Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 011824 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 224 PM EDT FRI AUG 1 2014 .SYNOPSIS... HIGH PRESSURE REMAINS JUST OFFSHORE THROUGH SATURDAY AS A FRONTAL BOUNDARY OVER THE ATLANTIC COAST AND LOW PRESSURE TO THE SOUTH WILL IMPACT THE AREA THROUGH THE BEGINNING OF THE WEEK. HIGH PRESSURE THEN BUILDS INTO THE REGION ON TUESDAY...WITH A COLD FRONT PASSING THROUGH ON WEDNESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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18Z RADAR INDICATING PULSE SCT TSTMS ACROSS THE AREA IN ASSOCIATION WITH A PASSING MID LVL SHORTWAVE COMBINING WITH DEVELOPED SEA BREEZES ALONG BOTH THE LI AND CT COASTS. CONTINUING WITH SCT POPS FOR THE AFTN. DECENT INSTABILITY BUT WEAK SHEAR WOULD LEND TO THE TSTMS STAYING ON THE WEAKER SIDE. HOWEVER...FLOW ALOFT WEAK AROUND 10 KTS...SO THE MAIN THREAT LOOKS TO BE PESKY FLOODING WITH THE SLOW MOVING CELLS. NAM/MET GUIDANCE HAD A BETTER HANDLE ON THE SW FLOW WARMING INTERIOR AREAS SLIGHTLY MORE THAN COASTAL LOCATIONS. 13-14C 850 TEMPS LEND TO HIGHS IN THE LOWER 80S WHICH MATCHED WELL WITH GUIDANCE AND LEANED TOWARDS THE NAM NUMBERS. TEMPS ON TRACK FOR THE DAY.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... NEXT FOCUS OF RAIN WILL BE THE STATIONARY FRONT BACKING IN FROM THE EAST WITH THE WESTERN ATLANTIC HIGH PRESSURE EXPANDING SLIGHTLY WESTWARD. SOME MODEL DIFFERENCES EXIST ON THE TIMING OF WHEN THE PRECIP WILL REACH THE AREA WITH THE NAM THE SLOWEST AND DRIEST FOR THE DAY ON SATURDAY. HIGHEST PRECIP AMOUNTS WILL BE LONG ISLAND AND SOUTHEAST CT WITH THE FRONT POSITIONED JUST TO THE SOUTH OF THE ISLAND. WILL CONTINUE CHANCE POPS ELSEWHERE THOUGH AS SHOWERS SHOULD STILL BE ABLE TO DEVELOP WITH UPPER JET AND MID LEVEL SHORTWAVE ENHANCEMENT. AS WELL...DEEP MOISTURE STREAMING FROM THE SOUTH WILL BE IN PLACE SO ANY SHOWERS WILL PRODUCE LOCALLY HEAVY RAINFALL. VERY LOW CONFIDENCE ON ANY THUNDER FOR SATURDAY. LITTLE TO NO INSTABILITY OR SHEAR...JUST MODERATE LIFT. EXPECT SHOWERS TO BE VERY TROPICAL IN NATURE AND MAYBE AN ISOLATED LIGHTNING STRIKE OR TWO. WIND PROFILES ALOFT ARE AGAIN LIGHT SO TRAINING OF CELLS IS LIKELY. AS FOR TEMPERATURES...NAM 2M TEMPS MUCH WARMER THAN ALL GUIDANCE FOR LOWS TONIGHT EVEN WITH SIMILAR CLOUD COVER FORECASTS. WENT WITH A BLEND OF MAV/MOSGUIDE FOR LOWS FOR TEMPS IN THE LOWER TO MID 60S. GUIDANCE FOR HIGHS ON SAT IS LOWER THAN PREVIOUS. POSSIBLY DUE TO THE MODELS COMING INTO AGREEMENT FOR A RAINY DAY. WILL LOWER HIGHS A FEW DEG FROM PREVIOUS FORECAST. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... A SHORTWAVE WEAKENS AT THE BASE OF A 500MB TROUGH AXIS AS IT APPROACHES THE FORECAST AREA...EVENTUALLY PASSING THROUGH SUNDAY NIGHT INTO MONDAY MORNING. THIS WILL HELP SLOWLY NUDGE THE OFFSHORE FRONTAL BOUNDARY FARTHER OUT TO SEA. SOME SYNOPTIC LIFT WILL BE PRESENT THROUGH MONDAY WITH THE RIGHT ENTRANCE OF AN UPPER JET STREAK IN THE VICINITY. LESS CERTAIN ARE THE TIMING AND POSITION OF LOW-MID LEVEL SHORTWAVES THAT PASS THROUGH/NEARBY THE CWA BEFORE THE TROUGH AXIS ALOFT PASSES THROUGH. POPS THEREFORE CAPPED AT CHANCE...WHICH IS CLOSE TO WHAT A MODEL BLEND WOULD PRODUCE. BEST OVERALL CHANCES OF RAINFALL WOULD BE SATURDAY NIGHT INTO SUNDAY MORNING AND CLOSER THE OFFSHORE FRONTAL BOUNDARY. MONDAY COULD EVEN TURN OUT TO BE COMPLETELY DRY...ESPECIALLY IF THE ECMWF IS CORRECT WITH THE TROUGH AXIS PASSING THROUGH SUNDAY NIGHT AND A LACK OF LOW-MID LEVEL SHORTWAVES TRAILING IT ON MONDAY. DO NOT HAVE ENOUGH CONFIDENCE TO REMOVE POPS ALTOGETHER ON MONDAY...SO HAVE LEFT THE PREVIOUS FORECAST OF SLIGHT CHC/CHC POPS. WEAK HIGH PRESSURE PROBABLY KEEPS TUESDAY AND THURSDAY DRY...BUT A COLD FRONT AND CYCLONIC FLOW ALOFT COULD BRING AN ISOLATED SHOWER/TSTM TO THE AREA ON WEDNESDAY. CLOUDS AND AN ONSHORE FLOW WILL HOLD HIGH TEMPERATURES ON MONDAY BELOW NORMAL...HIGHS OTHERWISE NEAR NORMAL FOR THE REST OF THE LONG TERM FORECAST. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
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SHOWERS AND THUNDERSTORMS HAVE DEVELOPED ALONG THE SEABREEZE FRONT THIS AFT...PRIMARILY OUTSIDE THE NY METROPLEX. THE MAIN AREA ALONG THE NJ COAST IS WEAKENING WITH SECONDARY AREAS TO THE NORTH AND WEST. OVERALL...EXPECT A GENERAL DECREASE IN COVERAGE AND INTENSITY THE NEXT COUPLE OF HOURS WITH MOST OF THE ACTIVITY REMAINING ACROSS THE LOWER HUDSON VALLEY AND NE NJ. S WINDS WILL PREVAIL AROUND 10 KT WITH SOME VARIABILITY IN DIRECTION BY 20 TO 30 DEGREES. WINDS WILL GRADUALLY BACK AROUND LATE TONIGHT TO THE E/NE AS A FRONTAL WAVE APPROACHES FROM THE SOUTH. A PERIOD OF MVFR CIGS/VSBYS WITH MAINLY LIGHT RAIN IS FORECAST SAT MORNING/AFT. NY METRO ENHANCED AVIATION WEATHER SUPPORT... DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE) KJFK FCSTER COMMENTS: LOW CHANCE OF A THUNDERSTORM THROUGH 20Z. WINDS MAY VARY THIS AFT FROM 150 TO 180. KLGA FCSTER COMMENTS: LOW CHANCE OF A THUNDERSTORM THROUGH 20Z. WINDS MAY VARY THIS AFT FROM 150 TO 180. KEWR FCSTER COMMENTS: LOW CHANCE OF A THUNDERSTORM THROUGH 20Z. WINDS MAY VARY THIS AFT FROM 130 TO 160. KTEB FCSTER COMMENTS: LOW CHANCE OF A THUNDERSTORM THROUGH 20Z. WINDS MAY VARY THIS AFT FROM 150 TO 180. KHPN FCSTER COMMENTS: ISOLATED THUNDERSTORMS IN THE VICINITY 18-19Z MAY IMPACT AIRFIELD. WINDS MAY VARY 140 TO 160. KISP FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. .OUTLOOK FOR 18Z SATURDAY THROUGH TUESDAY... .SATURDAY-SAT NIGHT...SHRA WITH MVFR OR LOWER CONDS LIKELY. LOW PROB FOR TSRA. .SUN-SUN NIGHT...SHRA/TSRA POSSIBLE...MVFR OR LOWER CONDS POSSIBLE. .MONDAY-WEDNESDAY...VFR. MVFR POSSIBLE IN ISOLD SHRA/TSTMS IN THE AFTERNOON/EVENING.
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&& .MARINE... WITH A WEAK PRESSURE GRADIENT OVER THE WATERS...SUB-SMALL CRAFT ADVISORY CONDITIONS ARE EXPECTED ON THE WATERS THROUGH TUESDAY. && .HYDROLOGY...
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BRIEF HEAVY DOWNPOURS POSSIBLE IN SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTN. LOCALIZED URBAN/POOR DRAINING FLOODING IS POSSIBLE DUE TO SLOW MOVEMENT. A SIMILAR SET UP EXISTS FOR THE WEEKEND INTO MONDAY WITH SHOWERS MORE NUMEROUS IN COVERAGE ACROSS THE AREA AND SLOW MOVEMENT OF CELLS. ALTHOUGH THUNDERSTORMS ARE UNLIKELY...THE MOIST AIRMASS WILL PRODUCE MODERATE TO HEAVY DOWNPOURS. THIS COULD ONCE AGAIN RESULT MAINLY IN URBAN/POOR DRAINAGE FLOODING.
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&& .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...JC/LN NEAR TERM...LN/SEARS SHORT TERM...LN LONG TERM...JC AVIATION...DW MARINE...JC/LN/PW HYDROLOGY...JC/LN

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