Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 191151 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 651 AM EST FRI DEC 19 2014 .SYNOPSIS... HIGH PRESSURE BUILDS IN FROM THE WEST AND MOVES OVER THE NORTHEAST INTO EARLY NEXT WEEK. A SERIES OF LOW PRESSURE SYSTEMS WILL THEN AFFECT THE REGION THROUGH THE MID-WEEK PERIOD. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... CLOUD COVERAGE INCREASED THROUGH THE MORNING. TEMPERATURES RUNNING A FEW DEGREES TOO LOW. INCREASED THE MAX TEMPS BY ONE DEGREE AND INCREASED SLIGHTLY WITH WIND GUSTS ON LAND. OTHERWISE...REST OF FORECAST ON TRACK. WITH LOW PRESSURE EXITING WELL UP INTO NORTHERN LATITUDES...THE LOCAL REGION WILL BE MORE UNDER THE INFLUENCE OF HIGH PRESSURE TODAY AND RIDGING ALOFT. THERE WILL BE LESSENING CYCLONIC FLOW ALOFT THROUGH THE DAY TODAY. THE PRESSURE GRADIENT WILL WEAKEN WITH BOUNDARY LAYER WINDS LOWERING IN RESPONSE. ONE MAIN FACTOR WITH THE FORECAST IS THE CURRENT SUBSIDENCE INVERSION IN THE LOW LEVELS AND WHETHER OR NOT THIS WEAKENS THROUGH THE DAY TODAY. IF IT WEAKENS...CLOUDS WILL DECREASE MORE AND ALLOW FOR MORE SUN AND IT IF HOLDS...A MOSTLY CLOUDY DAY IS IN STORE. FROM MODEL BUFKIT SOUNDINGS AND OBSERVATIONS...IT SEEMS LIKE THIS INVERSION IS PRETTY STRONG AND PROBABLY WILL REMAIN THROUGH THE MORNING AND START TO WEAKEN THIS AFTERNOON. THEREFORE...EXPECTING AN ABUNDANCE OF CLOUDS TO REMAIN MUCH OF THE DAY. MODELS HAVE HAD DIFFICULTY RESOLVING THE LOWER CLOUDS BEING EXPERIENCED IN DIFFERENT LOCATIONS SO FAR SO A MANUAL ADJUSTMENT UPWARD WAS MADE TO MODEL CLOUD COVERAGE WITHIN THE FORECAST DATABASE FOR TODAY. HOWEVER...A DOWNWARD TREND WAS CONVEYED GOING INTO THE EVENING WITH THE CENTER OF HIGH PRESSURE MOVING CLOSER TO THE LOCAL REGION. FOR MAX TEMPS...USED A BLEND OF GMOS AND MAV GUIDANCE. THE MAV GUIDANCE HAD RELATIVELY LESS ERROR COMPARED TO MET GUIDANCE FOR HIGH TEMPERATURES THE PREVIOUS DAY. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... FOR TONIGHT...THERE IS STILL SOME UNCERTAINTY WITH LINGERING LOW CLOUDS AND HOW MUCH OF A LOW LEVEL INVERSION THERE WILL BE. OTHERWISE...WITH HIGH PRESSURE CONTINUING TO BUILD INTO THE REGION...WINDS WILL FURTHER LOWER. THEREFORE...THE RADIATIONAL COOLING WILL BE DEPENDENT MAINLY ON THE CLOUD COVERAGE. WENT WITH SOME SCATTERED CLOUD COVERAGE AND AS A RESULT OF THAT USED A BLEND OF GMOS/MET/MAV GUIDANCE FOR LOWS. THIS PRESENTS LOWS A FEW DEGREES HIGHER BUT STILL...THESE LOW TEMPERATURES ARE REMARKABLY LOWER THAN RECENT NIGHTS...RANGING FROM THE LOWER 20S TO NEAR 30. FOR SATURDAY...SAME SCENARIO HERE WITH HIGH PRESSURE CONTINUING TO BUILD IN. THIS DAY WILL FEATURE LOWER MAX TEMPS THOUGH BECAUSE OF LIMITED VERTICAL MIXING. THE WINDS IN THE LOW LEVELS WILL BE TRANSITIONING TO LIGHT N-NE FLOW...HELPING TO ADVECT IN SOME COOLER AIR. MAX TEMPS AGAIN WERE A BLEND OF GMOS/MET/MAV GUIDANCE AND UP TO 3-4 DEGREES COOLER ALONG THE COAST THAN THE PREVIOUS DAY. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... AS HIGH PRESSURE IN THE VICINITY OF MAINE SAT NIGHT SLOWLY SHIFTS EAST THROUGH MONDAY...MOISTURE STREAMS INTO THE TRI STATE AREA FROM OFF THE WATERS. DURING SATURDAY NIGHT...THIS MOISTURE WILL BE SHALLOW...SUPPORTING ONLY LIGHT/VERY LIGHT PCPN. SLIGHT CHC POPS FOR ROUGHLY THE SE HALF OF THE CWA. MID LEVELS WILL PROBABLY BE DRY WITH A LACK OF ICE NUCLEI. THERE IS HOWEVER A CHANCE THAT THE COLDEST TEMPERATURE IN THE SATURATED LAYER CLOSER TO THE SURFACE WILL BE COLD ENOUGH TO SUPPORT ICE CRYSTALS FOR LIGHT SNOW. WOULD BE MORE CONFIDENT FOR SNOW AS A PCPN TYPE IF THE LOW LEVEL FLOW WAS MORE VEERED TO THE EAST (SEA SALT AS NUCLEI)...BUT IN ANY CASE...OVERALL CHANCES OF PCPN ARE LOW. HAVE GONE WITH A MIX OF LIGHT SNOW/RAIN/FREEZING RAIN DEPENDING ON SURFACE TEMPS. MID LEVELS MOISTEN SUNDAY MORNING WITH A SHORTWAVE PASSING THROUGH...SO FREEZING RAIN IS PROBABLY OUT OF THE EQUATION BY THIS TIME. SLIGHT CHC OF LIGHT SNOW OR RAIN THEREFORE FOR SUNDAY. POPS INCREASE MONDAY...MAINLY IN THE AFTERNOON...AS A WAVE OF LOW PRESSURE FORMS ALONG A STALLED BOUNDARY NEAR CAPE HATTERAS AND PUSHES NORTH. A SLIGHT CHANCE OF LIGHT RAIN AND SNOW IN THE MORNING...THEN A CHANCE OF RAIN IN THE AFTERNOON AS THERMAL PROFILES BECOME TOO WARM FOR ANYTHING ELSE. WILL ALSO NEED TO MONITOR FOR THE POSSIBILITY OF MINOR COASTAL FLOODING STARTING WITH THE MONDAY MORNING HIGH TIDE CYCLE. WINDS WILL NOT BE PARTICULARLY STRONG LEADING UP IT...BUT THEY WILL BE ENE FOR SOME TIME AND TIDES WILL BE ON THE HIGHER SIDE ASTRONOMICALLY AS THERE IS A NEW MOON ON SUNDAY. FOR TUES AND WEDS...A MUCH STRONGER LOW PRESSURE SYSTEM AFFECTS THE AREA. LOOKS LIKE A PRIMARY LOW CENTER MOVES ACROSS THE GREAT LAKES WHILE A SECONDARY LOW CENTER FORMS BEFORE PASSING NEARBY WEDS EVENING. THIS STILL LOOKS LIKE AN ALL-RAIN EVENT. HAVE CAPPED POPS AT 50% FOR TUES DUE TO UNCERTAINTY WITH NORTHWARD ADVANCEMENT OF THE WEAKENING INITIAL LOW THAT HAD BEEN APPROACHING FROM THE CAROLINA COAST. MORE CONFIDENCE IN RAINFALL DURING WEDS AS THE SECONDARY LOW CENTER OF THE STRONGER STORM SYSTEM PASSES NEARBY. MINOR STREET FLOODING IS POSSIBLE DURING WEDS/WEDS EVENING. STILL A LOW CHANCE OF CONVECTION ENHANCING THE RAINFALL AS SOME ELEVATED INSTABILITY IS FORECAST BY BOTH GFS AND ECMWF. WINDS WILL PROBABLY BE THE BIGGER CONCERN WITH A TIGHTENING PRESSURE GRADIENT AND A DECENT LOW LEVEL JET PASSING THROUGH SOME TIME ON WEDS AFTERNOON/EVENING. A WIND ADVISORY COULD EVENTUALLY BE NEEDED FOR SOME AREAS. RIGHT NOW IT APPEARS THAT PCPN WILL BE OVER BY CHRISTMAS MORNING. HOWEVER...WITH A FAIRLY STRONG WESTERLY FLOW...LAKE EFFECT RAIN/SNOW SHOWERS COULD REACH THE NW ZONES. NEAR-WIND ADVISORY CRITERIA COULD STILL BE MET. TEMPERATURES ON CHRISTMAS MOSTLY 40-45. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... A STRONG LOW PRESSURE SYSTEM WILL MOVE FURTHER EAST ACROSS THE CANADIAN MARITIMES AS HIGH PRESSURE MOVES EAST TOWARD THE REGION BY 12Z SAT. TODAY...CIGS 030-040FT UNTIL 22Z. LOW CHC OF BRIEF MVFR CIGS UNTIL 15Z. WINDS 310-350 DEGREES MAGNETIC AT SPEEDS OF 10-15KT WITH GUSTS TO ARND 20KT UNTIL 22Z. TONIGHT...VFR WITH WINDS DECREASING TO LESS THAN 10 KT. SATURDAY...VFR WITH CIGS ABV 030FT DEVELOPING AFT 18Z. LIGHT N-NE WINDS 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. THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD. KTEB FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. KHPN FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. KISP FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. .OUTLOOK FOR 18Z SAT THROUGH WED... .SAT NIGHT...VFR CIGS POSSIBLY MVFR. LIGHT EAST WINDS. SLIGHT CHC OF LIGHT SNOW/RAIN. .SUNDAY...MVFR CIGS. LIGHT EAST WINDS. SLIGHT CHC OF AM SNOW/PM RAIN. .MON...MVFR OR LOWER POSSIBLE IN SE FLOW. CHC OF RAIN. .MON NIGHT-TUE...IFR LIKELY AT TIMES IN RAIN...CIGS AND VSBYS. SE WINDS 10-20 KT. .WED...HIGH IMPACT EVENT POSSIBLE...IFR LIKELY WITH HEAVY RAIN AND STRONG GUSTY SE WINDS 25KT+ SHIFTING TO W LATE. && .MARINE... THE MAIN FEATURE WILL BE HIGH PRESSURE GRADUALLY BUILDING IN FROM THE WEST THROUGH SATURDAY. FOR THIS MORNING...A STEEP ENOUGH PRESSURE GRADIENT BETWEEN THE HIGH TO THE WEST AND LOW NEAR NEWFOUNDLAND WILL ALLOW FOR SOME GUSTY WINDS. HOWEVER...ANY 25KT GUSTS ARE ONLY EXPECTED TO BE OCCASIONAL WITH MOST GUSTS BELOW 25 KT. THE LOW RACES TO THE NORTHERN LATITUDES DURING THE DAY AND HIGH PRESSURE WILL CONTINUE TO BUILD IN FROM THE WEST. THIS WILL ALLOW FOR A STEADY DECREASE IN THE PRESSURE GRADIENT. THE BOUNDARY LAYER FLOW AND SURFACE WINDS WILL DECREASE IN RESPONSE. OVERALL...MAINLY SUB SCA CONDITIONS SHOULD PREVAIL THROUGH SATURDAY. TRANQUIL CONDITIONS CONTINUE THROUGH THE REST OF THE WEEKEND. WINDS AND SEAS BUILD ON MONDAY WITH A TIGHTENING PRESSURE GRADIENT. SCA CONDS THEN LIKELY FOLLOW MON NIGHT AND TUES. && .HYDROLOGY... DRY WEATHER IS FORECAST THROUGH SATURDAY WITH ONLY SLIGHT CHANCES OF PRECIP SATURDAY NIGHT AND SUNDAY. NO HYDRO IMPACTS EXPECTED INTO EARLY NEXT WEEK. 1/4 TO 1/2 INCH OF RAIN IS POSSIBLE MONDAY AFTERNOON THROUGH TUESDAY AS LOW PRES PASSES SOUTH OF LONG ISLAND. NO HYDROLOGICAL IMPACTS EXPECTED. RAIN ON WEDNESDAY/WEDS NIGHT MAY AVERAGE 1-2 INCHES ACROSS THE REGION. MINOR STREET FLOODING IS POSSIBLE. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...JC/JM NEAR TERM...JM SHORT TERM...JM LONG TERM...JC AVIATION...GC MARINE...JM HYDROLOGY...JC/JM

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