136  
FXUS61 KBOX 232014  
AFDBOX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE TAUNTON MA  
414 PM EDT SUN JUL 23 2017  
   
SYNOPSIS
 
 
COOLER, DAMP CONDITIONS ARE FORECAST FOR MONDAY AND TUESDAY.  
HIGH PRESSURE BRINGS PLEASANT CONDITIONS BACK FOR WEDNESDAY AND  
MOST OF THURSDAY WITH A RETURN OF MORE UNSETTLED CONDITIONS FOR  
THURSDAY NIGHT INTO THE EARLY WEEKEND.  
 

 
   
NEAR TERM /UNTIL 6 AM MONDAY MORNING/
 
 
RATHER TRANQUIL WEATHER CONTINUES INTO THE EARLY EVENING. BAND  
OF LOW CLOUDS FROM THIS MORNING CONTINUED TO SLOWLY DISSIPATE  
THIS AFTERNOON. ELSEWHERE, MID AND HIGH LEVEL CLOUDS ASSOCIATED  
WITH OUR NEXT WEATHER-MAKER HAD ALREADY STARTED TO MOVE IN FROM  
THE WEST. MINOR TWEAKS TO BRING THE AFTERNOON FORECAST BACK IN  
LINE WITH OBSERVED TRENDS.  
 
INCREASING CLOUDS TONIGHT, WITH RAIN ARRIVING FROM WEST TO EAST,  
MOST LIKELY AFTER MIDNIGHT AND ESPECIALLY TOWARD DAYBREAK  
MONDAY. 23/12Z GUIDANCE HAS RATHER GOOD AGREEMENT ON THE TRACK  
AND TIMING OF A LOW PRESSURE PASSING BY TO OUR SOUTH, SO HAVE  
HIGH CONFIDENCE IN THIS TIMING.  
 
CONTINUING ONSHORE FLOW AND INCREASING CLOUDS SHOULD PREVENT  
TEMPERATURES FROM LOWERING TOO FAR BELOW NORMAL.  
 

 
   
SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/
 
 
IMPRESSIVE 5 TO 6 STANDARD DEVIATION EASTERLY FLOW AT 925 MB  
MONDAY. VERY RARE EVENT FOR LATE JULY. PRECIPITABLE WATER VALUES  
ALSO ABOUT 2 STANDARD DEVIATIONS ABOVE NORMAL. THINKING A  
WIDESPREAD RAIN WILL RESULT, DESPITE THE STRONGEST LIFT STAYING  
OVER THE SOUTH COAST OF NEW ENGLAND DURING THE MORNING. LOCALLY  
HEAVY RAIN WILL BE POSSIBLE AT TIMES, ESPECIALLY TOWARD THE  
SOUTH COAST OF NEW ENGLAND. GENERALLY THINKING ONE HALF TO ONE  
INCH OF RAINFALL, WITH LOCALLY HIGHER AMOUNTS.  
 
THE STEADIER RAIN SHOULD TAPER OFF TO SHOWERS MONDAY AFTERNOON  
INTO MONDAY NIGHT. THIS SHOULD BE FORCED MAINLY BY A COLD POOL  
ALOFT AND A TRAILING MID LEVEL SHORTWAVE. RAINFALL AMOUNTS  
EXPECTED TO BE QUITE A BIT LESS THAT WHAT HAPPENS MONDAY MORNING  
AND EARLY AFTERNOON.  
 
WITH OUR REGION REMAINING ON THE NORTH SIDE OF THIS LOW  
PRESSURE, EXPECTING TEMPERATURES TO REMAIN GENERALLY BELOW  
NORMAL.  
 

 
   
LONG TERM /TUESDAY THROUGH SUNDAY/
 
 
HIGHLIGHTS...  
 
* UNSETTLED/WET CONDITIONS PERSIST TUE AND TUE NIGHT.  
* DRY AND PLEASANT WED AND PROBABLY INTO MUCH OF THU AFTERNOON  
* UNSETTLED/WET WEATHER LIKELY RETURNS BY THU NIGHT AND/OR FRI  
* TEMPS WILL REMAIN BELOW NORMAL THROUGH THE END OF THE WEEK  
 
OVERVIEW AND MODEL PREFERENCES...  
WITH THE 23.12Z UPDATE, MODELS CONTINUE TO SHOW THE SAME  
GENERAL SYNOPTIC PATTERN THEY HAVE FOR THE PAST 48-72 HOURS,  
ONLY MINOR DIFFERENCES MAINLY WITH THE DEVELOPMENT OF THE LATE  
WEEK-WEEKEND LONG-WAVE TROF. GIVEN THIS, NO PARTICULAR MODEL  
WILL BE FAVORED AND WILL CONTINUE TO BLEND IN SOME PERSISTENCE  
WITH THIS FORECAST UPDATE. IN ESSENCE, WEAKENING TROF TUE BEGETS  
WEAK RIDGING FOR MID WEEK FOLLOWED BY A RETURN OF SHORTWAVE  
DIGGING LATE WEEK INTO THE WEEKEND. THE LATTER IS FAIRLY ROBUST  
BY JUNE STANDARDS AS NOTED BY PREVIOUS FORECASTER, AND ACTS TO  
PROMOTE LONG-WAVE TROF DIGGING TOWARD THE END OF THIS LONG-TERM  
FORECAST CYCLE.  
 
DETAILS...  
 
TUE...  
NOTING ONE LAST VORTICITY-MAX ROTATING THROUGH THE REMNANTS OF  
THE WEAKENING TROF ACROSS THE REGION ON TUE. LINGERING PWATS  
BETWEEN 1.00-1.25 INCHES SUGGEST THAT WITH THIS FEATURE ROTATING  
THROUGH, REMNANT SHRA COULD CONTINUE THROUGH AT LEAST THE  
DAYLIGHT HOURS ON TUE. CONTINUED E-FLOW WILL ENHANCE THIS RISK  
AND ALSO HELP MAINTAIN THE WIDESPREAD BKN-OVC CLOUDINESS AS  
WELL. NOT EXPECTING A WASHOUT AS PWATS WILL BE DIMINISHING AND  
MID LVL HEIGHTS ARE RISING THROUGH THE PERIOD. OTHERWISE, THE E  
FLOW, LITTLE CHANGE IN AIRMASS AND OVERALL CLOUD COVER WILL  
MAINTAIN THE COOL TEMPS ACROSS THE REGION, WITH DAYTIME MAXES  
STRUGGLING TO BREAK OUT OF THE 60S OR LOW 70S.  
 
WED AND THU...  
BRIEF RIDGING FOLLOWS THE EXITING SHORTWAVE AND ACTUALLY SHOWS  
SIGNS OF A MODEST AND SLOW BUILDING PROCESS ENHANCED BY THE  
DEEPENING, MORE ROBUST WAVE SKIRTING THE N CONUS. AS SUCH, AM  
FAVORING A SLIGHTLY SLOWER PROGRESSION IN THE ADVANCING FRONT  
FOR THU, SUGGESTING IT, ALONG WITH WED WILL REMAIN MOSTLY DRY.  
ALTHOUGH THE ADDITIONAL CLOUD COVER AND SLIGHT MODERATION OF  
THE AIRMASS IS EXPECTED, MID LVL TEMPS STILL HOVER MAINLY AROUND  
+10C, WHICH IS SLIGHTLY COOLER THAN SEASONAL NORMAL VALUES.  
HENCE, HIGHS ARE LIKELY TO REMAIN MAINLY IN THE UPPER 70S AND  
LOW 80S, STILL SLIGHTLY ON THE COOLER SIDE OF NORMAL. MINS,  
THANKS TO AFTERNOON DWPTS DROPPING INTO THE 50S SHOULD BE QUITE  
PLEASANT, MAINLY IN THE 50S THEMSELVES.  
 
THU NIGHT INTO FRI...  
COLD FRONT WILL BE CROSSING THE REGION. AS MENTIONED ABOVE, DUE  
TO UNCERTAINTY IN THE DEEPENING/DIGGING PROCESS OF THE  
ATTENDANT SHORTWAVE, THERE REMAINS SOME UNCERTAINTY IN THE  
TIMING OF THIS FEATURE. FAVORED THE SLIGHTLY SLOWER TIMING WITH  
THIS UPDATE GIVEN THE RIDGE BUILDING PROCESS INITIALLY. HOWEVER,  
BY THE OVERNIGHT HOURS, NOTING A RAPID DROP IN MID-LVL HEIGHTS  
AND MOISTURE LOADING OF THE COLUMN. MODEST DESTABILIZATION OF  
THE COLUMN ALSO NOTED AS H5 VALUES DROP TO ABOUT -10C.  
THEREFORE, WILL BE CONTINUING TREND OF INCREASING RISK FOR SHRA  
AND ISOLATED TSRA GIVEN THE CONDITIONALLY UNSTABLE PROFILE. THIS  
RISK WILL LINGER INTO FRI THANKS TO THE FRONTS SLOWED MOVEMENT  
AND DIURNAL HEATING LEADING TO FURTHER DESTABILIZATION. POPS  
MAINLY AT CHANCE. TEMPS STILL RUNNING MAINLY AT OR BELOW  
SEASONAL NORMALS GIVEN MINIMAL AIRMASS CHANGE IN THE LOW-LVLS.  
 
SAT...  
CONDITIONS FOR SAT CONTINGENT ON TIMING OF FRONT. THE SLOWER  
SOLUTION SUGGESTS IT MAY HANG NEAR ENOUGH TO THE S COAST TO  
PROVIDE WEAK FORCING FOR LIFT DURING PEAK HEATING. THEREFORE,  
WILL CONTINUE TO HIGHLIGHT SLIGHT TO LOW CHANCE POPS AT THIS  
TIME GIVEN THE UNCERTAINTY IN TIMING.  
 
SUN...  
SIGNALS SUGGESTING IMPROVEMENT AS THE CYCLONIC CURVATURE  
ASSOCIATED WITH THE DIGGING LONGWAVE TROF SHIFT A BIT FURTHER S  
ALLOWING FOR INFLUENCE OF SFC HIGH PRES. STILL RELATIVELY COOL  
GIVEN MID LVL TEMPS COOL WITH THE DIGGING TROF.  
 

 
   
AVIATION /20Z SUNDAY THROUGH FRIDAY/
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
SHORT TERM /THROUGH MONDAY NIGHT/...  
 
THROUGH 00Z...VFR. EAST TO NORTHEAST WINDS CONTINUE.  
 
TONIGHT...HIGH CONFIDENCE. CIGS LOWERING SW TO NE TOWARDS MVFR-  
IFR AS -RA BEGINS TO SPREAD ACROSS THE REGION. CONTINUED E FLOW  
WITH GUSTS UP TO 25 KTS TOWARDS THE SOUTH COAST.  
 
MONDAY...MODERATE CONFIDENCE. MVFR-IFR CIGS. IMPACTS TO THE AM  
PUSH POSSIBLE WITH RA/+RA. VSBY RESTRICTIONS EXPECTED.  
CONTINUED BREEZY NE FLOW WITH GUSTS UP TO 25 KTS.  
 
MONDAY NIGHT...MODERATE CONFIDENCE. MVFR-IFR CIGS LINGER WITH  
-SHRA/DZ. LIFR CONDITIONS POSSIBLE TOWARDS THE CAPE AND ISLANDS.  
NE WINDS CONTINUE WITH GUSTS UP TO 25 KTS POSSIBLE DURING THE  
EVENING, ESPECIALLY ACROSS E MA.  
 
KBOS TERMINAL...HIGH CONFIDENCE IN TAF.  
 
KBDL TERMINAL...HIGH CONFIDENCE IN TAF.  
 
OUTLOOK /TUESDAY THROUGH FRIDAY/...  
 
TUE AND TUE NIGHT...MODERATE CONFIDENCE.  
LINGERING IFR/MVFR CONDITIONS IN LOW CIGS AND OCCASIONAL VSBY  
RESTRICTIONS IN SHRA/FOG. THESE BEGIN TO DISSIPATE MAINLY DURING  
THE OVERNIGHT HOURS TUE NIGHT. E FLOW BEGINS TO SHIFT TOWARD THE  
S BY EARLY WED MORNING.  
 
WED AND THU...HIGH CONFIDENCE.  
MAINLY VFR. S WINDS GUST TO NEAR 20 KT ESPECIALLY E COASTAL MA  
ON THU. ALSO, OVERNIGHT SHRA/ISOLATED TSRA MAINLY THU NIGHT.  
 
FRI...MODERATE CONFIDENCE.  
MAINLY VFR, BUT LINGERING RISK FOR SHRA/ISOLATED TSRA WITH  
LOCALIZED LOWER CATEGORIES.  
 

 
   
MARINE
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
SHORT TERM /THROUGH MONDAY NIGHT/...  
 
A MORE WINTER-LIKE LOW PRESSURE IS EXPECTED TO TRAVEL SOUTH OF  
NEW ENGLAND MONDAY MORNING. THIS WILL RESULT IN AN INCREASING  
EASTERLY FLOW WITH GUSTS UP TO 30 KT AT TIMES. ITS POSSIBLE FOR  
A BRIEF PERIOD OF GALE FORCE GUSTS AROUND THE CAPE AND ISLANDS  
MONDAY MORNING, BUT HAVE LOW CONFIDENCE IT WILL PERSIST LONG  
ENOUGH TO WARRANT A GALE WATCH OR WARNING AT THIS TIME. ISSUED  
A SMALL CRAFT ADVISORY FOR ALL WATERS.  
 
OUTLOOK /TUESDAY THROUGH FRIDAY/...  
 
TUE AND TUE NIGHT...HIGH CONFIDENCE.  
LOW PRES MOVES E OF THE WATERS. WINDS GRADUALLY SHIFT FROM NE TO  
THE S BY EARLY WED MORNING WITH GUSTS THROUGH THE PERIOD MAINLY  
BELOW 20 KT. HOWEVER, LINGERING HIGHER SEAS ON THE OCEAN WATERS  
5-6 FT SUGGEST SMALL CRAFT ADVISORIES WILL NEED TO CONTINUE INTO  
THE OVERNIGHT HOURS. OTHERWISE, SHOWERS/FOG LINGER.  
 
WED THROUGH FRI...MODERATE CONFIDENCE.  
OVERALL QUIET BOATING WEATHER AS HIGH PRES MOVES OVER THE WATERS  
WED AND THU. A SLOW MOVING COLD FRONT WILL CROSS LATE THU NIGHT  
INTO FRI, BUT OUTSIDE OF SHOWERS AND ISOLATED THUNDERSTORMS  
WINDS/SEAS SHOULD REMAIN BELOW SMALL CRAFT ADVISORY THRESHOLDS.  
 

 
   
TIDES/COASTAL FLOODING
 
 
STRONG EASTERLY FLOW, AT LEAST BY JULY STANDARDS, WILL CONTINUE  
TONIGHT. LATEST TIDE GAGE DATA SHOWS A RESIDUAL BETWEEN 0.5-0.8  
FEET ALONG THE EAST COAST OF MA. ISSUED A COASTAL FLOOD  
ADVISORY FOR THE TIME OF HIGH TIDE THIS EVENING. CONTINUED  
EASTERLY FLOW INTO MONDAY MAY ALSO CAUSE SOME ISSUES WITH THE  
DAYTIME HIGH TIDE.  
 

 
   
BOX WATCHES/WARNINGS/ADVISORIES
 
 
CT...NONE.  
MA...SMALL CRAFT ADVISORY FROM 8 AM TO 10 AM EDT MONDAY FOR MAZ023.  
COASTAL FLOOD ADVISORY FROM 10 PM THIS EVENING TO 2 AM EDT  
MONDAY FOR MAZ015-016-019-022-024.  
SMALL CRAFT ADVISORY FROM 8 AM TO 6 PM EDT MONDAY FOR MAZ020-  
021.  
RI...SMALL CRAFT ADVISORY FROM 8 AM TO 10 AM EDT MONDAY FOR  
RIZ004>008.  
MARINE...SMALL CRAFT ADVISORY FROM 8 AM TO 6 PM EDT MONDAY FOR ANZ232-  
234-236.  
SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EDT MONDAY FOR ANZ233.  
SMALL CRAFT ADVISORY FROM 10 AM MONDAY TO 6 AM EDT TUESDAY FOR  
ANZ230-250-251.  
SMALL CRAFT ADVISORY FROM 8 AM TO 11 PM EDT MONDAY FOR ANZ231.  
SMALL CRAFT ADVISORY FROM 6 AM TO 11 PM EDT MONDAY FOR ANZ235-  
237.  
SMALL CRAFT ADVISORY FROM 8 AM MONDAY TO 6 AM EDT TUESDAY FOR  
ANZ254.  
SMALL CRAFT ADVISORY UNTIL 6 AM EDT TUESDAY FOR ANZ255-256.  
 

 
 

 
SYNOPSIS...BELK/DOODY  
NEAR TERM...BELK  
SHORT TERM...BELK  
LONG TERM...DOODY  
AVIATION...BELK/DOODY  
MARINE...BELK/DOODY  
TIDES/COASTAL FLOODING...BELK  
 
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