634  
FXUS61 KOKX 020542  
AFDOKX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NEW YORK NY  
142 AM EDT TUE SEP 2 2014  
   
SYNOPSIS
 
 
WEAK HIGH PRESSURE REMAINS OVER THE REGION TONIGHT IN THE WAKE OF A  
SURFACE TROUGH. A COLD FRONT THEN APPROACHES DURING TUESDAY BEFORE  
PASSING THROUGH TUESDAY NIGHT. HIGH PRESSURE BUILDS IN FOR THE LATTER  
HALF OF THE WEEK. ANOTHER COLD FRONT WILL IMPACT THE REGION THIS  
WEEKEND.  
 

 
   
NEAR TERM /UNTIL 6 AM THIS MORNING/
 
 
SOME MINOR ADJUSTMENTS WERE MADE WITH TEMPS AND DEWPOINTS.  
SLIGHTLY BUMPED UP TEMPS WITH HIGHER DEWPOINTS IN PLACE AND  
INCREASING CLOUDS FROM THE WEST WELL AHEAD OF NEXT UPPER LEVEL  
TROUGH. PATCHY FOG ALREADY STARTING TO DEVELOP AND EXPECTING MORE  
OF THIS TOWARDS DAYBREAK TUESDAY WITH LOW LEVELS STAYING MOIST.  
 
MULTIPLE MESOSCALE MODELS INDICATE MOSTLY DRY CONDITIONS THROUGH  
THE REST OF THE NIGHT. DRIER UPPER LEVELS AND LESS SHEAR ALONG WITH  
STABLE CONDITIONS WILL LIMIT ANY SHOWER DEVELOPMENT.  
 

 
   
SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/
 
 
COLD FRONT APPROACHES DURING THE DAY TUESDAY. A PRE-FRONTAL TROUGH  
AHEAD OF IT DEVELOPS NEAR OUR WESTERN ZONES. SHOWER/TSTM THREAT  
BEGINS IN THE AFTERNOON ALONG THIS TROUGH...AND ENDS FOR MOST SPOTS  
OVERNIGHT WHEN THE TRAILING COLD FRONT PASSES THROUGH. CAPPED POPS  
IN THE CHC CATEGORY. PARAMETERS DURING THE AFTERNOON AND EARLY  
EVENING SUPPORT THE POTENTIAL OF THUNDERSTORMS WITH STRONG WIND  
GUSTS. LARGE HAIL WOULD BE LESS OF POSSIBILITY DUE TO RELATIVELY  
HIGH WBZ/FREEZING LEVEL HEIGHTS. TSTM STRENGTH DIMINISHES AFTER  
EARLY EVENING WITH LESS CAPE IN SPITE OF BETTER LIFT FROM THE  
PASSING COLD FRONT. PWATS STILL RATHER HIGH...SO HEAVY DOWNPOURS  
POSSIBLE IN ANY SHOWER.  
 
ABOVE NORMAL TEMPERATURES WITH MUGGY CONDITIONS CONTINUE THROUGH  
THIS PERIOD. WITH 850MB TEMPS OF 17-18C...PARTLY TO MOSTLY SUNNY  
CONDITIONS FOR MOST OF THE DAY AND A SW FLOW...EXPECTING PARTS OF NE  
NJ TO REACH INTO THE LOW-MID 90S...WITH LOW 90S IN THE CITY AND A  
GOOD PORTION OF THE LOWER HUDSON VALLEY. MOST OTHER SPOTS EXPECTED  
TO END UP AT 85-90. REGARDING HEAT ADVISORY CONCERNS IN THE  
CITY...ALTHOUGH IT APPEARS THAT A DECENT PORTION OF THE CITY WILL  
REACH A HEAT INDEX OF AT LEAST 95 FOR AN HOUR OR TWO TOMORROW  
AFTERNOON...INDICES HAD FAILED TO REACH 95 MONDAY AFTERNOON. NO  
ADVISORIES WILL THEREFORE BE POSTED AS PER LOCAL POLICY.  
 
THERE IS A MODERATE RISK OF RIP CURRENTS ON TUESDAY.  
 

 
   
LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/
 
 
COLD FRONT OFFSHORE WILL CONTINUE TO PUSH EAST ON WEDNESDAY AS HIGH  
PRESSURE BUILDS IN. DRY CONDITIONS ARE EXPECTED THROUGH FRIDAY AS  
THE CENTER OF THE HIGH MOVES OVER THE REGION AND OFF THE EAST COAST  
BY THURSDAY WHILE ALOFT THERE WILL BE A RATHER ZONAL PATTERN.  
HUMIDITY LEVELS DURING THIS PERIOD WILL EASE UP A BIT AS DEWPOINTS  
DROP TO THE LOWER 60S ON WEDNESDAY...WITH SOME UPPER 50S DEWPOINTS  
POSSIBLE ON THURSDAY. HOWEVER...THEY CREEP BACK UP TOWARDS THE LOWER  
AND MIDDLE 60S AGAIN ON FRIDAY ON THE RETURN FLOW WITH THE HIGH  
OFFSHORE.  
 
A COLD FRONT WILL APPROACH THE AREA FRIDAY NIGHT INTO  
SATURDAY...PUSHING OFFSHORE SOMETIME SATURDAY NIGHT. THERE IS SOME  
MODEL CONSENSUS ON PUSHING THE COLD FRONT OFFSHORE SATURDAY  
NIGHT...BUT THERE ARE DIFFERENCES THEREAFTER. THE 00Z ECMWF STALLS  
THE FRONT JUST OFFSHORE AND THERE WOULD BE A CHANCE FOR POST-FRONTAL  
RAIN THROUGH SUNDAY NIGHT. THE 12Z GFS AND CMC KEEP THE SYSTEM  
PROGRESSIVE...ENDING THE RAIN SATURDAY NIGHT...KEEPING SUNDAY DRY.  
GFS ENSEMBLE MEAN IS ACTUALLY MORE PROGRESSIVE WITH THE COLD  
FRONT...PUSHING IT OFFSHORE DURING THE DAY SATURDAY...BUT ALSO ENDS  
IT SATURDAY NIGHT. ALSO...MODELS DIFFER IN DEVELOPMENT AND PLACEMENT  
OF LOW PRESSURE ALONG THE FRONTAL BOUNDARY...WHICH LEAD TO LARGE  
DIFFERENCES IN PLACEMENT OF ANY HEAVY RAINFALL. ALTHOUGH THE GFS IS  
MORE PROGRESSIVE...THE FRONT HAS SLOWED DOWN SIGNIFICANTLY FROM THE  
PREVIOUS 06Z RUN. SO...GIVEN UNCERTAINTY WILL KEEP AT LEAST SLIGHT  
CHANCE POPS IN FOR SUNDAY MORNING...DRYING OUT BY THE AFTERNOON.  
 
TEMPERATURES WILL BE ABOVE NORMAL THROUGH SATURDAY.  
THEREAFTER...BELOW NORMAL TEMPERATURES EXPECTED AS A CONTINENTAL  
POLAR AIRMASS BUILDS IN.  
 

 
   
AVIATION /06Z TUESDAY THROUGH SATURDAY/
 
 
MVFR/IFR STRATUS/FOG LIKELY ALONG EASTERN TERMINALS...POSSIBLE  
ACROSS INTERIOR TERMINALS.  
 
ANY STRATUS/FOG SHOULD BURNS OFF IN THE MORNING...WITH VFR CONDS  
IN AFTN.  
 
LIGHT AND VRB WINDS THE REMAINDER OF THE NIGHT THRU THE COMING  
MORNING...GIVING WAY TO AFTN SEABREEZE DEVELOPMENT ALONG THE  
COAST.  
 
INCREASING CHANCE FOR SCT SHRA/TSRA THE COMING EVENING ACROSS NYC  
TERMINALS AND TO THE W & NW WITH APPROACHING COLD FRONT. WILL  
MAINTAIN PROB30 NOW...GENERALLY THINKING BETWEEN 02-08Z.  
   
OUTLOOK FOR 06Z WED THROUGH FRI
 
   
TUE NIGHT
 
MAINLY VFR. WINDS SHIFTING SW TO NW BEHIND FRONT  
BETWEEN 06-12Z.    
WED-FRI NIGHT
 
VFR CONDITIONS ARE EXPECTED.   
SAT
 
SUB VFR POSSIBLE IN SCATTERED SHRA/TSRA.  
 

 
   
MARINE
 
 
SUB-SCA CONDITIONS EXPECTED ON THE WATERS THROUGH THE FORECAST  
PERIOD WITH A RELATIVELY WEAK PRESSURE GRADIENT MOST OF THE TIME.  
THERE COULD BE SHOWERS AND TSTMS TUESDAY NIGHT...AND AGAIN LATE  
FRIDAY INTO SATURDAY AS A FRONT APPROACHES.  
 

 
   
HYDROLOGY
 
 
ISO/SCT SHOWERS/TSTMS LATE TUESDAY/TUES NIGHT WOULD LIKELY RESULT  
IN NO MORE THAN LOCALIZED MINOR URBANIZED/SMALL STREAM FLOODING.  
 
NO HYDROLOGIC ISSUES EXPECTED WEDNESDAY THROUGH THE WEEKEND.  
 

 
   
OKX WATCHES/WARNINGS/ADVISORIES
 
 
CT...NONE.  
NY...NONE.  
NJ...NONE.  
MARINE...NONE.  
 

 
 

 
SYNOPSIS...JC/JP  
NEAR TERM...JC/JM  
SHORT TERM...JC  
LONG TERM...JP  
AVIATION...SEARS/NV  
MARINE...JC/JP  
HYDROLOGY...JC/JP  
 
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