480  
FXUS61 KBOX 081058  
AFDBOX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BOSTON/NORTON MA  
658 AM EDT WED APR 8 2020  
   
SYNOPSIS
 
 
WEAK AREA OF LOW PRESSURE TRACKING OVER OR JUST SOUTH OF NEW ENGLAND  
WILL SPREAD A PERIOD OF RAIN ACROSS THE REGION THIS MORNING. AS THE  
LOW DEPARTS A DRYING TREND DEVELOPS THIS AFTERNOON ALONG WITH A FEW  
BREAKS OF SUNSHINE LATE IN THE DAY. ANOTHER SYSTEM MOVES IN  
THURSDAY, BRINGING MORE RAIN AND SCATTERED THUNDERSTORMS. SCATTERED  
SHOWERS ARE POSSIBLE THURSDAY NIGHT THROUGH FRIDAY. DRIER WEATHER  
FOR THIS WEEKEND BEFORE OUR NEXT WET WEATHER SYSTEM EARLY NEXT  
WEEK.  
 

 
   
NEAR TERM /UNTIL 6 PM THIS EVENING/
 
 
700 AM UPDATE ...  
 
THE BACK EDGE OF THE PRECIP IS MOVING QUICKLY INTO  
WESTERN/CENTRAL MA AND CT. PRECIP AMOUNTS HAVE GENERALLY ADDED  
UP TO A FEW HUNDREDTHS IN NORTHERN ZONES TO A FEW TENTHS IN  
NORTH WESTERN CT. NO MAJOR CHANGES TO THE FORECAST THIS MORNING.  
 
PREVIOUS DISCUSSION...  
 
TODAY ...  
 
MID LEVEL WARM FRONT AND ASSOCIATED SURFACE WAVE MOVING ACROSS OR  
JUST SOUTH OF THE REGION THIS MORNING. GIVEN NW FLOW ALOFT DEEP  
LAYER MOISTURE AND INSTABILITY WILL STRUGGLE TO ADVECT NORTHEAST.  
THEREFORE LOWEST POPS AND LEAST QPF WILL BE ACROSS NORTHEAST MA. IN  
ADDITION CONVECTION CURRENTLY OVER SOUTHEAST PA INTO NJ APPEARS TO  
BE PRECLUDING DEEP LAYER MOISTURE AND INSTABILITY FROM ADVECTING  
NORTHEAST. FURTHERMORE, LEFTOVER DRY AIR (DEW PTS IN THE 30S) FROM  
TUE INITIALLY ERODING LEADING EDGE OF PRECIP AS IT ATTEMPTS TO ENTER  
EASTERN MA DURING THE PREDAWN HOURS. THUS LEANING TOWARD THE LOWER  
QPF GUIDANCE. 00Z HREF PROBABILITY MATCHED MEAN SEEMS REASONABLE  
WITH GREATEST QPF FROM WESTERN MA INTO CT, RI AND SOUTHEAST MA  
INCLUDING CAPE COD AND ISLANDS WHERE UP TO 0.25 INCHES OF QPF IS  
POSSIBLE. MEANWHILE OVER ESSEX COUNTY OF NORTHEAST MA ONLY A FEW  
HUNDREDS IS LIKELY.  
 
PROGRESSIVE NW FLOW ALOFT WILL RESULT IN A SHORT DURATION PERIOD OF  
RAIN WITH DRYING TREND FOR THE AFTERNOON. BACK EDGE OF PRECIP SHIELD  
CURRENTLY FROM UTICA NY TO LAKE GEORGE AREA. LOW LEVEL WINDS BECOME  
LIGHT NORTHEAST THIS AFTERNOON BEHIND DEPARTING FRONTAL WAVE.  
TYPICALLY THIS WOULD KEEP LOW CLOUDS LOCK IN ACROSS THE REGION.  
HOWEVER GIVEN LOW LEVEL DRY AIR CURRENTLY OVER THE REGION WITH DEW  
PTS IN THE 30S, LOWER CLOUDS WILL BE CONFINED TO WESTERN MA/CT INTO  
RI AND SOUTHEAST MA THIS MORNING. THUS PARTIAL CLEARING WILL ADVECT  
FROM NORTH-NORTHEAST TO SOUTHWEST THIS AFTERNOON AND ESPECIALLY LATE  
IN THE DAY WHEN SOME BREAKS OF SUNSHINE ARE POSSIBLE. MODELS HAVE  
BEEN TRENDING MILDER WITH EACH RUN. AS A RESULT WILL FOLLOW THESE  
TRENDS WITH HIGHS TODAY IN THE LOW TO MID 50S, UPPER 50S POSSIBLE  
HARTFORD TO SPRINGFIELD. NOT AS WARM AS THE PAST TWO DAYS BUT VERY  
CLOSE TO NORMAL. COOLEST TEMPS ALONG THE IMMEDIATE EASTERN MA  
COASTLINE INCLUDING BOSTON GIVEN THE NORTHEAST WINDS, LIMITING HIGHS  
HERE TO THE UPPER 40S.  
 

 
   
SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/
 
 
TONIGHT ...  
 
WEAK SHORT WAVE RIDGING PROVIDES THE REGION WITH DRY WEATHER AND  
SEASONABLE TEMPERATURES. GIVEN LIGHT WINDS AND DEW PTS 35-40 (AT OR  
ABOVE THE AVERAGE NIGHTTIME LOWS), RISK FOR PATCHY FOG ESPECIALLY  
ALONG THE COAST WHERE HIGHEST DEW PTS WILL BE OBSERVED.  
 
THURSDAY ...  
 
CLOSED LOW JUST NORTH OF THE GREAT LAKES INTO SOUTHERN ONTARIO  
EJECTS A VERY STRONG SHORT WAVE INTO NEW ENGLAND DURING THE  
AFTERNOON. VERY STRONG JET DYNAMICS WITH THIS SYSTEM THAT INDUCES  
979 MB TRIPLE PT/SECONDARY OVER NORTHEAST MA AROUND 21Z THU. STRONG  
CYCLONIC CURVATURE TO THE MID/UPPER LEVEL FLOW COUPLED WITH PWAT  
PLUME OF 1+ INCHES AND STEEP MID LEVEL LAPSE RATES SUGGEST A GOOD  
BET FOR ELEVATED CONVECTION AND BRIEF HEAVY SHOWERS. IN FACT COULD  
BE A FINE LINE OF LOW TOP CONVECTION. KEY FOR SURFACE BASED  
CONVECTION WILL BE HOW FAR NORTH DOES WARM SECTOR TRACK BEFORE  
TRIPLE PT LOW PINCHES OFF WARM SECTOR FROM ADVECTING NORTHWARD. SOME  
OF THE HIGH RES GUIDANCE HINT AT WARM SECTOR BRIEFLY ADVECTING INTO  
RI AND EASTERN MA WITH SURFACE TEMPS AND DEW PTS CLIMBING INTO THE  
50S! SOME OF THE GUIDANCE HAS TRENDED FARTHER NORTH-NORTHEAST WITH  
TRIPLE PT/SECONDARY LOW. THIS WOULD RESULT IN WARM SECTOR SURGING  
FARTHER NORTH INCREASING THE THREAT OF STRONG TO SEVERE STORMS. SPC  
DAY 2 FORECAST HAS ALSO TRENDED NORTHWARD WITH MARGINAL RISK NOW  
INTO NYC AREA. WILL JUST HAVE TO WATCH HOW THIS EVOLVES. AS OF NOW  
SB INSTABILITY APPEARS TO BE LACKING.  
 
BREEZY CONDITIONS WILL DEVELOP IN THE WARM SECTOR LATE THU MORNING  
INTO THU AFTERNOON WITH SOUTH WINDS 10-15 MPH GUSTING UP TO 25-35  
MPH AT TIMES, THEN ABRUPTLY SHIFTS TO THE WEST LATE IN THE DAY WITH  
THE FROPA.  
 

 
   
LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/
 
 
HIGHLIGHTS...  
 
* GUSTY WINDS, LIGHT RAIN, AND HIGH ELEVATION SNOW ON FRIDAY WITH A  
FEW RUMBLES OF THUNDER POSSIBLE  
 
* POTENTIAL FOR MINOR COASTAL FLOODING THROUGH EARLY FRIDAY AROUND  
HIGH TIDE ACROSS THE EAST AND SOUTH COASTS OF MA AND RI.  
SEE THE TIDES AND COASTAL FLOODING SECTION BELOW FOR MORE DETAILS.  
 
* TEMPERATURES RUNNING NEAR TO BELOW NORMAL THROUGH SATURDAY, THEN A  
WARM UP SUNDAY- TUESDAY  
 
* RAIN AND GUSTY WINDS RETURN MONDAY  
 
DETAILS...  
 
THURSDAY NIGHT AND FRIDAY...  
 
BY LATE THURSDAY EVENING/EARLY OVERNIGHT HOURS THE COLD FRONT WILL  
HAVE EXITED OFFSHORE USHERING IN A DRIER AIRMASS AND LEAVING  
CLEARING SKIES IN ITS WAKE. STRONG JET DYNAMICS REMAIN, NOW OUT OF  
THE W/NW. THIS BRINGS MID LEVEL CAA AND STEEPENING LAPSE RATES,  
HELPING TO MIX DOWN A STRONG 40-50 KT 850 MB LLJ. THE STRONGEST  
WINDS SHOULD REMAIN ALOFT DURING THE OVERNIGHT HOURS, BUT WITH  
DIURNAL HEATING ON FRIDAY AND THE COLD POOL ALOFT THE BOUNDARY LAYER  
SHOULD MIX VERY WELL ALL THE WAY UP TO AT LEAST 750 MB. THIS WILL  
ALLOW FOR WIDESPREAD VERY STRONG WIND GUSTS TO MIX DOWN, POTENTIALLY  
NECESSITATING A WIND ADVISORY OR EVEN A HIGH WIND WARNING; 40-50  
MPH GUSTS ARE LIKELY.  
 
EVEN THOUGH THE SFC LOW WILL BE WELL TO OUR NORTH, THE UPPER LOW  
LINGERS OVERHEAD KEEPING CYCLONIC FLOW IN PLACE WITH WRAPAROUND  
MOISTURE AND THE STRONG LLJ. THIS WILL MEAN SCATTERED RAIN SHOWERS,  
ESPECIALLY DURING THE DAY. THIS AS DIURNAL HEATING OF THE SFC  
TOGETHER WITH THE COLD POOL ALOFT CONTRIBUTE TO SOME SFC BASED  
INSTABILITY WHICH COULD BRING ABOUT A THUNDERSTORMS OR TWO AS WELL.  
 
SATURDAY AND SUNDAY...  
 
NICE WEEKEND IN STORE, THOUGH SUNDAY LOOKS TO BE THE NICER OF THE  
TWO DAYS (WARMER WITH LESS WIND). A RIDGE OF HIGH PRESSURE BEGINS TO  
MOVE OVERHEAD EARLY SATURDAY, AND THIS MEANS THE PRESSURE GRADIENT  
WILL BE SLOWLY RELAXING, SO WINDS LIKELY REMAIN BREEZY ON SATURDAY  
BEFORE CALMING SATURDAY NIGHT AND SUNDAY. TEMPERATURES REMAIN IN THE  
LOW 50S ON SATURDAY UNDER NW FLOW ON THE DOWNSTREAM SIDE OF THE  
RIDGE. BY SUNDAY THOUGH, THE RIDGE AXIS APPROACHES AND SW RETURN  
FLOW WARMS US UP INTO THE UPPER 50S. LOW TEMPERATURES ON SUNDAY  
MORNING WERE TRENDED TOWARD THE COLDER MOS GUIDANCE TO ACCOUNT FOR  
LIKELY RADIATIONAL COOLING UNDER CLEAR SKIES AND LIGHT WINDS...INTO  
THE UPPER 20S AND LOW 30S.  
 
MONDAY AND TUESDAY...  
 
THE MILD TEMPERATURES CONTINUE ON MONDAY AND TUESDAY. HOWEVER, IT  
COMES WITH THE RETURN OF WIDESPREAD RAIN. A DEEP MID LEVEL TROUGH  
AND SFC LOW WILL BRING RAIN AND GUSTY WINDS AROUND MONDAY, WITH  
ANOTHER POTENTIALLY WET DISTURBANCE RIGHT ON ITS HEELS.  
 

 
   
AVIATION /12Z WEDNESDAY THROUGH SUNDAY/
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
12Z UPDATE ... HIGH CONFIDENCE IN TRENDS, LOWER ON EXACT  
DETAILS.  
 
THIS MORNING ... RAIN IN MVFR FROM WESTERN MA INTO CT/RI AND  
SOUTHEAST MA. VFR ELSEWHERE WITH LIGHT RAIN. LIGHT AND VARIABLE  
WINDS TRENDING LIGHT NE.  
 
THIS AFTERNOON ... TRENDING TOWARD VFR ALONG WITH DRIER WEATHER.  
LIGHT NE WIND.  
 
TONIGHT ... VFR IN THE EVENING BUT TRENDING TOWARD MVFR/IFR  
INCLUDING PATCHY FOG. MAINLY DRY WEATHER PREVAILS.  
 
THURSDAY ... STRONG COLD FRONT APPROACHES THE REGION AND SWEEPS  
THRU THE AREA LATE IN THE DAY. MAINLY MVFR BUT IFR POSSIBLE IN  
HILLY TERRAIN. WIDESPREAD SHOWERS DEVELOPING WEST TO EAST THRU  
THE DAY WITH A FINE LINE OF LOW TOP SHOWERS/THUNDERSTORMS  
POSSIBLE ALONG AND AHEAD OF THE FRONT. LLWS LIKELY GIVEN  
MAGNITUDE OF LOW LEVEL SOUTHERLY JET. STRONG WIND SHIFT LATE IN  
THE DAY WITH THE FRONTAL PASSAGE FROM SOUTH TO WEST.  
 
KBOS TERMINAL...HIGH CONFIDENCE IN THE TAF.  
 
KBDL TERMINAL...HIGH CONFIDENCE IN THE TAF.  
 
OUTLOOK /THURSDAY NIGHT THROUGH SUNDAY/...  
 
THURSDAY NIGHT: VFR. STRONG WINDS WITH LOCAL GUSTS UP TO 40 KT.  
 
FRIDAY: VFR. STRONG WINDS WITH GUSTS UP TO 45 KT. SLIGHT CHANCE  
SHRA, ISOLATED TSRA.  
 
FRIDAY NIGHT: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. WINDY WITH  
GUSTS UP TO 35 KT.  
 
SATURDAY THROUGH SATURDAY NIGHT: VFR. BREEZY.  
 
SUNDAY: VFR.  
 

 
   
MARINE
 
 
TODAY ... WEAK SURFACE LOW TRACKS SOUTH OF NEW ENGLAND THIS MORNING  
THEN EASTWARD TO GEORGES BANK THIS AFTERNOON. MORNING RAIN GIVES WAY  
TO A DRYING TREND IN THE AFTERNOON. LIGHT SSW WINDS BECOME NE THIS  
AFTERNOON.  
 
TONIGHT ... WEAK HIGH PRESSURE OVER THE WATERS PROVIDES DRY QUIET  
WEATHER.  
 
THURSDAY ... STRONG COLD FRONT SWEEPS ACROSS THE WATER LATE THU WITH  
WIDESPREAD SHOWERS AND EMBEDDED THUNDER LIKELY. STRONG SSW WINDS  
AHEAD OF THE FRONT ABRUPTLY SHIFTS TO THE WNW AND REMAINS STRONG  
AND GUSTY.  
 
OUTLOOK /THURSDAY NIGHT THROUGH SUNDAY/...  
 
THURSDAY NIGHT: MODERATE RISK FOR GALE FORCE WINDS WITH GUSTS  
UP TO 40 KT. ROUGH SEAS UP TO 11 FT. SLIGHT CHANCE OF RAIN  
SHOWERS.  
 
FRIDAY: MODERATE RISK FOR GALE FORCE WINDS WITH GUSTS UP TO  
40 KT. ROUGH SEAS UP TO 12 FT. SLIGHT CHANCE OF RAIN SHOWERS,  
ISOLATED THUNDERSTORMS.  
 
FRIDAY NIGHT: MODERATE RISK FOR SMALL CRAFT ADVISORY WINDS WITH  
GUSTS UP TO 30 KT. AREAS OF ROUGH SEAS.  
 
SATURDAY: LOW RISK FOR SMALL CRAFT ADVISORY WINDS WITH GUSTS UP  
TO 25 KT. LOCAL ROUGH SEAS.  
 
SATURDAY NIGHT: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING  
5 FT.  
 
SUNDAY: WINDS LESS THAN 25 KT.  
 

 
   
TIDES/COASTAL FLOODING
 
 
4 AM UPDATE:  
 
NEXT 4 TIDES (MIDDAY AND MIDNIGHT TODAY AND THURSDAY) ARE  
ASTRONOMICALLY HIGH AND RUN THE RISK OF MINOR COASTAL  
FLOODING/INUNDATION. MIDDAY TODAY AND THEN MIDNIGHT TONIGHT MAIN  
RISK IS EASTERN MA AND AGAIN TONIGHT GIVEN LIGHT ONSHORE FLOW. THEN  
TOMORROW WITH SOUTHERLY SURFACE WINDS RISK SHIFTS TO THE SOUTH COAST  
OF MA/RI.  
 

 
   
BOX WATCHES/WARNINGS/ADVISORIES
 
 
CT...NONE.  
MA...COASTAL FLOOD ADVISORY UNTIL 8 AM EDT FRIDAY FOR MAZ019-022.  
COASTAL FLOOD ADVISORY FROM 8 PM THIS EVENING TO 8 AM EDT  
FRIDAY FOR MAZ015-016.  
COASTAL FLOOD ADVISORY UNTIL 8 AM EDT FRIDAY FOR MAZ007.  
RI...COASTAL FLOOD ADVISORY FROM 8 PM THIS EVENING TO 8 AM EDT  
FRIDAY FOR RIZ002-004>007.  
MARINE...GALE WATCH FROM THURSDAY AFTERNOON THROUGH FRIDAY EVENING FOR  
ANZ232-250-254-255.  
GALE WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY EVENING FOR  
ANZ233>235-237-256.  
GALE WATCH FROM THURSDAY AFTERNOON THROUGH FRIDAY AFTERNOON  
FOR ANZ231-251.  
 

 
 

 
SYNOPSIS...NOCERA/BW  
NEAR TERM...NOCERA/BW  
SHORT TERM...NOCERA  
LONG TERM...BW  
AVIATION...NOCERA/BW  
MARINE...NOCERA/BW  
TIDES/COASTAL FLOODING...  
 
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