL TROUGH. THEY SEEM TO BE KEYING ON AN INVERTED TROUGH TYPE SIGNATURE. THE 12Z GFS/GEFS/CMC/CMC ENSEMBLE SEEM TO HAVE THIS SETTING UP NEAR THE AREA FOR ACCUMULATING SNOW TUESDAY INTO WEDNESDAY. THE 12Z ECMWF HAS THIS SETTING UP A BIT FURTHER SOUTH AWAY FROM OUR CWA. THE 15Z SREF MEAN IS SIMILAR TO THE ECMWF IDEA AS WELL AS THE 12Z NAM. THERE IS QUITE A BIT OF ENERGY WITHIN THIS TROUGH AND SUBTLE CHANGES COULD MAKE A DIFFERENCE WHERE BEST LIFT SETS UP. MODELS HAVE ALSO SHOWN PRETTY DRASTIC CHANGES WITH IMPORTANT DYNAMICS OVER THE LAST FEW WEEKS...WHICH LEADS TO A LOWER THAN NORMAL CONFIDENCE FOR THIS TIME PERIOD. WILL HOLD ONTO LIKELY POPS THROUGH THIS TIME FRAME. FEEL CONTINUITY IS THE WAY TO GO HERE AND HOPEFULLY AS WE GET CLOSER...WE WILL HAVE A BETTER IDEA FOR WHERE THE INVERTED TROUGH AND BEST LIFT FROM UPPER ENERGY WILL SET UP. THE TAKE HOME MESSAGE IS ACCUMULATING LIGHT SNOW IS POSSIBLE AT SOME POINT MONDAY NIGHT THROUGH TUESDAY NIGHT PERIOD. WEDNESDAY THROUGH THURSDAY...LOW PRESSURE MOVES FURTHER NE ON WEDNESDAY...BUT ANOMALOUS TROUGH IS LIKELY TO REMAIN OVERHEAD. CANNOT RULE OUT LIGHT SNOW WEDNESDAY...BUT FOR NOW IT APPEARS BEST LIFT SHIFTS EAST OF THE AREA. UPPER TROF AXIS SHIFTS EAST THURSDAY. POPS TAPER DOWN TO CHANCE WEDNESDAY AND THEN SLIGHT CHANCE ON THURSDAY. FRIDAY THROUGH SATURDAY...AN ARCTIC COLD FRONT CROSSES THE REGION FRIDAY INTO FRIDAY NIGHT AS DEEP UPPER LOW SETS UP ACROSS SOUTHEAST CANADA. THE FRONT SHOULD MOVE THROUGH DRY AS BEST MOISTURE AXIS HAS SHIFTED OFFSHORE FROM EARLIER WEEK ACTIVITY. ARCTIC HIGH BUILDS INTO THE AREA SATURDAY. THE 12Z ECMWF HAS 850 HPA TEMPS DROPPING TO BETWEEN -22C TO -26C. FORECAST TEMPERATURES ARE BELOW NORMAL THROUGHOUT THE LONG TERM...WITH INCREASING PROBABILITY OF A SHOT OF ARCTIC AIR AND WELL BELOW NORMAL TEMPERATURES AT THE WEEK AND NEXT WEEKEND. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... HIGH PRESSURE SLOWLY RETREATS TO THE NORTHEAST INTO SUNDAY EVENING. VFR THROUGH THE TAF PERIOD. WINDS BECOME LIGHT AND VARIABLE THROUGHOUT TONIGHT...AND SHOULD REMAIN SO INTO SUNDAY AFTERNOON. WINDS BECOME SE/E THEN ENE-NE AT UNDER 10 KT LATE SUNDAY AFTERNOON/EARLY SUNDAY EVENING. .OUTLOOK FOR 00Z MONDAY THROUGH THURSDAY... .SUNDAY NIGHT...VFR IN THE EVENING...THEN MVFR OR LOWER POSSIBLE LATE...ESPECIALLY AT EASTERN TERMINALS IN -SN...POSSIBLY MIXED WITH RAIN AT THE START FOR SOUTHERN/EASTERN TERMINALS. NE WINDS G20-30+KT POSSIBLE. HIGHEST GUSTS EASTERN CT/LONG ISLAND TERMINALS. .MONDAY...MVFR OR LOWER LIKELY IN SNOW. NE-N WINDS G20-30KT WESTERN TERMINALS AND 30-40KT EASTERN TERMINALS POSSIBLE. .MONDAY NIGHT-TUESDAY NIGHT...MVFR OR LOWER LIKELY IN SNOW. MIXED PRECIPITATION POSSIBLE NEAR THE COAST DURING THE DAY ON TUESDAY. N-NE WINDS G15-25KT POSSIBLE MONDAY NIGHT-TUESDAY. .WEDNESDAY THROUGH THURSDAY...SUB-VFR POSSIBLE IN -SN. W-NW WINDS G20-25KT POSSIBLE WEDNESDAY NIGHT-THURSDAY. && .MARINE... MADE MINOR CHANGES THIS UPDATE TO REFLECT THE LATEST TRENDS IN OBSERVATIONS AND GUIDANCE. THE FORECAST APPEARS ON TRACK. SUB-ADVISORY CONDITIONS WILL PREVAIL ON ALL WATERS THROUGH SUNDAY WITH A RELAXED PRESSURE GRADIENT OVER THE REGION. THE PRESSURE GRADIENT WILL TIGHTEN IN RESPONSE TO AN APPROACHING COASTAL LOW SUN NIGHT WITH GALE FORCE WINDS EXPECTED ACROSS CENTRAL AND EASTERN OCEAN WATERS AFTER MIDNIGHT AND CONTINUING INTO MONDAY. POTENTIAL FOR GALES ON THE WESTERN OCEAN WATERS AND EASTERN LONG ISLAND SOUND/BAYS. SCA CONDITIONS EXPECTED ON REMAINDER OF THE WATERS. THERE IS STILL SOME UNCERTAINTY WITH THE TRACK OF LOW PRESSURE...AND IF IT TRACKS CLOSER TO THE COAST...THE GALE THREAT WILL MOVE WESTWARD. SCA IS LIKELY ON MOST WATERS TUESDAY THROUGH THURSDAY. WINDS MAY TEMPORARILY DECREASE TUE NIGHT INTO WEDNESDAY...BUT SEAS ON THE OCEAN WILL REMAIN ABOVE 5 FT. WINDS THEN INCREASE ABOVE SCA LATE WEDNESDAY INTO THURSDAY. && .HYDROLOGY... WIDESPREAD LIGHT PRECIPITATION IS LIKELY LATE SUNDAY NIGHT THRU MON...WITH LOW PROB FOR MODERATE PRECIPITATION. MOST IF NOT ALL OF THE PRECIPITATION THAT FALLS LIKELY TO BE IN THE FORM OF SNOW AT THIS TIME. WIDESPREAD PRECIPITATION IS POSSIBLE MON NIGHT THROUGH TUESDAY NIGHT. THE PRECIPITATION THAT FALLS SHOULD BE IN THE FORM OF SNOW. && .TIDES/COASTAL FLOODING... POTENTIAL FOR MINOR COASTAL IMPACTS MONDAY INTO MIDWEEK WITH A NEW MOON ON MONDAY AND A SERIES OF LOW PRESSURES AFFECTING THE REGION. AN INTENSIFYING LOW PRESSURE WILL HAVE NE/N WINDS INCREASING TO POTENTIALLY GALE FORCE SUNDAY NIGHT AND CONTINUING INTO MONDAY. BASED ON A TRACK OF INTENSIFYING LOW THAT SHOULD BE SE OF THE 40/70 LAT/LON BENCHMARK AND COLD AIR DAMMING SIGNATURE...WOULD EXPECT POTENTIAL FOR WINDS TO BE BACKED MORE TO THE N THAN NE. THIS WOULD FAVOR THE LOWER SURGE GUIDANCE FOR MONDAY AND MONDAY NIGHT HIGH TIDE CYCLES...WHICH WOULD KEEP IMPACTS MINOR AND LIKELY LIMITED TO THE MOST VULNERABLE LOCALES. WILL HAVE TO MONITOR. AS WE HEAD INTO TUESDAYS HIGH TIDE CYCLES...POTENTIAL EXISTS FOR WINDS TO VEER MORE TO THE NE AS ADDITIONAL WAVE/S OF LOW PRESSURE TRACK TO THE SOUTH OF THE REGION. THE SPRING ASTRONOMICAL TIDES AND MULTI-TIDAL CYCLE NATURE OF THE EVENT WILL FAVOR ADDITIONAL MINOR FLOODING...WITH POTENTIAL FOR WIDESPREAD MINOR TO MODERATE IMPACTS IN THE BACK BAY AREAS TUESDAY AND WEDNESDAY. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY FROM MIDNIGHT SUNDAY NIGHT TO 6 PM EST MONDAY FOR ANZ335-338-345. GALE WATCH FROM LATE SUNDAY NIGHT THROUGH MONDAY AFTERNOON FOR ANZ330-340-355. GALE WARNING FROM MIDNIGHT SUNDAY NIGHT TO 6 PM EST MONDAY FOR ANZ350-353. && $$ SYNOPSIS...MALOIT/DS/NV NEAR TERM...MALOIT/DS/NV SHORT TERM...NV LONG TERM...DS AVIATION...MALOIT MARINE...MALOIT/DS/NV HYDROLOGY...DS/NV TIDES/COASTAL FLOODING...

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