Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 311936 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 336 PM EDT SUN AUG 31 2014 .SYNOPSIS...
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A COUPLE OF SURFACE TROUGHS WILL BE IN THE REGION THROUGH MONDAY EVENING. A WEAK PRESSURE GRADIENT TUESDAY WILL GIVE WAY TO A COLD FRONT MOVING THROUGH TUESDAY NIGHT WITH HIGH PRESSURE BUILDING IN FROM THE SOUTH AND WEST MID TO LATE IN THE WEEK. THE HIGH MOVES OFFSHORE FRIDAY WITH ANOTHER COLD FRONT MOVING IN LATER ON NEXT SATURDAY AND ACROSS THE AREA NEXT SATURDAY NIGHT WITH HIGH PRESSURE RETURNING FROM THE WEST THEREAFTER.
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&& .NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
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A SURFACE TROUGH REMAINS IN THE VICINITY WHILE MID LEVEL SHORTWAVE ENERGY PASSES THROUGH. MLCAPES START MOSTLY IN THE 1000-2000 J/KG RANGE THIS EVENING AND DIMINISH OVERNIGHT. SHOWERS LIKELY TONIGHT WITH BETTER CHANCES OF POTENTIALLY STRONG THUNDERSTORMS THIS EVENING. BULK SHEAR WILL BE STRONG ENOUGH TO SUPPORT ORGANIZED CONVECTION. WBZ/FREEZING LEVEL HEIGHTS WILL BE ON THE HIGH SIDE...SO THE MOST LIKELY THUNDERSTORM IMPACTS WOULD BE STRONG WIND GUSTS. HEAVY DOWNPOURS WILL BE POSSIBLE TOO WITH PWATS AROUND 2 INCHES...AND BOTH MOISTURE CONVERGENCE AND OMEGA INCREASING. ADDITIONALLY...THE FLOW ALOFT WILL BE FAIRLY ALIGNED WITH THE SURFACE TROUGH WHICH WOULD PROMOTE THE THREAT OF CELL TRAINING. THE LIKELIHOOD OF FLASH FLOODING STILL DOES NOT LOOK TO BE WIDESPREAD AND COULD BE CONFINED TO A RELATIVELY NARROW BAND SOMEWHERE IN OR NEAR THE CWA...SO NO WATCH WILL BE POSTED AT THIS TIME. OVERNIGHT LOWS WILL BE ABOVE NORMAL WITH CLOUD COVER AND A SW FLOW. A MODERATE RISK OF RIP CURRENTS IS EXPECTED AT THE ATLANTIC FACING BEACHES THIS EVENING.
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&& .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
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THE PATTERN REMAINS SIMILAR AS ANOTHER SURFACE TROUGH SETS UP JUST TO THE WEST ON MONDAY BEFORE PUSHING THROUGH DURING THE NIGHTTIME. ANOTHER MID LEVEL SHORTWAVE PASSES THROUGH DURING THE DAY. THIS TIME AROUND...SOME SYNOPTIC LIFT WILL BE SUPPORTED BY THE RIGHT ENTRANCE REGION OF AN UPPER JET STREAK PASSING OVER US. SCATTERED SHOWERS AT LEAST DURING THE DAYTIME...THEN DIMINISHING AND SHIFTING EAST DURING THE NIGHT AS THE ATMOSPHERE STABILIZES AND MOISTURE CONVERGENCE AND LIFT MOVE EAST. SOME THUNDERSTORMS WILL BE AROUND AS WELL AS MLCAPES PROBABLY RISE INTO THE 1000-1500 J/KG RANGE. THIS TIME HOWEVER THE WINDS ALOFT ARE NOT QUITE AS FAVORABLE FOR ORGANIZED CONVECTION OR TRAINING OF CELLS. BUT STRONG THUNDERSTORMS WITH GUSTY WINDS WILL STILL BE POSSIBLE...AND WITH PWATS AROUND 2 INCHES...LOCALIZED HEAVY RAINFALL WILL STILL BE A THREAT.
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&& .LONG TERM /TUESDAY THROUGH SUNDAY/...
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THE DOMINANT PATTERN IN THE LONG TERM IS THAT OF RIDGING ON AVERAGE. ON A LARGE SCALE...RIDGE IS APPARENT ON THE MODEL HEIGHT FIELDS ALOFT FROM CANADIAN MARITIMES TO THE MID-ATLANTIC TUESDAY. A RELATIVELY STRONGER UPPER LEVEL TROUGH PASSES NORTH OF THE REGION LATE TUESDAY INTO EARLY WEDNESDAY WITH SOME MORE HEIGHT FALLS AND A TRANSITION TO ZONAL FLOW. THE LOCAL REGION WILL BE ON THE EDGE OF THIS TROUGH...WITH MOST FORCING TO THE NORTH OF THE REGION. RIDGING RESUMES THEREAFTER MID TO LATE WEEK WITH A LARGE RIDGE ACROSS THE SOUTHERN U.S. PUSHING NORTH. ANOTHER SHORTWAVE WILL APPROACH FROM THE NORTHWEST FOR NEXT WEEKEND. A WEAK PRESSURE GRADIENT IS LEFT IN THE REGION BEHIND THE LOW PRESSURE TROUGH WITHOUT A STRONG PRESENCE OF HIGH PRESSURE TUESDAY. THE JET PUSHES BACK SOUTH TUESDAY NIGHT INTO EARLY WEDNESDAY...SO THIS WILL HELP PUSH ANOTHER COLD FRONT THROUGH THE REGION. THIS WILL TRANSITION WINDS TO MORE OF A NORTHERLY FLOW FOR WEDNESDAY. THE FLOW WEAKENS THURSDAY ALLOWING FOR SEA BREEZES TO DEVELOP AS HIGH PRESSURE BUILDS IN FROM THE SOUTH AND WEST. THE HIGH MOVES OFFSHORE FRIDAY WITH ANOTHER COLD FRONT APPROACHING SATURDAY AND MOVING ACROSS SATURDAY NIGHT. THEN HIGH PRESSURE RETURNS...BUILDING IN FROM THE WEST TO CLOSE OUT NEXT WEEKEND. OUTSIDE OF WEDNESDAY...A GENERAL SOUTH TO SOUTHWEST FLOW DOMINATES NEXT WEEK. THE JET STREAM OVERALL KEEPS TO THE NORTH OF THE REGION. A VERY WARM AND HUMID AIRMASS WILL REMAIN ACROSS THE REGION. TEMPERATURES REMAIN ABOVE NORMAL THROUGH THE PERIOD...WITH GREATEST WIDESPREAD POSITIVE TEMPERATURE ANOMALIES TUESDAY THROUGH WEDNESDAY. MAX TEMPS WILL BE WELL INTO THE 80S AND LOWER 90S IN THE VICINITY OF NYC AND URBAN NORTHEAST NJ ON TUESDAY...AROUND 10 DEGREES ABOVE NORMAL FOR THIS TIME OF YEAR. LOWS TUESDAY NIGHT AND HIGHS WEDNESDAY ARE STILL EXPECTED TO BE GENERALLY 5-10 DEGREES ABOVE NORMAL. TEMPERATURES WILL BE A FEW DEGREES ABOVE NORMAL ON AVERAGE THEREAFTER FOR THE REST OF THE FORECAST PERIOD. IN TERMS OF WEATHER...A CHANCE OF SHOWERS AND THUNDERSTORMS FROM NORTHWEST TO SOUTHEAST TUESDAY INTO TUESDAY NIGHT WITH A LITTLE MORE SHEAR TO WORK...AROUND 25 TO 35 KT 0-6 KM BULK SHEAR...AND INSTABILITY AS DIAGNOSED BY MUCAPE VALUES RANGING BETWEEN AROUND 500 TO 2000 J/KG. DRY WEATHER RETURNS THEREAFTER WITH THE NEXT CHANCE OF SHOWERS AND THUNDERSTORMS ON SATURDAY AND SATURDAY NIGHT.
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&& .AVIATION /20Z SUNDAY THROUGH FRIDAY/...
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A TROUGH OF LOW PRESSURE APPROACHES LATE THIS AFTERNOON AND MOVES THROUGH TONIGHT. ANOTHER TROUGH APPROACHES MONDAY FROM THE WEST. VERY MOIST AND UNSTABLE AIRMASS WILL SET THE STAGE FOR SCATTERED THUNDERSTORMS TO IMPACT NYC TERMINALS THROUGH 22Z. THEN A LARGER AREA OF THUNDERSTORMS WILL APPROACH AND LIKELY IMPACT NYC METRO AROUND THE 22-01Z TIME FRAME. MUCH OF THIS ACTIVITY THEN MOVES EAST...WITH MOST TERMINALS IMPACTED. TOWERING CU...MAINLY VFR EXPECTED THIS AFTERNOON...WITH LOCAL MVFR OR EVEN IFR IN HEAVIER CONVECTION LATE THIS AFTERNOON AND EVENING. FOR THE OVERNIGHT...MVFR OR IFR CEILINGS AND VSBYS ARE POSSIBLE. SHOWERS BECOME MORE SCATTERED TO ISOLATED. ANY MORNING STRATUS AND FOG WILL SLOWLY BURN OFF MONDAY. STRONG GUSTY WINDS ARE POSSIBLE IN ANY THUNDERSTORM. OTHERWISE SOUTH TO SOUTHWEST WINDS 10 TO 15 KTS THIS AFTERNOON WILL LIGHTEN TO 5 TO 10 KTS AFTER SUNSET. WINDS REMAIN LIGHT THROUGH THE OVERNIGHT AND MONDAY MORNING HOURS. .OUTLOOK FOR 18Z MON THROUGH FRI... .MON AFTERNOON-MON NIGHT...ADDITIONAL SCT SHRA/TSRA POSSIBLE MON AFT/EVE. MVFR STRATUS/FOG POSSIBLE LATE MON NIGHT. .TUE...MAINLY VFR EXCEPT FOR SCT AFT/EVE SHRA/TSRA. .WED-FRI...VFR CONDITIONS ARE EXPECTED.
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&& .MARINE...
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SW FLOW OF AROUND 15KT ON THE OCEAN WATERS TONIGHT IS EXPECTED TO BUILD SEAS ON THE OCEAN TO 5FT. THERE IS A CHANCE THAT SEAS FALL JUST SHORT OF 5FT...HOWEVER THERE IS NOT ENOUGH CONFIDENCE THAT SEAS DON`T TOUCH 5FT TO REMOVE THE CURRENT SCA WHICH IS POSTED FOR TONIGHT. FOR THE OTHER WATERS...WINDS ARE EXPECTED TO REMAIN BELOW SCA LEVELS. LOCALLY STRONG GUSTS WOULD HOWEVER BE POSSIBLE IN ANY THUNDERSTORMS THAT HOLD TOGETHER THIS EVENING. THE PRESSURE GRADIENT REMAINS WEAK MONDAY THROUGH FRIDAY WITH RIDGING THE MORE DOMINANT PATTERN. CONDITIONS ARE EXPECTED TO REMAIN BELOW SCA ON THE WATERS THROUGH THIS TIME PERIOD.
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&& .HYDROLOGY...
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ON AVERAGE...ABOUT AN INCH TO AN INCH AND A HALF OF RAINFALL IS EXPECTED THROUGH MONDAY ACROSS THE BASINS. DUE TO THE CONVECTIVE NATURE OF THE RAINFALL DISTRIBUTION...THERE WILL BE AREAS THAT RECEIVE MUCH LESS...AND SOME AREAS THAT COULD SEE AT LEAST 2 INCHES OF RAINFALL DURING THIS PERIOD. WIDESPREAD FLASH FLOODING IS NOT EXPECTED...BUT IT APPEARS THAT THE BEST CHANCES OF ANY FLOODING WOULD OCCUR BEFORE MIDNIGHT. ADDITIONALLY...LOCALIZED HEAVY RAINFALL/FLOODING COULD OCCUR AT ANY POINT THROUGH MONDAY. NO SIGNIFICANT WIDESPREAD RAINFALL EXPECTED TUESDAY THROUGH THE REST OF THE WORK WEEK.
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&& .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT MONDAY FOR ANZ350-353-355.
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&& $$ SYNOPSIS...JC/JM NEAR TERM...JC SHORT TERM...JC LONG TERM...JM AVIATION...PW MARINE...JC/JM HYDROLOGY...JC/JM

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