Area Forecast Discussion
Issued by NWS Upton, NY

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KOKX 230021 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 721 PM EST THU JAN 22 2015 .SYNOPSIS... HIGH PRESSURE BUILDS IN THROUGH FRIDAY. IT THEN MOVES OFF THE MID ATLANTIC COAST FRIDAY NIGHT AS A RAPIDLY DEEPENING LOW EMERGES FROM THE GULF COAST STATES. THE LOW WILL TRACK TO THE MID ATLANTIC COAST SATURDAY MORNING...PASSING SOUTH AND EAST OF SOUTHERN NEW ENGLAND SATURDAY NIGHT. HIGH PRESSURE BRIEFLY BUILDS 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. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
-- Changed Discussion --
WEAK NORTHERN STREAM SHORTWAVE MOVES EAST THROUGH THE REGION TONIGHT WITH HIGH PRESSURE BUILDING IN FROM THE WEST TONIGHT. FORECAST IS GENERALLY ON TRACK. LOWERED LOWS ON LI AND NYC A FEW DEGREES AS TEMPS ARE ALREADY DROPPING QUICKLY UNDER CLEAR SKIES AND LIGHT WINDS.
-- End Changed Discussion --
&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/... MAIN FOCUS WILL BE QUICK MOVING BUT INTENSE LOW PRESSURE AFFECTING THE REGION LATE FRIDAY NIGHT INTO SATURDAY EVENING. FRI WILL THE TRANQUIL WITH INCREASING CLOUDS LATE AND NEAR SEASONABLE TEMPS. MODELS IN GOOD GENERAL AGREEMENT WITH UPPER LOW OVER THE SW US SLIDING EAST THROUGH SATURDAY...INTERACTING WITH THE NORTHERN STREAM ON SATURDAY. SIMILARLY MODELS IN GOOD GENERAL AGREEMENT WITH LOW PRESSURE DEVELOPING ALONG THE GULF COAST FRIDAY AND THEN QUICKLY TRACKING NE FRIDAY NIGHT TOWARDS THE MID-ATLANTIC...AND THEN NEAR THE 40/70 LAT/LON BENCHMARK SATURDAY EVENING. SOME DIFFERENCES EXIST BETWEEN MODELS IN AMOUNTS OF PHASING BETWEEN THE NORTHERN AND SOUTHERN STREAM AND RESULTANT SHORTWAVE INTENSIFICATION AS IT PIVOTS THROUGH OUR REGION...BUT IN GENERAL LATEST OPERATIONAL RUNS ARE A BIT WEAKER WITH THE UPPER ENERGY AND A LITTLE BIT MORE PROGRESSIVE. THIS POINTS TO AN INTENSE BUT QUICK MOVING SYSTEM. WITH NO HIGH TO THE NORTH OF THE REGION...A MARGINALLY COLD AIRMASS WILL BE IN PLACE...WITH P-TYPE STRONGLY PREDICATED ON DISTANCE FROM LOW AND UPPER DYNAMICS AND BANDING. THERMAL PROFILES LOOKS COLD ENOUGH FOR A START AS SNOW FOR ALL AREAS LATE FRIDAY NIGHT/EARLY SATURDAY MORNING. BUT AS INTENSIFYING LOW PRESSURE APPROACHES FROM THE SW SAT MORN/AFT...AN EASTERLY 850 MB JET BEGINS TO WRAP WARM AIR/MOISTURE AHEAD/AROUND THE LOW ACROSS NYC/NJ METRO AND POINTS EAST. THE THERMAL PROFILES POINT TO NYC/NJ METRO AND POINTS EAST OF SNOW EARLY SAT MORN TO WINTRY MIX/RA LATE SAT MORN/SAT AFT AND THEN POTENTIALLY BACK TO SNOW SAT EVE BEFORE ENDING. WHILE AREAS FAR NW OF NYC WILL LIKELY BE MAINLY SNOW. THERMAL PROFILES ARE ONE ISSUE...BUT THE OTHER ISSUE IS BANDING PLACEMENT AND QPF. BASED ON AN ENSEMBLE OPER MODELS...BEST DEFORMATION/HEAVY PRECIP BANDING POTENTIAL LOOKS TO BE ACROSS LI/CT...WITH LIGHTER AMOUNTS TO THE NW. SO ALTHOUGH AREAS WELL NW OF NYC WILL LIKELY BE MAINLY SNOW...LIGHTER QPF AMOUNTS THERE WILL KEEP SNOW AMOUNTS LIGHTER. INCREASED MIXING EXPECTED FARTHER S AND SE TOWARDS NYC/LI/SE CT WITH WARMING ALOFT AND BOUNDARY LAYER WARMING WHICH WILL KEEP SNOW AMOUNTS LOWER. THE SWEET SPOT FOR BANDING POTENTIAL AND COLDER THERMAL PROFILE APPEARS TO BE ACROSS INTERIOR SOUTHERN CONNECTICUT ZONES...WITH THE HIGHEST SIGNIFICANT SNOWFALL THREAT. SO OVERALL CONTINUES TO LOOKS LIKE AN ADVISORY LEVEL EVENT FOR MUCH OF THE REGION...GENERALLY 2 TO 5 INCHES...WITH LOWEST AMOUNTS ACROSS EASTERN LI. FOR NYC METRO AND COASTAL AREAS...MUCH OF THE SNOW MAY BE ON THE FRONT END SAT MORNING. THE POTENTIAL FOR 5 TO 7 INCHES LIES ACROSS INTERIOR PORTIONS OF THE SOUTHERN CT ZONES...WHERE A WATCH HAS BEEN HOISTED. IN TERM OF FREEZING RAIN THREAT...ISSALOBARIC RESPONSE FROM THE RAPIDLY INTENSIFYING LOW SHOULD KEEP WINDS MORE NORTHERLY THROUGH THE PEAK OF THE STORM...WITH SURFACE TEMPS HOLDING NEAR FREEZING OR JUST BELOW FOR NYC/NJ METRO...NORTH SHORE OF LI...AND SW/SC CT DURING THE MORNING AND POSSIBLY INTO EARLY AFTERNOON. SO POTENTIAL OF UP TO TENTH OF AN INCH OF ICE ACCRETION HERE IN LATE MORN/AFT. THIS WILL LIKELY BE MIXED WITH SLEET AS WELL. IN TERMS OF WINDS...NORTHERLY WINDS INCREASE SAT AFTERNOON...PEAKING IN THE EVENING. GENERALLY 10 TO 20 MPH WITH GUSTS IN THE 30S. PEAK GUSTS OF 40 MPH POSSIBLE ACROSS EASTERN LI/SE CT. ACROSS E LI/SE CT A PERIOD OF JUST HEAVY RAIN LIKELY LATE SAT MORNING INTO SAT AFT...WITH SOME NUISANCE FLOODING ISSUES. OTHERWISE...WITH MORE PROGRESSIVE TREND OF THE UPPER TROUGH...MAY NOT BE LOOKING AT MUCH SNOW ON BACK END LATE SAT AFT/EVE AS COLDER AIR WORKS IN FOR AREAS THAT EARLIER TRANSITIONED TO RAIN. THIS WILL HAVE TO BE REFINED...AND MAY NOT COME IN TO CLARITY UNTIL 6 TO 12 HOURS BEFORE THE EVENT. ANY SNOW COMES TO AND END SAT EVENING...WITH BREEZY AND NEAR SEASONABLE TEMPS SAT NIGHT. && .LONG TERM /SUNDAY THROUGH THURSDAY/... BEHIND THE COASTAL STORM...ATTENTION THEN TURNS TOWARD EARLY WEEK SYSTEM. VIGOROUS SHORTWAVE BEGINS TO DIVE OUT OF CENTRAL CANADA SUNDAY. INITIALLY THOUGH THE UPPER FLOW BACKS BEHIND THE DEPARTING TROUGH/CSTL STORM. AS SUCH...A DRY...SEASONABLY CHILLY AND BREEZY DAY IS EXPECTED. SUNSHINE IS FORECAST...BUT CLOUDS INCREASE QUICKLY SUNDAY NIGHT. THEN...SHORTWAVE TRACKS TOWARD THE MID ATLANTIC COAST SUNDAY NIGHT AND MONDAY AS SFC LOW PRESSURE PASSES JUST SOUTH. QUESTIONS ARISE WITH EXACT PLACEMENT OF SFC LOW...STRENGTH AND EVOLUTION OF THIS UPPER SHORTWAVE...WITH GFS QUITE ROBUST WITH THE STRENGTH OF THIS OVERALL SYSTEM. LATEST ECMWF SOLUTION IS WEAKER ALOFT...AND SFC LOW IS SUPPRESSED FURTHER TO THE SOUTH BY MONDAY. INITIALLY PLENTY OF COLD AIR IS IN PLACE. AS SUCH...ANY PRECIPITATION THAT WE DO OBSERVE SHOULD BE MAINLY IN THE FORM OF SNOW. HOWEVER...SOME WARM AIR COULD ADVECT NORTHWARD DURING THE DAY MONDAY WITH A WINTRY MIX...AGAIN IF GFS IS CORRECT. ECMWF THOUGH WOULD BE MAINLY SNOW...BUT MOST OF THE PRECIP REMAINS JUST SOUTH OF THE AREA. ANY WINTRY MIX CHANGES BACK TO SNOW BEFORE ENDING MONDAY NIGHT. GIVEN THE UNCERTAINTY...WILL CAP POPS AT HIGH CHANCE AT THIS TIME. ONCE THE DEEPENING TROUGH MOVES EAST MONDAY NIGHT INTO TUESDAY...SFC HIGH AND LOW LEVEL RIDGING BUILDS IN FROM THE WEST...AS UPPER TROUGH SLOWLY DEPARTS. GENERALLY DRY WEATHER SHOULD PREVAIL...BUT NORTHERN STREAM SHORTWAVES WILL NEED TO BE WATCHED FOR POTENTIAL MINOR PRECIP EVENTS MID TO LATE WEEK. NEAR NORMAL TEMPS SUNDAY ARE EXPECTED...THEN WILL LEAN TOWARD NEW WPC NUMBERS...WHICH ARE SLIGHTLY COLDER THAN GFS MEX GUIDANCE MID WEEK. COLD AIR WILL ADVECT IN FROM THE NORTH BEHIND THE LOW...WITH A MODERATING TREND BY THURSDAY. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
HIGH PRESSURE BUILDS IN TONIGHT AND REMAINS ACROSS THE REGION INTO FRIDAY...MOVING OFFSHORE LATE IN THE DAY. VFR. LIGHT NW WIND TO NEAR CALM BECOMES SOUTHWEST LATE IN THE MORNING INTO THE AFTERNOON FRIDAY...WITH SPEEDS LESS THAN 10 KT. 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: NO UNSCHEDULED AMENDMENTS EXPECTED. KLGA FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. KEWR FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. KTEB FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. KHPN FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. KISP FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. .OUTLOOK FOR 00Z SATURDAY THROUGH TUESDAY... .FRIDAY NIGHT-SATURDAY EVENING...VFR AT THE START. SNOW DEVELOPS BY LATE EVENING WITH CONDITIONS QUICKLY LOWERING TO IFR. TOWARD SATURDAY MORNING A WINTRY MIX IS LIKELY AT THE NYC AREA TERMINALS...ACROSS LONG ISLAND AND INTO COASTAL CONNECTICUT. SOME RAIN IS POSSIBLE ALONG THE COAST SATURDAY AFTERNOON. THE PRECIPITATION ENDS LATE SATURDAY INTO SATURDAY EVENING. .SATURDAY NIGHT...IMPROVING TO VFR WITH GUSTY NORTHWEST TO WEST WIND. .SUNDAY...VFR. .SUNDAY NIGHT-MONDAY NIGHT...CONDITIONS LOWERING TO IFR IN SNOW. .TUESDAY...LINGERING SNOW SHOWERS POSSIBLE...OTHERWISE...IMPROVING CONDS.
-- End Changed Discussion --
&& .MARINE... WINDS PICK UP TONIGHT AS THE PRESSURE GRADIENT INCREASES OVER THE WATERS. WINDS AT THE TOP OF THE MIXED LAYER AREN`T MUCH STRONGER THAN THE SURFACE WINDS...SO NOT EXPECTING TO SEE ADVISORY-LEVEL GUSTS AS HIGH PRESSURE BUILDS IN BEHIND A LOW PRESSURE SYSTEM STRENGTHENING WELL OUT TO SEA. A WEST FLOW AROUND 10 KT ON FRIDAY WILL THEN MAINTAIN SUB-ADVISORY CONDITIONS ACROSS ALL WATERS. ON SATURDAY...COASTAL LOW PRESSURE DEEPENS AS IT PASSES NEAR THE 40N/70W BENCHMARK LATE IN THE DAY...JUST EAST OF THE CSTL WATERS. AT THIS TIME...MODEL CONSENSUS WOULD SUGGEST A 990-995 HPA LOW EARLY SATURDAY DEEPENING TO A 975-980 HPA LOW BY EVENING. AS SUCH...THINK SCA CONDITIONS ARE LIKELY...EXCEPT POSSIBLE GALES OVER THE OCEAN AND EASTERN WATERS SATURDAY AFTERNOON POSSIBLY INTO SATURDAY NIGHT. WILL POST GALE WATCH AT THIS TIME FOR SAT AFTERNOON. WINDS TURN TOWARD THE WEST/NW SAT NIGHT AND SUNDAY...THEN SHIFT AGAIN TO THE EAST AS ANOTHER AREA OF LOW PRESSURE PASSES TO THE SOUTH MONDAY. THE WINDS SHIFT BACK TO THE N MONDAY NIGHT AND TUESDAY AS THE LOW DEPARTS. OVERALL...ROUGH CONDITIONS ARE LIKELY FOR THE AREA WATERS THROUGH AT LEAST MONDAY. && .HYDROLOGY... LOW PRESSURE IMPACTS THE REGION SATURDAY AND SATURDAY NIGHT WITH QPF UP TO 1 INCH ACROSS FAR EASTERN LI/SE CT...1/2 TO 3/4 ACROSS NYC NJ METRO SW CT...TO 1/4 INCH OR LESS FOR AREAS FAR NW OF NYC. THIS WILL FALL AS A MIX OF SNOW...RAIN...AND FREEZING RAIN. QPF OF UP TO 1/2 INCH LIQUID EQUIVALENT IS POSSIBLE 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 STORM WATCH FROM SATURDAY MORNING THROUGH SATURDAY EVENING FOR CTZ006>008. NY...NONE. NJ...NONE. MARINE...GALE WATCH SATURDAY AFTERNOON FOR ANZ330-340-350-353-355. && $$

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.