327  
FXUS61 KBOX 260609  
AFDBOX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE TAUNTON MA  
209 AM EDT FRI MAY 26 2017  
   
SYNOPSIS
 
 
LOW PRESSURE AND ITS ATTENDANT WARM FRONT WILL BRING A STEADY  
RAIN AND DRIZZLE TO THE REGION THROUGH TONIGHT ALONG WITH COOL  
NORTHEAST WINDS. THE RAIN WILL BE HEAVY AT TIMES TONIGHT INTO  
FRIDAY MORNING AS THIS LOW TRACKS ACROSS SOUTHERN NEW ENGLAND.  
BIG IMPROVEMENT TO START OF THE HOLIDAY WEEKEND AS WEAK HIGH  
PRESSURE DELIVERS DRY WEATHER WITH MILD DAYS AND COOL NIGHTS  
BOTH SATURDAY AND SUNDAY. HOWEVER BY SUNDAY NIGHT AND INTO  
MONDAY ANOTHER COASTAL LOW MAY BRING THE RISK OF SHOWERS,  
ALTHOUGH A WASHOUT IS NOT EXPECTED.  
 

 
   
NEAR TERM /UNTIL 6 AM THIS MORNING/
 
 
*/ HIGHLIGHTS...  
 
- WIDESPREAD LIGHT RAIN / DRIZZLE  
- MODERATE-HEAVY RAIN TOWARDS MIDNIGHT INTO EARLY MORN FRIDAY  
- INCREASING ONSHORE EASTERLY WINDS, COOLER AIR OFF WATERS  
- THIS ALL PRIOR TO A WARM FRONT AND LOW PRESSURE SWEEPING OVER  
S NEW ENGLAND FRIDAY MORNING  
 
*/ LATEST DISCUSSION...  
 
200 AM UPDATE...  
 
OVERALL TREND IN THE FORECAST REMAINS ON TRACK THIS EARLY THIS  
MORNING. BULK OF THE HEAVY PRECIPITATION AND THUNDER WILL  
CONTINUE TO MOVE NORTHWARD INTO NH. SURFACE LOW THAT HAD  
DEVELOPED IS CURRENTLY OVER NYC AND WILL MOVE ACROSS SOUTHERN  
NEW ENGLAND INTO THE MORNING HOURS. THIS WILL KEEP THE CHANCE  
FOR SHOWERS AND DRIZZLE FOR THE ENTIRE AREA OVERNIGHT. WIND  
GUSTS ARE BEGINNING TO INCREASE AS PRESSURE GRADIENT CONTINUES  
TO TIGHTEN WITH APPROACHING SYSTEM. GUSTS NEAR 15-20 MPH ARE  
EXPECTED.  
 
DENSE FOG ADVISORY WILL BE LET GO AT THE TOP OF THE HOUR AS  
HEAVY RAINFALL HAS MIXED OUT THE CONDITIONS. COASTAL FLOOD  
ADVISORY WITH ALSO BE ALLOWED TO EXPIRE AS WE ARE NOW PAST THE  
HIGH TIDE.  
 
PREVIOUS DISCUSSION...  
 
MODERATE TO HEAVY RAIN EXPECTED WITH THE POSSIBILITY OF A RUMBLE OF  
THUNDER. LOW OCCLUSION SWEEPING NE ACROSS S NEW ENGLAND OVERNIGHT.  
CRUX OF DEEP-LAYER SYNOPTIC FORCING OUT AHEAD OF THE LOW THROUGH A  
FAIRLY MOIST PROFILE WELL UP TO H3 BENEATH THE LEFT FRONT QUADRANT  
OF THE UPPER LEVEL CYCLONIC JET STREAK. STRONG OMEGA FORCING NOT OUT  
OF THE QUESTION THAT WILL EASILY AND EFFICIENTLY WRING OUT MOISTURE,  
RATHER THE NATURE AND MAGNITUDE OF SAID MOISTURE WRAPPING INTO THE  
OCCLUSION, ITS ASSOCIATED PRECIPITABLE WATERS / THETA-E. CONFIDENT  
AS TO MOISTURE POOLING ALONG THE LOW TO MID LEVEL WARM FRONT LIFTING  
GRADUALLY N ACROSS THE REGION. CONDITIONALLY UNSTABLE MOIST PROFILE  
ALOFT, AND GIVEN STRONG OMEGA, CAN NOT RULE OUT THUNDER. THE SYSTEM  
ITSELF IS QUICK-MOVING, SHORT DURATION, THE BULK OF THE RAIN FALLING  
AROUND MIDNIGHT INTO THE 6A TIMEFRAME. BUT THERE'S STILL SPREAD,  
EVEN BETWEEN THE GEFS AND SREF MEMBERS, WITH THE SREF EXHIBITING  
MEMBERS WITH HIGHER AMOUNTS UP AROUND 2.0 TO 2.5 INCHES.  
 
QUITE AN ANOMALOUS SYSTEM WITH WINTER-LIKE CHARACTERISTICS, TAKING  
NOTHING FOR GRANTED, AND AS SUCH AM LEANING MORE TOWARDS THE HIGH-  
RES GUIDANCE AS CONSENSUS OF ENSEMBLE PROBABILITIES ALONG WITH CIPS  
ANALOGS SIGNAL A LOW-PROB OF GREATER THAN 3-INCHES STORM TOTAL RAIN-  
FALL OVER E/SE MA AND RI. CAN NOT RULE OUT AN INCH OF RAINFALL IN  
THE ROUGHLY 6-HOUR PERIOD NOTED EARLIER. POTENTIAL URBAN AND POOR  
DRAINAGE ISSUES, MAINLY INLAND AS LOW TIDE PROCEEDS AFTER MIDNIGHT  
INTO MORNING ALONG THE SHORES. NOT THINKING ANY IMPACT TO THE RIVERS  
RATHER NUISANCE ISSUES ALONG AREA ROADWAYS, LOW-LYING SPOTS AND  
CULVERTS NOTORIOUS FOR HAVING ISSUES. FOCUSING ON THE I-95 CORRIDOR  
AND IMMEDIATE ROADWAYS SURROUNDING.  
 

 
   
SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/
 
 
FRIDAY...  
 
SCATTERED SHOWER ACTIVITY LINGERING WITHIN THE WRAPPING COMMA-HEAD  
OCCLUSION. INFLUX OF COOLER AIR REARWARD AS THE PRESSURE GRADIENT  
TIGHTENS WITH THE LOW LIFTING E WITH A WEAK RIDGE OF HIGH PRESSURE  
BUILDING FROM THE W, WILL SEE A STEEPENING BOUNDARY-LAYER PROFILE  
ALLOWING FOR BOTH MOISTURE AND MOMENTUM TO MIX OUT. SO THINKING BULK  
OF WET-WEATHER ACTIVITY WILL BE EARLY ON, WITH THE LATER-HALF MOSTLY  
DRY AS WINDS INCREASE OUT OF THE NW. CLOUDS BREAKING, MORE SUNSHINE,  
GIVEN THE TIME OF YEAR AND THE FACT THAT THE LOW LACKS A MORE POLE-  
WARD CONNECTION OF COLDER AIR, WITH THE COOLER AIR AN ARTIFACT OF  
BEING DRAGGED DOWN FROM ALOFT, SHOULD TURN OUT NEAR-SEASONABLE WITH  
HIGHS AROUND THE MID TO UPPER 60S, WARMER SW CT WHILE COOLER NE MA.  
 
FRIDAY NIGHT...  
 
DRYING OUT. OCCLUSION CONTINUES TO LIFT E OUT TO SEA. STILL A N FLOW  
ON THE BACKSIDE WITH COOLER AIR, THE BOUNDARY LAYER REMAINS WELL-  
MIXED BENEATH RISING HEIGHTS FROM THE W AND AN INVERSION AROUND H8.  
SOME SCATTERED TO ISOLATED SHOWER ACTIVITY INITIALLY, DIMINISHING  
THROUGH THE OVERNIGHT HOURS. LOW CLOUDS LINGER GIVEN BOUNDARY-LAYER  
MIXING AND MOISTURE POOLING BENEATH THE INVERSION. WITH THE WARM  
WARM BLANKET IN PLACE, KEEPING IT MILD WITH LOWS DOWN INTO THE UPPER  
40S TO LOW 50S.  
 

 
   
LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/
 
 
*/ HIGHLIGHTS...  
 
* MAINLY DRY WEATHER W/MILD DAYS AND COOL NIGHTS SATURDAY AND SUNDAY  
* RISK OF RAIN RETURNS SUN NIGHT INTO MONDAY  
* SLIGHTLY ABOVE NORMAL TEMPERATURES TUE & WED, WITH A RISK FOR  
SCATTERED SHOWERS  
 
*/ DETAILS...  
 
SATURDAY AND SUNDAY...  
 
NEAR TO SLIGHTLY BELOW NORMAL TEMPERATURES. WEAK HIGH PRESSURE  
CENTERED JUST OFF TO THE EAST. LIMITED MOISTURE WITHIN THE  
VERTICAL COLUMN SHOULD KEEP MOST OF SOUTHERN NEW ENGLAND DRY.  
WILL HAVE TO WATCH OUT FOR DIURNAL SHOWERS WEST OF THE CT RIVER  
EACH AFTERNOON, WITH SUNDAY BEING THE MORE LIKELY DAY. WEAK  
PRESSURE GRADIENT WILL SUPPORT COOLING AFTERNOON SEABREEZES  
FOR THE COASTLINE.  
 
SUNDAY NIGHT AND MONDAY...  
 
PARENT LOW PRESSURE EXPECTED TO REMAIN NORTH OF THE GREAT LAKES,  
WHILE A TRIPLE POINT LOW TRAVERSES SOUTH OF NEW ENGLAND.  
EXPECTING AN INCREASING RISK FOR SHOWERS. WHILE THERE SHOULD BE  
PERIODS OF SHOWERS, NOT EXPECTING A WASHOUT. SOME ELEVATED  
INSTABILITY, BUT OTHERWISE NOT A GREAT SETUP FOR STRONG  
THUNDERSTORMS. INCLUDED AT LEAST A LOW RISK FOR ISOLATED  
THUNDERSTORMS THOUGH. NEAR TO SLIGHTLY BELOW NORMAL  
TEMPERATURES CONTINUE.  
 
TUESDAY INTO THURSDAY...  
 
LINGERING FRONTS FINALLY SHOULD MOVE AWAY FROM OUR REGION. HIGH  
PRESSURE MOVING INTO THE CENTRAL APPALACHIANS SHOULD PROVIDE  
SOME SUNSHINE AND AT LEAST A LIGHT SOUTH TO SOUTHWEST FLOW. THIS  
SHOULD MEAN SLIGHTLY ABOVE NORMAL DAYTIME TEMPERATURES, WITH  
NEAR NORMAL LOW TEMPERATURES THROUGH THIS PERIOD. A COLD POOL  
ALOFT CENTERED JUST SOUTH OF JAMES BAY SHOULD MEAN A CYCLONIC  
FLOW FOR OUR REGION. WILL HAVE TO BE WARY OF DIURNAL SHOWERS  
EACH DAY.  
 

 
   
AVIATION /06Z FRIDAY THROUGH TUESDAY/
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
SHORT TERM /THROUGH SATURDAY/...MODERATE CONFIDENCE.  
 
TONIGHT...  
VFR BREAKS IN THE CIGS WILL DROP BACK TO IFR/MVFR BY THE  
MORNING. HEAVY RAIN TO THE NORTH AND WEST WITH AREAS OF FOG AND  
DRIZZLE FOR THE REST OF THE REGION. NE WINDS CONTINUE WITH  
MAINLY 20-25 KT GUSTS.  
 
FRIDAY...  
IFR/MVFR CIGS WITH SCT-BKN -SHRA, ON AND OFF THROUGH THE DAY.  
CONDITIONS MAY IMPROVE TO VFR ACROSS WESTERN TERMINALS IN THE  
LATE AFTERNOON. NORTHWEST WINDS FOR ALL TERMINALS, BECOMING  
GUSTY INTO THE LATER HALF OF THE DAY.  
 
FRIDAY NIGHT...  
SHRA DISSIPATING WHILE IMPROVING VFR. NW WINDS BLUSTERY  
INITIALLY, RELAXING. CIGS BECOMING BKN TO SCT.  
 
KBOS TAF...HIGH CONFIDENCE IN TAF TREND, BUT MODERATE CONFIDENCE  
IN TIMING.  
 
KBDL TAF...HIGH CONFIDENCE IN TAF TREND, BUT MODERATE CONFIDENCE  
IN TIMING.  
 
OUTLOOK /SATURDAY NIGHT THROUGH TUESDAY/...MODERATE CONFIDENCE.  
 
SATURDAY AND SUNDAY...MAINLY VFR. LIGHT WINDS SATURDAY, WITH  
SEABREEZES AT THE COASTS. LIGHT S-SE WINDS SUNDAY.  
 
SUNDAY NIGHT THROUGH MONDAY...CIGS/VSBYS TRENDING TO MVFR/IFR IN  
SHOWERS. WINDS FROM THE SOUTHEAST, TRENDING FROM THE SOUTH MONDAY.  
 
TUESDAY...MAINLY VFR, WITH SCATTERED MVFR IN LEFTOVER SHOWERS.  
 

 
   
MARINE
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
SHORT TERM /THROUGH SATURDAY/...HIGH CONFIDENCE.  
 
TONIGHT...RAIN AND FOG, POSSIBLE THUNDER. THIS AS LOW PRESSURE  
LIFTS N/E ACROSS S NEW ENGLAND AHEAD OF WHICH ALONG A WARM  
FRONTAL BOUNDARY E/NE WINDS WILL BE SUSTAINED AROUND 15 KTS  
INITIALLY, BECOMING SOMEWHAT LIGHT WITH LOW PASSAGE AND  
BEGINNING TO TURN N/NW. SEAS 6 TO 8 FEET ON THE OUTER WATERS.  
 
FRIDAY INTO FRIDAY NIGHT...  
LOW PRESSURE EXITING BEHIND WHICH SHOWERS WILL LINGER AS WINDS  
WILL BE INITIALLY BLUSTERY OUT OF THE NW WITH SUSTAINED FLOW  
AROUND 15 KTS, GRADUALLY DIMINISHING WITH TIME AS A WEAK RIDGE  
OF HIGH PRESSURE BUILDS IN FROM THE W.  
 
OUTLOOK /SATURDAY NIGHT THROUGH TUESDAY/...  
 
RELATIVELY LIGHT WINDS AND SEAS THROUGH THIS PERIOD, ONCE SEAS  
SUBSIDE ACROSS THE OUTER WATERS SATURDAY MORNING.  
 

 
   
TIDES/COASTAL FLOODING
 
 
*/ TONIGHT...  
 
COMBINATION OF A VERY HIGH ASTRONOMICAL TIDE AND ONSHORE FLOW  
WILL RESULT IN WIDESPREAD MINOR COASTAL FLOODING TONIGHT, MAINLY  
FOR THE E MA COAST.  
 
PERSISTENT EASTERLY FLOW AROUND 15 MPH WILL RESULT IN A SURGE OF  
0.8 TO 1.0 FEET ALONG THE E MA COAST. IN ADDITION TO VERY HIGH  
ASTRONOMICAL TIDES WILL RESULT IN MINOR FLOODING. GREATEST CONCERN  
CONTINUES TO BE FROM SALISBURY TO CAPE ANN. THIS IS BECAUSE THIS  
IS WHERE THE STRONGEST EASTERLY FLOW IS FORECAST ALONG WITH A  
COMBINATION OF E SWELL AND WIND WAVE DIRECTION. GREATEST RISK OF  
BOTH MINOR COASTAL FLOODING AND BEACH EROSION.  
 
A COASTAL FLOOD ADVISORY CONTINUES FOR THE MA E COAST INCLUDING  
CAPE COD AND NANTUCKET FOR TONIGHT'S HIGH TIDE. WAVES WILL NOT  
BE A MAJOR FACTOR BUT LOOKS LIKE ENOUGH LOW LEVEL WIND GRADIENT  
TO PRODUCE 6 TO 8 FOOT WAVES IN THE NEAR SHORE WATERS IN IPSWICH  
BAY, ABOUT CAPE ANN, AND MASSACHUSETTS BAY COULD BE AN ISSUE.  
 
SOME EROSION IS LIKELY ALONG THE SALISBURY AND PLUM ISLAND  
SHORELINES WHERE WAVE ACTION WILL BE SOMEWHAT MORE SIGNIFICANT.  
 
ELSEWHERE ALONG THE MA AND RI COASTS, THE COMBINATION OF THE HIGH  
ASTRONOMICAL TIDE AND A TIDAL DEPARTURE NEAR A HALF FOOT MAY BE  
ENOUGH TO CAUSE POCKETS OF MINOR COASTAL FLOODING AS HAS BECOME MORE  
COMMON DURING SUCH KING TIDE CYCLES. BUT OUR CONFIDENCE CONTINUES  
TO BE LOW AND WILL NOT BE ISSUING A STATEMENT FOR THE REMAINING  
COASTLINE.  
 
*/ FRIDAY NIGHT INTO VERY EARLY SATURDAY MORNING...  
 
A SURGE OF 0.2 TO 0.4 FEET IS FORECAST AND COMBINED WITH THE PEAK  
OF ASTRONOMICAL TIDES (BOSTON AT 12.41 FEET), SHOULD SEE AT A  
MINIMUM COASTAL FLOODING OF LOW-LYING LOCATIONS NOTORIOUS FOR  
BECOMING INUNDATED DURING SUCH TIDES (I.E., MORRISSEY BOULEVARD  
IN BOSTON). ADDITIONAL COASTAL FLOOD STATEMENTS MAY BE NECESSARY.  
WILL CONTINUE TO MONITOR AND MAKE UPDATES AFTER THIS EVENINGS TIDE  
CYCLE.  
 

 
   
BOX WATCHES/WARNINGS/ADVISORIES
 
 
CT...NONE.  
MA...DENSE FOG ADVISORY UNTIL 3 AM EDT EARLY THIS MORNING FOR  
MAZ022>024.  
COASTAL FLOOD ADVISORY UNTIL 3 AM EDT EARLY THIS MORNING FOR  
MAZ007-015-016-019-022-024.  
RI...DENSE FOG ADVISORY UNTIL 3 AM EDT EARLY THIS MORNING FOR  
RIZ008.  
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT SATURDAY FOR ANZ235-237-  
250-254>256.  
SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ251.  
 

 
 

 
SYNOPSIS...BELK/SIPPRELL  
NEAR TERM...DUNTEN  
SHORT TERM...SIPPRELL  
LONG TERM...BELK  
AVIATION...BELK/DUNTEN  
MARINE...BELK/SIPPRELL  
TIDES/COASTAL FLOODING...STAFF  
 
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