Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 260230 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 1030 PM EDT MON APR 25 2016 .SYNOPSIS... A BACKDOOR COLD FRONT PUSHES INTO THE TRI-STATE OVERNIGHT...AND LIKELY STALLS JUST TO THE SOUTH OF THE REGION THROUGH TUESDAY...AS WAVES OF LOW PRESSURE WAVES TRACK EAST ALONG IT. THE FRONTAL SYSTEM PUSHES WELL TO THE SOUTHEAST TUESDAY NIGHT. HIGH PRESSURE BRIEFLY BUILD OVER THE REGION WEDNESDAY AND WEDNESDAY NIGHT BEFORE MOVING OFFSHORE ON THURSDAY. LOW PRESSURE WILL APPROACH FROM THE WEST LATE THURSDAY AND NIGHT...PASSING SOUTH OF LONG ISLAND FRIDAY. HIGH PRESSURE RETURNS FOR THE WEEKEND. && .NEAR TERM /THROUGH TUESDAY/... ADJUSTED POPS OVERNIGHT BASED ON LATEST TRENDS IN RADAR/HIGH RESOLUTION MODELS. MAIN CHANGE WAS TO CONTINUE TO SLOW ONSET OF RAIN...ESPECIALLY OVER EASTERN AREAS. MODELS IN GOOD AGREEMENT WITH POTENT SHORTWAVE ENERGY CROSSING THE GREAT LAKES OVERNIGHT AND THEN SLIDING SE TOWARDS THE REGION TUESDAY. THE FORECAST CHALLENGE IS BEING THE EXACT PLACEMENT OF THE BACKDOOR COLD FRONT...WHICH WILL BE DETERMINED BY THE STRENGTH/DEPTH OF A COLD CANADIAN AIRMASS BEING REINFORCED TO THE NORTH. INCREASING LIFT AND THETA-E ADVECTION AHEAD OF THE BACKDOOR FRONT AND FIRST SURFACE WAVE WILL INCREASE THE LIKELIHOOD FOR RAIN FROM WEST TO EAST AFTER MIDNIGHT. BASED ON CLIMATOLOGY...COOL WATER TEMPS...AND ONLY A 30-35 KT WESTERLY 850 HPA JET...HIGHER PROBABILITY IS SURFACE FRONT STALLS JUST SOUTH OF THE TRI-STATE. WITH WESTERLY FLOW ALOFT...MARGINAL ELEVATED INSTABILITY WILL LIKELY WORK INTO THE REGION LATE TONIGHT...PROMOTING A CHANCE FOR EMBEDDED THUNDERSTORMS ACROSS WESTERN AND SOUTHERN PORTIONS OF THE TRI- STATE REGION THROUGH TUESDAY. INCREASING CHANCE OF THE SURFACE FRONT PUSHING FARTHER S/SW LATER MON MORNING WITH REINFORCEMENT OF CAD IN WAKE OF FIRST SURFACE WAVE ON LOW-LEVEL NE FLOW. THEN A SECOND WAVE APPROACHES TUE AFTERNOON CONTINUING THE FORCING FOR RAIN THROUGH THE AFTERNOON. MAIN QUESTION ONCE AGAIN IS WHETHER FAR SW PORTIONS OF THE TRI-STATE GETS INTO THE WARM SECTOR AHEAD OF THE SECOND WAVE. THE MAIN IMPLICATIONS WITH THIS WOULD BE A SIGNIFICANT JUMP IN TEMPERATURES...AND A FOCUS FOR POTENTIAL SURFACE BASED SEVERE THUNDERSTORMS WITH SUFFICIENT INSTABILITY AND DEEP/LOW LEVEL SHEAR. AGAIN...HIGHER PROBABILITY IS THAT THIS FRONT STAYS SW OF THE REGION...KEEPING THE SEVERE THREAT ACROSS NE PA/CENTRAL NJ...BUT WILL BE CLOSE FOR NE NJ. EVEN IF THE FRONT REMAINS SOUTH...POTENTIAL FOR ELEVATED THUNDERSTORM ACTIVITY SHOULD INCREASE ACROSS NE NJ/NYC METRO AND LONG ISLAND TUE AFT/EARLY EVE WITH INCREASED FORCING AHEAD OF SHORTWAVE/LEFT FRONT QUAD OF UPPER JET AND AS WESTERLY LOW LEVEL JET ADVECTS IN INSTABILITY FROM PA/NJ. A SMALL HAIL THREAT EXISTS FOR TUE AFT/EARLY EVE WITH SUFFICIENT ELEVATED INSTABILITY...DEEP LAYER SHEAR...AND COLD AIR ALOFT...WITH A SLIGHT PROB FOR SEVERE HAIL. TEMPERATURES WILL BE CHALLENGING...WITH GREATER LIKELIHOOD FOR A CHILLY DAY WITH HIGH HOLDING IN THE 40S ACROSS CT...50S FOR MUCH OF THE REMAINDER OF THE REGION...EXCEPT LOWER 60S FOR NE NJ. IF WARM FRONT POKES NORTHEAST INTO NE NJ...TEMPS WOULD LIFT INTO THE 70S THERE. && .SHORT TERM /TUESDAY NIGHT/... SHORTWAVE ENERGY SWINGS THROUGH TUESDAY EVENING...WITH COLD FRONT AND SURFACE WAVES PUSHING FARTHER SOUTH. CANADIAN HIGH PRESSURE BUILDS INTO THE REGION IN ITS WAKE...WITH DRYING CONDITIONS. STRATUS WILL LIKELY BE SLOW TO SCOUR OUT DUE A STRONG LOW- LEVEL INVERSION. LOW TEMPERATURES SLIGHTLY BELOW SEASONABLE DESPITE CLOUD COVER DUE TO LOW LEVEL COLD AIR ADVECTION. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... HIGH PRESSURE BUILDS OVER THE REGION WITH DRY WEATHER EXPECTED ON WEDNESDAY AND WEDNESDAY NIGHT. HIGH PRESSURE MOVES OFFSHORE THURSDAY AS A LOW PRESSURE SYSTEM AND ASSOCIATED WARM FRONT APPROACH THE REGION FROM THE WEST. CLOUDS INCREASE WEDNESDAY NIGHT AND THURSDAY AND POPS GRADUALLY INCREASE FROM WEST TO EAST DURING THE DAY THURSDAY. WILL LIMIT POPS TO EITHER SLIGHT CHANCE OR CHANCE...AND THEY WILL CONTINUE THROUGH THE DAY FRIDAY. WITH THE LOW PASSING SOUTH OF LONG ISLAND...AN EASTERLY FLOW WILL DEVELOP. THIS WILL RESULT IN A COOL...RAINY PERIOD OF WEATHER. DRIER WEATHER RETURNS FRIDAY NIGHT AND THE WEEKEND AS HIGH PRESSURE BUILDS BACK INTO THE REGION FROM THE NORTH. EXPECT A DRY...MOSTLY SUNNY WEEKEND. ANOTHER STORM SYSTEM IS FORECAST TO IMPACT THE REGION EARLY NEXT WEEK...BRINGING ANOTHER ROUND OF UNSETTLED WEATHER. REGARDING TEMPERATURES...EXPECT CONDITIONS TO REMAIN AT OR BELOW NORMAL FOR THIS TIME OF YEAR. HIGHS WILL BE IN THE 50S OR 60S EACH DAY. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/...
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A WARM FRONT APPROACHES OVERNIGHT AND LIKELY STALLS JUST TO THE SOUTH OF THE REGION THROUGH TUESDAY...AS A COUPLE OF LOW PRESSURE WAVES TRACK EAST ALONG IT. VFR WITH A MID DECK CEILING UNTIL AROUND 08Z WHEN CONDITIONS WILL LOWER TO MVFR AS RAIN/FOG DEVELOPS. CONDITIONS LOWER FURTHER AROUND 10-12Z...TO LOW END MVFR AND HIGH IFR IN RAIN AND FOG. THERE IS ALSO A LOW CHANCE OF ISOLATED THUNDERSTORMS ON TUESDAY...MAINLY FROM THE NYC TERMINALS WEST. SE FLOW REMAIN LIGHT OVERNIGHT...THEN TURNS TO THE E/NE TUESDAY MORNING. NE TO N WINDS INCREASE LATE IN THE DAY. LOW CONFIDENCE FORECAST IN THE WIND FORECAST...AS DIRECTIONS WILL BE DEPENDENT ON EXACTLY WHERE THE WARM FRONT SETS UP. SLIGHTLY HIGHER CONFIDENCE IN WIND FORECAST FOR LONG ISLAND AND CT TERMINALS. .OUTLOOK FOR 00Z WEDNESDAY THROUGH SATURDAY... .TUESDAY NIGHT...RETURN TO VFR AS RAIN ENDS. .WEDNESDAY-WEDNESDAY NIGHT...VFR. .THURSDAY-FRIDAY...MVFR OR LOWER POSSIBLE IN RAIN. .FRIDAY NIGHT-SATURDAY...VFR.
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&& .MARINE... MINOR CHANGES WERE MADE WITH THIS UPDATE TO REFLECT THE LATEST TRENDS IN OBSERVATIONS AND GUIDANCE. THE FORECAST APPEARS ON TRACK. SUB SCA CONDITIONS TONIGHT. E/NE WINDS SHOULD INCREASE TO 15 TO 20 KT TUE AFT/EVE ACROSS OCEAN AND LONG ISLAND SOUND WATERS...WITH MARGINAL SCA GUSTS POSSIBLE TUE EVE IN WAKE OF LOW PRESSURE. ACCORDINGLY SEAS BUILDING TO 4 TO 6 FT ON THE OCEAN TUE AFTERNOON/EVENING AND REMAINING SO THROUGH TUESDAY NIGHT. AS A RESULT...HAVE ISSUED A SMALL CRAFT ADVISORY FOR THE COASTAL OCEAN WATERS FROM 12Z TUESDAY-10Z WEDNESDAY. WINDS SUBSIDE TUE NIGHT AS HIGH PRESSURE BUILDS IN FROM THE NW...WITH SCA SEAS ON THE OCEAN SLOWLY SUBSIDING BELOW SCA. A WEAK PRESSURE GRADIENT WILL RESULT IN SUB SCA CONDITIONS ON THE AREA WATERS WEDNESDAY THROUGH THE WEEKEND. && .HYDROLOGY... AROUND 1/2 OF AN INCH OF RAIN IS EXPECTED FROM LATE TONIGHT THROUGH TUE. SOME LOCALLY HIGHER AMOUNTS ARE POSSIBLE IN ANY TSTMS THAT DEVELOP. NO SIGNIFICANT WIDESPREAD RAINFALL EXPECTED TUESDAY NIGHT THROUGH THE NEXT WEEKEND. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY FROM 8 AM TUESDAY TO 8 AM EDT WEDNESDAY FOR ANZ350-353-355. && $$ SYNOPSIS...BC/MALOIT/NV NEAR TERM...MALOIT/NV SHORT TERM...NV LONG TERM...BC AVIATION...PW MARINE...BC/MALOIT/NV HYDROLOGY...BC/MALOIT/NV

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