435  
FXUS61 KOKX 302344  
AFDOKX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NEW YORK NY  
744 PM EDT SAT JUL 30 2016  
   
SYNOPSIS
 
 
LOW PRESSURE SLOWLY APPROACHES FROM THE OHIO VALLEY THROUGH SUNDAY.  
THIS LOW SLOWLY TRACKS ALONG A FRONTAL BOUNDARY THAT BECOMES NEARLY  
STATIONARY THROUGH CENTRAL NEW JERSEY TO SOUTH OF LONG ISLAND  
MONDAY. WAVES OF LOW PRESSURE TRACK ALONG THE BOUNDARY MONDAY AND  
MONDAY NIGHT. HIGH PRESSURE BEGINS TO BUILD TOWARD THE REGION  
TUESDAY, AND MOVES OVER THE AREA WEDNESDAY. THE HIGH THEN SLIDES  
OFF THE NORTHEAST COAST THURSDAY. A COLD FRONT APPROACHES FRIDAY.  
 

 
   
NEAR TERM /UNTIL 6 AM SUNDAY MORNING/
 
 
THE SHOWERS AND THUNDERSTORMS HAVE EVOLVED INTO MAINLY A  
STRATIFORM RAIN WITH EMBEDDED CONVECTIVE ELEMENTS AND  
THUNDERSTORMS. THE RAIN WAS SLOW MOVING WITH A GENERAL MOVEMENT OF  
5 TO 10 MPH. WITH PERIODS OF HEAVY RAIN THERE WERE LOCAL DOPPLER  
ESTIMATED RAINFALL TOTALS THROUGH 2330Z OF 2 TO 4 INCHES, ACROSS  
NORTHEASTERN NJ, THE LOWER HUDSON VALLEY AND ACROSS NORTHERN  
MIDDLESEX COUNTY CT.  
 
THE ACTIVITY CONTINUES TO DEVELOP AHEAD OF AN APPROACHING LOW  
PRESSURE SYSTEM OVER THE OHIO VALLEY WITH INCREASING LOW LEVEL  
WARM ADVECTION.  
 
CONTINUING WITH THE CATEGORICAL POPS THIS EVENING ACROSS NE NJ  
AND THE LOWER HUDSON VALLEY, BUT THIS MAY NEED TO BE PUSHED  
FURTHER EAST ACROSS THE METRO AND POSSIBLY WESTERN LONG ISLAND AND  
SW CT IF LATEST RADAR TRENDS CONTINUE. THE MAIN CONCERN IS LOCALLY  
HEAVY RAINFALL AS PWATS ARE RUNNING BETWEEN 1.7 AND 1.9 INCHES PER  
LATEST SPC MESOANALYSIS.  
 
AS THE ACTIVITY TRANSLATES EASTWARD ACROSS SOUTHERN CT AND EASTERN  
LI, THERE SHOULD BE A DOWNWARD TREND IN INTENSITY AS THE  
AIRMASS IS MORE STABLE AND THE SURFACE HIGH JUST TO THE EAST.  
 
THERE MAY BE A LULL IN SHOWERS AROUND MIDNIGHT, BUT THERE IS  
DECENT AGREEMENT AMONG LATEST NWP MODEL GUIDANCE THAT WARM  
ADVECTION INCREASES FURTHER AS A WARM FRONT ASSOCIATED WITH THE  
LOW SETS UP NEAR THE REGION TOWARDS DAYBREAK. LOW LEVEL WINDS ALSO  
INCREASE WHICH SHOULD SUPPLY DEEP MOISTURE AND LIFT FOR COVERAGE  
OF SHOWERS/ISOLATED STORMS TO EXPAND.  
 

 
   
SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/
 
 
WHILE NOT A STRONG LOW LEVEL JET, THERE IS DECENT AGREEMENT AMONG  
THE LATEST NWP GUIDANCE FOR 25-35 KT OF LOW LEVEL FLOW HELPING TO  
ENHANCE OVERRUNNING PRECIPITATION SUNDAY MORNING. THE WARM FRONT  
WILL CONTINUE TO LIE NEAR THE REGION AS WELL WITH THE LOW SLOWLY  
MOVING EASTWARD ACROSS PA ALONG THIS BOUNDARY. SHOWERS AND A FEW  
THUNDERSTORMS SHOULD BE MOVING ACROSS THE REGION IN THE MORNING  
FROM WEST TO EAST. THERE IS SOME UNCERTAINTY IN WHERE THE HEAVIEST  
RAINFALL WILL ULTIMATELY END UP OCCURRING, WITH HIGHEST CONFIDENCE  
AT THIS TIME FROM THE CITY NORTH AND WEST. THERE WILL ALSO BE SOME  
SHORTWAVE ENERGY MOVING AROUND THE BROAD TROUGH OVER THE OHIO  
VALLEY WHICH COULD FURTHER SUPPORT SHOWERS AND A FEW STORMS.  
 
BEST WARM ADVECTION AXIS SHIFTS TO THE EASTERN PORTION OF THE AREA  
IN THE AFTERNOON, SO THERE MAY BE A LULL IN ACTIVITY ACROSS THE  
WEST. HOWEVER, THIS MAY PRESENT AN OPPORTUNITY FOR SOME BREAKS IN  
THE CLOUDS AND SOME INCREASING INSTABILITY FOR REDEVELOPMENT OF  
SHOWERS/STORMS. LIKELY POPS CONTINUE INTO THE EARLY EVENING MAINLY  
ALONG AND WEST OF THE HUDSON RIVER.  
 
LOCALLY HEAVY RAINFALL CONTINUES TO BE THE MAIN THREAT WITH ANY OF  
THE HEAVIER SHOWERS AND THUNDERSTORMS.  
 
FRONTAL BOUNDARY LOOKS TO SET UP SOUTH OF LONG ISLAND SUNDAY NIGHT  
WITH WEAK WAVES OF LOW PRESSURE RIDING ALONG IT, SO THE POTENTIAL  
FOR A FEW SHOWERS CONTINUES THROUGH THE NIGHT, BUT COVERAGE SHOULD  
BE LESS THAT DURING THE DAY.  
 

 
   
LONG TERM /MONDAY THROUGH SATURDAY/
 
 
RIDGING REMAINS OVER THE COUNTRY WITH A NEAR ZONAL FLOW CONTINUING  
ALONG THE CANADIAN/US BORDER AS SHORTWAVES MOVE THROUGH DURING THE  
UPCOMING WEEK.  
 
MONDAY INTO MONDAY NIGHT A TROUGH WILL BE MOVING THROUGH THE  
NORTHEASTERN AND UPPER MIDWESTERN STATES, AS A SERIES OF SHORTWAVES  
MOVE THROUGH THE TROUGH. AT THE SURFACE A FRONTAL BOUNDARY WILL BE  
NEARLY STATIONARY SOMEWHERE IN THE VICINITY OF THE OHIO VALLEY INTO  
THE MID ATLANTIC STATES AND SOUTH OF LONG ISLAND. THE LOCATION OF  
THE FRONTAL BOUNDARY WILL BE AFFECTED BY ON GOING CONVECTION THIS  
WEEKEND INTO THE BEGINNING OF THE WEEK.  
CURRENT INDICATIONS ARE THAT A SERIES OF BROAD LOWS MOVE ALONG THE  
BOUNDARY MONDAY INTO EARLY TUESDAY. MONDAY MORNING INSTABILITY IS  
MARGINAL WITH ISOLATED THUNDER POSSIBLE. WITH DAYTIME HEATING AND  
MONDAY AND ANOTHER WAVE MOVING THROUGH CHANCES FOR CONVECTION WILL  
BE INCREASING. MOISTURE WILL BE A LITTLE MORE LIMITED MONDAY INTO  
TUESDAY AS MOISTURE FROM THE GULF OF MEXICO IS CUTOFF. HOWEVER, SOME  
STORMS COULD PRODUCE LOCALLY HEAVY RAIN.  
 
THE UPPER TROUGH AXIS SLIDES THROUGH THE REGION EARLY TUESDAY WITH  
THE LAST WAVE EXITING OFFSHORE TUESDAY MORNING. UPPER RIDGING THEN  
BUILDS INTO THE EAST THROUGH THURSDAY.  
 
A RATHER VIGOROUS SHORTWAVE WILL BE COMING ONSHORE OF THE PACIFIC  
NORTHWEST EARLY NEXT WEEK AND WILL TRACK ALONG THE NORTHERN US,  
DIGGING A TROUGH INTO THE UPPER MIDWEST AND GREAT LAKES BY THE END  
OF THE WEEK. DEEPENING SURFACE LOW PRESSURE WILL SEND A COLD FRONT  
TOWARD THE AREA FRIDAY INTO SATURDAY AS THE RIDGE MOVES OFFSHORE.  
HUMIDITY WILL BE INCREASING FOR FRIDAY AND SATURDAY AS A DEEP  
SOUTHWESTERLY FLOW SETS UP.  
 

 
   
AVIATION /00Z SUNDAY THROUGH THURSDAY/
 
 
RAIN WILL CONTINUE ACROSS THE AREA TERMINALS TIL AROUND 04Z-06Z.  
THE HEAVIEST OF THE RAINFALL WILL BE ACROSS THE NYC TERMINALS AND  
POINTS WEST. FORECAST GUIDANCE IS HINTING AT A LULL IN THE  
PRECIPITATION BETWEEN 04-06 UNTIL AROUND 08Z-10Z. SHOWERS DEVELOP  
AGAIN TOWARDS SUNDAY MORNING, AND ARE EXPECTED TO PERSIST THROUGH  
THE DAY. CONDITIONS WILL DROP TO MVFR WITH LOCAL IFR. LOW  
CONFIDENCE OF IFR CONDITIONS AT THE NYC TERMINALS.  
 
PERSISTENT ONSHORE, SE FLOW EXPECTED INTO SUNDAY. FOR OUTLYING  
TERMINALS, WINDS MAY BECOME LGT/VRB TONIGHT FOR A FEW HOURS.  
   
OUTLOOK FOR 00Z MONDAY THROUGH THURSDAY
 
   
SUNDAY NIGHT-MONDAY NIGHT
 
CHANCE OF SHOWERS AND POSSIBLY A  
TSTM. MVFR OR LOWER CONDITIONS POSSIBLE.   
TUESDAY
 
MAINLY VFR, ALTHOUGH ISOLATED SHOWERS ARE POSSIBLE.   
WEDNESDAY-THURSDAY
 
VFR.  
 

 
   
MARINE
 
 
WINDS AND SEAS FORECAST ON TRACK AND NO CHANGES WERE MADE AT THIS  
TIME.  
 
LOW PRESSURE APPROACHES THE WATERS FROM THE OHIO VALLEY  
THROUGH SUNDAY. THE FLOW MAY INCREASE SUNDAY WITH GUSTS UP TO 20  
KT POSSIBLE ON THE OCEAN WATERS. OTHERWISE...WINDS AND SEAS WILL  
REMAIN BELOW SCA LEVELS THROUGH SUNDAY NIGHT.  
 
A FRONTAL SYSTEM IS EXPECTED TO BE IN THE VICINITY OF THE FORECAST  
WATERS MONDAY WITH WAVES OF LOW PRESSURE TRACKING ALONG A NEARLY  
STATIONARY FRONT MONDAY INTO EARLY TUESDAY. WINDS AND SEAS LIKELY  
REMAIN BELOW SMALL CRAFT ADVISORY LEVELS.  
 
HIGH PRESSURE BUILDS INTO THE WATERS TUESDAY AND REMAINS WEDNESDAY.  
THE HIGH THEN SHIFTS OFF THE COAST THURSDAY. SUB ADVISORY CONDITIONS  
ARE EXPECTED THROUGH THURSDAY NIGHT.  
 

 
   
HYDROLOGY
 
 
SHOWERS AND EMBEDDED THUNDERSTORMS WILL BRING AN AVERAGE OF ONE  
HALF TO AROUND ONE INCH OF RAINFALL WITH THE HIGHEST AMOUNTS ALONG  
AND WEST OF THE HUDSON RIVER. ANY THUNDERSTORMS CAN PRODUCE  
LOCALIZED HIGHER AMOUNTS. MINOR URBAN FLOODING WILL BE THE MAIN  
THREAT WITHIN HEAVIER SHOWERS/THUNDERSTORMS.  
 
A QUARTER TO ONE-HALF INCH OF RAINFALL IS POSSIBLE MONDAY INTO  
EARLY TUESDAY MORNING WITH LOCALLY HIGHER AMOUNTS. THE GREATER  
RAINFALL TOTALS ARE EXPECTED ACROSS THE LOWER HUDSON VALLEY INTO  
SOUTHERN CONNECTICUT. HOWEVER, WITH UNCERTAINTY AS TO THE TRACK OF  
LOW PRESSURE CONFIDENCE IN THE RAINFALL TOTALS IS LOW.  
 
DRY WEATHER RETURNS TUESDAY AND CONTINUES THROUGH THE MIDWEEK  
PERIOD.  
 

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

 
 

 
SYNOPSIS...DS/MET  
NEAR TERM...DS/MET  
SHORT TERM...DS  
LONG TERM...MET  
AVIATION...BC  
MARINE...DS/MET  
HYDROLOGY...DS/MET  
 
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