523  
FXUS61 KBOX 211421  
AFDBOX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BOSTON/NORTON MA  
1021 AM EDT SAT MAY 21 2022  
   
SYNOPSIS
 
 
MID SUMMER HEAT AND INCREASING HUMIDITY FOR THE WEEKEND. A FEW  
STRONGER THUNDERSTORMS COULD DEVELOP LATE SUNDAY AFTERNOON IN  
WESTERN AREAS OF SOUTHERN NEW ENGLAND. SHOWERS WILL ACCOMPANY A COLD  
FRONT SUNDAY NIGHT. THE FIRST HALF OF NEXT WEEK WILL FEATURE  
SEASONABLE TEMPERATURES AND DRY WEATHER, WITH THE WEATHER TURNING  
UNSETTLED FOR LATE NEXT WEEK.  
 

 
   
NEAR TERM /UNTIL 6 PM THIS EVENING/
 
 
1020 AM UPDATE...  
 
* HEAT & HUMIDITY ARRIVE THIS AFTERNOON AWAY FROM THE COAST  
 
LOW CLOUDS REMAIN ACROSS MOST OF SOUTHERN NEW ENGLAND AT LATE  
MORNING WITH WIDESPREAD FOG ACROSS THE CAPE AND ISLANDS.  
HOWEVER, THE STRONG LATE MAY SUN ANGLE WILL ALLOW CLOUDS TO  
QUICKLY DISSIPATE ACROSS MUCH OF THE REGION OVER THE NEXT FEW  
HOURS. WHILE TEMPS WERE STILL IN THE 60S AT LATE MORNING; THEY  
WILL QUICKLY JUMP AS THE SUN EMERGES. HIGHLY ANOMALOUS 850T  
ARE ON THE ORDER OF +20C TO +22C; WHICH SHOULD ALLOW HIGH TEMPS  
TO REACH THE LOWER TO MIDDLE 90S NORTHWEST OF I-95. FURTHER  
EAST MIXING WILL BE A BIT MORE LIMITED; SO THINKING HIGHS ACROSS  
PORTIONS OF INTERIOR EASTERN MA/RI MAY END UP MORE IN THE UPPER  
80S TO NEAR 90. ALONG THE IMMEDIATE COAST; ONSHORE FLOW COUPLED  
WITH DELAYED CLEARING WILL KEEP HIGHS IN THE 70S TO NEAR 80  
INCLUDING BOSTON.  
 
THE MAIN STORY WILL BE THE RATHER LIGHT WINDS AND HIGH  
DEWPOINTS; WHICH WILL RESULT IN HEAT INDICES IN THE MIDDLE TO  
UPPER 90S WITH A FEW LOCATIONS NEAR 100 DEGREES NORTHWEST OF  
I-95. FURTHER EAST THEY WILL BE A BIT LOWER AND NOT AN ISSUE  
NEAR THE IMMEDIATE COAST. NO CHANGES PLANNED TO THE CURRENT HEAT  
ADVISORY EVEN THOUGH THE EASTERN PORTIONS OF THE REGION MAY FALL  
A BIT SHORT. THIS IS ESPECIALLY TRUE SINCE TEMPS WILL BE A FEW  
DEGREES WARMER ON SUNDAY AND MUCH WARMER ACROSS THE EASTERN MA  
COAST.  
 
DESPITE AN EML PRESENT ALONG WITH IMPRESSIVE INSTABILITY THIS  
AFTERNOON; UPPER LEVEL RIDGING AND CAPPING INVERSION SHOULD KEEP  
US DRY.  
 

 
   
SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/
 
 
315 AM UPDATE...  
 
00Z SUITE DOESN'T SHOW ANYTHING DIFFERENT FROM WHAT WE HAD ALREADY  
GOING. SO MY FORECAST EDITS WERE RATHER MINIMAL. MOST AREAS WILL NOT  
COOL OFF MUCH OVERNIGHT WITH LOWS OF 65-70F IN MANY AREAS -- PERHAPS  
LOW-MID 70S FOR SOME URBAN CENTERS. EXPECT ANOTHER ROUND OF LATE  
NIGHT PATCHY FOG AND STRATUS, HOWEVER SOUTHWEST WINDS JUST ABOVE THE  
SURFACE WILL BE STRENGTHENING OVERNIGHT SO THIS SHOULD KEEP THE AREA  
IMPACTED MUCH LESS, PERHAPS JUST THE IMMEDIATE SOUTH COASTAL AREAS,  
CAPE AND ISLANDS.  
 
SUNDAY WILL BE ANOTHER HOT DAY. GUIDANCE SUGGEST THE 850MB AND  
925MB TEMPERATURES WILL BE 1-2C WARMER. GIVEN PLENTY OF SUNSHINE,  
IT'S PRETTY MUCH TAKE TODAY'S HIGHS AND ADD A DEGREE OR TWO. SO LOTS  
MORE MID-90S FOR HIGHS, AND ANOTHER DAY WITH DAILY RECORD HIGHS  
BEING SET. WHAT WILL BE DIFFERENT ON SUNDAY IS DEEPER MIXING IN THE  
BOUNDARY LAYER, WHICH WILL RESULT IN SLIGHTLY LOWER DEWPOINTS  
IN THE AFTERNOON (LOWER-MID 60S) AND TAPPING INTO SOME STRONGER  
WINDS ALOFT. THUS THE AFTERNOON SHOULD GIVE US FREQUENT GUSTS OF  
20-25MPH OR PERHAPS A BIT HIGHER. SO DESPITE SLIGHTLY WARMER  
TEMPERATURES, LOWER DEWPOINTS WILL RESULT IN VERY SIMILAR HEAT  
INDEX VALUES AND SOME WIND MAY MAKE IT MORE BEARABLE. STILL HOT  
IS HOT, AND THE HEAT ADVISORY WILL CONTINUE. THE STRONGER WINDS  
WILL ALSO KEEP A SEA BREEZE FROM FORMING, SO THE IMMEDIATE EAST  
COAST WILL HAVE TEMPERATURES RISE ABOVE 90F. ONLY THE IMMEDIATE  
SOUTH COAST OF RI/MA AND CAPE/ISLANDS WILL GET THE COOLING FROM  
THE OCEAN WATERS.  
 
VERY LATE IN THE AFTERNOON WE MAY SEE SOME STRONGER THUNDERSTORMS  
ROLL INTO FAR WESTERN SECTIONS OF MA AND CT. LOOKS TO BE A VERY GOOD  
SETUP FOR SEVERE WEATHER JUST TO OUR WEST, HOWEVER THE TIMING MAY BE  
A LITTLE TOO LATE IN THE DAY FOR US TO GET IN ON THE BIGGEST STORMS.  
SPC DID TRIM THEIR SLIGHT RISK AREA SLIGHTLY TO THE WEST, AND BASED  
ON THE 00Z GUIDANCE, THAT SEEMS REASONABLE. HOWEVER IF THE MODELS  
ARE JUST 3 HOURS TOO SLOW, WE COULD SEE SOME HEFTY T-STORMS IN MORE  
OF SOUTHERN NEW ENGLAND IN THAT 4-8PM TIMEFRAME. KEPT THE MENTION OF  
GUSTY WINDS/SMALL HAIL.  
 

 
   
LONG TERM /MONDAY THROUGH FRIDAY/
 
 
HIGHLIGHTS...  
 
* COLD FRONT ARRIVES LATER SUNDAY WITH THE CHANCE FOR SHOWERS AND  
THUNDERSTORMS, SOME OF WHICH MAY BE STRONG.  
* MORE SEASONABLE TEMPERATURES RETURN FOR THE NEW WORK WEEK WITH  
LOWER DEW POINTS AND ONSHORE FLOW.  
* TURNING WARMER AND UNSETTLED AGAIN BY LATE WEEK.  
 
DETAILS...  
 
SUNDAY NIGHT...  
 
COLD FRONT CROSSES THE AREA LATER SUNDAY. DUE TO LESS MID-LEVEL  
INSTABILITY AND WEAKER LAPSE RATES, WHILE THERE IS A RISK FOR  
THUNDER, THE POTENTIAL FOR STRONG STORMS SHOULD QUICKLY DIMINISH  
WITH SUNSET. IN OTHER WORDS, EXPECT MAINLY GARDEN-VARIETY ISOLATED  
THUNDERSTORMS ON SUNDAY EVENING WITH THE MAIN RISKS BEING BRIEF  
GUSTY WIND, SMALL HAIL AND LOCAL DOWNPOURS. SUNDAY OVERNIGHT LOWS  
WILL RANGE FROM UPPER 50S IN WESTERN ZONES TO LOWER TO MID 60S IN  
THE EASTERN ZONES (EXCEPT FOR UPPER 60S IN THE URBAN HEAT ISLANDS).  
FOLLOWING COORDINATION WITH SPC, THE SLIGHT AND MARGINAL SEVERE  
RISKS HAVE BEEN TRIMMED FURTHER WEST GIVEN THE CONDITIONAL NATURE OF  
THE STORMS. NONETHELESS, SOMETHING TO WATCH IF YOU HAVE OUTDOOR  
PLANS SUNDAY EVENING AS ANY STORMS THAT FIRE UP COULD BECOME SEVERE  
QUICKLY.  
 
MONDAY INTO FRIDAY...  
 
MONDAY HIGHS WILL BE ABOUT 5 DEGREES ABOVE NORMAL BUT A LOT MORE  
SEASONABLE AND A LOT MORE COMFORTABLE WITH DEW POINTS FALLING INTO  
THE 40S TO NEAR 50. EXPECT MOSTLY DRY CONDITIONS WITH MIX OF SUN AND  
CLOUDS ON MONDAY ALTHOUGH THERE COULD BE LINGERING SHOWERS AROUND,  
ESPECIALLY ACROSS SOUTHEAST MA.  
 
INDEED, A MUCH MORE SEASONABLE AIR MASS WILL DOMINATE TUESDAY  
THROUGH MID WEEK, WITH A BROAD RIDGE OF HIGH PRESSURE OVER CANADA  
LEADING TO ONSHORE FLOW FOR MOST DAYS. THEN A WARMING TREND TOWARDS  
THE LATTER HALF OF THE WORK WEEK AS LOW-LEVEL FLOW BECOMES MORE  
SOUTHERLY AND EVENTUALLY SOUTHWESTERLY. EXPECT TEMPS TO RETURN TO  
ABOVE NORMAL. FOR REFERENCE, AVERAGE HIGHS FOR LATE MAY ARE IN THE  
LOW TO MID 70S. SO UPPER 70S TO LOW 80S MAKE A RETURN BY LATE WEEK.  
IN ADDITION, SHOWERS AND THUNDERSTORMS MAKE A RETURN TO THE FORECAST  
BUT PLENTY OF UNCERTAINTY REMAINS WITH REGARDS TO THE TIMING. SO  
MAINLY STUCK TO A BLEND OF GUIDANCE FOR THIS TIME PERIOD. OVERALL,  
PRETTY BENIGN WEATHER PATTERN TO FINISH OFF METEOROLOGICAL SPRING!  
 

 
   
AVIATION /14Z SATURDAY THROUGH WEDNESDAY/
 
 
LOW - LESS THAN 30 PERCENT.  
MEDIUM - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
06Z TAF UPDATE:  
 
OVERALL MODERATE CONFIDENCE.  
 
MVFR TO IFR CONDITIONS ACROSS THE REGION, WITH THE EXPECTATION  
FOR CONTINUED DETERIORATION WITH WIDESPREAD IFR AND AREAS WITH  
LIFR. BOTH LOW CEILINGS AND FOG ARE THE DRIVERS OF THAT.  
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ACROSS SE PORTION  
OF SOUTHERN NEW ENGLAND WILL BE PUSHING OFFSHORE BY 13Z. AS THE  
MORNING GOES ON, THE LOW CLOUDS AND FOG WILL DISSIPATE RESULTING  
IN SKC AND VFR CONDITIONS, FIRST INLAND AND EVENTUALLY TO THE  
COASTAL AREAS BY 16-18Z. HOWEVER ACK MAY NOT HAVE MUCH VFR.  
LIGHT SOUTHWEST SURFACE WINDS WILL DEVELOP ACROSS MOST OF THE  
REGION, HOWEVER ONSHORE SEA BREEZES WILL OCCUR ALONG THE COAST,  
AND WILL DEFINITELY BE A FACTOR FOR BOS. EXPECTING ANOTHER ROUND  
OF FOG AND LOW CLOUDS TO DEVELOP SATURDAY EVENING, HOWEVER IT IS  
NOT EXPECTED TO BE AS WIDESPREAD NOR DENSE AS IT WILL BE THIS  
MORNING. STILL, MANY LOCATIONS WILL SEE MVFR TO IFR CONDITIONS  
AFTER ROUGHLY 04Z SUNDAY.  
 
SUNDAY WILL START OUT WITH PATCHY FOG/IFR, HOWEVER EXPECT VFR  
CONDITIONS TO DEVELOP AREA WIDE BY 14-15Z. SURFACE WINDS SHOULD  
GUST 20-25KT DURING THE AFTERNOON. LATE SUNDAY WE SHOULD SEE  
SCATTERED SHOWERS AND THUNDERSTORMS APPROACH FROM THE WEST,  
PERHAPS IMPACTING BDL AND BAF PRIOR TO 00Z.  
 
KBOS TAF...MODERATE CONFIDENCE. EXPECT LIFR TO DEVELOP SHORTLY  
AND LINGER TO ABOUT 13Z. VISIBILITIES SHOULD QUICKLY IMPROVE  
AFTER THAT, HOWEVER LOW STRATUS WILL BE SLOW TO DISSIPATE.  
EXPECT PRIMARILY ONSHORE WIND/SEA BREEZE MUCH OF THE DAY.  
 
KBDL TAF: HIGH CONFIDENCE IN TRENDS, MODERATE CONFIDENCE WITH  
TIMING AND SPECIFIC DETAILS. EXPECT IFR/LIFR CONDITIONS  
DEVELOPING PRIOR TO 09Z, BUT WILL QUICKLY DISSIPATE IN THE  
13-15Z TIMEFRAME WITH VFR THE REST OF THE DAY.  
 
OUTLOOK /MONDAY THROUGH WEDNESDAY/...  
 
MONDAY: VFR. BREEZY.  
 
MONDAY NIGHT: VFR.  
 
TUESDAY: MAINLY VFR, WITH AREAS MVFR POSSIBLE. BREEZY. SLIGHT  
CHANCE SHRA, ISOLATED TSRA.  
 
TUESDAY NIGHT: MAINLY VFR, WITH AREAS MVFR POSSIBLE. SLIGHT  
CHANCE SHRA, ISOLATED TSRA.  
 
WEDNESDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. SLIGHT CHANCE  
SHRA, ISOLATED TSRA.  
 

 
   
MARINE
 
 
LOW - LESS THAN 30 PERCENT.  
MEDIUM - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
300 AM UPDATE...  
 
HIGH CONFIDENCE IN THE FORECAST.  
 
PRIMARY CONCERNS FOR THE MARINE AREAS WILL BE THE AREAS OF FOG,  
SOME OF WHICH WILL BE LOCALLY DENSE. SHOULD SEE SOME IMPROVEMENT  
THIS AFTERNOON, BUT FOG/LOW CLOUDS WILL REDEVELOP THIS EVENING AND  
LAST OVERNIGHT. ON SUNDAY THE FOG SHOULD DISSIPATE ACROSS THE WATERS  
OFF THE EASTERN COAST OF MA, HOWEVER AREAS OF FOG MAY PERSIST AROUND  
THE ISLANDS AND SOUTH OF RI AND MA. A COLD FRONT WILL MOVE  
THROUGH THE WATERS SUNDAY NIGHT, POSSIBLY BRINGING A FEW SHOWERS  
OR A THUNDERSTORM. SOUTHWEST WINDS WILL CONTINUE THROUGH THE  
WEEKEND, ALTHOUGH GENERALLY IN THE 10-15KT RANGE. AS A RESULT,  
SEAS ARE EXPECTED TO REMAIN LESS THAN 4 FEET.  
 
OUTLOOK /MONDAY THROUGH WEDNESDAY/...  
 
MONDAY THROUGH MONDAY NIGHT: WINDS LESS THAN 25 KT. AREAS OF  
SEAS APPROACHING 5 FT.  
 
TUESDAY: WINDS LESS THAN 25 KT. SEAS UP TO 5 FT. SLIGHT CHANCE  
OF RAIN SHOWERS, ISOLATED THUNDERSTORMS.  
 
TUESDAY NIGHT: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING  
5 FT. SLIGHT CHANCE OF RAIN SHOWERS, ISOLATED THUNDERSTORMS.  
 
WEDNESDAY: WINDS LESS THAN 25 KT. SEAS UP TO 5 FT.  
 

 
   
CLIMATE
 
 
DAILY RECORD HIGH TEMPERATURES...  
 
SAT MAY 21ST...  
BOS 93F (1921)  
PVD 93F (1996)  
BDL 93F (1996)  
ORH 88F (1975)  
 
SUN MAY 22ND...  
BOS 93F (1959)  
PVD 94F (1941, 1992)  
BDL 95F (1992)  
ORH 90F (1911, 1992)  
 
MONTHLY RECORD HIGH TEMPERATURES...  
BOS 97F (05/26/1880)  
PVD 96F (05/26/2010)  
BDL 99F (05/26/2010, 05/20/1996)  
ORH 94F (05/26/2010)  
 

 
   
BOX WATCHES/WARNINGS/ADVISORIES
 
 
CT...AIR QUALITY ALERT UNTIL 11 PM EDT THIS EVENING FOR CTZ002.  
HEAT ADVISORY UNTIL 8 PM EDT SUNDAY FOR CTZ002>004.  
MA...HEAT ADVISORY UNTIL 8 PM EDT SUNDAY FOR MAZ003>006-010>018-026.  
RI...AIR QUALITY ALERT UNTIL 11 PM EDT THIS EVENING FOR RIZ001>008.  
HEAT ADVISORY UNTIL 8 PM EDT SUNDAY FOR RIZ001>004.  
MARINE...NONE.  
 

 
 

 
SYNOPSIS...NASH  
NEAR TERM...FRANK  
SHORT TERM...NASH  
LONG TERM...CHAI  
AVIATION...CHAI/NASH  
MARINE...CHAI/NASH  
CLIMATE...  
 
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