Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 302043 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 443 PM EDT SAT MAY 30 2015 .SYNOPSIS... HIGH PRESSURE WILL REMAIN OVER THE WESTERN ATLANTIC THROUGH THIS EVENING. A COLD FRONT APPROACHES TONIGHT...MOVES INTO THE REGION SUNDAY...AND PUSHES SOUTH SUNDAY NIGHT. WAVES OF LOW PRESSURE TRACK OVER OR JUST SOUTH OF THE AREA MONDAY INTO TUESDAY. HIGH PRESSURE WILL THEN BUILD IN FROM THE NORTH LATE TUESDAY INTO WEDNESDAY...AND SHIFT TO THE SOUTH THURSDAY INTO FRIDAY. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... A FEW SHOWERS AND THUNDERSTORMS WILL DEVELOP OR ADVECT ACROSS THE NW INTERIOR LATE THIS AFTERNOON INTO EARLY EVE. SURFACE CAPE VALUES OF 1500-2000 J/KG NOTED ACROSS THIS AREA THIS AFTERNOON WITH CONVECTIVE INITIATION TAKING PLACE ACROSS E PA. WEAK SHEAR FIELDS WILL KEEP THIS ACTIVITY PULSEY...BUT CANT RULE OUT A STRONG STORM. CONVECTION LIKELY DISSIPATES THIS EVENING AS IT MOVES EAST WITH LOSS OF DAYTIME HEATING AND WITH A STRONG MARINE LAYER WORKING NORTHWEST OF THE NYC/NJ METRO THIS AFTERNOON/EVENING. OTHERWISE...REGION WILL BE ON WESTERN PERIPHERY OF WESTERN ATLANTIC RIDGING WITH DEEP TROUGH DIGGING INTO MISSISSIPPI AND OHIO RIVER VALLEYS...AND A STRONG NORTHERN STREAM SHORTWAVE TRACKING INTO QUEBEC TONIGHT. AT THE SURFACE...AN ASSOCIATED SLOW MOVING COLD FRONT WILL APPROACH THE REGION FROM THE WEST. THE NORTHERN STREAM SHORTWAVE WILL PUSH THE NORTHERN PART OF THIS COLD FRONT INTO CENTRAL NY TONIGHT. WEAK VORT ALOFT...LLJ FORCING...AND ELEVATED INSTABILITY LATE TONIGHT COULD SUPPORT ISOLATED SHRA/TSRA ACTIVITY AHEAD OF THE FRONT TONIGHT...BEST CHANCE N&W OF NYC METRO. OTHERWISE...AN UNSEASONABLY WARM AND HUMID NIGHT WITH LOWS GENERALLY IN THE 60S...NEAR 70 NYC/NJ METRO. COASTAL STRATUS/DENSE FOG LIKELY ONCE AGAIN TONIGHT WITH MOIST AIRMASS OVERRIDING THE COMPARABLY COOLER WATERS. SREF PROBS ARE NOT THAT HIGH FOR TONIGHT...BUT MORE WIDESPREAD COVERAGE OF LOW PROBS THAN WHAT IT WAS SHOWING FOR THIS MORNING. A HIGH RISK OF RIP CURRENTS AT THE ATLANTIC OCEAN BEACHES CONTINUES EVENING. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... REGION WILL CONTINUE TO BE ON THE WESTERN PERIPHERY OF WESTERN ATLANTIC RIDGING WITH DEEP TROUGH DIGGING INTO THE MISSISSIPPI AND OHIO RIVER VALLEYS. AT THE SURFACE...MODELS IN PRETTY GOOD AGREEMENT WITH A COLD FRONT SINKING INTO NORTHERN PORTIONS OF THE REGION SUNDAY AFT/EVE IN THE WAKE OF A STRONG NORTHERN STREAM SHORTWAVE SLIDING THROUGH QUEBEC. THE COLD FRONT...A POSSIBLE WARM FRONT APPROACHING FROM THE SOUTH ASSOCIATED WITH A WEAK SURFACE WAVE APPROACHING FROM THE WEST...AND VORT ENERGY RIDING IN THE UPPER FLOW SHOULD ACT AS TRIGGER/FOCUSES FOR NUMEROUS SHOWERS AND TSTMS DEVELOPING SUN AFT IN A MARGINALLY UNSTABLE ENVIRONMENT ACROSS THE LOWER HUDSON VALLEY...SW CT AND NE NJ...NYC METRO. MAIN THREAT APPEARS TO BE HEAVY DOWNPOURS AND POTENTIAL FOR LOCALIZED URBAN FLASH FLOODING WITH ANY TRAINING THUNDERSTORMS AS STEERING FLOW ALIGNS WITH THE FRONT AND PWATS POOL TO 1.5 TO 2 INCHES AHEAD OF THE FRONT. OVERALL SEVERE THREAT APPEARS TO BE SPARSE AND LOW...MAINLY ACROSS NE NJ/LOWER HUD...AS INCREASING CLOUD COVER AND CONVECTIVE ACTIVITY SHOULD TEMPER INSTABILITY IN AREAS OF INCREASING SHEAR FARTHER NORTH. POTENTIAL FOR ROTATION IF ANY SEVERE STORMS DO DEVELOP...WITH INCREASED LOW LEVEL SHEAR/HELICITY IN VICINITY AHEAD OF THE SURFACE WAVE AND IN VICINITY OF FRONTAL BOUNDARIES. MODELS COMING INTO BETTER AGREEMENT WITH COLD FRONT SINKING THROUGH THE REGION SUNDAY NIGHT AS STRONG CANADIAN HIGH PRESSURE NOSES IN FROM THE N/NE. WANING INSTABILITY SHOULD DECREASE COVERAGE AND INTENSITY OF TSTMS IN THE EVENING. SHOWER AND ISOLATED EMBEDDED TSTM THREAT IN THE VICINITY OF THE COLD FRONT AS IT PUSHES THROUGH...LIKELY TRANSITIONING TO STRATIFORM IN ITS WAKE. HIGHEST PROB FOR SHOWER AND EMBEDDED TSTM ACTIVITY IN THE EVENING AND RAIN OVERNIGHT WILL BE ACROSS THE NYC/NJ METRO...SW CT AND LOWER HUD VALLEY WITH LLJ FORCING TO THE NE OF THE SURFACE WAVE AND MORE IN THE WAY OF VORT ENERGY...AND POSSIBLE SOME WEAK ELEVATED INSTABILITY. HIGHS ON SUNDAY WILL BE IN THE UPPER 70S TO LOWER 80S...WARMEST ACROSS NE NJ. COOLER AND LESS MUGGY CANADIAN MARITIME AIRMASS ADVECTS IN SUNDAY NIGHT. THERE WILL BE A MODERATE RISK FOR RIP CURRENTS AT OCEAN FACING BEACHES ON SUNDAY. && .LONG TERM /MONDAY THROUGH SATURDAY/... FRONTAL BOUNDARY BECOMES NEARLY STATIONARY OVER OR JUST SOUTH OF THE AREA EARLY THIS WEEK. SEVERAL AREAS OF LOW PRES WILL DEVELOP OVER THE DELMARVA AREA AND TRACK TO THE NORTHEAST MONDAY THROUGH TUESDAY. HIGH PRES BUILDS INTO THE REGION BEHIND THE FRONT WEDNESDAY AND THURSDAY. WILL CARRY LIKELY POPS FOR MONDAY AND MONDAY NIGHT...AND THEN LIKELY POPS ON TUESDAY FOR THE EASTERN HALF OF THE CWA AS THE FINAL LOW DEPARTS. COULD HAVE SOME EMBEDDED THUNDERSTORMS FROM TIME TO TIME DURING THE DAY MONDAY AND TUESDAY. HIGHS MONDAY AND TUESDAY WILL TOP OFF IN THE 60S TO AROUND 70...AND THEN TEMPS WARM BACK UP THROUGH THE 70S FOR THE MID-WEEK PERIOD. LOW PRES WILL IMPACT THE AREA LATE IN THE WEEK AND FOR THE FIRST HALF OF THE WEEKEND. WILL CARRY CHANCE POPS FOR NOW. && .AVIATION /21Z SATURDAY THROUGH THURSDAY/... HIGH PRESSURE GIVES WAY TO A COLD FRONT ON SUNDAY. SOUTHERLY FLOW WILL BE AT ITS STRONGEST FOR THE DAY NOW THRU APPROX SUNSET. KJFK/KISP COULD SEE A BRIEF PD OF LLWS AFTER DARK AS SFC WINDS DIE OFF BUT REMAIN AT 30-40 KT ONLY A FEW HUNDRED FT AGL. CANNOT RULE OUT A SHOWER/TSTM NEAR KSWF. A BRIEF SHOWER COULD ALSO PASS THROUGH KJFK/KLGA/KEWR/KTEB/KHPN UNTIL SHORTLY BEFORE SUNSET AS SHOWERS FORM OFF A NEARBY SEA BREEZE. EXPECT A RETURN OF LOW STRATUS AND FOG WITH IFR CONDS LATE TONIGHT INTO MID MORNING SUNDAY. LIFR CONDS MAY BE POSSIBLE AT KJFK/KISP/KBDR/KGON. SHOWERS AND A FEW TSTMS WITH MVFR AND LOCAL IFR VSBY ARE THEN POSSIBLE LATE SUNDAY MORNING INTO THE EARLY AFTERNOON FROM NYC METRO NORTH/WEST. .OUTLOOK FOR 18Z SUNDAY THROUGH THU... .SUNDAY AFTERNOON-TUE...CHANCE OF LOW STRATUS WITH IFR CIGS DEVELOPING LATE EACH NIGHT AND MORNING. MVFR TO IFR CONDS ALSO POSSIBLE AT TIMES IN SHOWERS/TSTMS. .TUE NIGHT...BECOMING VFR. .WED-THU...VFR. && .MARINE... WIND GUSTS OF 25 TO 30 KT EXPECTED ACROSS THE WESTERN OCEAN WATERS...WESTERN LI SOUND...LOWER HARBOR...AND SOUTH SHORE BAYS OF LI WITH A DEVELOPING COASTAL JET THIS EVENING. 4 TO 5 FT SEAS LIKELY ON THE OCEAN WATERS LATE THIS AFTERNOON INTO EVENING. SCA FOR THIS AFTERNOON INTO EVENING FOR THESE LOCATIONS. ELSEWHERE WINDS AND SEAS REMAIN JUST BELOW SMALL CRAFT LEVELS INTO TONIGHT. DENSE FOG POSSIBLE ONCE AGAIN TONIGHT ACROSS OCEAN WATERS AND SOUTHERN AND EASTERN NEARSHORE WATERS. WITH A PROLONGED SOUTHERLY FLOW AHEAD OF AN APPROACHING COLD FRONT...MARGINAL SCA SEAS POSSIBLE ON ALL OCEAN WATERS LATE TONIGHT INTO SUNDAY NIGHT. CONFIDENCE NOT HIGH ENOUGH FOR AN SCA AT THIS POINT WITH OBSERVED LONG PERIOD SE SWELLS RUNNING ABOUT 1 FT BELOW WNA. WILL LET EVENING/OVERNIGHT SHIFT RE-EVAL. SEAS ON THE OCEAN WATERS REMAIN AT OR ABOVE 5 FT FOR THE FIRST HALF OF THE NEW WEEK...AND THEN SEAS WILL BEGIN TO SUBSIDE ON WEDNESDAY. A PERSISTENT EASTERLY FLOW FOR THE START OF THE NEW WEEK COULD GUST TO 25 KT FROM TIME TO TIME. TRANQUIL CONDS RETURN FOR WEDNESDAY AND THURSDAY. && .HYDROLOGY... BETWEEN 1/2 TO 1 1/2 INCHES OF RAIN LIKELY FOR MUCH OF NYC METRO...NE NJ...LOWER HUD VALLEY...AND SOUTHERN CT SUNDAY AFTERNOON THROUGH SUNDAY NIGHT WITH SLOW MOVING COLD FRONT APPROACHING. LOCALLY HIGHER AMOUNTS OF 2 TO 3 INCHES ARE POSSIBLE WITH ANY TRAINING CONVECTION...WHICH WOULD POSE A FLASH FLOODING THREAT. THE PROBABILITY IN ANY GIVEN LOCATION IS LOW. OF NOTE...SBU WRF IS INDICATING POTENTIAL OF LOCALLY 3 TO 5 INCHES DURING THIS 24 HR PERIOD. RAINFALL AMOUNTS WILL TAPER DOWN TO 1/4 TO 1/2 INCH ACROSS EASTERN LI AND SE CT...WITH MORE STABLE MARINE AIRMASS LIMITING CONVECTION. AN ADDITIONAL 1 TO 2 INCHES OF RAIN POSSIBLE MONDAY THROUGH TUESDAY. LOCALLY HIGHER AMOUNTS WILL BE POSSIBLE WITH ANY THUNDERSTORM ACTIVITY. MINOR URBAN/POOR DRAINAGE/SMALL STREAM FLOODING WOULD BE MOST LIKELY DURING THIS TIME. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR ANZ335- 338-345-353-355. && $$ SYNOPSIS...MPS/NV NEAR TERM...NV SHORT TERM...NV LONG TERM...MPS AVIATION...JC/GOODMAN MARINE...MPS/NV HYDROLOGY...MPS/NV

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