Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 200153 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 953 PM EDT SUN APR 19 2015 .SYNOPSIS... HIGH PRESSURE MOVES OFFSHORE THIS EVENING. A WARM FRONT APPROACHES FROM THE SOUTH THROUGH MONDAY MORNING AND REMAINS NEAR THE REGION THROUGH THE DAY. A COLD FRONT MOVES THROUGH ON TUESDAY. A SERIES OF WEAK COLD FRONTS AND/OR TROUGHS OF LOW PRESSURE WILL MOVE THROUGH DURING THE MIDDLE TO LATE WEEK PERIOD. LOW PRESSURE PASSES WELL TO THE SOUTH NEXT WEEKEND. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... NORTHERN EDGE OF RAIN SHIELD ASSOCIATED WITH APPROACHING WARM FRONT MAKING ITS WAY INTO SOUTHERN AND CENTRAL NJ. MUCH OF THE NORTHERN EDGE IS VIRGA...THOUGH A STRAY SHOWER IS POSSIBLE OVER THE NEXT FEW HOURS FOR WESTERN SECTIONS OF THE CWA...SO INCREASED POPS TO SLIGHT CHANCE FOR THESE AREAS. OTHERWISE...FORECAST IS ON TRACK. HIGH PRESSURE WILL CONTINUE MOVING OFFSHORE THIS EVENING. WITH WINDS OFF THE COLD OCEAN...TEMPERATURES WILL FALL INTO THE 40S AND LOW 50S AFTER SUNSET. DEVELOPING LOW PRESSURE SYSTEM ACROSS THE SOUTHEAST STATES WILL SEND A WARM FRONT TOWARDS THE AREA OVERNIGHT. CLOUDS WILL INCREASE...LOWER...AND THICKEN THROUGHOUT THE NIGHT AS THE UPPER LEVEL RIDGE AXIS SLIDES OFFSHORE. RAIN WILL LIKELY HOLD OFF UNTIL AFTER 06Z WHEN GOOD ISENTROPIC LIFT AND WARM ADVECTION AHEAD OF THE WARM FRONT MOVE INTO WESTERN ZONES. LATEST HI RES MODELS CONTINUE TO SUPPORT THIS. EXPECT RAIN TO BREAK OUT AFTER 06Z...AND MOVE EAST ACROSS THE REST OF THE AREA THROUGH DAY BREAK. AS LIFT AND MOISTURE INCREASE...RAINFALL RATES WILL BEGIN TO PICK UP AS WELL. A BLEND OF THE MAV/MET GUIDANCE LOOKS GOOD FOR LOW TEMPERATURES TONIGHT...IN THE LOWER AND MIDDLE 40S. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... SUBTROPICAL PLUME OF MOISTURE WILL RIDE THROUGH THE AREA MONDAY MORNING INTO MONDAY AFTERNOON. PRECIPITABLE WATERS WILL LIKELY FALL BETWEEN 1.25 AND 1.50 INCHES...NEARLY 2 STANDARD DEVIATIONS ABOVE NORMAL FOR THIS TIME OF YEAR MAKING FOR A VERY MOIST ATMOSPHERE. RAINFALL WILL BECOME MODERATE TO LOCALLY HEAVY AT TIMES WITH GOOD ISENTROPIC LIFT AHEAD OF THE WARM FRONT. LOW LEVEL JET WILL ALSO MOVE ACROSS DURING THE MORNING AND EARLY AFTERNOON HOURS AIDING IN ENHANCED LIFT. MODERATE TO LOCALLY HEAVY RAIN WILL LIKELY CONTINUE IN EARLY AFTERNOON...TAPERING OFF FROM WEST TO EAST LATE AFTERNOON AS THE LOW LEVEL JET AND DEEPEST MOISTURE SHIFT EAST OF THE AREA. THIS RAINFALL COULD CAUSE LOCALIZED MINOR FLOODING OF URBAN AND POOR DRAINAGE AREAS. NO FLASH FLOODING IS ANTICIPATED AT THIS TIME. THE WARM FRONT MAY STRUGGLE TO COMPLETELY MOVE NORTH OF THE REGION. IT IS LIKELY TO HANG JUST SOUTH OR OVER LONG ISLAND IN THE AFTERNOON. IT MAY NOT BE UNTIL MONDAY EVENING OR MONDAY NIGHT THAT THE WARM FRONT BRIEFLY MOVES THROUGH AS A WAVE OF LOW PRESSURE ALONG A COLD FRONT APPROACHES. INCREASING ELEVATED INSTABILITY IS DEPICTED BY THERMODYNAMIC SOUNDINGS LATE MONDAY AFTERNOON INTO MONDAY NIGHT...SO CONTINUING TO MENTION ISOLATED THUNDER. SHOWERS WILL REMAIN LIKELY THROUGH THE NIGHT AS THIS WAVE OF LOW PRESSURE AND COLD FRONT APPROACH. STRONG ESE-SE WINDS ARE NEAR THE COAST...20 TO 25 SUSTAINED WITH GUSTS TO 35 MPH POSSIBLE. THE WINDS WILL BE STRONGEST AS THE LOW LEVEL JET MOVES OVERHEAD IN THE MORNING AND EARLY AFTERNOON. WINDS SHOULD DIMINISH LATE IN THE DAY. TEMPERATURES ON MONDAY WILL REACH THE UPPER 50S TO LOWER 60S AND ONLY FALL INTO THE LOWER 50S ON MONDAY NIGHT. && .LONG TERM /TUESDAY THROUGH SUNDAY/... ALOFT...THE MERGING OF THE CLOSED LOW WITH A DIGGING NORTHERN STREAM SHORTWAVE WILL PRODUCE A LARGE TROUGH OVER THE WESTERN GREAT LAKES REGION TUESDAY. THIS CLOSED LOW SLOWLY MOVES TO A POSITION JUST NORTH OF THE GREAT LAKES BY WED. AT THE SURFACE...MODELS INDICATE A COLD FRONT CROSSES THE AREA... MOVING TO THE EAST DURING THE DAY TUESDAY. DEVELOPING WESTERLY FLOW BEHIND THE FRONT WILL AID IN DRYING THE ATMOSPHERE OUT. SFC LOW PRESSURE REMAINS IN CANADA NORTH OF THE GREAT LAKES REGION TUESDAY INTO WEDNESDAY. THE NEXT COLD FRONT APPROACHES WED LATE IN THE DAY. THERE IS GENERALLY GOOD MODEL AGREEMENT ON THE LARGE SCALE. ANY MORNING CLOUDS AND PATCHY FOG QUICKLY GIVE WAY TO CLEARING TUESDAY AS WESTERLY FLOW PICKS UP. STATISTICAL NAM/GFS MOS SUGGEST TEMPS WELL INTO THE 60S TO AROUND 70 TUESDAY. THIS SEEMS TO AGREE WITH EXPECTED TEMPS ALOFT (CAA) AND EXPECTED MIXING LEVELS. THEREAFTER...THE COLD FRONT MOVES THROUGH RESULTING IN SCATTERED SHOWERS LATE WEDNESDAY AND WEDNESDAY NIGHT. BEHIND THIS FRONT...WESTERLY FLOW PREVAILS AS THE SFC LOW REMAINS LOCATED WELL TO THE NORTH. THIS SLOW MOVEMENT DUE TO THE SLOW MOVEMENT OF THE UPPER LOW/TROUGH THROUGH THE PERIOD. HIGH PRESSURE EVENTUALLY BUILDS TO THE WEST BY THE WEEKEND. ANOTHER AREA OF LOW PRESSURE PASSES WELL TO THE SOUTH LATE SATURDAY AND SUNDAY...ASSOCIATED WITH SRN STREAM ENERGY THAT EJECTS OUT OF THE SW UNITED STATES. TIMING AND POSITIONAL DIFFERENCES NOTED IN THE GFS AND ECMWF. WOULD NOT EXPECT THIS LOW TO MAKE MUCH NORTHWARD PROGRESS THOUGH GIVEN UPPER PATTERN AND PESKY STACKED LOW NEAR THE CANADIAN MARITIMES. AS MENTIONED...NEAR TO SLIGHTLY ABOVE NORMAL TEMPS TUESDAY CAN BE EXPECTED. THEN AS HEIGHTS LOWER AND THE AREA REMAINS UNDER THE INFLUENCE OF THE LARGE SLOW MOVING TROUGH...TEMPS WILL AVERAGE BELOW NORMAL THROUGH THE REMAINDER OF THE WEEK. FOLLOWED WPC AND GRIDDED MOS WEDNESDAY THROUGH SUNDAY...WHICH SEEMS CLOSE TO 12Z MEX NUMBERS. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... HIGH PRESSURE OFF THE NORTHEAST COAST MOVES EAST OVERNIGHT AS A WARM FRONT SLOWLY APPROACHES FROM THE SOUTHWEST. THE WARM FRONT NEARS THE TERMINALS DURING THE DAY MONDAY...AND MAY MOVE THROUGH AT LEAST THE COASTAL TERMINALS BY LATE IN THE AFTERNOON. THERE IS LOW CONFIDENCE THAT THE WARM FRONT MOVES THROUGH. CONDITIONS START AT VFR AND QUICKLY LOWER TO MARGINAL VFR AND THEN IFR LATE TONIGHT AND EARLY MONDAY MORNING...08Z TO 13Z...AS RAIN DEVELOPS. THERE IS SOME UNCERTAINTY AS TO TIMING OF LOWERING AND MAY BE OFF AN HOUR OR SO. ONCE CONDITIONS DO LOWER TO IFR...IFR TO LIFR CEILINGS WILL PERSIST THROUGH THE DAY WITH PERIODS OF MODERATE TO HEAVY RAINFALL. WIND E TO SE 10 TO 15 KT...BECOMES MORE EASTERLY AND INCREASES TO AROUND 20 KT WITH POTENTIAL GUSTS 25 TO 30 KT. WIND AND GUSTS DIMINISH LATE MONDAY AFTERNOON WITH THE GUSTS POTENTIALLY ENDING TOWARD 00Z. LLWS WILL IMPACT THE TERMINALS WITH A LOW LEVEL JET DEVELOPING WITH 2000 FT WIND 50 TO 60 KT. MODERATE CONFIDENCE IN WIND AND GUST FORECAST WITH HIGHER CONFIDENCE IN THE LLWS. .OUTLOOK FOR 00Z TUESDAY THROUGH FRIDAY... .MONDAY NIGHT...IFR OR LOWER. AN ISOLATED TSTM POSSIBLE 00Z TO 06Z. .TUESDAY...MVFR EARLY...OTHERWISE VFR. W-SW WINDS GUSTS 15-20KT POSSIBLE. .TUESDAY NIGHT...VFR. .WEDNESDAY-WEDNESDAY NIGHT...MVFR POSSIBLE IN THE AFTERNOON AND NIGHT IN -SHRA. SW-WSW WINDS G20-25KT POSSIBLE. .THURSDAY-FRIDAY...MAINLY VFR...WITH LOW CHANCE MVFR IN ANY -SHRA. W-NW WINDS G15-20KT POSSIBLE. && .MARINE... SMALL CRAFT ADVISORY CONDITIONS WILL DEVELOP ON THE OCEAN/NY HARBOR/SOUTH SHORE BAYS LATER THIS EVENING WITH GUSTS UP TO 25 KT. OCEAN SEAS WILL ALSO BUILD TO 5-7 FT DURING THE NIGHT. AS A WARM FRONT APPROACHES THE WATERS...CONDITIONS ON THE WATERS WILL DETERIORATE QUICKLY. WIDESPREAD WINDS AROUND 25 KT WILL GUST UP T0 30 KT. WITH LOW LEVEL INVERSION AND COLDER OCEAN TEMPERATURES...CONFIDENCE IN SEEING WIDESPREAD GALES IS LOW. HAVE CONTINUED TO MENTION OCCASIONAL GUSTS TO 35 KT. IF THESE GUSTS OCCUR...IT WILL BE OVER A SHORT TIME PERIOD AS A LOW LEVEL JET MOVES OVERHEAD. WILL CONTINUE WITH SMALL CRAFT ADVISORIES ON ALL WATERS ON MONDAY. SEAS WILL BUILD 7 TO 12 FEET. THE STRONGEST WINDS SUBSIDE FROM WEST TO EAST ON MONDAY AFTERNOON AND EVENING. SEAS WILL CONTINUE TO REMAIN HIGH THROUGH MONDAY NIGHT. AS A COLD FRONT MOVES TO THE EAST OF THE WATERS TUESDAY...WESTERLY WINDS WILL INCREASE. IN FACT...A WEST FLOW...AT TIMES BACKING TO THE SW AND THEN VEERING TO THE NW...IS EXPECTED THROUGH THE LATE WEEK PERIOD. A SERIES OF WEAK COLD FRONTS OR TROUGHS OF LOW PRESSURE WILL MOVE THROUGH MID TO LATE WEEK. A FAIRLY TIGHT PRESSURE GRADIENT REMAINS IN PLACE. SEAS GRADUALLY SUBSIDE OVER THE OCEAN WATERS TUESDAY...BUT DO REMAIN ELEVATED THROUGH THE WEEK AS WAVE WATCH III SUGGESTS. && .HYDROLOGY... SIGNIFICANT RAINFALL WILL DEVELOP ACROSS THE REGION LATE TONIGHT THROUGH MONDAY NIGHT AS A WARM FRONT WILL SET UP NEAR THE REGION. A COLD FRONT THEN MOVES THROUGH ON TUESDAY. STORM TOTAL RAINFALL WITH THIS SYSTEM WILL RANGE FROM 1 TO 2 INCHES WITH LOCALLY HIGHER AMOUNTS. THIS COULD CAUSE POSSIBLE MINOR FLOODING OF URBAN AND POOR DRAINAGE AREAS. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEB SITE. && .TIDES/COASTAL FLOODING... WITH STRENGTHENING E/SE FLOW AND HIGH ASTRONOMICAL TIDES...WILL NEED TO WATCH DEPARTURES OVER THE NEXT FEW HIGH TIDE CYCLES. FOR NOW...WILL ISSUE A COASTAL FLOOD STATEMENT FOR THE WESTERN LONG ISLAND SOUND FOR TONIGHT`S HIGH TIDE...AND FOR MONDAY AFTERNOON`S HIGH TIDE. FOR TONIGHT...ONLY A HALF A FOOT OR LESS IS NEEDED FOR THE WESTERN PORTION OF THE LONG ISLAND SOUND. SLIGHTLY MORE IS NEEDED FOR THE REMAINDER OF THE AREA. ASTRONOMICAL TIDES ARE A LITTLE LOWER DURING THE DAY MONDAY...BUT WINDS DO INCREASE...LEADING TOWARD ADDITIONAL STORM SURGE POTENTIALLY. AGAIN...WILL ONLY ISSUE A CSTL FLOOD STATEMENT FOR THE WESTERN SOUND FOR NOW. THE MONDAY NIGHT HIGH TIDE COULD EXPERIENCE MORE WIDESPREAD MINOR CSTL FLOODING...BUT WILL WAIT TO SEE SUBSEQUENT MODEL RUNS TO DETERMINE IF ANY FUTURE ADVISORIES ARE NEEDED. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT MONDAY FOR ANZ338-345. SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EDT MONDAY FOR ANZ330- 335-340. SMALL CRAFT ADVISORY UNTIL 6 AM EDT TUESDAY FOR ANZ350-353-355. && $$ SYNOPSIS...DS/PW NEAR TERM...JP/DS/PW SHORT TERM...DS LONG TERM...PW AVIATION...MET MARINE...DS/PW HYDROLOGY...DS/PW TIDES/COASTAL FLOODING...

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