970  
FXUS61 KOKX 301942  
AFDOKX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NEW YORK NY  
342 PM EDT THU JUN 30 2016  
   
SYNOPSIS
 
 
HIGH PRESSURE WILL MOVE EAST TONIGHT. A FRONTAL SYSTEM WILL  
APPROACH ON FRIDAY AND THEN MOVE ACROSS FRIDAY NIGHT. HIGH  
PRESSURE WILL BUILD IN FOR THE HOLIDAY WEEKEND. LOW PRESSURE MAY  
TRACK CLOSE ENOUGH ON TUESDAY TO SPARK A FEW SHOWERS AND  
THUNDERSTORMS, THEN FAIR WEATHER WILL RETURN FOR THE REST OF THE  
WEEK.  
 

 
   
NEAR TERM /UNTIL 6 AM FRIDAY MORNING/
 
 
NORTHERN STREAM SHORTWAVE DIGS INTO THE GREAT LAKES TONIGHT...WITH A  
WEAK LEAD SHORTWAVE ROTATING THROUGH THIS EVENING. AT THE  
SURFACE...A WARM FRONT DEVELOPS OVER THE FROM THE MID ATLANTIC  
STATES TONIGHT AND BEGINS LIFTING TOWARDS THE REGION.  
 
MOISTURE LACKING WITH FIRST SHORTWAVE THIS EVENING...BUT WITH  
DEVELOPING DEEP SW FLOW AHEAD OF DIGGING GREAT LAKES  
TROUGH...INCREASING CLOUD COVER EXPECTED OVERNIGHT...WITH INCREASING  
CHANCE OF SHOWERS TOWARDS DAYBREAK WITH DEVELOPING LLJ AND THETA-E  
ADVECTION. WITH WEAK INSTABILITY DEVELOPING TOWARDS DAYBREAK...CANT  
RULE OUT AN ISOLATED TSTM.  
 
MILD NIGHT ON TAP WITH LOWS GENERALLY IN THE 60S WITH INCREASING  
DEWPOINTS AND LOWERING CLOUD COVER.  
 

 
   
SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/
 
 
STRONG SHORTWAVE FOR THIS TIME OF YEAR NEGATIVELY TILTS FROM THE  
GREAT LAKES TOWARDS THE NE FRIDAY AFTERNOON. SHORTWAVE AXIS PIVOTS  
THROUGH FRI EVENING...WHILE THE MAIN TROUGH CONTINUES TO DEEPEN INTO  
THE NE FRI NIGHT. AT THE SURFACE...THE WARM FRONT CONTINUES TO LIFT  
NORTH TOWARDS THE REGION ON FRI...WHILE A PRE-FRONTAL TROUGH  
DEVELOPS/APPROACHES FROM THE WEST FRI AFT/EVE...BEFORE COLD FRONT  
SWINGS THROUGH FRI NIGHT.  
 
GENERALLY SCATTERED SHOWER/ISOLATED TSTM THREAT EXPECTED AREAWIDE IN  
THE MORNING IN WAA PATTERN...BUT WITHOUT A CLEAR FOCUSING BOUNDARY.  
 
WITH INCREASING LIFT...MOISTURE AND INSTABILITY FRI AFTERNOON AHEAD  
OF THE APPROACHING SURFACE TROUGH...EXPECTATION IS FOR INCREASING  
COVERAGE OF SHOWERS AND TSTMS FROM W TO E ACROSS THE NYC/NJ METRO  
AND POINTS WEST. DEEP LAYER SHEAR IS EXPECTED TO BE SUPPORTIVE OF  
ORGANIZED CONVECTION...WITH SCT MORNING SHOWER ACTIVITY AND  
AFTERNOON CLOUD COVER BEING KEY FOR INSTABILITY FORECAST. WITH AN  
INCREASINGLY MOIST AIRMASS BEING ADVECTED IN...A MODELED BORDERLINE  
MARGINAL TO MODERATELY UNSTABLE AIRMASS LOOKS REASONABLE FOR THIS  
AREA...WHICH PRESENTS POTENTIAL FOR A FEW SEVERE STORMS...EVEN A  
SUPERCELL IF A LOW-LEVEL BOUNDARY (SEA-BREEZE, OUTFLOW, WARM  
FRONT) CAN ENHANCE LOW-LEVEL VEERING. MAIN CONVECTIVE THREAT  
APPEARS TO BE WET MICROBURSTS BASED ON THE MODERATELY STRONG MID-  
LEVEL WIND FIELDS...BUT CANT RULE OUT LARGE HAIL WITH ANY ROTATING  
STORMS...OR EVEN A WEAK TORNADO IF COINCIDENT WITH A LOW- LEVEL  
SHEAR ENHANCING BOUNDARY.  
 
EXPECTATION IS THAT THIS SHOWER/TSTM ACTIVITY WILL MOVE EAST INTO  
LI/CT IN THE LATE AFTERNOON/EVENING WITH THE SHORTWAVE FORCING. WIND  
SHEAR AND FORCING WILL REMAIN SUPPORTIVE OF ORGANIZED CONVECTION  
INTO THE EVENING...AND WITH AMPLE ELEVATED INSTABILITY IF NOT  
SURFACE AS WELL...COULD SUPPORT A LOCALIZED STRONG TO SEVERE  
THREAT TO THE COAST. DEPTH OF MARINE LAYER WILL BE THE LIMITING  
FACTOR.  
 
SEE HYDRO SECTION FOR DETAILS ON LOCALIZED HEAVY RAINFALL THREAT.  
 
SHORTWAVE AXIS CROSSES IN THE EVENING...WHICH SHOULD BRING ANY  
ORGANIZED CONVECTION THREAT TO AN END. TRAILING COLD FRONT CROSSES  
THE AREA THROUGH MIDNIGHT WITH LINGERING SHOWER/TSTMS ACTIVITY  
COMING TO AND END...AND COOLER DRIER AIRMASS ADVECTING IN BY SAT  
MORNING.  
 

 
   
LONG TERM /SATURDAY THROUGH THURSDAY/
 
 
MAINLY FAIR AND SEASONABLY WARM WEATHER CAN BE EXPECTED THROUGH THE  
LONG TERM. FOR THE FOURTH OF JULY WEEKEND, ANY RAIN IS EXPECTED TO  
QUICKLY WIND DOWN BY AROUND SUNRISE SATURDAY PER THE 12Z MODEL  
CONSENSUS. THE DATA SUGGESTS THIS FORECAST TIMING MAY EVEN BE TOO  
CONSERVATIVE, AND THE RAIN COULD END MORE QUICKLY. REGARDLESS, A  
MASSIVE SWEEP OF DRY AIR IN THE MID LEVELS OF THE ATMOSPHERE WILL  
BRING A SUNNY DAY. PERHAPS SOME FAIR WEATHER CUMULUS ON SUNDAY, THEN  
HIGH CLOUDS MAY BEGIN TO FILTER IN BY EVENING. MORE EXTENSIVE HIGH  
CLOUDS POSSIBLE ON MONDAY, BUT LIMITED OPACITY IS EXPECTED WITH THE  
MOISTURE ABOVE 30,000 FT. THE ONLY APPARENT THREAT FOR RAIN IS IN  
THE TUESDAY TIME PERIOD AS A MID LEVEL TROUGH PASSES THROUGH THE  
REGION. THE MODEL TREND HOWEVER IS FOR THE BULK OF THIS ACTIVITY TO  
PASS SOUTH OF THE TRI-STATE REGION, SO THE PROBABILITY OF  
PRECIPITATION HAS BEEN LIMITED TO 20 PERCENT. DRY WEATHER APPEARS  
LIKELY THEREAFTER AS AN UPPER LEVEL RIDGE BUILDS IN. THE SUPERBLEND  
WAS USED FOR TEMPERATURES, WITH HIGHS CLOSE TO OR A FEW DEGREES  
ABOVE AVERAGE.  
 

 
   
AVIATION /19Z THURSDAY THROUGH TUESDAY/
 
 
HIGH PRESSURE MOVES OFFSHORE TONIGHT. A WARM FRONT APPROACHES FROM THE  
SOUTH FRIDAY MORNING.  
 
VFR. SEA BREEZES ARE A LITTLE SLOWER TO MOVE ACROSS KLGA, KEWR, AND KTEB.  
HAVE DELAYED THE TIMING TO AROUND 21Z WHEN THE SEA BREEZE SHOULD MOVE ACROSS  
THOSE TERMINALS. FLOW BECOMES LIGHT AND VARIABLE AT OUTLYING TERMINALS AND OUT  
OF THE S-SE AT CITY TERMINALS AROUND 5 KT OVERNIGHT. SE WINDS THEN INCREASE TO  
AROUND 10 KT FRIDAY MORNING.  
 
SHOWERS ARE POSSIBLE FRIDAY MORNING, BUT CONFIDENCE IS LOW IN LOCATION  
AND TIMING OF ANY SHOWER. MVFR CONDITIONS ALSO CANNOT BE RULED  
OUT NEAR THE COAST. SHOWERS ARE MORE LIKELY IN THE AFTERNOON WITH  
THUNDERSTORMS POSSIBLE. TIMING AND LOCATION UNCERTAIN AT THIS  
TIME, SO HAVE LEFT THUNDER OUT OF THE EXTENDED TAFS FOR NOW.  
 
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-SSE WINDS 10-13 KT THROUGH EARLY EVENING.  
 
KLGA TAF COMMENTS: SEA BREEZE BOUNDARY JUST SOUTH OF TERMINAL. WINDS ARE  
LIKELY TO VARY IN DIRECTION FROM NW TO SW UNTIL SEA BREEZE PASSAGE AROUND  
20-21Z.  
 
KEWR TAF COMMENTS: SEA BREEZE BOUNDARY A FEW MILES EAST OF TERMINAL. WINDS ARE  
LIKELY TO STAY OUT OF THE WEST UNTIL SEA BREEZE PASSAGE AROUND 21Z.  
 
KTEB TAF COMMENTS: SEA BREEZE BOUNDARY A FEW MILES EAST OF TERMINAL. WINDS ARE  
LIKELY TO STAY OUT OF THE WEST UNTIL SEA BREEZE PASSAGE AROUND 21Z.  
 
KHPN TAF COMMENTS: SEABREEZE LIKELY TO MOVE THROUGH TERMINAL BETWEEN 20 AND 21Z.  
 
KISP TAF COMMENTS: SOUTHERLY WINDS 10-13 KT THROUGH EARLY EVENING.  
   
OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY
 
   
FRIDAY AFTERNOON-FRIDAY NIGHT
 
MVFR OR IFR CONDITIONS POSSIBLE  
IN SHOWERS/THUNDERSTORMS.   
SATURDAY
 
VFR. NW WINDS G20-25KT.    
SUNDAY AND MONDAY
 
VFR.   
TUESDAY
 
MAINLY VFR. SLIGHT CHANCE FOR SHOWERS/THUNDERSTORMS.  
 

 
   
MARINE
 
 
WINDS AND SEAS SHOULD REMAIN BELOW SCA THROUGH FRI MONRING AS WEAK  
HIGH PRESSURE MOVES OVER THE WATERS.  
 
ISOLATED AND MARGINAL SCA GUSTS POSSIBLE ON THE OCEAN FRI AFT/EVE  
AHEAD OF APPROACHING COLD FRONT...WITH POTENTIAL FOR MARGINAL SCA  
OCEAN SEAS DEVELOPING LATE FRI NIGHT INTO SAT AS SOUTHERLY SWELLS  
ARRIVE. CONFIDENCE TOO LOW FOR SCA AT THIS POINT.  
 
HIGH PRESSURE WILL KEEP WINDS AND WAVES BELOW SMALL CRAFT ADVISORY  
LEVELS SATURDAY THROUGH TUESDAY. SEAS MAY BUILD TO AROUND 5 FT ON  
THE OCEAN WEDNESDAY, AS WEAK LOW PRESSURE PASSES SOUTH OF THE  
COASTAL WATERS.  
 

 
   
HYDROLOGY
 
 
NUMEROUS SHOWERS AND TSTMS SHOULD BRING A BASIN AVERAGE OF 1/4 TO  
1/2 INCH OF RAIN FRI AFT/EVE. LOCALLY THOUGH...POTENTIAL FOR 1 TO 3  
INCHES OF RAIN WITH ANY TRAINING TSTM ACTIVITY...RESULTING IN A  
LOCALIZED URBAN FLASH FLOOD THREAT. NCAR ENSEMBLE AND SBU WRF  
SUPPORT THIS NOTION WITH LOCALIZED 2+ INCH PROBS AND EXPLICIT  
OUTPUT RESPECTIVELY.  
 
THERE IS A CHANCE FOR SOME RAIN ON OR ABOUT TUESDAY. OTHERWISE,  
WIDESPREAD MEASURABLE RAINFALL IS NOT EXPECTED SATURDAY THROUGH  
THURSDAY.  
 

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

 
 

 
SYNOPSIS...JMC/NV  
NEAR TERM...NV  
SHORT TERM...NV  
LONG TERM...JMC  
AVIATION...DS  
MARINE...JMC/NV  
HYDROLOGY...JMC/NV  
 
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