309  
FXUS61 KBOX 121838  
AFDBOX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BOSTON/NORTON MA  
238 PM EDT THU JUL 12 2018  
   
SYNOPSIS
 
 
HIGH PRESSURE BRINGS DRY WEATHER WITH SEASONABLE TEMPERATURES  
AND COMFORTABLE HUMIDITY THROUGH SATURDAY MORNING. 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 /THROUGH TONIGHT/
 
 
HIGH PRESSURE AT THE SURFACE REMAINS OVER NEW ENGLAND TONIGHT  
WHILE UPPER TROUGH SLOWLY MOVES EAST. THIS SHOULD BE A DRY  
PATTERN, BUT PRESENCE OF THE TROUGH SUGGESTS A FEW CLOUDS FROM  
NORTHERN NEW ENGLAND MAY HANG AROUND LONG ENOUGH TO SWEEP ACROSS  
SOUTHERN NEW ENGLAND.  
 
OTHERWISE A QUIET NIGHT WITH CLEAR SKIES AND LIGHT WIND. DEW  
POINTS REMAIN IN THE 50S, SO RADIATIONAL COOLING WILL ALLOW  
TEMPS TO COOL INTO THE 50S MOST PLACES, WITH LOW 60S IN SOME  
URBAN CENTERS. PATCHY LATE NIGHT RADIATION FOG IS POSSIBLE IN  
THE TYPICAL PRONE LOCATIONS.  
 

 
   
SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/
 
 
TROUGH MOVES OFF TO THE EAST OF OUR AREA WHILE UPPER RIDGE MOVES  
IN. EXPECT SUNNY SKIES AND DRY WEATHER WITH ANOTHER ROUND OF  
DIURNAL CUMULUS FOR THE MIDDAY AND AFTERNOON. THE MIXED LAYER  
ONCE AGAIN GOES DEEP, UP TO 800 MB, TAPPING SIMILAR TEMPERATURES  
TO TODAY...THUS SUPPORTING MAX SFC TEMPS IN THE UPPER 70S TO MID  
80S INLAND. LIGHT FLOW AT THE SURFACE WILL AGAIN ALLOW SEA  
BREEZES ALONG THE COAST WITH SFC TEMPS IN THE 70S.  
 
STILL UNDER THE INFLUENCE OF THE RIDGE, WE EXPECT QUIET WEATHER  
FOR FRIDAY NIGHT WITH LIGHT SURFACE FLOW. TEMPS WILL COOL TO  
BETWEEN 55 AND 65 DEGREES.  
 

 
   
LONG TERM /SATURDAY THROUGH WEDNESDAY/
 
 
OVERVIEW...  
 
00Z MODEL GUIDANCE CONTINUES TO SHOW GOOD AGREEMENT ON THE EVOLUTION  
OF THE SYNOPTIC PATTERN THROUGH NEXT WEDNESDAY. STILL SOME MINOR  
TIMING AND STRENGTHEN ISSUES. THEREFORE WILL CONTINUE TO FAVOR A  
CONSENSUS APPROACH TO SMOOTH OVER THE LESS PREDICTABLE DETAILS.  
 
FLAT HIGH PRESSURE OVER THE CENTRAL CONUS AND BUILDING NORTH  
ATLANTIC RIDGE WILL LEAD TO A TROUGH OVER NEW ENGLAND TO START THE  
MEDIUM RANGE. MODELS HAVE TRENDED TOWARDS A CUT-OFF LOW PRESSURE  
SYSTEM WHICH MEANDERS SOUTH AND EAST OF ACK/CAPE ON SATURDAY.  
APPROACHING COLD FRONT WILL BECOME MORE DIFFUSED WITH TIME AS IT  
MOVES TOWARDS THE NORTHEAST DURING THE WEEKEND. WEAK RIDGING EARLY  
NEXT WEEK AS A POTENT UPPER LEVEL LOW MOVES INTO ALBERTA. THIS LOW  
WILL PUSH A FRONT TOWARDS THE REGION BY MID-WEEK.  
 
DETAILS...  
 
TEMPERATURES...  
 
SEASONABLE CONDITIONS TO START AS WEAK FRONT SLOWLY SWINGS THROUGH  
THE REGION. TEMPERATURES WILL RANGE INTO THE MID 80S ACROSS THE CT  
RIVER VALLEY TO MID 70S FOR THE MA EAST COAST THANKS TO OFFSHORE LOW  
PRESSURE SYSTEM. HEAT AND HUMIDITY WILL MAKE A RETURN BEGINNING ON  
SUNDAY LASTING INTO MID-WEEK DUE TO SOUTHERLY FLOW. THIS COULD BRING  
ANOTHER ROUND OF 90+ DEGREES TEMPERATURES FOR LOCATIONS ACROSS THE  
INTERIOR. HEAT AND HUMIDITY ARE ANTICIPATED TO DROP OFF BEHIND A  
COLD FRONT SOMETIME LATE WED INTO THURSDAY.  
 
PRECIPITATION...  
 
MAINLY DRY WEATHER FOR THE END OF THE WEEK, INTO THE WEEKEND AS  
APPROACHING FRONTAL SYSTEM WEAKENS. STILL CANNOT RULE OUT AN ISO  
SHOWER. POP-UP SHOWERS/THUNDERSTORMS ARE POSSIBLE ON MONDAY IN THE  
WARM, MOIST AIRMASS. BUT THESE WILL BE MAINLY AIRMASS TYPE STORMS.  
APPROACHING COLD FRONT ON TUESDAY/WEDNESDAY HAS THE BEST CHANCE TO  
BRING SOME MEASURABLE PRECIP FOR THE REGION PER LATEST GEFS AND EPS  
PROBS. PWAT VALUES ABOVE 2.3 INCHES AND INCREASING THETA-E VALUES  
COULD LEAD TO SOME WIDESPREAD RAINFALL. STILL SOME TIMING ISSUES,  
BUT CANNOT RULE OUT THE POTENTIAL FOR THUNDER AS THE REGION WILL BE  
IN A WARM, MUGGIER AIRMASS AHEAD OF THE FRONT.  
 

 
   
AVIATION /18Z THURSDAY THROUGH TUESDAY/
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
SHORT TERM /THROUGH FRIDAY NIGHT/...HIGH CONFIDENCE.  
 
VFR MOST OF THE PERIOD. SOME MVFR POSSIBLE TONIGHT IN PATCHY  
LATE NIGHT FOG IN THE USUAL LOCATIONS. LIGHT WIND WILL AGAIN  
ALLOW SEA BREEZES TO DEVELOP ALONG THE COASTS MID-LATE MORNING  
AND THROUGH THE AFTERNOON.  
 
KBOS TERMINAL...HIGH CONFIDENCE IN TAF. SEA BREEZE CONTINUES  
THROUGH 8-11 PM. A NEW SEA BREEZE DEVELOPS 10 AM-NOON FRIDAY.  
 
KBDL TERMINAL...HIGH CONFIDENCE IN TAF. BRIEF MVFR VSBYS  
POSSIBLE IN LATE NIGHT/EARLY MORNING FOG 5-7 AM.  
 
OUTLOOK /SATURDAY THROUGH MONDAY/...  
 
SATURDAY THROUGH SATURDAY NIGHT: VFR. SLIGHT CHANCE SHRA,  
ISOLATED TSRA.  
 
SUNDAY: VFR. SLIGHT CHANCE SHRA.  
 
SUNDAY NIGHT THROUGH MONDAY: VFR.  
 

 
   
MARINE
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
SHORT TERM /THROUGH FRIDAY NIGHT/...HIGH CONFIDENCE.  
 
HIGH PRESSURE MOVES OVER THE WATERS. LIGHT WINDS TREND OUT OF  
THE SOUTHEAST OR SOUTH FRIDAY, WITH SEA BREEZES REDEVELOPING  
NEARSHORE DURING FRIDAY. WINDS LESS THAN 25 KNOTS AND SEAS LESS  
THAN 5 FEET THROUGH FRIDAY NIGHT.  
 
OUTLOOK /SATURDAY THROUGH MONDAY/...  
 
SATURDAY: WINDS LESS THAN 25 KT.  
 
SATURDAY NIGHT: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING  
5 FT. SLIGHT CHANCE OF RAIN SHOWERS, ISOLATED THUNDERSTORMS.  
 
SUNDAY: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING 5 FT.  
SLIGHT CHANCE OF RAIN SHOWERS, ISOLATED THUNDERSTORMS.  
 
SUNDAY NIGHT: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING  
5 FT.  
 
MONDAY: WINDS LESS THAN 25 KT.  
 

 
   
TIDES/COASTAL FLOODING
 
 
ASTRONOMICAL TIDES WILL BE RATHER HIGH DURING THE NIGHT TIME  
HIGH TIDE CYCLES TONIGHT THROUGH SAT NIGHT. FORTUNATELY WAVE  
ACTION WILL NOT BE MUCH OF A FACTOR AND SURGE IS LIMITED.  
HOWEVER, LEFTOVER SE SWELL MAY RESULT IN MINOR SPLASHOVER FOR  
VULNERABLE AREAS ALONG EAST COASTAL MA TONIGHT.  
 
TIDES ARE SLIGHTLY HIGHER FRI NIGHT AND SAT NIGHT SO ADDITIONAL  
ROUNDS OF SPLASHOVER ARE POSSIBLE DURING THESE HIGH TIDE  
CYCLES.  
 
INTERESTING TO NOTE...HIGH TIDES WILL AGAIN BE HIGH IN MID-  
AUGUST BUT A LITTLE LOWER THAN THE CURRENT SET OF HIGH TIDES.  
THE NEXT SET OF HIGH HIGH TIDES IN JAN-FEB WILL BE LOWER THAN  
THE AUGUST HIGH TIDES. THIS TREND TO LOWER VALUES FOR THE  
HIGHEST TIDES CONTINUES THROUGH THE END OF 2019.  
 
BOSTON ASTRO HIGH TIDE...  
 
12.06 FEET THURSDAY 11:22 PM  
12.25 FEET SATURDAY 12:16 AM  
12.23 FEET SUNDAY 1:11 AM  
 
NANTUCKET ASTRO HIGH TIDE...  
 
4.33 FEET FRIDAY 12:21 AM  
4.38 FEET SATURDAY 1:18 AM  
4.34 FEET SUNDAY 2:15 AM  
 

 
   
BOX WATCHES/WARNINGS/ADVISORIES
 
 
CT...NONE.  
MA...NONE.  
RI...NONE.  
MARINE...NONE.  
 

 
 

 
SYNOPSIS...WTB/DUNTEN  
NEAR TERM...WTB/DUNTEN  
SHORT TERM...WTB  
LONG TERM...DUNTEN  
AVIATION...WTB/DUNTEN  
MARINE...WTB/DUNTEN  
TIDES/COASTAL FLOODING...  
 
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