Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 210533 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 133 AM EDT THU AUG 21 2014 .SYNOPSIS... HIGH PRESSURE REMAINS CENTERED TO THE NORTH AND EAST OF THE AREA THROUGH THURSDAY NIGHT. MEANWHILE...WAVES OF LOW PRESSURE ALOFT MOVE ACROSS THE REGION TONIGHT AND AGAIN THURSDAY INTO THURSDAY NIGHT. AN UPPER LEVEL DISTURBANCE WILL TRACK THROUGH THE AREA ON FRIDAY AS HIGH PRESSURE BUILDS DOWN FROM EASTERN CANADA. THIS HIGH WILL GRADUALLY BUILD DOWN THE EASTERN SEABOARD THROUGH THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... SHOWERS OVER EASTERN PA AND WESTERN NJ SHOULD BEGIN TO IMPACT WESTERN SECTIONS OF THE CWA BETWEEN 5-6Z. H5 SHORTWAVE WILL CONTINUE TO MOVE SLOWLY EAST ACROSS THE REGION TONIGHT AS LOW LEVEL MOISTURE INCREASES THROUGH THE NIGHT...ALLOWING FOR PRECIP TO REACH THE GROUND. BEST CHANCES WILL BE ACROSS WESTERN ZONES...BUT WILL KEEP POPS CAPPED AT CHANCE AS THE ACTIVITY WILL BE SCATTERED. LOWS TONIGHT WILL DROP INTO THE UPPER 60S IN/AROUND NYC AND IN THE LOW TO MID 60S MOST OTHER LOCATIONS. EASTERN ZONES WILL DROP INTO THE MID/UPPER 50S. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/... THERE WILL BE SOME SHOWERS ONGOING DURING THE FIRST HALF OF THE DAY...AS A SHORTWAVE SWINGS ACROSS THE AREA. BEST CHANCES WILL AGAIN BE ACROSS WESTERN AND NORTHERN ZONES...AS RIDGING NOSES IN ACROSS OUR EASTERN SECTIONS. INCLUDED ISO THUNDER ACROSS THE APPROXIMATE WESTERN THIRD OF THE AREA...WHERE MODEL FIELDS INDICATE A LITTLE MORE IN THE WAY OF MUCAPE. ADDITIONALLY...THESE AREAS WILL BE LESS INFLUENCED BY THE MARITIME AIR BEING ADVECTED ACROSS THE AREA THANKS TO E/SE ONSHORE FLOW. DUE TO THE AFOREMENTIONED ONSHORE FLOW AND INCREASED CLOUD COVER...TEMPS WILL BE COOLER THAN THE PREVIOUS DAY...WITH MANY AREAS STAYING IN THE 70S / BELOW NORMAL FOR THIS TIME OF YEAR. AS THE FIRST WAVE DEPARTS TO THE EAST THURSDAY AFTERNOON AND EVENING...SUBSIDENCE ALOFT AND THE CONTINUED SURFACE RIDGING POKING IN FROM THE NORTH AND EAST WILL ALLOW MOST PLACES TO BE DRY LATER IN THE DAY. CHANCES WILL THEN INCREASE AGAIN OVERNIGHT...AS THE UPPER LOW TO THE NW OPENS AND APPROACHES THE AREA. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... MODELS ARE IN GOOD AGREEMENT THAT THE H5 PATTERN ACROSS NOAM AT THE START OF THE LONG TERM PERIOD WILL CONSIST OF A STRONG BROAD RIDGE ACROSS THE SE CONUS WITH A DEEP TROUGH OUT WEST WITH AN UPPER LOW CUTTING OFF OVER THE PAC NW AND AN OMEGA BLOCK OVER ERN CANADA WITH A WEAK CUTOFF LOW MOVING THROUGH NEW ENGLAND. SOME UNCERTAINTY WITH THE SPECIFIC DETAILS AND TIMING OF VORT MAXES MOVING AROUND THE LEFT SIDE OF THE UPPER LOW ONCE IT SLIDES OFFSHORE...BUT THE GENERAL TREND APPEARS TO BE DECREASING CHC`S OF SHOWERS DURING FRI AS DEEP LAYERED RIDGING BUILDS INTO THE NORTHEAST FROM THE N. MAY NEED TO ADD SLIGHT TO LOW CHC POPS AT TIMES THROUGH SAT IN SUBSEQUENT FORECAST PACKAGES TO ACCOUNT FOR THESE TIMING DIFFERENCES. ADDITIONALLY...THE AMOUNT OF CLOUD COVER FOR FRI AND SAT IS ALSO QUESTIONABLE AS A RESULT. OTHERWISE...EXPECT DRY AND SEASONABLE CONDS THROUGH THE MIDDLE OF NEXT WEEK AS THE H5 FLOW AMPLIFIES IN RESPONSE TO THE BLOCKING PATTERN. SFC HIGH PRES WILL BUILD DOWN THE ERN SEABOARD DURING THIS TIME WITH AN ELY FLOW EXPECTED AT LEAST INTO MON. THIS WILL CONTRIBUTE TO BELOW NORMAL TEMPERATURES THOUGHT THIS TIME...BUT AS HEIGHTS RISE TUE AND WED...TEMPERATURES WILL REBOUND TO NEAR NORMAL LEVELS. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... WEAK HIGH PRESSURE REMAINS OVER THE AREA. WITH THE EXCEPTION OF POSSIBLE IFR CONDITIONS IN FOG AT KGON...MAINLY EXPECT VFR CONDITIONS THROUGH THE MORNING AND AFTERNOON HOURS. THERE WILL BE ISOLATED TO SCATTERED SHOWERS...AND ANY SHOWER COULD REDUCE CEILINGS OR VSBYS TO MVFR BRIEFLY. BEST CHANCE FOR SHOWERS ACROSS NYC METRO AND NORTH AND WEST. POSSIBLE HIGHER COVERAGE OF SHOWERS TONIGHT AS AN UPPER LEVEL DISTURBANCE MOVES THROUGH. BEST CHANCE NYC METRO AND NORTH AND WEST. LIGHT WINDS BECOME SOUTHEAST OR SOUTH 5 TO 10 KTS DURING THE DAYTIME. .OUTLOOK FOR 06Z FRI THROUGH MON... .TONIGHT...VFR...ALTHOUGH MVFR CEILINGS/VSBYS ARE POSSIBLE IN SCT SHOWERS/TSTMS. .FRI-MON...VFR. && .MARINE... WITH HIGH PRESSURE STILL EXTENDING ACROSS THE WATERS THURSDAY...AND ONLY STARTING TO LIFT OUT THURSDAY NIGHT...WINDS AND SEAS WILL REMAIN BELOW SCA CRITERIA DURING THIS TIME. EASTERLY FLOW WILL BE ON THE INCREASE LATE THURSDAY THOUGH. WIND GUSTS ARE EXPECTED TO REMAIN BLO SCA LEVELS...ALTHOUGH COULD COME CLOSE TO 25 KT ON THE OCEAN WATERS LATE FRI/FRI EVE. AN INCREASING E-NE FLOW WILL RESULT IN BUILDING SEAS ON THE OCEAN WITH SCA CONDS EXPECTED BETWEEN FRI NIGHT AND SUN NIGHT. THE GRADIENT RELAXES THEREAFTER WITH SEAS DIMINISHING. && .HYDROLOGY... A FEW THUNDERSTORMS ARE POSSIBLE ON THURSDAY ACROSS THE LOWER HUDSON VALLEY AND INTERIOR NE NJ. ANY STORMS WILL HAVE THE POTENTIAL TO PRODUCE LOCALLY HEAVY RAIN...BUT BASIN AVERAGED TOTALS ARE FORECAST TO REMAIN LIGHT...AS ANY THUNDERSTORMS SHOULD BE ISOLATED. NO SIGNIFICANT RAINFALL IS EXPECTED IN THE EXTENDED. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...24/PICCA NEAR TERM...PICCA/JP/MPS SHORT TERM...PICCA LONG TERM...24 AVIATION...PW MARINE...24/PICCA HYDROLOGY...24/PICCA

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