Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 131352 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 852 AM EST SAT FEB 13 2016 .SYNOPSIS... HIGH PRESSURE BUILDS IN THROUGH SUNDAY NIGHT BEFORE SLIDING OFFSHORE ON MONDAY. A LOW PRESSURE SYSTEM DEVELOPS ACROSS THE SOUTHEAST MONDAY NIGHT AND TRACKS UP THE EASTERN SEABOARD TUESDAY INTO TUESDAY NIGHT. A COLD FRONT MOVES THROUGH WEDNESDAY FOLLOWED BY HIGH PRESSURE FOR THE REMAINDER OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... THE ARCTIC FRONT WAS OFFSHORE AS OF 830AM. TEMPS HAVE SHOT UP BEHIND THE FRONT DUE TO MIXING. CHANGES HAVE BEEN MADE TO THE FCST ACCORDINGLY. POLAR LOW CONTINUES TO DESCEND INTO THE NORTHEAST THROUGH TONIGHT WITH A SHORT LIVED BUT DANGEROUS TO POTENTIALLY LIFE THREATENING ARCTIC INTRUSION TODAY INTO SUN. TEMPS SHOULD STEADILY FALL INTO THE SINGLE DIGITS AND LOWER TEENS THIS AFTERNOON...WITH WIND CHILLS FALLING TO 5 TO 15 DEGREES BELOW ZERO. TEMPS DROP OF 6 TO 10 DEGREES IN 2 HOURS BEING NOTED ACROSS WESTERN NY EARLY THIS MORNING...INTO THE SINGLE DIGITS BELOW ZERO. HEART OF COLD ENTERS TONIGHT...WITH TEMPS LIKELY TO FALL TO AROUND ZERO FOR NYC/NJ METRO AND LI...AND 5 TO 10 BELOW ZERO ACROSS INTERIOR PORTIONS OF THE TRI-STATE LATE TONIGHT INTO EARLY SUN MORNING. COMBINED WITH MODERATELY STRONG WINDS...DANGEROUS TO POTENTIALLY LIFE THREATENING WIND CHILLS OF 20 TO 30 BELOW EXPECTED. WIND CHILL WARNINGS HAVE BEEN EXPANDED TO COASTAL AND SOUTHERN WESTCHESTER BASED ON EXPECTED TRAJECTORY OF COLD POOL. ADVISORIES CONTINUE ACROSS METRO NY/NJ AND COASTAL PLAIN WITH A BIT OF MODERATION IN TEMPS DUE TO URBANIZATION AND SURROUNDING BODIES OF WATER. ISO SNOW SHOWERS/SCT FLURRIES EXPECTED WITH ARCTIC FRONTAL PASSAGE THIS MORNING...BEST CHANCE ACROSS NW HIGHER ELEVATIONS AND EASTERN LI/SE CT WITH A BIT MORE LIFT/MOISTURE TO WORK WITH RESPECTIVELY. IN ITS WAKE...WITH UPPER LOW APPROACHING IN THE AFT/EVE AND RESIDUAL LAKE STREAMER MOISTURE...SCT INSTABILITY CU AND ISO SNOW SHOWER/SCT FLURRY EXPECTED INTO EARLY EVENING. ACROSS TWIN FORKS OF LI...APPEARS SHOULD BE ENOUGH OF A FETCH OVER LONG ISLAND SOUND AND INSTABILITY FOR SCATTERED SNOW SHOWERS/FLURRIES THIS MORNING THROUGH THIS EVE. IN FACT...ALREADY SEEING SIGNS OF THIS ON RAD/SAT. A LOCALIZED DUSTING AND REDUCED VSBY IS POSSIBLE WITH ANY SNOW SHOWER ACTIVITY. SNOW SHOWER/FLURRY ACTIVITY COMES TO AN END LATE THIS EVENING...WITH CLEARING SKIES ON BACKSIDE OF DEPARTING POLAR LOW. WINDS WILL INCREASE IN THE WAKE OF THE ARCTIC FRONT WITH NW WINDS OF 20 TO 30 MPH AND GUSTS TO 45 MPH DEVELOPING LATE MORNING INTO EARLY AFTERNOON. POTENTIAL FOR SUSTAINED WINDS INTO THE LOWER 30S AND A FEW GUSTS TO 50 MPH THIS AFT/EVE AS WINDS ALOFT PEAK ACROSS THE NJ/NYC METRO...COAST AND HIGHER ELEVATIONS. THE WIND HAZARD AND IMPACTS ARE COVERED IN THE WINTER WEATHER ADVISORY. WINDS WILL BE SLOW TO SUBSIDE TONIGHT WITH STRONG GRADIENT BETWEEN ARCTIC HIGH AND CANADIAN MARITIMES LOW. && .SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/... POLAR LOW SLIDES OFFSHORE SUNDAY...WITH MODERATING ARCTIC HIGH PRESSURE BUILDING IN FROM THE WEST SUN INTO SUN NIGHT. SUNDAY SHOULD BE SUNNY...FRIGID...AND DRY WITH NW FLOW ALOFT AND ARCTIC HIGH PRESSURE BUILDING IN. AFTER A DANGEROUSLY COLD START TO THE DAY...DIMINISHING WINDS AND A MODERATING AIRMASS SHOULD ALLOW TEMPS TO MODERATE INTO THE TEENS...WITH WIND CHILLS FINALLY RISING ABOVE ZERO IN THE MID TO LATE AFTERNOON. HIGH PRESSURE MOVES ACROSS SUNDAY NIGHT...WITH STRONG RADIATIONAL COOLING CONDS LIKELY FOR THE FIRST HALF OF THE NIGHT...BEFORE HIGH CLOUDS BEGIN TO MOVE IN. THIS SHOULD ALLOW FOR TEMPS TO FALL TO 5 TO POSSIBLY 10 BELOW ZERO ACROSS RURAL LOCALES LIKE THE PINE BARRENS OF LI AND INTERIOR VALLEYS OF CT WHERE A SOLID SNOWPACK EXISTS. TEMPS MAY BEGIN TO MODERATE LATE WITH INCREASING HIGH CLOUD COVER. ELSEWHERE TEMPS WILL LIKELY BOTTOM OUT IN THE SINGLE DIGITS ALONG THE COASTAL PLAIN...WHILE HOLDING STEADY INT HE MID TEENS FOR NYC METRO. && .LONG TERM /MONDAY THROUGH FRIDAY/... MONDAY THROUGH TUESDAY...HIGH PRESSURE WILL MOVE OFFSHORE ON MONDAY ALLOWING FOR A RETURN FLOW TO SET UP WITH LOW LEVEL WARM ADVECTION COMMENCING DURING THE DAY. ALOFT...AMPLIFYING RIDGING ACROSS WESTERN NORTH AMERICA SENDS SEVERAL PIECES OF ENERGY INTO A DIGGING TROUGH ACROSS THE CENTRAL STATES. MODELS ARE COMING INTO BETTER GENERAL AGREEMENT WITH THIS TROUGH...BUT STILL SUBTLE DIFFERENCES IN PHASING OF ENERGIES REMAINS. THIS IS NOT SURPRISING AS THIS ENERGY IS EMANATING FROM THE NORTH PACIFIC AND IS COMING ASHORE LATE TODAY INTO EARLY SUNDAY. GENERAL AGREEMENT THAT LOW PRESSURE WILL DEVELOP ACROSS THE SOUTHEAST LATE MONDAY INTO MONDAY NIGHT AS THIS ENERGY AMPLIFIES THE MIDDLE AND UPPER LEVEL TROUGH. WARM ADVECTION AND INCREASING MOISTURE AHEAD OF THIS LOW SHOULD ALLOW FOR PRECIPITATION TO BREAK OUT MONDAY AFTERNOON AND EVENING...WITH THERMAL PROFILES SUPPORTING SNOW. IT IS AFTER THIS TIME THAT UNCERTAINTY CONTINUES AS THE LOW INTENSIFIES AND TRACKS ALONG THE COAST OR JUST INLAND TUESDAY. DETERMINISTIC AND ENSEMBLE MODELS STILL SHOW SPREAD WITH THE TRACK AND INTENSITY OF THIS LOW PRESSURE MONDAY NIGHT INTO TUESDAY. THIS WILL ULTIMATELY DETERMINE EXACT THERMAL PROFILES AND HOW MUCH PRECIPITATION WE END UP SEEING ACROSS THE AREA. THE SIGNALS ARE THERE FOR A RAPIDLY INTENSIFYING LOW TO MOVE FROM THE MIDDLE ATLANTIC REGION TUESDAY MORNING TO NORTHERN NEW ENGLAND AND SE CANADA BY TUESDAY NIGHT. HAVE FOLLOWED A CONSENSUS FORECAST DUE TO THE REMAINING MODEL SPREAD ON THE TIMING/TRACK/INTENSITY OF THIS LOW...BUT HAVE INCREASED POPS TO CATEGORICAL MON NIGHT INTO TUE BASED ON SOME CONVERGENCE IN TIMING OF SOLUTIONS AND ENSEMBLE PROBS FOR GREATER THAN .05 INCHES QPF DURING THIS TIME. IN TERMS OF SENSIBLE WEATHER...A LIKELY SCENARIO AT THIS POINT IS SNOW CHANGING TO RAIN AT THE COAST MONDAY NIGHT...WITH A WINTRY MIX CHANGING TO RAIN INLAND LATE MONDAY NIGHT INTO TUESDAY. TEMPERATURES MAY TAKE A LITTLE LONGER TO WARM ABOVE FREEZING INLAND...SO A PERIOD OF FREEZING RAIN IS POSSIBLE MONDAY NIGHT...BEFORE CHANGING TO RAIN TUESDAY MORNING. WILL ALSO HAVE TO MONITOR GROUND TEMPS SENSORS MONDAY NIGHT. IF GROUND TEMP WARM UP LAGS AIR TEMP WARMUP...THIS WOULD RESULT IN SERIOUS SURFACE ICING ISSUES. ON TUESDAY...RAIN...POSSIBLY HEAVY AT TIMES...WITH TEMPERATURES WELL INTO THE 40S. TIMING AND AMOUNTS REMAIN UNCERTAIN AT THIS TIME...BUT A GENERAL RANGE OF 1 TO 3 INCHES OF TOTAL QPF IS FORECAST IN THE CONSENSUS OF THE MODELS. SEE HYDRO SECTION FOR MORE INFORMATION. IT COULD ALSO BECOME QUITE BREEZY TUESDAY...BUT THIS AGAIN WILL ULTIMATELY BE DETERMINED BY THE EXACT TRACK AND INTENSITY AS THE LOW MOVES ACROSS THE AREA. MUCH OF THE PRECIPITATION SHOULD END TUESDAY NIGHT AS THE LOW MOVES WELL NE OF THE AREA. WEDNESDAY THROUGH THE END OF THE WEEK....A TRAILING SHORTWAVE MAY SWING THROUGH ON WEDNESDAY...SO HAVE LEFT POPS IN THE LOW CHANCE RANGE. A COLD FRONT ALSO MOVES THROUGH ON WEDNESDAY. TEMPERATURES WILL BE NEAR NORMAL IN THE LOWER 40S. TEMPERATURES SHOULD FALL BACK BELOW NORMAL LEVELS THURSDAY AS HIGH PRESSURE BUILDS OVER THE REGION. THE HIGH IS CURRENTLY PROGGED TO MOVE OFFSHORE FRIDAY AS ANOTHER FRONTAL SYSTEM APPROACHES. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... ARCTIC FRONT MOVING ACROSS THE TERMINALS THIS MORNING...AND WINDS ARE SHIFTING TO THE NW...AND WILL BE TO THE RIGHT OF 310 MAG THROUGH THE TAF PERIOD. WINDS WILL INCREASE TO 20-30 KT WITH 30-40 KT GUSTS INTO THIS EVENING. WINDS SLOWLY DIMINISH TOWARDS SUNDAY MORNING. GENERALLY VFR CONDS. HOWEVER...A BRIEF PERIOD OF MVFR CONDS IS POSSIBLE IN -SHSN THAT MAY DEVELOP AHEAD OF AND WITH THE PASSAGE OF THE COLD FRONT. A DUSTING OF SNOW ON RUNWAYS IS POSSIBLE...BUT NOT PROBABLE. .OUTLOOK FOR 12Z SUNDAY THROUGH WEDNESDAY... .SUN...VFR. NW GUSTS 20-25KT IN THE MORNING. .MON...VFR AM. CHANCE AFTERNOON SNOW WITH SUB-VFR. .MON NIGHT...IFR POSSIBLE. UNCERTAIN FORECAST...ALTHOUGH MIXED P- TYPE POSSIBLE ALL TERMINALS. SE GUSTS AROUND 25KT POSSIBLE LATE. .TUE...IFR/RAIN. SE-S WINDS G30-35KT AND LLWS POSSIBLE. .WED...MOSTLY VFR. CHC RAIN/SNOW SHOWER AND BRIEF SUB-VFR. && .MARINE... STRONG NW WINDS TODAY IN THE WAKE OF AN ARCTIC FRONT. GALE WARNING IN EFFECT UNTIL 11Z SUNDAY FOR NY HARBOR AND WESTERN LI SOUND...AND UNTIL 15Z FOR THE OCEAN...EASTERN LI SOUND...AND LI BAYS. ISOLATED SNOW SHOWERS ARE POSSIBLE WITH BRIEF REDUCTIONS IN VSBY TODAY. A BRIEF SMALL CRAFT ADVISORY MAY BE NEEDED SUNDAY MORNING AFTER THE GALES END...BUT TRANQUIL CONDS ON ALL WATERS EXPECTED BY SUNDAY AFTERNOON. THE COMBINATION OF GALES AND COLD TEMPERATURES WILL PRODUCE AT LEAST MODERATE FREEZING SPRAY ON ALL BUT THE SOUTH SHORE BAYS (FORECAST WAVES ARE TOO LOW FOR SIGNIFICANT SPRAY THERE) INTO SUNDAY...WITH HEAVY FREEZING SPRAY FORECAST TONIGHT ON THE SOUND/NY HARBOR/E BAYS...AND INTO SUNDAY MORNING FOR THE EASTERN SOUND/BAYS. SUB-SCA CONDITIONS FORECAST SUNDAY NIGHT THROUGH MONDAY AS HIGH PRESSURE MOVES OVER THE WATERS. THEN...DEVELOPING LOW PRESSURE ACROSS THE SE TRACKS UP THE EASTERN SEABOARD MONDAY NIGHT INTO TUESDAY. THIS WILL INCREASE SEAS WELL ABOVE SCA LEVELS ON TUESDAY AND BRING THE LIKELIHOOD OF SCA WINDS ACROSS ALL WATERS. THERE IS ALSO A CHANCE FOR GALE FORCE GUSTS...AT LEAST ON THE OCEAN...ON TUESDAY. THE LOW MOVES WELL NE OF THE WATERS TUESDAY NIGHT INTO WEDNESDAY WITH...BUT CONDITIONS SHOULD AT LEAST REMAIN ABOVE SCA LEVELS THROUGH WEDNESDAY. && .HYDROLOGY... NO HYDROLOGIC IMPACTS THROUGH SUNDAY NIGHT. A DEVELOPING LOW PRESSURE SYSTEM MOVING NEAR OR ALONG THE COAST MONDAY NIGHT INTO TUESDAY HAS THE POTENTIAL TO PRODUCE 1 TO 3 INCHES OF LIQUID EQUIVALENT PRECIPITATION. SOME OF THIS WILL FALL AS FROZEN PRECIPITATION MONDAY NIGHT...BUT THEN RUNOFF VIA MELTING SNOW AND HEAVY RAIN TUESDAY COULD CAUSE AT LEAST URBAN AND SMALL STREAM FLOODING PROBLEMS. IT IS TOO EARLY TO SAY IF MAIN STEM RIVERS WOULD BE AFFECTED DUE TO UNCERTAINTY IN WHERE THE HEAVIEST RAINFALL WILL OCCUR AS WELL AS THE EXACT TRACK AND INTENSITY OF THE LOW PRESSURE. && .TIDES/COASTAL FLOODING... POTENTIAL EXISTS FOR MINOR COASTAL IMPACTS WITH THE LATE MONDAY NIGHT/EARLY TUESDAY MORNING HIGH TIDE AHEAD OF A DEVELOPING LOW PRESSURE SYSTEM MOVING UP THE COASTAL PLAIN. STILL QUITE A BIT OF UNCERTAINTY EXISTS ON THE EVOLUTION OF THIS SYSTEM. POSITIVE TIDAL DEPARTURES OF 2 TO 2 1/2 FT ARE NEEDED FOR MINOR FLOOD THRESHOLDS TO BE REACHED...AND 3 TO 3 1/2 FT FOR MODERATE THRESHOLDS. && .CLIMATE... WITH THE EXTREMELY COLD AIR MASS FORECAST TODAY INTO SUNDAY...RECORD MINIMUMS AND RECORD LOW MAXIMUMS MAY BE REACHED. HERE ARE THE RECORDS AND FORECASTS... STATION......RECORD/FORECAST MINIMUM FOR 2/14 CENTRAL PARK.....2 (1916) / 0 LAGUARDIA........1 (1979) / 1 KENNEDY..........4 (1979) / 2 ISLIP............7 (2015) / 1 NEWARK...........0 (1979) / 0 BRIDGEPORT.......3 (2015*) / -2 STATION......RECORD LOW MAXIMUM/FORECAST HIGH FOR 2/14 CENTRAL PARK....17 (1979) / 14 LAGUARDIA.......15 (1979) / 15 KENNEDY.........17 (1979) / 16 ISLIP...........26 (1987) / 14 NEWARK..........15 (1979) / 15 BRIDGEPORT......18 (1979) / 14 *IN 1979 AS WELL && .OKX WATCHES/WARNINGS/ADVISORIES... CT...WIND CHILL WARNING FROM 1 PM THIS AFTERNOON TO NOON EST SUNDAY FOR CTZ005>012. NY...WIND CHILL ADVISORY FROM 1 PM THIS AFTERNOON TO NOON EST SUNDAY FOR NYZ072>075-078>081-176>179. WIND CHILL WARNING FROM 1 PM THIS AFTERNOON TO NOON EST SUNDAY FOR NYZ067>071. NJ...WIND CHILL ADVISORY FROM 1 PM THIS AFTERNOON TO NOON EST SUNDAY FOR NJZ004-006-103>108. WIND CHILL WARNING FROM 1 PM THIS AFTERNOON TO NOON EST SUNDAY FOR NJZ002. MARINE...GALE WARNING UNTIL 10 AM EST SUNDAY FOR ANZ330-340-345-350-353- 355. HEAVY FREEZING SPRAY WARNING FROM 6 PM THIS EVENING TO NOON EST SUNDAY FOR ANZ330-335-340. FREEZING SPRAY ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ330- 335-338-340. HEAVY FREEZING SPRAY WARNING FROM 6 PM THIS EVENING TO 6 AM EST SUNDAY FOR ANZ338. GALE WARNING UNTIL 6 AM EST SUNDAY FOR ANZ335-338. FREEZING SPRAY ADVISORY UNTIL 6 PM EST SUNDAY FOR ANZ350-353- 355. && $$ SYNOPSIS...NV/JMC NEAR TERM...JMC/NV SHORT TERM...NV LONG TERM...DS/NV AVIATION...MPS MARINE...MPS/JMC HYDROLOGY...DS/NV TIDES/COASTAL FLOODING... CLIMATE...

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