909  
FXUS61 KBOX 250202  
AFDBOX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BOSTON/NORTON MA  
1002 PM EDT THU SEP 24 2020  
   
SYNOPSIS
 
 
QUIET AND DRY WEATHER, COURTESY OF HIGH PRESSURE, WILL CONTINUE  
TO ROUND OUT THE WORK WEEK. THIS WEEKEND WILL BE MAINLY DRY,  
ALTHOUGH THERE IS A SLIGHT CHANCE OF SHOWERS. EARLY NEXT WEEK  
WILL FEATURE INCREASINGLY MOIST SOUTHERLY FLOW OUT AHEAD OF A  
COLD FRONT, WHICH ARRIVES LATE TUESDAY INTO WEDNESDAY. THERE  
WILL BE CHANCES OF SHOWERS EACH DAY, BUT GREATEST WITH THE FRONT  
ITSELF. TEMPERATURES WILL BE NEAR OR A LITTLE ABOVE NORMAL.  
 

 
   
NEAR TERM /UNTIL 6 AM FRIDAY MORNING/
 
 
1002 PM UPDATE  
 
THICK CIRRUS CLOUD SHIELD CONTINUED TO MOVE EASTWARD LATE THIS  
EVENING. SOME MODELS ATTEMPT TO DEVELOP A FEW LOW CLOUDS OVER  
NANTUCKET OVERNIGHT. OTHERWISE, NO MAJOR CHANGES TO THE  
FORECAST WITH THIS UPDATE PACKAGE.  
 
PREVIOUS DISCUSSION...  
HIGH PRESSURE OFF OF THE EAST COAST CONTINUES TO RULE THE  
FORECAST FOR SOUTHERN NEW ENGLAND. HIGH CIRRUS CLOUDS FILTERED  
IN EARLY THIS AFTERNOON LEAVING US WITH A MILKY WHITE/OVERCAST  
APPEARANCE. TONIGHT WE EXPECT MILD CONDITIONS, ONCE AGAIN.  
ACROSS INTERIOR MASSACHUSETTS TEMPERATURES DROP TO THE LOW 50S  
AND ELSEWHERE MORNING TEMPERATURES ARE IN THE MIDDLE AND UPPER  
50S.  
 

 
   
SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/
 
 
ANOTHER DRY DAY AHEAD, HIGH PRESSURE CONTINUES TO INFLUENCE OUR  
FORECAST WITH MAINLY CLEAR SKIES. THOUGH THE SKY WILL HAVE MORE  
CLOUDS FURTHER NORTH AS A QUASI STATIONARY BOUNDARY EXTENDS ACROSS  
SOUTHERN VERMONT AND SOUTHERN NEW HAMPSHIRE. GUIDANCE SUPPORTS A  
BACKING SOUTHWEST WIND DURING THE MORNING HOURS - BEFORE BECOMING  
SOUTH SOUTHEAST DURING THE EARLY AFTERNOON. TEMPERATURE TRENDS  
CONTINUE RIGHT INTO FRIDAY WITH AFTERNOON TEMPERATURES CLIMBING INTO  
THE UPPER 70S AND LOWER 80 DEGREE RANGE. THE QUIET TREND EXTENDS  
THROUGH FRIDAY EVENING AND EARLY SATURDAY.  
 

 
   
LONG TERM /SATURDAY THROUGH THURSDAY/
 
 
HIGHLIGHTS...  
 
* INCREASINGLY MOIST SOUTHERLY FLOW EARLY NEXT WEEK, WHICH  
BRINGS CHANCES OF SHOWERS AHEAD OF A COLD FRONT, WHICH ARRIVES  
LATE TUESDAY OR WEDNESDAY.  
 
DETAILS...  
 
SATURDAY AND SUNDAY...  
 
A RATHER NONDESCRIPT WEATHER PATTERN EXISTS OVER OUR REGION THIS  
WEEKEND. WEAK HIGH PRESSURE WILL REMAIN TO OUR NORTHEAST WHILE  
WEAK LOW PRESSURE PASSES WELL TO OUR SOUTH AND SOUTHEAST. IT  
LOOKS LIKE THERE WILL BE A BIT OF AN INCREASE IN PRECIPITABLE  
WATER VALUES ALOFT...TO ABOUT 1.2 INCHES...IN ASSOCIATION WITH  
REMNANTS OF BETA. BUT THERE IS NO REAL TRIGGER FOR PRECIPITATION.  
SKIES WILL BE PARTLY CLOUDY, WITH MORE CLOUD COVER ON SUNDAY  
THAN SATURDAY. CANNOT RULE OUT A SLIGHT CHANCE OF A SHOWER, WITH  
SOUTHERLY FLOW INCREASING DEWPOINTS FROM UPPER 50S SATURDAY  
MORNING TO THE MID 60S BY SUNDAY AFTERNOON. HIGHS WILL BE A  
LITTLE ABOVE NORMAL...MAINLY 75 TO 80 ACROSS THE INTERIOR.  
 
SUNDAY NIGHT THROUGH MONDAY NIGHT...  
 
THE GFS HINTS AT A BIT OF AN INSTABILITY BURST IN RI AND EASTERN  
MA SUNDAY NIGHT WITH K INDICES REACHING 34. DEWPOINTS WILL BE IN  
THE LOWER TO MID 60S ACROSS THE REGION. THERE IS A CHANCE OF  
SHOWERS SUNDAY NIGHT. THE CHANCE OF SHOWERS CONTINUES MONDAY  
INTO MONDAY NIGHT, AS AN UPPER LEVEL DISTURBANCE PASSES  
THROUGH. WE ARE NOT TALKING ABOUT WASHOUTS...AND CERTAINLY NO  
DROUGHT- REDUCING RAINFALL. HIGHS MONDAY WILL AGAIN BE IN THE  
MID AND UPPER 70S ACROSS THE INTERIOR.  
 
TUESDAY INTO WEDNESDAY...  
 
A VERY ANOMALOUS DEEP TROUGH DEVELOPS IN MIDWEST, MOVING INTO  
THE OHIO VALLEY. SOUTHERLY FLOW BECOMES A BIT GUSTY OVER  
SOUTHERN NEW ENGLAND, WITH GUSTS TO 15-25 MPH. ON TUESDAY NIGHT  
INTO EARLY WEDNESDAY, THE TROUGH BECOMES SLIGHTLY NEGATIVELY  
TILTED AND A 140-160 KT JET AT 250 MB ADVANCES TOWARD NEW  
ENGLAND. AT THE SURFACE A COLD FRONT WILL BE SLOWLY ADVANCING  
ACROSS NEW YORK STATE. THE GFS IS MUCH FASTER, WITH THE FRONT  
MOVING THROUGH ON TUESDAY NIGHT. THE ECMWF IS SIGNIFICANTLY  
SLOWER, WITH THE FRONT COMING THROUGH ON WEDNESDAY. AT SOME  
POINT, MOST LIKELY TUESDAY EVENING, A SOUTHERLY LOW LEVEL JET OF  
60-70 KNOTS AT 850 MB MOVES ACROSS SOUTHERN NEW ENGLAND. THERE  
IS ABOUT 500-1000 JOULES OF CAPE FORECAST WITH 0-1KM HELICITY  
VALUES IN THE 200-300 RANGE IN THE SLOPES OF THE BERKSHIRES AND  
CT RIVER VALLEY. HAVE INTRODUCED A SLIGHT CHANCE OF  
THUNDERSTORMS FOR THOSE AREAS TUESDAY AFTERNOON AND TUESDAY  
NIGHT. WHILE IT IS WAY TOO FAR IN ADVANCE TO PREDICT SEVERE  
WEATHER, THIS PATTERN IS ONE THAT COULD PRODUCE IT, ESPECIALLY  
TO OUR SOUTHWEST...SOMETHING TO WATCH FOR IN THE DAYS AHEAD.  
 
THE SHOWERS WITH THIS FRONT HAVE THE POTENTIAL TO PRODUCE  
LOCALLY HEAVY RAINFALL. THIS IS OUR BEST SHOT AT PLACES  
RECEIVING ANY SIGNIFICANT RAINFALL.  
 
THURSDAY...  
 
THERE IS A SIGNIFICANT DISCREPANCY AMONGST THE MODELS FOR  
THURSDAY. THE ECMWF DEVELOPS A CLOSED LOW OVER THE SOUTHERN  
STATES THAT LIFTS NORTHEAST OVER NEW ENGLAND, PRODUCING LOW  
PRESSURE AT THE SURFACE AND RAINY CONDITIONS. RIGHT NOW, WE ARE  
STICKING WITH THE CONSENSUS OF OTHER MODELS WHICH HAVE A DRY DAY  
IN THE WAKE OF THE DEPARTED COLD FRONT.  
 
SO, FOR NOW, MAINLY SUNNY SKIES ARE FORECAST, WITH DEWPOINTS  
DROPPING INTO THE COMFORTABLE UPPER 40S AND 50S AND MORE  
SEASONABLE HIGH TEMPERATURES...IN THE UPPER 60S TO LOWER 70S.  
 

 
   
AVIATION /02Z FRIDAY THROUGH TUESDAY/
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
HIGH CONFIDENCE THROUGH FRIDAY  
 
VFR. LIGHT SOUTHWEST WINDS CONTINUE INTO FRIDAY. FRIDAY, WITH A  
WEAK PRESSURE GRADIENT, EXPECT DEVELOPMENT OF SEA BREEZES ACROSS  
EASTERN MA DURING THE EARLY AFTERNOON.  
 
KBOS TERMINAL...HIGH CONFIDENCE IN TAF.  
 
KBDL TERMINAL...HIGH CONFIDENCE IN TAF.  
 
OUTLOOK /SATURDAY THROUGH TUESDAY/...  
 
SATURDAY: VFR.  
 
SATURDAY NIGHT THROUGH SUNDAY: MAINLY VFR, WITH LOCAL MVFR  
POSSIBLE. SLIGHT CHANCE SHRA.  
 
SUNDAY NIGHT: MAINLY MVFR, WITH LOCAL IFR POSSIBLE. SLIGHT  
CHANCE SHRA.  
 
MONDAY: MAINLY MVFR, WITH LOCAL VFR POSSIBLE. BREEZY. CHANCE  
SHRA.  
 
MONDAY NIGHT: MAINLY MVFR, WITH LOCAL IFR POSSIBLE. CHANCE  
SHRA.  
 
TUESDAY: MAINLY MVFR, WITH AREAS VFR POSSIBLE. BREEZY. CHANCE  
SHRA.  
 

 
   
MARINE
 
 
740 PM UPDATE...  
 
RELATIVELY LIGHT WINDS AND SEAS ARE EXPECTED THROUGH FRIDAY  
NIGHT, WITH HIGH PRESSURE CENTERED SOUTH OF THE WATERS.  
 
OUTLOOK /SATURDAY THROUGH TUESDAY/...  
 
SATURDAY THROUGH SUNDAY: WINDS LESS THAN 25 KT.  
 
SUNDAY NIGHT: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING  
5 FT. SLIGHT CHANCE OF RAIN SHOWERS.  
 
MONDAY THROUGH MONDAY NIGHT: WINDS LESS THAN 25 KT. SEAS UP TO  
5 FT. CHANCE OF RAIN SHOWERS.  
 
TUESDAY: WINDS LESS THAN 25 KT. AREAS OF ROUGH SEAS. CHANCE OF  
RAIN SHOWERS.  
 

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

 
 

 
SYNOPSIS...GAUCHER/GAF  
NEAR TERM...BELK/GAUCHER/GAF  
SHORT TERM...GAUCHER  
LONG TERM...GAF  
AVIATION...GAUCHER/GAF  
MARINE...GAUCHER/GAF  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab MA Page
The Nexlab RI Page
The Nexlab NH Page
The Nexlab CT Page Main Text Page