Area Forecast Discussion
Issued by NWS Upton, NY

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967 FXUS61 KOKX 031815 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 115 PM EST WED FEB 3 2016 .SYNOPSIS... LOW PRESSURE MOVES NORTHEAST INTO QUEBEC TONIGHT LIFTING A WARM FRONT ACROSS THE LOCAL AREA LATE THIS AFTERNOON FOLLOWED BY A SLOW MOVING COLD FRONT LATE TONIGHT BEFORE MOVING SOUTH OF LONG ISLAND THURSDAY. THE COLD FRONT STALLS JUST SOUTHEAST OF THE REGION THURSDAY NIGHT WITH A WAVE OF LOW PRESSURE DEVELOPING ALONG IT. HIGH PRESSURE SLOWLY BUILDS INTO THE AREA FRIDAY THROUGH SATURDAY. A COLD FRONT PASSES THROUGH ON SUNDAY. THERE CONTINUES TO BE POTENTIAL FOR MULTIPLE COASTAL LOWS MOVING NEAR THE EAST COAST EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... LATEST FORECAST WAS UPDATED BASED ON LATEST OBSERVATION AND NEAR TERM FORECAST TRENDS... HIGHLIGHTS INCLUDE...SLOWER MOVING WARM FRONT NORTH AND SLIGHTLY LATER TIMING OF SIGNIFICANT RAINFALL. TOTAL RAINFALL THROUGH 18Z INCLUDES .57 AT MGJ/.43 AT SUSSEX NJ AND LESS THAN 1/4 INCH FURTHER EAST WITH THE HIGHEST HOURLY RATES NEAR 1/4 INCH PER HOUR. THE AXIS OF HEAVIEST RAIN IS ADVECTING NE FROM THE WASH DC METRO AREA NE ACROSS SE PA...WHICH SHOULD ADVECT NE ACROSS NE NJ BY 20Z/3 PM AND NYC AFT 21Z/4 PM. MINOR URBAN FLOODING IS LIKELY WITH THIS HEAVIER RAIN. OTHERWISE...A VIGOROUS UPPER MISSISSIPPI RIVER VALLEY SHORT WAVE WILL LIFT INTO THE UPPER GREAT LAKES TODAY...WITH A STRONG SURFACE LOW TAKING A SIMILAR TRACK. ITS TRAILING COLD FRONT WILL SLOWLY APPROACH THE REGION LATE TODAY. THE HEAVIEST RAIN WILL COINCIDE WITH ENTRANCE OF ANOMALOUSLY HIGH PW VALUES NEAR 1.5 INCHES BY MID TO LATE THIS AFTERNOON. THERE MAY BE SOME TRAINING OF HEAVY RAIN ACTIVITY WITH THE SW FLOW FROM LOW LEVELS INTO THE UPPER LEVELS. SEE HYDROLOGY SECTION FOR POTENTIAL FLOODING IMPACTS. WITH THE INCREASED WARM ADVECTION...MOIST AIR IS ALSO GETTING ADVECTED IN. EXPECTING SOME FOG DEVELOPMENT...PARTICULARLY OVER ANY REMAINING SNOWPACK...LATE TODAY INTO THIS EVENING AS THE SOUTHWESTERLY FLOW REMAINS AND DEWPOINTS RISE GOING INTO THIS EVENING. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... THE REGION STARTS OFF IN THE PEAK OF THIS RAIN EVENT WITH MODERATE TO HEAVY RAIN STILL ONGOING THIS EVENING WITH THE AXIS OF HIGH PW VALUES STILL WITHIN THE AREA. BY OVERNIGHT...WARM CONVEYOR BELT OF LIFT/MOISTURE TRANSLATES TO EASTERN LONG ISLAND AND TO THE SOUTHEAST...SO THE HEAVIER RAIN WILL BE IN THOSE LOCATIONS LATE TONIGHT. THE COLD FRONT WILL BE SLOWLY APPROACHING THIS EVENING AND WILL MOVE ACROSS OVERNIGHT INTO DAYBREAK THURSDAY. WEAK HIGH PRESSURE RETURNS FROM THE WEST FOR THE AFTERNOON. RAIN WILL BEGIN TO TAPER OFF LATE TONIGHT INTO EARLY THURSDAY FOR THE LOWER HUDSON VALLEY BUT WILL LINGER FARTHER SOUTHEAST INTO THURSDAY MORNING BEFORE WIDESPREAD DRY CONDITIONS RETURN. THE LIFT FROM THE REGION BEING IN THE RIGHT REAR QUAD OF THE UPPER LEVEL JET WILL BE ONE OF THE REASONS THE RAIN HOLDS ON. VERY MILD NIGHT TONIGHT AS THE COLD FRONT HAS SLOWED DOWN COMPARED TO PREVIOUS FORECASTS. LOWEST TEMPERATURE COMES NEAR DAYBREAK THURSDAY WITH VALUES IN THE UPPER 40S TO NEAR 50. NORTHWEST FLOW AND COLD AIR ADVECTION WILL PROVIDE A LIMIT TO HIGHS THURSDAY AS COLDER WORKS DOWN INTO THE BOUNDARY LAYER. HIGHS ARE FORECAST MAINLY IN THE LOWER 50S FOR THURSDAY. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... THE FIRST FORECAST CHALLENGE IN THE LONG TERM REVOLVES AROUND LOW PRESSURE DEVELOPMENT ALONG A STALLED COLD FRONT JUST OFFSHORE THURSDAY NIGHT. THE FRONT THAT MOVES THROUGH ON THURSDAY WILL STALL AS IT MOVES OFFSHORE DUE TO ANOMALOUS RIDGING ACROSS THE WESTERN ATLANTIC. UPPER TROUGH AXIS WILL BE APPROACHING THURSDAY NIGHT...WITH ENERGY ROUNDING THE BASE OF THE TROUGH OVER THE SOUTHEAST. THIS TROUGH IS FORECAST TO TAKE ON A NEGATIVE TILT AS IT APPROACHES. AHEAD OF THE TROUGH AXIS WILL BE A STRENGTHENING 300 HPA JET STREAK...160 T0 180 KT. THE REGION WILL LIE NEAR THE RIGHT ENTRANCE REGION OF THIS JET STREAK. THERE HAS BEEN A TREND OVER THE LAST SEVERAL MODEL CYCLES TO STALL THE FRONT CLOSER TO THE AREA. AS THE WAVE OF LOW PRESSURE DEVELOPS ON THE FRONT...PRECIPITATION GETS FORCED NORTHWARD DUE TO THE ORIENTATION OF THE TROUGH AND THE ENHANCEMENT OF THE UPPER JET. LATEST CONSENSUS OF THE MODELS AND ENSEMBLES HAS MEASURABLE PRECIPITATION THURSDAY NIGHT BETWEEN 0.1 AND 0.25 LIQUID EQUIVALENT...MAINLY FOR CENTRAL AND EASTERN LONG ISLAND AND SOUTHEAST CONNECTICUT. LOOKING AT MIDDLE AND UPPER LEVEL FIELDS...THERE DOES APPEAR TO BE SOME ROOM FOR MODELS TO CONTINUE TRENDING A BIT MORE TO THE NW. WITH ALL OF THIS IN MIND...HAVE INCREASED POPS ACROSS LONG ISLAND AND CONNECTICUT. HAVE ELECTED TO CAP THEM AT CHANCE FOR NOW...BUT IF THE MODELS AND ENSEMBLES CONTINUE TO TREND AS THEY HAVE OVER THE LAST SEVERAL CYCLES...THEN POPS WOULD NEED TO BE RAISED FURTHER AND POSSIBLY EXPANDED WESTWARD. IT IS ALSO WORTH NOTING THAT THE LATEST 03Z SREF HAS SEVERAL MEMBERS WITH AROUND AN INCH OF SNOW AS FAR WEST AS THE NYC METRO. THE TREND ON THE LAST SEVERAL SREF MEANS HAS BEEN FOR SMALL SHIFTS WESTWARD WITH THE PRECIP...AND SMALL SHIFTS UPWARD FOR MEAN SNOW ACCUM. THERMAL PROFILES SHOULD BE SUPPORTIVE OF SNOW THURSDAY NIGHT...ESPECIALLY AFTER MIDNIGHT. LIGHT SNOW ACCUMULATION IS POSSIBLE ACROSS PARTS OF LONG ISLAND AND SOUTH EAST CT TOWARDS DAYBREAK FRIDAY. THERE IS POTENTIAL FOR ADVISORY LEVEL AMOUNTS HERE. IF MODEL TRENDS CONTINUE...THEN SOME LIGHT ACCUMULATING SNOW WOULD BE POSSIBLE FURTHER WEST. HIGH PRESSURE BUILDS INTO THE AREA FRIDAY INTO SATURDAY WITH WEAK RIDGING TAKING SHAPE ALOFT. THEN...A COLD FRONT CROSSES THE AREA ON SUNDAY. THE NEXT FORECAST CHALLENGE REVOLVES AROUND POSSIBLE COASTAL LOW DEVELOPMENT EARLY NEXT WEEK. MODELS HAVE COME INTO BETTER AGREEMENT REGARDING A COASTAL LOW SUNDAY NIGHT INTO MONDAY MOVING WELL SOUTH AND EAST OF THE AREA WITH LITTLE IMPACT. THIS IS STILL 6 DAYS OUT SO UNCERTAINTY STILL REMAINS. A STRONG NORTHERN STREAM TROUGH DIGS INTO THE EASTERN US MONDAY INTO MONDAY NIGHT AND CARVES OUT A LONG WAVE TROUGH. WESTERN NORTH AMERICA RIDGING BECOMES QUITE ANOMALOUS AS THIS TROUGH DEVELOPS. THE 00Z GFS AND ECMWF DEVELOP ANOTHER COASTAL LOW ALONG THE MIDDLE ATLANTIC MONDAY NIGHT INTO TUESDAY...WHICH TRACKS UP THE COAST NEAR THE AREA. WILL HAVE TO MONITOR THIS TIME PERIOD AS THE OVERALL SYNOPTIC PATTERN SHOWN BY THE GFS...ECMWF AND THEIR ENSEMBLES IS SUPPORTIVE OF A COASTAL STORM. UNCERTAINTY IS QUITE HIGH WITH TIMING...STRENGTH...AND PTYPE WITH THIS SYSTEM. FOR NOW...HAVE INCREASED POP TO LOW CHANCE MONDAY NIGHT INTO TUESDAY. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... HIGH IMPACT LLWS/COMPRESSION EVENT INTO THIS EVENING... A WARM FRONT WILL REMAIN NORTH OF THE REGION. A COLD FRONT WILL SLOWLY PASS THROUGH THE REGION TONIGHT. VFR TO MVFR CIGS WILL GRADUALLY BECOME IFR OR LESS LATE THIS AFTERNOON AS RAIN BECOME MORE WIDESPREAD. THE RAIN...IS EXPECTED TO BECOME MODERATE TO HEAVY AT TIMES. SOME OF THE HEAVY RAIN WILL RESULT IN REDUCED VISIBILITIES. CONDITIONS SLOWLY IMPROVE LATE TONIGHT...AFTER 07Z...WITH THE RAIN ENDING. SOUTH TO SOUTHEAST WINDS AHEAD OF THE WARM WILL REMAIN BETWEEN 10 TO 15 KTS. GUSTS UP TO 30 KT CAN BE EXPECTED ALONG THE COAST. WINDS WILL DIMINISH AND SHIFT TO THE WEST-NORTHWEST WITH THE FRONTAL PASSAGE. THE FRONT SHOULD MOVE THROUGH AFTER MIDNIGHT...WITH THE EXACT TIMING OF THE PASSAGE STILL UNCERTAIN. LOW LEVEL WIND SHEAR WILL CONTINUING INTO THIS EVENING. ...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: AMENDMENTS LIKELY FOR CHANGING FLIGHT CATEGORIES. THE TIMING OF HEAVY RAIN MAY BE OFF BY AN HOUR OR TWO. ANY HEAVY RAIN MAY LOWER VISIBILITIES TO LESS THAN A HALF MILE. GUSTS TO 30 KT MAY LAST LONGER THAN FORECAST. KLGA FCSTER COMMENTS: AMENDMENTS LIKELY FOR CHANGING FLIGHT CATEGORIES. THE TIMING OF HEAVY RAIN MAY BE OFF BY AN HOUR OR TWO. ANY HEAVY RAIN MAY LOWER VISIBILITIES TO LESS THAN A HALF MILE. GUSTS TO 30 KT MAY LAST LONGER THAN FORECAST. KEWR FCSTER COMMENTS: AMENDMENTS LIKELY FOR CHANGING FLIGHT CATEGORIES. THE TIMING OF HEAVY RAIN MAY BE OFF BY AN HOUR OR TWO. ANY HEAVY RAIN MAY LOWER VISIBILITIES TO LESS THAN A HALF MILE. GUSTS TO 20 KT MAY LAST LONGER THAN FORECAST. KTEB FCSTER COMMENTS: AMENDMENTS LIKELY FOR CHANGING FLIGHT CATEGORIES. THE TIMING OF HEAVY RAIN MAY BE OFF BY AN HOUR OR TWO. ANY HEAVY RAIN MAY LOWER VISIBILITIES TO LESS THAN A HALF MILE. GUSTS TO 20 KT MAY LAST LONGER THAN FORECAST. KHPN FCSTER COMMENTS: AMENDMENTS LIKELY FOR CHANGING FLIGHT CATEGORIES. THE TIMING OF HEAVY RAIN MAY BE OFF BY AN HOUR OR TWO. ANY HEAVY RAIN MAY LOWER VISIBILITIES TO LESS THAN A HALF MILE. KISP FCSTER COMMENTS: AMENDMENTS LIKELY FOR CHANGING FLIGHT CATEGORIES. THE TIMING OF HEAVY RAIN MAY BE OFF BY AN HOUR OR TWO. ANY HEAVY RAIN MAY LOWER VISIBILITIES TO LESS THAN A HALF MILE. GUSTS TO 30 KT MAY LAST LONGER THAN FORECAST. .OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY... .THURSDAY-FRIDAY...BECOMING VFR IN THE MORNING...ALTHOUGH SUB VFR EAST OF NYC METRO IS POSSIBLE THURSDAY NIGHT IN LIGHT SNOW. WNW-NW WINDS G15-20 KT POSSIBLE DURING THE DAY. .FRIDAY NIGHT-MONDAY...VFR. SW WINDS G15-20KT POSSIBLE DURING THE DAY ON SATURDAY. && .MARINE... SCA CONDITIONS WILL CONTINUE ON NEARSHORE WATERS THROUGH THIS AFTERNOON...AND INCREASE TO MARGINAL GALE ON THE OCEAN WATERS. THERE WILL BE SOME GALE GUSTS ON NEARSHORE WATER AS WELL...BUT THESE WILL LIKELY BE ISOLATED AND CONFINED TO DOWNWARD MOMENTUM TRANSPORT VIA MODERATE TO HEAVY RAIN LATE IN THE DAY AND DURING THE EVENING. CONDITIONS LOWER OVERNIGHT INTO THURSDAY FOR WINDS WITH A WEAKENING PRESSURE GRADIENT. HOWEVER...SCA OCEAN SEAS WILL REMAIN DUE TO RESIDUAL SWELL. A WAVE OF LOW PRESSURE DEVELOPS ALONG A STALLED FRONT NEAR THE WATERS THURSDAY NIGHT. SCA CONDITIONS ARE LIKELY ON THE OCEAN WATERS THURSDAY NIGHT INTO FRIDAY MORNING AS SEAS REMAIN ABOVE 5 FT DUE TO THE PROXIMITY OF THIS DEVELOPING SYSTEM. HIGH PRESSURE THEN BUILDS OVER THE WATERS FRIDAY INTO SATURDAY WITH SUB-SCA CONDITIONS FORECAST. A COLD FRONT CROSSES THE WATERS ON SUNDAY...BUT CONDITIONS SHOULD REMAIN SUB-SCA. && .HYDROLOGY... RAINFALL EVENT THROUGH TONIGHT LOOKS TO AVERAGE BETWEEN 1 AND 1.5 INCHES WITH LOCALLY HIGHER AMOUNTS...PERHAPS UP TO AROUND 2 INCHES BASED ON HIGH RES OUTPUT. THE HILLS OF LOWER HUDSON VALLEY...NE NJ AND SOUTHERN CT...COULD SEE SOME OF THOSE HIGHER AMOUNTS DUE TO SLOPE ENHANCEMENT WITH TOPOGRAPHY. THIS RAINFALL COMBINED WITH SATURATED GROUNDS FROM RECENT SNOW MELT AND SNOW CLOGGED DRAINS IS EXPECTED TO RESULT IN AREAS OF URBAN AND POOR DRAINAGE FLOODING. SIGNIFICANT RISES ARE ALSO LIKELY FOR QUICK RESPONDING SMALL STREAM IN NORTHEASTERN NEW JERSEY...WITH POTENTIAL FOR MINOR FLOODING OF VULNERABLE ADJACENT LOCALES. THERE IS A SLIGHT CHANCE...LESS THAN 20 PERCENT CHANCE...OF FLASH FLOODING...MEANING THIS IS AN ISOLATED THREAT. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR ANZ330-335- 338-340-345. GALE WARNING UNTIL MIDNIGHT EST TONIGHT FOR ANZ350-353-355. && $$ SYNOPSIS...NV NEAR TERM...GC/NV SHORT TERM...JM LONG TERM...DS AVIATION...BC/MET MARINE...JM/DS HYDROLOGY...JM/DS

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