508  
FXUS61 KOKX 211502  
AFDOKX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NEW YORK NY  
1102 AM EDT MON AUG 21 2017  
   
SYNOPSIS
 
 
HIGH PRESSURE OVER THE REGION MOVES OFFSHORE TODAY AND TONIGHT.  
A COLD FRONT APPROACHES FROM THE WEST TUESDAY AND PASSES THROUGH  
TUESDAY NIGHT INTO WEDNESDAY MORNING. HIGH PRESSURE THEN BUILDS  
IN THEREAFTER THROUGH THE END OF THE WEEK WITH A MUCH DRIER AND  
COOLER AIRMASS.  
 

 
   
NEAR TERM /UNTIL 6 PM THIS EVENING/
 
 
FORECAST STILL MAINLY ON TRACK WITH JUST SLIGHT ADJUSTMENTS TO  
TEMPERATURES AND DEWPOINTS TO BETTER MATCH OBSERVED TRENDS.  
 
WEAK QUASI-ZONAL FLOW ALOFT WITH MAIN UPPER LEVEL JET STREAM  
WELL NORTHWEST OF THE REGION.  
 
SURFACE HIGH PRESSURE MOVES ACROSS THE REGION THIS MORNING AND  
OFFSHORE THIS AFTERNOON. EXPECTING A MAINLY DRY DAY WITH JUST A  
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS FOR FAR WESTERN  
ORANGE COUNTY LATE THIS AFTERNOON. 850MB TEMPERATURES FORECAST  
TO REACH NEAR 15-16 DEGREES C. SURFACE TEMPERATURES FORECAST TO  
REACH SEVERAL DEGREES WARMER THAN YESTERDAY. MID 80S TO NEAR 90  
DEGREES F FOR MUCH OF THE REGION WITH MOSTLY SUNNY CONDITIONS  
FOR MOST LOCATIONS.  
 
FOR SKY COVER, THE WESTERN EDGE OF A CIRRUS SHIELD SHOULD BE  
EAST OF THE FORKS REGION AND SE CT BY 200 PM. ANOTHER AREA OF  
TRANSLUCENT CIRRUS MOVING THROUGH NORTHERN PA WOULD APPEAR TO  
SHIFT THROUGH PRIMARILY NORTH OF THE CITY IN THE TIMEFRAME OF  
THE PARTIAL SOLAR ECLIPSE, WHICH RUNS ABOUT 120 PM TO 400 PM IN  
NYC WITH A PEAK AT 244 PM. CIRRUS MAY HOWEVER DEVELOP AND PASS  
THROUGH THE CITY AND LONG ISLAND DURING THIS PERIOD AS WELL,  
ESPECIALLY IF ANY CONVECTION POPS UP TO OUR WEST. HRRR  
INDICATES THIS CONVECTIVE POTENTIAL, BUT MAY HAPPEN TOO LATE TO  
BE OF MUCH SIGNIFICANCE. FINALLY, SOME CUMULUS DEVELOPMENT ALONG  
SEA BREEZES THIS AFTERNOON MAY CAUSE SOME OBSTRUCTION WITHIN  
ABOUT 10 MILES OF SOUTH-FACING COASTS. THINKING IS THAT ANY  
CUMULUS WOULD BE NO MORE THAT SCATTERED IN NATURE FOR MOST SPOTS  
THAT SEE IT.  
 
LIKE PREVIOUS FORECAST, A LOOK AT THE HRRRX CONVEYS A SLIGHT  
DECREASE DURING MAXIMUM OBSCURATION OF SUN DURING ECLIPSE, SO  
ADJUSTED TEMPERATURE A DEGREE DOWNWARD AT 19Z (3PM LOCAL TIME).  
 
THERE IS A LOW RISK OF RIP CURRENTS TODAY, BECOMING MODERATE  
LATE TODAY AT ATLANTIC BEACHES.  
 

 
   
SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/
 
 
REST OF THE FORECAST SHOWS HIGH PRESSURE MOVING FARTHER OFFSHORE  
AND A COLD FRONT GRADUALLY APPROACHING FROM THE WEST. UPPER  
LEVELS CONVEY AN UPPER LEVEL TROUGH WITH ITS UPPER LEVEL LOW BASED  
IN ONTARIO APPROACHING THE REGION. CONTINUALLY MORE WARM AND  
HUMID CONDITIONS ARE EXPECTED. FORECAST HAS WARMER TEMPERATURES  
TUESDAY, GETTING HOT AND HUMID FOR QUITE A FEW LOCATIONS. COULD  
SEE HEAT INDICES UP TO 100 DEGREES IN AND AROUND NYC.  
 
PRECIP FORECAST REMAINS NEAR OR BELOW 30 PERCENT FOR SHOWERS AND  
THUNDERSTORMS. NOT MUCH FORCING BUT INCREASING INSTABILITY AND  
POSSIBLE LEE TROUGH FORMING TUESDAY COULD PROVIDE FOCUS FOR  
CONVERGENCE. MODELS ARE PRETTY MINIMAL WITH FORECAST RAINFALL  
AMOUNTS OVERALL TONIGHT THROUGH TUESDAY. WEAK TROUGH EVIDENT IN  
LOWER LEVELS LATE TONIGHT INTO EARLY TUESDAY WILL LEAD TO POPS  
MORE IN LOW END CHANCE FOR SHOWERS AND THUNDERSTORMS AND THEN  
EXPECTING MUCH OF TUESDAY TO BE DRY EXCEPT FOR INTERIOR  
LOCATIONS WHICH WILL HAVE RELATIVELY HIGHER CHANCES FOR SHOWERS  
AND THUNDERSTORMS. THESE LOCATIONS WILL BE CLOSER TO LEE TROUGH  
AS WELL.  
 

 
   
LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/
 
 
A COLD FRONT APPROACHES THE REGION TUESDAY NIGHT AND PUSHES ACROSS  
THE FORECAST AREA ON WEDNESDAY. EXPECT CLOUD COVER TO INCREASE AND  
SHOWERS AND THUNDERSTORMS TO DEVELOP AND MOVE ACROSS THE REGION  
THROUGH THIS TIME FRAME. BY WEDNESDAY EVENING, SKIES WILL BEGIN TO  
CLEAR AND A MUCH COOLER AIRMASS WILL BE ARRIVING.  
 
CANADIAN HIGH PRESSURE BUILDS INTO THE REGION THURSDAY THROUGH THE  
WEEKEND, PROVIDING DRY AND SUNNY CONDITIONS. TEMPERATURES WILL  
REMAIN BELOW NORMAL AS HIGHS ONLY REACH THE 70S TO NEAR 80 EACH DAY.  
 
THE DRY AND COOLER CONDITIONS ARE EXPECTED TO CONTINUE INTO  
MONDAY.  
 

 
   
AVIATION /14Z MONDAY THROUGH FRIDAY/
 
 
VFR THROUGH THE TAF PERIOD AS HIGH PRESSURE REMAINS IN CONTROL.  
 
ISOLATED SHRA/TSRA POSSIBLE LATE EVENING FOR NYC/NJ AND NW  
TERMINALS.  
 
SW WINDS WILL INCREASE THIS MORNING INTO THE AFTERNOON, WITH  
SOUTHERLY SEA BREEZE DEVELOPMENT AT COASTAL TERMINALS. GUSTS OF  
15 TO 20 KT LIKELY THIS AFTERNOON. SW WINDS DIMINISH TO LESS  
THAN 10 KT THIS EVENING.  
 
NY METRO ENHANCED AVIATION WEATHER SUPPORT...  
 
DETAILED INFORMATION, INCLUDING HOURLY TAF WIND COMPONENT FORECASTS,  
CAN BE FOUND AT: HTTP:/WWW.WEATHER.GOV/ZNY/N90  
 
KJFK TAF COMMENTS: S GUSTS TO 20 KT POSSIBLE FOR EARLY EVENING  
PUSH. LOW PROB OF SHRA/TSRA AFT 01Z.  
 
THE AFTERNOON KJFK HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES  
SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD.  
 
KLGA TAF COMMENTS: S GUSTS TO 20 KT POSSIBLE FOR LATE AFT/EARLY  
EVENING PUSH. LOW PROB OF SHRA/TSRA AFT 01Z.  
 
THE AFTERNOON KLGA HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES  
SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD.  
 
KEWR TAF COMMENTS: LOW PROB OF SE SEA BREEZE BTWN 20-24Z. LOW  
PROB OF SHRA/TSRA AFT 01Z. SW GUSTS 15 TO 20 KT POSSIBLE IN THE  
AFTERNOON.  
 
THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES  
SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD.  
 
KTEB TAF COMMENTS: MODERATE PROB OF OF S SEA BREEZE BTWN  
20-24Z. LOW PROB OF SHRA/TSRA AFT 01Z. SW GUSTS 15 TO 20 KT  
POSSIBLE IN THE AFTERNOON.  
 
KHPN TAF COMMENTS: LOW PROB OF SHRA/TSRA AFT 00Z.  
 
KISP TAF COMMENTS: SSW GUSTS 15 TO 20 KT POSSIBLE LATE  
AFTERNOON.  
   
OUTLOOK FOR 06Z TUESDAY THROUGH FRIDAY
 
   
LATE TONIGHT
 
ISOLATED SHOWER/TSRA POSSIBLE. POTENTIAL FOR  
MVFR OR LOWER STRATUS/FOG DEVELOPMENT...PARTICULARLY EASTERN  
TERMINALS.   
TUESDAY-TUESDAY NIGHT
 
VFR. ISOLATED AFT SHRA/TSRA. CHANCE OF  
MORE WIDESPREAD SHOWERS AND THUNDERSTORMS WITH MVFR OR LOWER  
TUESDAY NIGHT INTO EARLY WED MORNING. SW WINDS G15-20KT TUESDAY  
AFTERNOON.   
WEDNESDAY
 
BECOMING VFR IN THE MORNING WITH NW GUSTS 15-20 KT.   
WEDNESDAY NIGHT-FRIDAY
 
VFR.  
 

 
   
MARINE
 
 
STARTING OFF WITH QUIET CONDITIONS ON THE WATERS WELL BELOW SCA  
THRESHOLDS WITH THE HIGH PRESSURE AREA BUILDING IN. THE HIGH  
TRAVERSES OVER THE WATERS THIS MORNING AND MOVES OFFSHORE THIS  
AFTERNOON. THE INCREASING RETURN SOUTHERLY FLOW WILL LEAD TO  
BUILDING SEAS LATE WITH OCEAN SEAS ACCORDING TO NWPS REACHING  
NEAR 3 FT BY THE END OF TODAY. WINDS GUSTS MAXIMIZE NEAR 20 KT  
LATE TODAY INTO EARLY THIS EVENING. OCEAN SEAS REMAIN MOSTLY 3  
FT TONIGHT INTO EARLY TUESDAY WITH WINDS SLIGHTLY SUBSIDING AND  
THEN THESE BOTH INCREASE TUESDAY AFTERNOON WITH SCA CONDITIONS  
COMING INTO PLACE BY MID TO LATE AFTERNOON ON THE OCEAN. THE  
SOUTHERLY FETCH BY THAT TIMEFRAME BUILDS THE OCEANS SEAS UP TO  
NEAR 5 FT.  
 
SMALL CRAFT CONDITIONS CONTINUE TUESDAY NIGHT INTO WEDNESDAY AS  
WINDS AND SEAS REMAIN HIGH WITH THE APPROACH AND PASSAGE OF A COLD  
FRONT. FOR NOW, A SMALL CRAFT ADVISORY IS IN EFFECT FOR THE OCEAN  
WATERS THROUGH TUESDAY NIGHT. IT IS LIKELY THE SCA WILL NEED TO BE  
EXPANDED TO THE NON-OCEAN WATERS. ALSO, SCA CONDITIONS WILL LIKELY  
CONTINUE INTO WEDNESDAY.  
 
CONDITIONS FALL BELOW SCA LEVELS LATE WEDNESDAY INTO WEDNESDAY  
NIGHT. WINDS AND SEAS ARE THEN FORECAST TO REMAIN, IN THE ABSENCE OF  
ANY INCREASED SWELL, BELOW SCA LEVELS THROUGH THE WEEKEND.  
 

 
   
HYDROLOGY
 
 
NO WIDESPREAD HYDROLOGIC IMPACTS ARE FORECAST THROUGH THE WEEK.  
 

 
   
TIDES/COASTAL FLOODING
 
 
TIDES ARE RUNNING HIGH ASTRONOMICALLY. FOR THE SOUTH SHORE  
BAYS, THERE IS THE POTENTIAL FOR WATER LEVELS TO JUST REACH THE  
MINOR COASTAL FLOODING BENCHMARKS WITH THIS EVENING'S HIGH TIDE.  
THINKING IS THAT IT'S MORE LIKELY THAT ALL AREAS FALL JUST SHORT  
OF FLOODING WITH AT MOST ONLY A SPOT OR TWO PERHAPS TOUCHING  
MINOR FLOODING BENCHMARKS. WILL THEREFORE NOT ISSUE A STATEMENT  
AT THIS TIME. WITH A STRONGER ONSHORE FLOW ON TUESDAY, THERE IS  
A BETTER CHANCE FOR SOME SPOTS ALONG THE SOUTH SHORE BAYS TO  
REACH MINOR FLOODING. TOO SOON TO ISSUE ANY PRODUCTS FOR THIS,  
SO WILL ALLOW SUBSEQUENT SHIFTS TO ASSESS TRENDS AND ISSUE ANY  
STATEMENTS OR ADVISORIES AS NEEDED. .  
 

 
   
OKX WATCHES/WARNINGS/ADVISORIES
 
 
CT...NONE.  
NY...NONE.  
NJ...NONE.  
MARINE...SMALL CRAFT ADVISORY FROM 3 PM TUESDAY TO 6 AM EDT WEDNESDAY  
FOR ANZ350-353-355.  
 

 
 

 
SYNOPSIS...JC  
NEAR TERM...JC/JM  
SHORT TERM...JM  
LONG TERM...BC  
AVIATION...NV  
MARINE...BC/JM  
HYDROLOGY...BC/JM TIDES/COASTAL  
FLOODING...JC  
 
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