Area Forecast Discussion
Issued by NWS Upton, NY

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689 FXUS61 KOKX 301554 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 1154 AM EDT SAT APR 30 2016 .SYNOPSIS... HIGH PRESSURE BUILDS IN TODAY...THEN SLIDES OFFSHORE TONIGHT. A WARM FRONT APPROACHES SUNDAY...STALLING OUT TO THE SOUTH OF LONG ISLAND EARLY NEXT WEEK...WITH WAVES OF LOW PRESSURE RIDING ALONG IT. HIGH PRESSURE THEN BUILDS IN TUESDAY...THEN SLOWLY SLIDES OFFSHORE TUESDAY NIGHT. A COMPLEX STORM SYSTEM WILL THEN BRING UNSETTLED WEATHER TO THE REGION WEDNESDAY THROUGH FRIDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... EARLY MORNING CLOUDS HAVE ERODED AS RIDGE BUILDS. HOWEVER...SC CLOUDS HAVE DEVELOPED AND GENERALLY EXPECT SCT TO BKN CLOUDS THROUGH THE AFTERNOON. PARTLY TO MOSTLY SUNNY. TEMPS THIS AFTERNOON SHOULD RANGE FROM THE UPPER 50S NEAR THE COAST...AND MID 60S INTERIOR. THE SEABREEZE SHOULD ALLOW FOR WIND GUSTS UP TO 20 MPH AT COASTAL AREAS AT TIMES THIS AFTERNOON. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... THE AXIS OF THE DEEP LAYERED RIDGE SLIDES TO THE EAST TONIGHT...HOW FAST IT DOES SO WILL DETERMINE HOW FAST RAIN MOVES INTO THE TRI-STATE AFTER MIDNIGHT. MINDFUL THAT THE GFS HAS A BIAS OF BEING TO PROGRESSIVE WITH DEEP LAYERED RIDGING MOVING OFF THE ATLANTIC SEABOARD...LEANED TOWARDS SLOWER ECMWF/NAM. KEPT FAR EASTERN AREAS DRY...AND LIMITED LIKELY POPS TO FAR WESTERN ZONES LATE TONIGHT. LOWS TONIGHT WERE BASED ON A BLEND OF MET/ECS/MAV GUIDANCE WITH NAM 2-METER TEMPERATURES...AND SHOULD BE A FEW DEGREES BELOW NORMAL. 00Z ECMWF IS THE ONLY MODEL WHICH DOES NOT DEVELOP A SECONDARY LOW OVER THE MID-ATLANTIC STATES SUNDAY NIGHT...THEN TRACK THE LOW S OF LONG ISLAND MONDAY. THE CMC DOES THIS...IT JUST TRACKS THE LOW TO THE S OF LONG ISLAND MUCH FASTER THAN OTHER GUIDANCE. THE 00Z ECMWF IS ALSO THE ONLY MODEL TO NOT HAVE A FRONT MOVE FAR ENOUGH S MONDAY NIGHT TO PRECLUDE RAIN MONDAY NIGHT INTO TUESDAY AS WAVES OF LOW PRESSURE RIDE ALONG IT. THIS IS BECAUSE IT IS FARTHER N THAN OTHER MODELS WITH A 700 HPA SHORTWAVE AND ASSOCIATED VORTICITY MAXIMA AS THEY TRANSIT THE GREAT LAKES/NORTHEAST SUNDAY NIGHT-MONDAY. THE 00Z CMC TAKES THE FRONT ABOUT AS FAR S AS THE NON 00Z-ECMWF MODELS...HOWEVER IT HAS A STRONGER WAVE OF LOW PRESSURE RIDE ALONG THE FRONT THAN OTHER GUIDANCE. AS A RESULT DID NOT INCLUDE THE 00Z ECMWF OR CMC-GLOBAL IN THE BLEND OF GUIDANCE SUNDAY-MONDAY NIGHT...HOWEVER DID USE THE 12Z/29 ECMWF AS IT WAS MORE CONSISTENT WITH REMAINDER OF 00Z MODEL SUITE. AS A RESULT...EXPECT PERIODS OF RAIN TO DEVELOP FROM SW TO NE SUNDAY MORNING...WITH THE RAIN LIKELY CONTINUING SUNDAY NIGHT AND MONDAY MORNING...BEFORE TAPERING OFF MONDAY AFTERNOON AS THE AFOREMENTIONED SHORTWAVE EXITS TO THE NE. ALSO WITH THE REGION PROGGED TO HAVE SHOWALTERS OF -2 TO 2 FROM LATE SUNDAY NIGHT INTO MONDAY AND TO BE IN A COUPLED UPPER JET STRUCTURE ON MONDAY...HAVE ADDED A SLIGHT CHANCE OF THUNDER FOR MONDAY. ANY CONVECTION SHOULD BE OF AN ELEVATED NATURE. FOR HIGHS SUNDAY...A BLEND OF MAV/MET/12Z ECS GUIDANCE...00Z NAM AND 12Z ECMWF 2-METER TEMPERATURES...AND A MIX DOWN FROM 975-950 HPA WAS USED PER BUFKIT SOUNDINGS. HIGHS SHOULD BE AROUND 10-15 DEGREES BELOW NORMAL. FOR LOWS SUNDAY NIGHT A BLEND OF 12Z ECS/00Z MET/MAV GUIDANCE WITH 12Z ECMWF AND 00Z NAM 2-METER TEMPERATURES WAS USED...WITH VALUES FORECAST TO BE AROUND NORMAL. HIGHS MONDAY SHOULD BE AROUND 5-10 DEGREES ABOVE NORMAL...CONSISTENT WITH A BLEND OF MIX DOWN FROM 975-900 HPA...00Z NAM AND 12Z ECMWF 2-METER TEMPERATURES...AND A MIXTURE OF 00Z MAV/MET AND 12Z ECS GUIDANCE. WEAK RIDGING BUILDS IN MONDAY NIGHT...SO IT SHOULD BE DRY. LOWS WERE BASED ON A BLEND OF 00Z NAM AND 12Z ECMWF 2-METER TEMPERATURES WITH A BLEND OF MEX/MEN/EKD/12Z ECE/ECM GUIDANCE. LOWS SHOULD BE NEAR TO SLIGHTLY BELOW NORMAL. && .LONG TERM /TUESDAY THROUGH FRIDAY/... IT SHOULD BE DRY ON TUESDAY AS THE LOW LEVELS SHOULD BE SUFFICIENTLY DRY TO PRECLUDE PRECIPITATION EVEN WITH A 700-500 HPA NORTHERN STREAM SHORTWAVE CROSSING THE REGION. THERE REMAINS QUITE A BIT OF VARIANCE IN MODEL SOLUTIONS TUESDAY NIGHT-FRIDAY. IN A SWITCH FROM THE 12Z RUNS...THE 00Z ECMWF NOW ENDS UP WITH THE CUTOFF LOW TO THE N BY THE END OF THE WEEK AND THE GFS HAS IT TO OUR S. THE REASONS DEAL WITH DIFFERENCES IN HANDLING A CUTOFF LOW OVER HUDSON BAY AND SHORTWAVE ENERGY TRACKING DOWN ITS SW FLANK. GIVEN THE UNCERTAINTY LIMITED POPS TUESDAY NIGHT TO SLIGHT CHANCE...THEN POPS WEDNESDAY-THURSDAY (THIS IS THEN GENERAL TIME FRAME WHEN REGARDLESS OF SOLUTION THE MODELS INDICATED THE BEST CHANCE FOR PRECIPITATION IN ALL SOLUTIONS) TO LOW END CHANCE...WITH SLIGHT CHANCE POPS THURSDAY NIGHT AND FRIDAY. THIS IS A VERY LOW CONFIDENCE FORECAST THROUGHOUT THE LONG TERM PERIOD DUE TO THE LARGE MODEL SPREAD AND RUN TO RUN VARIABILITY. THIS UNCERTAINTY IS AMPLIFIED BY THE MODELS FORECASTING CUTOFF LOWS...WHICH IS AN ITEM THEY ALL HAVE A LOWER THAN AVERAGE SKILL AT FORECASTING. FOR TEMPERATURES TUESDAY-FRIDAY THE SUPER BLEND WAS USED. FOR NOW FORECASTING BELOW NORMAL HIGHS AND LOWS A FEW DEGREES ABOVE NORMAL IN THIS TIME FRAME. && .AVIATION /16Z SATURDAY THROUGH WEDNESDAY/... SEA BREEZE IS ALREADY THROUGH KBDR. FOR MOST OTHER TERMINALS...WINDS WILL RANGE FROM N TO NE...AND WILL TURN S BEHIND LATE MORNING/EARLY AFTERNOON SEA BREEZES WITH SPEEDS GENERALLY 8-12 KT. .OUTLOOK FOR 15Z SUN THROUGH WED... .SUN-MON...RAIN WITH MVFR OR LOWER CONDS. ESE/E WIND GUSTS OF 20 TO 25 KT POSSIBLE SUNDAY AFT FOR CITY/COASTAL TERMINALS. .TUE...VFR. .WED...CHANCE OF RAIN WITH WITH MVFR OR LOWER CONDS. && .MARINE... OCEAN SEAS CONTINUE TO HOVER AROUND 5 FEET. HAVE EXTENDED THE SCA THROUGH THE AFTERNOON...22Z. NON OCEAN WATERS REMAIN TRANQUIL...LIGHT WINDS AND 1 FT OR LESS SEAS/WAVES. A RELAXED PRESSURE GRADIENT OVER THE WATERS WILL KEEP WINDS TO 10 KT OR LESS OVER THE WATERS THROUGH TONIGHT. SUB-SCA CONDITIONS THEN CONTINUE FOR ALL WATERS THROUGH AT LEAST SUNDAY MORNING. WINDS AND SEAS THEN PICK UP DURING THE AFTERNOON AS THE PRESSURE GRADIENT TIGHTENS AHEAD OF AN APPROACHING STORM. IT LOOKS LIKE SCA WILL BE NEEDED FOR SUNDAY AFTERNOON AT LEAST ON THE OCEAN...AND MAYBE FOR THE SOUND. A BETTER CHANCE FOR 25KT GUSTS ON THE SOUND AND PERHAPS FOR THE HARBOR AND BAYS ARRIVES SUNDAY NIGHT. SCA CONDITIONS OTHERWISE ON THE OCEAN THROUGH AT LEAST MONDAY...AND POSSIBLY INTO A PORTION OF MONDAY NIGHT AS SEAS SLOWLY SUBSIDE. A WEAK PRESSURE GRADIENT THEN MAINTAINS SUB-SCA CONDITIONS ON ALL WATERS THROUGH WEDNESDAY. && .HYDROLOGY... IT SHOULD BE DRY THROUGH AT LEAST THIS EVENING. FROM AROUND 3/4-1 INCH OF RAIN IS FORECAST FROM LATE TONIGHT INTO MONDAY EVENING...WITH LOCALLY HIGHER AMOUNTS POSSIBLE. AT THIS TIME THERE IS A LOW RISK OF PONDING OF WATER ON ROADWAYS FOR AREAS EXPERIENCING LOCALLY HEAVY RAINFALL. THERE IS ALSO A CHANCE FOR ANOTHER SIGNIFICANT RAINFALL DURING THE MIDDLE TO LATER PART OF NEXT WEEK. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 6 PM EDT THIS EVENING FOR ANZ350-353-355. && $$ SYNOPSIS...MALOIT NEAR TERM...MALOIT/PW SHORT TERM...MALOIT LONG TERM...MALOIT AVIATION...MPS MARINE...JC/MALOIT/PW HYDROLOGY...MALOIT

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