998  
FXUS61 KBOX 102347  
AFDBOX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BOSTON/NORTON MA  
747 PM EDT TUE JUL 10 2018  
   
SYNOPSIS
 
 
AN APPROACHING COLD FRONT MAY TRIGGER SCATTERED SHOWERS AND  
THUNDERSTORMS INTO THIS EVENING. HURRICANE CHRIS IS EXPECTED TO  
PASS WELL SOUTHEAST OF NANTUCKET WEDNESDAY. HIGH PRESSURE WILL  
BUILD OVER THE REGION THURSDAY AND FRIDAY, RESULTING IN MAINLY  
DRY WEATHER ALONG WITH SEASONABLE TEMPERATURES AND COMFORTABLE  
HUMIDITY. A RETURN TO HOT WEATHER IS EXPECTED LATER THIS WEEKEND  
INTO EARLY NEXT WEEK. WHILE A FEW THUNDERSTORMS CANNOT BE RULED  
OUT THIS WEEKEND INTO EARLY NEXT WEEK, DRY WEATHER LOOKS TO  
DOMINATE THE MAJORITY OF THE TIME.  
 

 
   
NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/
 
 
LATEST SPC MESOANALYSIS SHOWING RAPIDLY DECREASING CAPE VALUES  
ACROSS MUCH OF SOUTHERN NEW ENGLAND THIS EVENING. CONCERNS FOR  
SEVERE WEATHER POTENTIAL IN OUR REGION ALSO DIMINISHING. LATEST  
RUNS OF THE HIGH-RESOLUTION SHORT TERM GUIDANCE, INCLUDING THE  
HRRR, STILL INDICATING DECENT MID LEVEL LAPSE RATES OVERNIGHT.  
THIS IT REMAINS POSSIBLE FOR AN ISOLATED THUNDERSTORM OR TWO TO  
PERSIST OVERNIGHT, BUT NOT THINKING SEVERE WEATHER.  
 
TRIED TO TIME OUT THE RISK FOR SHOWERS AND THUNDERSTORMS THIS  
EVENING BASED ON LATEST GUIDANCE AND OBSERVED RADAR. BROUGHT THE  
REST OF THE FORECAST BACK IN LINE WITH OBSERVED TRENDS, TOO.  
 
PREVIOUS DISCUSSION...  
 
TEMPERATURES AT 850MB ARE NEAR 19C AND ARE MIXING DOWN TO THE  
SURFACE WHERE SITES ARE SEEING TEMPS NEAR OR SURPASSING 90F. THE  
APPROACHING COLD FRONT IS CURRENTLY JUST SE OF THE CANADIAN/NEW  
YORK BORDER WHERE A LINE OF CU AND A FEW ISOLATED THUNDERSTORMS  
ARE POPPING UP.  
 
LOOKING AT SEVERAL HI-RES MODELS, THE POTENTIAL FOR ANY STRONG  
TO SEVERE THUNDERSTORMS LOOKS TO BE DIMINISHING ACROSS SNE. DRY  
AIR ALOFT DOESN'T SEEM TO MOVE OUT OF THE REGION UNTIL 00Z AND  
GIVEN THAT CURRENT DEWPOINTS ACROSS THE REGION ARE IN THE LOW  
60S AND MID 50S, SHOWERS AND THUNDERSTORMS WILL HAVE A DIFFICULT  
TIME FORMING WITH THE LACK OF MOISTURE. IN ADDITION, WESTERLY  
WINDS WILL PROVIDE MINIMAL TO NO SURFACE CONVERGENCE. THE BEST  
CHANCE FOR ANY THUNDERSTORMS DEVELOPING WILL BE ON THE EASTERN  
SLOPES OF THE BERKSHIRES AND THE WORCESTER HILLS DUE TO  
UPSLOPING WINDS. HIGHER TERRAIN IS ALSO COLOCATED WITH THE  
STRONGEST SHEAR AND INSTABILITY. THE MAIN TIME FRAME FOR STORMS  
LOOKS TO BE BETWEEN 21Z AND 02Z.  
 
ISOLATED SHOWERS AND THUNDERSTORMS MAY CONTINUE INTO THE  
EVENING, WHEN THE BEST SYNOPTIC FORCING, SHEAR, COOLING TEMPS  
ALOFT, AND INSTABILITY ARRIVE IN SNE. SOME HEAVIER SHOWERS ARE  
POSSIBLE LATE TONIGHT WHERE PWATS OVERNIGHT REACH UP 1.75" AND K  
INDICIES ARE UP TO 38.  
 
TEMPS ARE EXPECTED TO REMAIN IN THE 60S OVERNIGHT, BUT IF  
CLOUDS ASSOCIATED WITH THE COLD FRONT CLEAR OUT BEFORE SUNRISE,  
SOME RADIATIONAL COOLING IS POSSIBLE, ESPECIALLY IN WESTERN MA  
ACROSS THE HIGHER TERRAIN.  
 
ACK MAY SEE A BRIEF PERIOD OF FOG JUST BEFORE SUNRISE TOMORROW  
AS SW WINDS DIMINISH AFTER THE FRONTAL PASSAGE AND AN INVERSION  
REMAINS OVERHEAD.  
 

 
   
SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/
 
 
WEDNESDAY...  
 
COLD FRONT WILL BE SITTING JUST EAST OF NANTUCKET COME SUNRISE  
TOMORROW MORNING WITH SOME POSSIBLE LINGERING SHOWERS AND  
THUNDERSTORMS ACROSS RI AND SE MASS.  
 
AS THE FRONT MOVES OFFSHORE AND INSTABILITY ERODES THROUGHOUT  
THE MORNING, ANY LINGERING SHOWERS AND THUNDERSTORMS WILL  
DISSIPATE ACROSS SE NEW ENGLAND.  
 
THERE'S A SMALL CHANCE FOR ISOLATED SHOWERS TOMORROW AFTERNOON  
ACROSS NORTHERN CT AND CENTRAL MA GIVEN CYCLONIC FLOW AND  
COOLING TEMPS ALOFT, BUT THESE WILL LIKELY BE SHORT LIVED WITH  
VERY LITTLE IMPACT.  
 
TROPICAL STORM CHRIS IS EXPECTED TO PASS 300 MILES TO OUR SE,  
RESULTING IN HIGH SURF AND DANGEROUS RIP CURRENTS ALONG SOUTH  
COASTAL BEACHES. HIGH SURF ADVISORIES MAY BE NEEDED.  
 
WEDNESDAY WILL BE MUCH COOLER THAN TODAY AS WINDS OUT OF THE NE  
KEEP THE REGION IN THE MID 70S. THE WARMEST TEMPERATURES ARE  
LIKELY TO BE IN THE CONNECTICUT RIVER VALLEY WHERE HARTFORD MAY  
SEE 80 DEGREES. BEHIND THE COLD FRONT, HUMIDITY WILL DECREASE AS  
DEWPOINTS WILL BE IN THE MID TO UPPER 50S ACROSS THE REGION.  
 
WEDNESDAY NIGHT...  
STRONG NE WINDS AND HIGH SURF WILL CONTINUE INTO THE EVENING  
AS TS CHRIS DEPARTS THE REGION AND CONTINUES MOVING NE. SKIES  
WILL BE MOSTLY CLEAR AS A 1024MB HIGH BUILDS INTO NEW ENGLAND,  
ALLOWING TEMPERATURES TO COOL INTO THE 50S OVERNIGHT.  
 

 
   
LONG TERM /THURSDAY THROUGH TUESDAY/
 
 
HIGHLIGHTS...  
 
* MAINLY DRY THU/FRI WITH SEASONABLE TEMPERATURES AND COMFORTABLE  
HUMIDITY  
 
* HOT WEATHER RETURNS LATE THIS WEEKEND INTO EARLY NEXT WEEK AND  
WHILE A FEW THUNDERSTORMS ARE POSSIBLE, DRY WEATHER SHOULD  
DOMINATE MOST OF THIS TIME  
 
DETAILS...  
 
THURSDAY AND FRIDAY...  
 
WITH CHRIS PASSING WELL SE OF THE 40N/70W BENCHMARK, AND MOVING  
FARTHER AWAY THURSDAY, ANY LINGERING SOUTH SWELL SHOULD  
DIMINISH. HIGH PRESSURE TO OUR NORTH WILL GRADUALLY OVERSPREAD  
OUR REGION, PROVIDING DRY WEATHER. EXPECTING NEAR NORMAL  
TEMPERATURES THROUGH THIS PERIOD. HUMIDITY INCREASES FRIDAY FROM  
THURSDAY, BUT STILL EXPECTED TO REMAIN RELATIVELY COMFORTABLE.  
 
THIS WEEKEND INTO EARLY NEXT WEEK...  
 
TRICKY PATTERN SHIFT DURING THIS TIME. A MID LEVEL TROUGH SHOULD  
LIFT OUT TO SOME EXTENT, WITH A DEEPER MID LEVEL TROUGH POISED  
TO ARRIVE TOWARDS THE MIDDLE OF NEXT WEEK. IT WILL ALL COME DOWN  
TO TIMING, WHICH REMAINS QUESTIONABLE DUE TO THE FAIRLY ZONAL  
FLOW. IN MOST CASES, EXPECTING TEMPERATURES TO START RISING THIS  
WEEKEND INTO EARLY NEXT WEEK, AT LEAST AWAY FROM ANY OCEAN  
INFLUENCE.  
 
HUMIDITY SHOULD SLOWLY INCREASE, TOO. WITH NO SYNOPTIC FEATURE  
TO REALLY FORCE THE ISSUE, ANY SHOWERS AND THUNDERSTORMS WOULD  
BE MORE OF THE AIRMASS VARIETY, DRIVEN ALMOST ENTIRELY BY  
DIURNAL HEATING. WHILE WE CANNOT ENTIRELY RULE OUT A FEW SHOWERS  
AND THUNDERSTORMS DURING THIS TIME, MUCH OF THIS PERIOD SHOULD  
REMAIN DRY FOR MOST LOCATIONS.  
 

 
   
AVIATION /00Z WEDNESDAY THROUGH SUNDAY/
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
SHORT TERM /THROUGH WEDNESDAY NIGHT/...HIGH CONFIDENCE.  
 
TONIGHT...  
SCATTERED SHOWERS, AND PERHAPS A THUNDERSTORM OR TWO, MOVING  
SOUTH ACROSS SNE. MAINLY VFR, BUT BRIEF MVFR POSSIBLE IN ANY  
SHOWERS/T-STORMS. WINDS SHIFTING TO NORTH. ACK MAY SEE A BRIEF  
PERIOD OF FOG RIGHT BEFORE SUNRISE AS WINDS WEAKEN OUT OF THE  
SW AND INVERSION REMAINS ALOFT.  
 
WEDNESDAY...  
MAINLY VFR. A FEW MORNING SHOWERS MAY LINGER ACROSS SE NEW ENG  
IN EARLY MORNING.  
 
WEDNESDAY NIGHT...  
MAINLY VFR. STRONG WINDS OUT OF THE NE ACROSS SE NEW ENG.  
 
KBOS TERMINAL...HIGH CONFIDENCE IN TAF. GREATEST RISK FOR A FEW  
THUNDERSTORMS AND/OR SHOWERS IN THE VICINITY OF THE TERMINAL  
BETWEEN 00-04Z.  
 
KBDL TERMINAL...HIGH CONFIDENCE IN TAF.  
 
OUTLOOK /THURSDAY THROUGH SUNDAY/...  
 
THURSDAY THROUGH FRIDAY NIGHT: VFR.  
 
SATURDAY THROUGH SATURDAY NIGHT: VFR. SLIGHT CHANCE SHRA.  
 
SUNDAY: VFR. SLIGHT CHANCE SHRA, ISOLATED TSRA.  
 

 
   
MARINE
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
SHORT TERM /THROUGH WEDNESDAY NIGHT/...HIGH CONFIDENCE.  
 
DIMINISHING WINDS TONIGHT WITH WIND SHIFT TO N BEHIND THE COLD  
FRONT. A FEW SHOWERS OR AN ISO T-STORM OR TWO WITH GUSTY WINDS  
POSSIBLE TONIGHT. NE WINDS 10-20 KT WED AFTERNOON ACROSS THE SE  
COASTS. WITH CHRIS OFF TO OUR SE, SEAS MAY BUILD UP TO 8 FT  
POSSIBLE OVER THE SOUTHERN WATERS. A HIGH SURF ADVISORY MAY BE  
NEEDED. WITH STRONG NE WINDS AND BUILDING SOUTHERLY SWELL,  
CHOPPY CONDITIONS ON THE WATERS IS POSSIBLE.  
 
OUTLOOK /THURSDAY THROUGH SUNDAY/...  
 
THURSDAY: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING  
5 FT.  
 
THURSDAY NIGHT: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING  
5 FT.  
 
FRIDAY THROUGH FRIDAY NIGHT: WINDS LESS THAN 25 KT.  
 
SATURDAY: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING 5 FT.  
 
SATURDAY NIGHT: WINDS LESS THAN 25 KT. AREAS OF SEAS  
APPROACHING 5 FT. SLIGHT CHANCE OF RAIN SHOWERS.  
 
SUNDAY: WINDS LESS THAN 25 KT.  
 

 
   
BOX WATCHES/WARNINGS/ADVISORIES
 
 
CT...NONE.  
MA...AIR QUALITY ALERT UNTIL 11 PM EDT THIS EVENING FOR MAZ013-  
016>023.  
RI...AIR QUALITY ALERT UNTIL 11 PM EDT THIS EVENING FOR RIZ001>008.  
MARINE...SMALL CRAFT ADVISORY FROM 11 AM TO 7 PM EDT WEDNESDAY FOR  
ANZ231>234.  
SMALL CRAFT ADVISORY FROM 11 AM WEDNESDAY TO 6 AM EDT THURSDAY  
FOR ANZ235-254>256.  
 

 
 

 
SYNOPSIS...BELK/CORREIA  
NEAR TERM...BELK/NOCERA/CORREIA  
SHORT TERM...NOCERA/CORREIA  
LONG TERM...BELK  
AVIATION...BELK/NOCERA/CORREIA  
MARINE...BELK/NOCERA/CORREIA  
 
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