Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 250550 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 150 AM EDT MON APR 25 2016 .SYNOPSIS... HIGH PRESSURE SLIDES OFFSHORE TONIGHT. A BACKDOOR COLD FRONT DEVELOPS TO THE NORTH ON MONDAY...SLOWLY SLIDES THROUGH THE TRI- STATE MONDAY NIGHT AND TUESDAY...THEN PUSHES WELL TO THE SOUTH TUESDAY NIGHT. HIGH PRESSURE BRIEFLY BUILDS ON WEDNESDAY...BEFORE ANOTHER LOW AFFECTS THE AREA FROM THURSDAY INTO FRIDAY. HIGH PRESSURE BUILDS IN FOR NEXT WEEKEND. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... FORECAST IS GENERALLY ON TRACK. DEWPOINTS WERE A BIT HIGHER THAN FORECAST DUE TO THE ONSHORE FLOW. DEEP LAYERED RIDGING REMAINS ANCHORED ALONG THE SOUTHEASTERN SEABOARD TONIGHT...WITH ASSOCIATED SUBSIDENCE KEEPING THINGS DRY. INCREASING MID LEVEL MOISTURE...AS WELL AS SOME MID-LEVEL FRONTOGENESIS SHOULD BRING SOME MID LEVEL CLOUDS IN...MAINLY OVERNIGHT. FOR LOWS TONIGHT USED A BLEND OF MAV/MET/ECS GUIDANCE AND NAM 2-METER TEMPERATURES...WITH VALUES NEAR TO SLIGHTLY ABOVE NORMAL. MINOR UPDATES BASED ON LATEST GUIDANCE AND TRENDS THIS EVENING. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/... DEEP LAYERED RIDGING CONTINUES TO BUILD OVER THE AREA ON MONDAY. THE SUBSIDENCE UNDER THE RIDGE SHOULD KEEP ANY PRECIPITATION AT BAY...HOWEVER MID AND HIGH CLOUDS WILL CONTINUE TO BUILD IN WITH STRENGTHENING LOW-MID LEVEL WARM AIR ADVECTION. A BLEND OF MAV/MET/ECS GUIDANCE...NAM 2-METER TEMPERATURES AND A MIX DOWN FROM 975-875 HPA PER BUFKIT SOUNDINGS WAS USED FOR HIGHS ON MONDAY. HIGHS SHOULD BE A FEW DEGREES ABOVE NORMAL. THE FORECAST FOR MONDAY NIGHT/TUESDAY IS A LITTLE TRICKY AS IT IS VERY MUCH DEPENDENT ON WHERE THE BACK DOOR COLD FRONT IS. THERE HAS BEEN A CHANGE IN MODEL SOLUTIONS...WITH AN OVERALL SLIGHT NORTHWARD TREND. THE NAM REMAINS THE FARTHEST N/LEAST PROGRESSIVE...WITH THE ECMWF THE MOST PROGRESSIVE/FARTHEST...WITH THE GFS AND CMC-REG IN BETWEEN. FOR NOW LEANED TOWARDS A COMPROMISE SOLUTION WEIGHED TOWARDS THE GFS/CMC-REG. WHAT IS BOTHERSOME IS THAT ONE OF THE STRENGTHS OF THE NAM IS ITS HANDLING OF SHALLOW COLD AIR MASSES EAST OF THE APPALACHIANS...OF WHICH THIS IS THE CASE...AND THIS TYPICALLY IS ONE OF THE WEAKNESS OF THE GFS. BASED ON THIS...THERE IS A LOW DEGREE OF CONFIDENCE IN THE DETAILS MONDAY NIGHT/TUESDAY. HOWEVER...THERE IS MODERATE- HIGH CONFIDENCE IN THE LARGER PICTURE THAT THERE WILL BE A PERIOD OF LIGHT TO MODERATE PRECIPITATION OVER THE REGION AT SOME POINT LATE MONDAY NIGHT/TUESDAY...AND AT SOME POINT IT WILL TURN NOTICEABLY COOLER DURING THE PROCESS. THERE IS ALSO MODERATE-HIGH CONFIDENCE IN THE POTENTIAL FOR ISOLATED THUNDERSTORMS MONDAY NIGHT AS WELL AS ALL MODELS SHOW SHOWALTER INDICES OF -2 TO 2 OVER THE REGION THEN - SUPPORTING THE IDEA OF ELEVATED CONVECTION. FOR NOW...THE MOST REASONABLE PREDICTION IS FOR SPOTTY SHOWERS TO MOVE IN FROM N TO S MONDAY EVENING...THEN BECOME A BIT MORE WIDESPREAD AFTER MIDNIGHT...EVEN BECOMING NUMEROUS ACROSS MAINLY THE N 1/2 OF THE CWA. THERE ALSO SHOULD BE A FEW ISOLATED ELEVATED THUNDERSTORMS AS WELL. THE SHOWERS WILL CONTINUE ON TUESDAY...WITH THE POTENTIAL FOR ISOLATED THUNDER AS WELL MAINLY TO THE S OF THE BACKDOOR COLD FRONT. FOR NOW AM INDICATING THE AREA WITH THE POTENTIAL FOR THUNDER AS THE S 1/2 OF THE CWA...BUT THIS WILL CHANGED BASED ON THE ACTUAL LOCATION OF THE FRONT ON TUESDAY. NOTE...IF THE NAM IS CORRECT...THEN THERE ACTUALLY COULD BE MORE WIDESPREAD CONVECTION ESPECIALLY OVER NE NJ...POSSIBLY STRONG TO MAYBE EVEN SEVERE IN NATURE. HOWEVER AT THIS TIME...THE RISK OF THIS IS LESS THAN 10 PERCENT. FOR LOWS MONDAY NIGHT...A BLEND OF MAV/MET/ECS GUIDANCE AND NAM/GFS/CMC/ECMWF 2-METER TEMPERATURES WAS USED...WITH VALUES FORECAST TO BE AROUND 5-10 DEGREES ABOVE NORMAL. A BLEND OF NAM/CMC/ECMWF/GFS 2-METER TEMPERATURES...A MIX DOWN FROM 975-850 HPA PER BUFKIT SOUNDINGS...AND A BLEND OF MAV/ECS/MET GUIDANCE WAS USED FOR HIGHS ON TUESDAY. HIGHS SHOULD BE AROUND NORMAL IN THE IMMEDIATE NYC METRO AND 5 OR SO DEGREES BELOW NORMAL ELSEWHERE. NOTE...THIS IS VERY DEPENDENT ON FRONTAL TIMING/PLACEMENT. IF THE ECMWF IS CORRECT TEMPERATURES COLD BE 5-10 DEGREES COLDER THAN FORECAST. HOWEVER...IF THE NAM IS RIGHT HIGHS COULD BE 10-15 DEGREES WARMER THAN FORECAST...ESPECIALLY OVER W LONG ISLAND/NYC/NE NJ AND THE LOWER HUDSON VALLEY. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... MODELS IN FAIRLY GOOD AGREEMENT FOR THE LONG TERM. COLD FRONT PUSHES FARTHER OFFSHORE TUESDAY NIGHT. THERE MAY BE SOME LINGERING SHOWERS FOR SOUTHERN AND EASTERN SECTIONS FOR THE FIRST PART OF TUESDAY NIGHT. HIGH PRESSURE BUILDS BEHIND THE FRONT THEREAFTER. VERTICALLY STACKED LOW OVER SOUTHEASTERN CANADA ON WEDNESDAY WILL WEAKEN AND HEAD NORTHEAST THROUGH THURSDAY. THIS ALLOWS HIGH PRESSURE TO CONTINUE TO BUILD IN AT THE SURFACE FOR WEDNESDAY AND WEDNESDAY NIGHT. A FRONTAL BOUNDARY APPROACHES THE AREA ON THURSDAY...WITH AN AREA OF LOW PRESSURE THAT WILL DEVELOP OVER THE CENTRAL PLAINS AND RIDE ALONG THE BOUNDARY...AND MOVE TOWARD THE MID-ATLANTIC THROUGH THURSDAY NIGHT. THIS LOW SHOULD PASS WELL SOUTH OF THE AREA THURSDAY NIGHT INTO FRIDAY MORNING. HOWEVER...WE WILL BE ON THE NORTHERN FRINGES OF THE PRECIPITATION SHIELD. THERE IS STILL UNCERTAINTY AS TO HOW MUCH RAIN WE WILL SEE FROM THIS LOW. A TRACK CLOSER TO THE AREA WILL MEAN MORE RAIN. SHOWERS ARE POSSIBLE...MAINLY LATE THURSDAY MORNING THROUGH THURSDAY NIGHT. SOME LINGERING SHOWERS POSSIBLE ON FRIDAY MORNING. HIGH PRESSURE BUILDS INTO THE AREA FROM SOUTH CENTRAL CANADA ONCE AGAIN FOR FRIDAY AFTERNOON AND INTO THE FIRST HALF OF NEXT WEEKEND. && .AVIATION /06Z MONDAY THROUGH FRIDAY/...
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HIGH PRESSURE REMAINS ALONG THE MID ATLANTIC COAST THROUGH TODAY THEN SHIFTS TO THE SOUTH TONIGHT AS A WARM FRONT MOVES INTO THE REGION. VFR THROUGH THE FORECAST PERIOD WITH A MID AND HIGH CEILING. THE EXCEPTION WILL BE KSWF WHERE LOWER CLOUDS...POSSIBLY 2500 TO 3000 FT CEILINGS TOWARD 06Z DEVELOP ALONG WITH SHOWERS. THERE IS ALSO A LOW CHANCE OF THUNDERSTORMS IN THE VICINITY OF KSWF. LIGHT AND VARIABLE WIND OVERNIGHT BECOMES SOUTH TO SOUTHWEST EARLY THIS MORNING...AND INCREASING TO 10 TO 15 KT. SOUTHERLY WINDS PREVAIL INTO THIS EVENING...AND DIMINISH...POSSIBLY BECOMING LIGHT AND VARIABLE. LOW CONFIDENCE FORECAST IN THE WIND DIRECTIONS...ESPECIALLY LATE THIS AFTERNOON AND EVENING...AS DIRECTIONS WILL BE DEPENDENT ON WHERE THE WARM FRONT SETS UP IN THE VICINITY AND WHEN. .OUTLOOK FOR 06Z TUESDAY THROUGH FRIDAY... .LATE MONDAY NIGHT...BECOMING MVFR WITH DEVELOPING SHOWERS AND ISOLATED THUNDERSTORMS. .TUESDAY-TUESDAY NIGHT...MVFR OR LOWER POSSIBLE IN SHOWERS. SLIGHT CHANCE OF EMBEDDED THUNDERSTORMS TUESDAY...MAINLY NYC TERMINALS AND WEST. .WEDNESDAY...VFR. .THURSDAY...MVFR OR LOWER POSSIBLE IN SHOWERS. .FRIDAY...BECOMING VFR.
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&& .MARINE... A LIGHT TO MODERATE PRESSURE GRADIENT WILL KEEP WINDS TO 15 KT OR LESS THROUGH MONDAY...WITH SEAS 4 FT OR LESS. A PERSISTENT SW FLOW OF 10-15KT GUSTING TO AROUND 20 KT ON THE COASTAL OCEAN WATERS ON MONDAY NIGHT/TUESDAY MORNING COULD BRING SEAS TO SCA LEVELS THERE. HOWEVER...CONFIDENCE IN THE FLOW REMAINING SW THROUGH TUESDAY MORNING THERE IS LOW...AS E-NE FLOW COULD DEVELOP FASTER THAN CURRENTLY FORECAST. ON THE NON-OCEAN WATERS...CONFIDENCE IS HIGHER IN THE FLOW BECOMING E...ESPECIALLY OVER THE SOUND/E BAYS OF LONG ISLAND ON TUESDAY. SUB-SMALL CRAFT CONDITIONS ARE LIKELY ON THESE WATERS AS WELL. WINDS SHOULD REMAIN BELOW SCA CRITERIA FOR THE LONG TERM. WAVES ON THE OCEAN ZONES WILL START OUT AT 5 TO 6 FT TUE NIGHT BUT WILL DIMINISH AS THE NIGHT PROGRESSES. 5 FT WAVES MAY LINGER INTO WEDNESDAY MORNING...ESPECIALLY FOR THE EASTERN OCEAN ZONE. WAVES WILL BE BELOW 5 FT ACROSS ALL WATERS FOR THE REST OF THE LONG TERM. && .HYDROLOGY... NO SIGNIFICANT PRECIPITATION IS FORECAST THROUGH MONDAY. THERE IS THE POTENTIAL FOR AROUND 1/2 INCH OF RAINFALL FROM MONDAY NIGHT INTO TUESDAY EVENING...WITH LOCALLY HIGHER AMOUNTS POSSIBLE WITH ANY STRONGER CONVECTION. AT THIS TIME...NO WIDESPREAD HYDROLOGIC IMPACTS ARE ANTICIPATED FROM THIS RAINFALL. NO HYDROLOGIC PROBLEMS ARE ANTICIPATED WEDNESDAY THROUGH SUNDAY. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...MALOIT/JP NEAR TERM...MALOIT/JP SHORT TERM...MALOIT LONG TERM...JP AVIATION...MET MARINE...MALOIT/JP/PW HYDROLOGY...MALOIT/JP

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