208  
FXUS61 KOKX 290902  
AFDOKX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NEW YORK NY  
502 AM EDT MON MAY 29 2017  
   
SYNOPSIS
 
 
A LOW PRESSURE SYSTEM APPROACHES PASSES THROUGH INTO THIS  
EVENING. A WEAK COLD FRONT APPROACHES FROM THE WEST TUESDAY,  
THEN CROSSES THE AREA TUESDAY NIGHT...FOLLOWED BY ANOTHER ON  
WEDNESDAY. HIGH PRESSURE THEN BUILDS TO THE SOUTH THROUGH  
THURSDAY NIGHT. ANOTHER COLD FRONT APPROACHES ON FRIDAY THEN  
SLOWLY CROSSES THE AREA FRIDAY NIGHT.  
 

 
   
NEAR TERM /UNTIL 6 PM THIS EVENING/
 
 
LIGHT RAIN SHOWERS CONTINUE TO MOVE NORTH AND EAST THIS MORNING  
IN ASSOCIATION WITH FRONTAL SYSTEM APPROACHING THE AREA FROM  
THE WEST. TWO AREAS OF LOW PRESSURE WILL BE THE FOCUS OF  
PRECIPITATION OVER THE REGION. ONE WEAK, BROAD LOW TO OUR  
NORTHWEST, NEAR THE EASTERN GREAT LAKES REGION, AND ANOTHER  
STRONGER LOW DEVELOPING WELL EAST OF THE DELMARVA PENINSULA THAT  
IS FORECAST TO PASS WELL SOUTH AND EAST OF THE AREA. MUCH OF THE  
TRI-STATE WILL BE CAUGHT IN BETWEEN THESE TWO LOWS, LEADING TO  
RELATIVELY HEAVIER RAINFALL FOR PORTIONS OF THE LOWER HUDSON  
VALLEY (CLOSER TO THE LOW NEAR THE GREAT LAKES) SOUTHERN  
AND EASTERN PORTIONS OF THE AREA, SUCH AS NORTHEAST NEW JERSEY,  
NEW YORK CITY AND LONG ISLAND (CLOSER TO THE LOW OFFSHORE).  
CONNECTICUT SHOULD SEE LOWER AMOUNTS AS THEY WILL BE FARTHER  
AWAY FROM BOTH LOWS. IN GENERAL, RAINFALL AMOUNTS HAVE BEEN  
LOWERED TO BETWEEN A 0.25"-0.50". HOWEVER, AMOUNTS COULD END UP  
EVEN LOWER THAN THIS, BUT NOT CONFIDENT ON LOWERING THEM THAT  
DRASTICALLY GIVEN UNCERTAINTY IN PLACEMENT OF LOWS.  
 
UNSEASONABLY COOL TEMPERATURES TODAY AS CLOUDS AND RAIN KEEP  
TEMPERATURES IN THE UPPER 50S TO AROUND 60 FOR HIGHS, SOME 10 TO  
15 DEGREES BELOW NORMAL.  
 

 
   
SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/
 
 
FRONTAL SYSTEM PUSHES EAST OF THE AREA TONIGHT, ALONG WITH THE  
COASTAL STORM. AFTER SOME LINGERING SHOWERS EARLY THIS EVENING,  
CONDITIONS SHOULD REMAIN DRY. HOWEVER, DRIZZLE AND FOG MAY  
DEVELOP OVERNIGHT, WITH LOW LEVEL MOISTURE TRAPPED UNDER AN  
INVERSION.  
 
ANOTHER FRONT APPROACHES SLOWLY FROM THE WEST. CHANCES FOR RAIN  
INCREASE FROM WEST TO EAST DURING THE DAY TUESDAY. ENOUGH  
INSTABILITY FOR SOME THUNDER, BUT NOTHING SEVERE EXPECTED.  
TEMPERATURES CONTINUE TO BE BELOW NORMAL.  
 

 
   
LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/
 
 
THE MODELS CONTINUE TO HAVE DIFFERENCES IN HOW THEY HANDLE THE VERY  
BROAD CLOSED LOW THAT WILL BE OVER SE CANADA TUESDAY NIGHT THROUGH  
THURSDAY NIGHT. AS A RESULT THEY ALSO DIFFER IN THE STRENGTH AND  
TIMING OF SHORTWAVES ROTATING AROUND THE BASE OF THE LOW, AND HENCE  
ON THE PRECISE TIMING OF PRECIPITATION DURING THIS TIME FRAME.  
 
HOWEVER, DO HAVE LIKELY POPS IN FOR TUESDAY NIGHT, AS THE MODELS DO  
AGREE THERE SHOULD BE SOME MEASURABLE RAINFALL ACROSS THE REGION  
THEN, BUT DO HAVE DIFFERENCES IN TIMING DURING THE NIGHT. LOWS  
TUESDAY NIGHT SHOULD BE A FEW DEGREES ABOVE NORMAL.  
 
FOR WEDNESDAY AND WEDNESDAY NIGHT HAVE MAINLY CHANCE POPS ACROSS  
NORTHERN ZONES AND SLIGHT CHANCE POPS ACROSS SOUTHERN ZONES. WITH  
SHOWALTER INDICES PROGGED TO 0 TO -2, ALSO HAVE A SLIGHT CHANCE OF  
THUNDER IN FOR WEDNESDAY AFTERNOON AND EVENING. HIGHS WEDNESDAY AND  
LOWS WEDNESDAY NIGHT SHOULD BE A FEW DEGREES ABOVE NORMAL AS WELL.  
 
ZONAL FLOW SETS UP THURSDAY AND THURSDAY NIGHT, AND IT APPEARS THE  
REGION AND WITH SIGNIFICANT SHORTWAVES PROGGED TO THE NE AND NW DURING  
THIS TIME FRAME, HAVE GONE WITH A DRY FORECAST THEN.  
 
THE MODEL DIFFERENCES BECOME EVEN MORE NOTICEABLE FRIDAY-SATURDAY.  
 
FOR FRIDAY, DO HAVE CHANCE POPS THROUGHOUT BY AFTERNOON AND CONTINUE  
THROUGH FRIDAY EVENING (ALONG WITH A SLIGHT CHANCE OF THUNDER). THEN  
LIMIT POPS TO SLIGHT CHANCE FROM LATE FRIDAY NIGHT-SATURDAY MORNING.  
 
THEN GO WITH A DRY FORECAST LATE SATURDAY/SATURDAY NIGHT AS BOTH THE  
GFS AND ECMWF SHOW THE CORE OF THE CLOSED LOW TO THE NE THEN.  
 
THE NEW ECMWF HAS JOINED THE 00Z GFS IN KEEPING SUNDAY DRY, BUT  
NOTING IT PREVIOUSLY HAD A COASTAL LOW APPROACHING (NOW JUST  
SUPPRESSED FARTHER S), DO HAVE SLIGHT CHANCE POPS FOR SUNDAY.  
 
TEMPERATURES THURSDAY THROUGH SATURDAY NIGHT WILL FEATURE NEAR  
NORMAL HIGHS AND LOWS A FEW DEGREES ABOVE NORMAL. HIGHS SUNDAY ARE  
CURRENTLY FORECAST TO BE A FEW DEGREES BELOW NORMAL.  
 

 
   
AVIATION /09Z MONDAY THROUGH FRIDAY/
 
 
A FRONTAL SYSTEM WILL APPROACH LATE TONIGHT INTO MONDAY, WHILE  
WEAK SURFACE HIGH PRESSURE REMAINS IN PLACE AND WEAK LOW  
PRESSURE PASSES TO THE SOUTH THIS MORNING. WITH THE SURFACE HIGH  
REMAINING IN PLACE AND DRY AIR STILL TO BE OVERCOME ESPECIALLY  
NE OF THE NYC METRO TERMINALS, THIS WILL MAKE FOR A VERY  
DIFFICULT FORECAST IN TERMS OF FLIGHT CATEGORY. RAIN OVER NJ AND  
EASTERN PA HAS BROUGHT WIDESPREAD IFR CIGS TO THOSE AREAS, BUT  
DO NOT THINK THIS WILL BE THE CASE IN THE NYC METRO, WITH MVFR  
CIGS DEVELOPING AFTER DAYBREAK AND REMAINING IN THAT CATEGORY AT  
LEAST THROUGH THE MORNING. THERE IS STILL A CHANCE THAT IFR  
CIGS COULD DEVELOP LATE THIS AFTERNOON OR THIS EVENING AS WINDS  
DIMINISH AND BACK A LITTLE MORE NE FOLLOWING PASSAGE OF THE WEAK  
LOW TO THE SOUTH.  
 
REMOVED EARLIER MENTION OF THUNDER, AS INSTABILITY FUELING  
STORMS OVER CENTRAL PA SHOULD WEAKEN AND COME TO A HALT JUST  
WEST OF THE AREA THIS MORNING. SHOWERS MOVING IN FROM THE WEST  
COULD STILL BRING TEMPO IFR VSBY TO THE NYC METROS TOWARD  
MIDDAY.  
 
HIGH CONFIDENCE IN WINDS INTO EARLY THIS AFTERNOON, WITH  
OCCASIONAL G18-20KT POSSIBLE THIS MORNING AT SOME COASTAL  
TERMINALS. LOW TO MEDIUM CONFIDENCE ON WIND DIRECTION LATER THIS  
AFTERNOON INTO TONIGHT, WHICH COULD RANGE ANYWHERE FROM NE TO  
SE.  
   
..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: HIGH CONFIDENCE IN WINDS THROUGH EARLY  
AFTERNOON. LOW CHANCE OF IFR CIGS DEVELOPING AS EARLY AS LATE  
THIS AFTERNOON.  
 
KLGA TAF COMMENTS: HIGH CONFIDENCE IN WINDS THROUGH EARLY  
AFTERNOON. LOW CHANCE OF IFR CIGS DEVELOPING AS EARLY AS LATE  
THIS AFTERNOON.  
 
KEWR TAF COMMENTS: HIGH CONFIDENCE IN WINDS THROUGH EARLY  
AFTERNOON. LOW CHANCE OF IFR CIGS DEVELOPING AS EARLY AS LATE  
THIS AFTERNOON.  
 
THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS YELLOW, WHICH  
IMPLIES SLANT RANGE VISIBILITY 4-6SM OUTSIDE OF CLOUD.  
 
KTEB TAF COMMENTS: HIGH CONFIDENCE IN WINDS THROUGH EARLY  
AFTERNOON. LOW CHANCE OF IFR CIGS DEVELOPING AS EARLY AS LATE  
THIS AFTERNOON.  
 
KHPN TAF COMMENTS: LOW CHANCE OF IFR CIGS DEVELOPING THIS  
AFTERNOON.  
 
KISP TAF COMMENTS: HIGH CONFIDENCE IN WINDS THROUGH EARLY  
AFTERNOON. LOW CHANCE OF IFR CIGS DEVELOPING AS EARLY AS LATE  
THIS AFTERNOON.  
   
OUTLOOK FOR 06Z TUESDAY THROUGH FRIDAY
 
   
LATE TONIGHT
 
IFR IN LOW CLOUDS. KGON COULD REMAIN MVFR.   
TUESDAY
 
IFR TO START, IMPROVING TO MVFR/VFR BY AFTERNOON.  
CHANCE OF AN AFTERNOON SHOWER OR TSTM FROM NYC METRO NW, BUT  
MAINLY AT KSWF.    
TUESDAY NIGHT
 
LOW CLOUDS WITH IFR CONDITIONS. SHOWERS ALSO  
LIKELY, POSSIBLY A TSTM.    
WEDNESDAY
 
IFR TO START, IMPROVING TO VFR BY AFTERNOON. CHANCE  
OF SHOWERS AND POSSIBLY A TSTM FROM THE NYC METRO TERMINALS NW.    
WEDNESDAY NIGHT AND THURSDAY
 
VFR.    
FRIDAY
 
AFTERNOON/EVENING SHOWERS/TSTMS POSSIBLE WITH MVFR OR  
LOWER CONDS.  
 

 
   
MARINE
 
 
SCA IN EFFECT TODAY WITH SEAS 4 TO 6 FT. EXTENDED THE ADVISORY  
THROUGH 11 PM TONIGHT AS SEAS REMAIN ELEVATED THROUGH THIS TIME.  
THEREAFTER, WAVES DIMINISH THROUGH THE REST OF THE SHORT TERM.  
 
A RELAXED PRESSURE GRADIENT OVER THE REGION FROM TUESDAY NIGHT INTO  
FRIDAY SHOULD KEEP SUSTAINED WINDS OVER THE WATERS AROUND LONG  
ISLAND TO AROUND 10 KT OR LESS DURING THIS TIME FRAME. THE PRESSURE  
GRADIENT IS CURRENTLY FORECAST TO TIGHTEN A TAD LATER ON FRIDAY, WITH  
SUSTAINED WINDS OF AROUND 15 KT OR LESS POSSIBLE OVER THE WATERS  
THEN.  
 
GIVEN THE RELATIVELY LIGHT WINDS, AND NO SIGNIFICANT SWELL, SUB  
SMALL CRAFT ADVISORY CONDITIONS ARE FORECAST TUESDAY NIGHT-  
FRIDAY.  
 

 
   
HYDROLOGY
 
 
0.25"-0.50" EXPECTED THROUGH TODAY. THIS SHOULD HAVE NO  
HYDROLOGIC IMPACT.  
 
NO SIGNIFICANT WIDESPREAD HYDROLOGIC IMPACTS ARE THEN EXPECTED  
AT THIS TIME FROM MONDAY NIGHT THROUGH AT LEAST THURSDAY NIGHT.  
 

 
   
TIDES/COASTAL FLOODING
 
 
ADDITIONAL MINOR COASTAL FLOODING MAY OCCUR WITH THE HIGH TIDE  
CYCLE TONIGHT...MAINLY FOR THE SOUTHERN BAYS OF NASSAU/NYC.  
 

 
   
OKX WATCHES/WARNINGS/ADVISORIES
 
 
CT...NONE.  
NY...NONE.  
NJ...NONE.  
MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR ANZ350-  
353-355.  
 

 
 

 
SYNOPSIS...MALOIT/JP  
NEAR TERM...JP  
SHORT TERM...JP  
LONG TERM...MALOIT  
AVIATION...GOODMAN  
MARINE...MALOIT/JP  
HYDROLOGY...MALOIT/JP  
TIDES/COASTAL FLOODING...  
 
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