487  
FXUS61 KOKX 182054  
AFDOKX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NEW YORK NY  
454 PM EDT THU JUL 18 2019  
   
SYNOPSIS
 
 
A WEAK COLD FRONT SAGS SLOWLY SOUTH OF THE WATERS THROUGH TONIGHT,  
WASHING OUT AS IT DOES SO. THE AREA WILL THEN COME UNDER THE  
INFLUENCE OF THE WESTERN EXTENT OF THE BERMUDA HIGH THROUGH THE  
WEEKEND. A COLD FRONT APPROACHES AND MOVES THROUGH SUNDAY NIGHT  
INTO MONDAY. HIGH PRESSURE RETURNS FOR TUESDAY AND WEDNESDAY.  
 

 
   
NEAR TERM /UNTIL 6 PM THIS EVENING/
 
 
A STALLED FRONTAL BOUNDARY ACROSS LONG ISLAND EARLY THIS  
EVENING WILL SLOWLY DROP TO THE SOUTH. PRIOR TO THAT TIME, WEAK  
WARM ADVECTION JUST TO THE NORTH OF THE BOUNDARY AND THE FRONT  
ITSELF WILL SERVE AS A FOCUS FOR SCATTERED SHOWERS AND POSSIBLY  
A THUNDERSTORM. EARLIER, THERE WERE REPORTS OF URBAN AND POOR  
DRAINAGE FLOODING ALONG THE CT COAST. THE HEAVIEST ACTIVITY HAS  
SINCE WORKED EAST OF THE AREA.  
 
AIRMASS IS MOISTURE LOADED WITH PW VALUES OVER 2 INCHES AND  
MARGINAL INSTABILITY. WIND SHEAR IS WEAK, SO THE MAIN THREAT  
WILL BE BRIEF HEAVY DOWNPOURS AND LOCALIZED URBAN AND POOR  
DRAINAGE FLOODING. A FEW SHOWERS MAY LINGER THROUGH THE  
OVERNIGHT DUE TO WEAK LIFT AS A FRONTAL PASSES JUST SOUTH OF  
THE AREA AND WEAK MID LEVEL SHORTWAVES TRAVERSE THE SOUTHERN  
EDGE OF THE WESTERLIES.  
 
IT WILL BE A WARM, HUMID NIGHT WITH READINGS RANGING FROM THE  
MID AND UPPER 60S INLAND, TO THE LOWER AND MID 70S ACROSS THE  
NYC METRO. THERE IS SOME HINT OF COOLER TEMPERATURES WORKING IN  
ON THE A LIGHT N/NE FLOW OVERNIGHT BEHIND THE FRONT AND WAVE.  
THESE READINGS ARE NEAR 5 DEGREES ABOVE NORMAL.  
 

 
   
SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/
 
 
FORECAST AREA WILL RESIDE AT THE SOUTHERN EDGE OF THE WESTERLIES  
WITH THE POTENTIAL FOR RECORD WARMTH AS WE HEAD INTO THE  
WEEKEND. THIS WILL BE THE START OF A HEAT WAVE FOR THE REGION  
FOLLOWING THE CLOUD COVER AND SHOWERS THAT TEMPERED THE  
TEMPERATURES ON THURSDAY.  
 
DEEP-LAYERED W FLOW AND THE WESTWARD EXPANSION OF THE SUBTROPICAL  
HIGH ALONG THE EAST COAST WILL COMBINE TO KEEP THE AIRMASS VERY  
HUMID WITH DEW POINTS INTO THE LOWER AND MIDDLE 70S ON FRIDAY.  
THIS COMBINED WITH HIGHS IN THE LOWER AND MIDDLE 90S FROM NYC  
AND POINTS NORTH AND WEST WILL PRODUCE HEAT INDEX VALUES AROUND  
105 ON FRIDAY FOR THE NYC METRO, NE NJ, AND THE LOWER HUDSON  
VALLEY. AN EXCESSIVE HEAT WARNING HAS BEEN ISSUED FOR THESE  
AREAS. TO THE EAST, A DEVELOPING ONSHORE FLOW WILL KEEP  
TEMPERATURES COOLER, MAINLY IN THE UPPER 80S TO NEAR 90. STILL  
THOUGH, HEAT INDEX VALUES WILL RANGE FROM MID 90S TO AROUND 100.  
THESE LOCATIONS ARE UNDER A HEAT ADVISORY. THIS WILL BEGIN A  
PROLONGED PERIOD OF HEAT HAZARDS FOR THE REGION.  
 
ADDITIONALLY, SOME OF THE CAMS ARE NOT HINTING AT LATE DAY  
CONVECTION DROPPING IN FROM THE NW DURING THE LATE  
AFTERNOON/EARLY EVENING HOURS. HIGH CAPE, WEAK SHEAR  
ENVIRONMENT WITH LACK OF A STRONG TRIGGER LENDS ONLY TO AN ISOLATED  
MENTION IN THE FORECAST AT THIS TIME. HOWEVER, ANY STORM BREAKING  
THE CAP COULD BE STRONG TO SEVERE WITH THE MAIN THREAT BE  
LOCALIZED DAMAGING WINDS.  
 
FOR FRIDAY NIGHT, NOT MUCH RELIEF WITH TEMPERATURES STRUGGLING  
TO GET INTO THE 70S. HEAT INDEX VALUES OVERNIGHT MAY GET NO  
LOWER THAN THE MID TO UPPER 80S FOR THE NYC METRO AREA.  
 
THERE IS A MODERATE RIP CURRENT RISK AT THE OCEAN BEACHES FOR  
FRIDAY.  
 

 
   
LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/
 
 
THE MAIN CONCERN FOR THIS PERIOD CONTINUES TO BE THE HIGH HEAT AND  
HUMIDITY THAT IS EXPECTED TO CONTINUE SATURDAY AND SUNDAY THANKS TO  
A BERMUDA HIGH OVER THE NORTHERN ATLANTIC. 850 HPA TEMPERATURE  
ANOMALIES OF +2-+3C OVER THE GREAT LAKES REGION WILL MOVE OVER THE  
AREA THROUGH SUNDAY. 500 HPA HEIGHTS OVER 5900 M ALSO NOTED IN  
GUIDANCE FOR SATURDAY, WITH SLIGHTLY LESS VALUES FOR SUNDAY. THIS IS  
IN LINE WITH CLIMATOLOGY FOR A WIDESPREAD HEAT WAVE TO IMPACT THE  
FORECAST AREA FROM FRIDAY THROUGH SUNDAY. MUCH OF THE GUIDANCE  
SUGGESTS HIGHS WELL INTO THE THE 90S DURING THIS TIME FRAME, WITH  
DEW POINTS WELL INTO THE 70S.  
 
HIGHS ON SATURDAY WILL RANGE FORM 95 TO 100 DEGREES, WITH PERHAPS  
ISOLATED AREAS IN NORTHEAST NEW JERSEY REACHING A DEGREE OR TWO  
ABOVE THE CENTURY MARK. SUNDAY WILL BE SLIGHTLY COOLER, AS HEIGHTS  
LOWER SOMEWHAT, BUT IT WILL CONTINUE TO BE VERY HOT AND HUMID. THERE  
IS ALSO A GREAT DEAL OF UNCERTAINTY WITH THE TEMPERATURES FOR SUNDAY  
DUE TO UNCERTAINTY IN CLOUD COVERAGE FROM AN APPROACHING COLD FRONT  
TO THE WEST. THE ECMWF ENSEMBLE HAS A RANGE OF HIGH TEMPERATURES  
FROM 89 TO 101 FOR CENTRAL PARK.  
 
REGARDLESS, WITH ANOMALOUSLY HIGH DEW POINTS IN THE MIDDLE TO UPPER  
70S IN SOME CASES, THIS TRANSLATES TO HEAT INDEX VALUES OF 105 TO  
JUST OVER 110 FOR MUCH OF THE FORECAST AREA (ISOLATED PORTIONS OF  
NORTHEAST NEW JERSEY MAY SEE HEAT INDEX VALUES OF 115) FOR SATURDAY.  
EXCESSIVE HEAT WATCHES HAVE BEEN CONVERTED TO EXCESSIVE HEAT  
WARNINGS FOR SATURDAY. WITH THE POTENTIAL FOR WIDESPREAD HEAT INDEX  
VALUES OF 105-110 ON SUNDAY, EXCESSIVE HEAT WARNINGS HAVE BEEN  
ISSUED FOR THEN AS WELL. THESE TEMPERATURES AND HEAT INDEX VALUES  
ARE LIFE THREATENING, PLEASE FOLLOW THE PREPAREDNESS/PRECAUTIONARY  
ACTIONS WITHIN OUR EXCESSIVE HEAT WARNING PRODUCTS TO PREPARE FOR  
THE UPCOMING HEAT.  
 
OF ADDITIONAL CONCERN ARE NIGHTTIME LOWS SATURDAY NIGHT INTO SUNDAY,  
AS LOWS ARE NOT FORECAST TO DIP BELOW 80 IN THE NEW YORK CITY METRO  
AREA, WITH THE LOWEST FORECAST HEAT INDEX VALUES DURING THAT TIME  
FRAME IN THE UPPER 80S TO LOWER 90S.  
 
AS FOR PRECIPITATION, THERMAL TROUGHS DEVELOPING WILL ALLOW FOR JUST  
A PASSING SHOWER OR THUNDERSTORM FOR LATE SATURDAY INTO SATURDAY  
NIGHT. AN APPROACHING COLD FRONT WILL BRING A LOW END CHANCE FOR  
SHOWERS AND THUNDERSTORMS SUNDAY AFTERNOON, MAINLY FOR NEW YORK CITY  
AND POINTS NORTH AND WEST. AS FOR NOW, NOTHING INDICATING A  
WIDESPREAD SEVERE EVENT IN THE LONG TERM. CHANCES INCREASE SUNDAY  
NIGHT INTO MONDAY, WITH BEST CHANCES FOR RAIN MONDAY AFTERNOON AS  
THE COLD FRONT REMAINS JUST OFF SHORE. THERE MAY BE LINGERING  
SHOWERS AND THUNDERSTORMS FOR TUESDAY, MAINLY FOR SOUTHERN PORTIONS  
OF THE AREA. TEMPERATURES WILL BE COOLER FOR MONDAY THANKS TO  
INCREASE CLOUDINESS AND RAIN, WITH LOWER HUMIDITY LEVELS. MORE  
SEASONABLE CONDITIONS ARE EXPECTED FOR TUESDAY THROUGH THURSDAY WITH  
HIGH PRESSURE IN CONTROL FOR THE MIDDLE OF THE WEEK.  
 

 
   
AVIATION /20Z THURSDAY THROUGH TUESDAY/
 
 
MVFR TO IFR CONDITIONS GENERALLY PREVAILING ACROSS THE AREA. A  
RETURN TO IFR/LIFR CONDITIONS EXPECTED THIS EVENING. SCATTERED  
SHOWERS WILL PREVAIL ACROSS THE AREA WHICH MAY REDUCED  
VISIBILITIES AT TIMES. A STRONG CLUSTER OF TSTMS ACROSS CENTRAL  
AND SOUTH NEW JERSEY SHOULD CONTINUE TO MOVE EAST AND STAY SOUTH  
OF THE NYC TERMINALS BUT WILL KEEP A CHANCE OF THUNDERSTORMS  
KJFK/KEWR/KTEB WITH VCTS DUE TO IMPACTS TO AIR TRAVEL. SHOWERS  
END THIS EVE WITH THE FRONT PUSHING SOUTH OF LONG ISLAND.  
 
A LIGHT, GENERALLY LESS THAN 10 KT E-NE FLOW IS EXPECTED ACROSS THE  
TERMINALS WITH A COASTAL SEA BREEZE VEERING WIND TO THE SE AT TIMES  
AT KJFK.  
 
WINDS SWITCH TO W-SW NEAR 10 KT AROUND 15Z ON FRIDAY AND VFR IS  
EXPECTED TO RETURN. TIMING COULD BE OF A FEW HOURS, ESPECIALLY AT  
KLGA WHERE A EASTERLY COMPONENT TO THE WIND MAY HANG ON A FEW HOURS  
LONGER.  
   
..NY METRO ENHANCED AVIATION WEATHER SUPPORT
 
 
DETAILED INFORMATION, INCLUDING HOURLY TAF WIND COMPONENT FCSTS, CAN  
BE FOUND AT: HTTP:/WWW.WEATHER.GOV/ZNY/N90  
 
KJFK TAF COMMENTS: AMENDMENTS POSSIBLE FOR CHANGING FLIGHT  
CATEGORIES.  
 
KLGA TAF COMMENTS: AMENDMENTS POSSIBLE FOR CHANGING FLIGHT  
CATEGORIES.  
 
KEWR TAF COMMENTS: AMENDMENTS POSSIBLE FOR CHANGING FLIGHT  
CATEGORIES.  
 
KTEB TAF COMMENTS: AMENDMENTS POSSIBLE FOR CHANGING FLIGHT  
CATEGORIES.  
 
KHPN TAF COMMENTS: AMENDMENTS POSSIBLE FOR CHANGING FLIGHT  
CATEGORIES.  
 
KISP TAF COMMENTS: AMENDMENTS POSSIBLE FOR CHANGING FLIGHT  
CATEGORIES.  
   
OUTLOOK FOR 21Z FRIDAY THROUGH TUESDAY
 
   
21Z FRIDAY THROUGH SUNDAY
 
VFR. ISOLATED SHRA/TSTMS POSSIBLE  
SUNDAY ESPECIALLY LATE   
MONDAY AND TUESDAY
 
MVFR POSSIBLE IN SCATTERED SHOWERS AND  
THUNDERSTORMS.  
 

 
   
MARINE
 
 
EASTERLY WINDS AHEAD OF FRONTAL WAVE COULD BRIEFLY PRODUCE GUSTS  
UP TO 20 KT ON THE SOUND THIS EVENING BEFORE DISSIPATING AS A  
WEAK NORTHERLY FLOW DEVELOPS OVERNIGHT. ON FRIDAY, S-SW WINDS ON  
THE OCEAN WATERS IN THE AFTERNOON WILL PUSH 15 TO 20 KT AND  
THEN WEAKEN FRIDAY NIGHT. A BRIEF PERIOD OF 5 FT SEAS LATE IN  
THE DAY IS POSSIBLE. CONFIDENCE IS LOW AT THIS TIME.  
 
THEREAFTER, A WEAK PRESSURE GRADIENT IN THE LONG TERM WILL MEAN  
WINDS REMAIN BELOW SCA CRITERIA. SOUTHERLY FLOW WILL ALLOW  
WAVES ON THE OCEAN TO BUILD TO 5 FT SUNDAY NIGHT THROUGH  
TUESDAY, MAINLY FOR THE CENTRAL AND EASTERN OCEAN ZONE.  
 

 
   
HYDROLOGY
 
 
VERY LOCALIZED RAINFALL AMOUNTS UP TO AN INCH ARE POSSIBLE THIS  
EVENING, MAINLY ACROSS THE NYC METRO AND WESTERN LONG ISLAND  
EARLY THIS EVENING. THIS COULD RESULT IN POOR DRAINAGE AND LOW  
LYING FLOODING.  
 
NO HYDROLOGIC IMPACTS ARE EXPECTED FRIDAY INTO NEXT WEEK.  
 

 
   
CLIMATE
 
 
THE FOLLOWING ARE RECORDS FOR THIS WEEKEND:  
 
RECORD HIGHEST MINIMUM TEMPERATURES FOR SATURDAY, JULY 20:  
 
NYC: 82 IN 2015  
LGA: 83 IN 2015  
JFK: 79 IN 2015  
EWR: 80 IN 2015  
ISP: 78 IN 2013  
BDR: 79 IN 2013  
 
RECORD HIGH TEMPERATURES FOR SATURDAY, JULY 20:  
 
NYC: 101 IN 1980  
LGA: 101 IN 1991  
JFK: 96 IN 2013 (ALSO OCCURRED IN PREVIOUS YEARS)  
EWR: 101 IN 1980  
ISP: 97 IN 1991  
BDR: 95 IN 1001  
 
RECORD HIGHEST MINIMUM TEMPERATURES FOR SUNDAY, JULY 21:  
 
NYC: 82 IN 1980  
LGA: 83 IN 1980  
JFK: 79 IN 2017  
EWR: 81 IN 1980  
ISP: 76 IN 1980  
BDR: 76 IN 1994  
 
RECORD HIGH TEMPERATURES FOR SUNDAY, JULY 21:  
 
NYC: 104 IN 1977  
LGA: 100 IN 1991  
JFK: 99 IN 1991  
EWR: 103 IN 2011  
ISP: 101 IN 1991  
BDR: 98 IN 1991  
 

 
   
EQUIPMENT
 
 
NYC NOAA WEATHER RADIO STATION KWO35 (162.55 MHZ) REMAINS OFF  
THE AIR.  
 

 
   
OKX WATCHES/WARNINGS/ADVISORIES
 
 
CT...EXCESSIVE HEAT WARNING FROM 6 AM SATURDAY TO 8 PM EDT SUNDAY  
FOR CTZ005>012.  
HEAT ADVISORY FROM NOON FRIDAY TO 6 AM EDT SATURDAY FOR  
CTZ005>012.  
NY...EXCESSIVE HEAT WARNING FROM 6 AM SATURDAY TO 8 PM EDT SUNDAY  
FOR NYZ078>081-177-179.  
HEAT ADVISORY FROM NOON FRIDAY TO 6 AM EDT SATURDAY FOR  
NYZ078>081-177-179.  
EXCESSIVE HEAT WARNING FROM NOON FRIDAY TO 8 PM EDT SUNDAY FOR  
NYZ067>075-176-178.  
NJ...EXCESSIVE HEAT WARNING FROM NOON FRIDAY TO 8 PM EDT SUNDAY FOR  
NJZ002-004-006-103>108.  
MARINE...NONE.  
 

 
 

 
 
SYNOPSIS...JP/DW  
NEAR TERM...DW  
SHORT TERM...DW  
LONG TERM...JP  
AVIATION...IRD  
MARINE...JP/DW  
HYDROLOGY...JP/DW  
CLIMATE...//  
EQUIPMENT...//  
 
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