543  
FNUS71 KBOX 210736  
FWSBOX  
 
SPOT FORECAST FOR SEPB RX FIRE...MASSWILDLIFE  
NATIONAL WEATHER SERVICE BOSTON/NORTON MA  
336 AM EDT THU OCT 21 2021  
 
FORECAST IS BASED ON IGNITION TIME OF 0500 EDT ON OCTOBER 21.  
IF CONDITIONS BECOME UNREPRESENTATIVE...CONTACT THE NATIONAL WEATHER  
SERVICE.  
   
DISCUSSION
 
 
HIGH PRESSURE CONTINUES BUILD EAST TODAY KEEPING DRY WEATHER AROUND  
INTO THE EARLY OVERNIGHT HOURS, THOUGH WINDS PICK UP LATER IN THE  
DAY. SCATTERED SHOWERS ARE POSSIBLE OVERNIGHT WITH GUSTY WINDS,  
ESPECIALLY ALONG THE SOUTH COAST. SHOWERS MOVE OUT BY SUNRISE FRIDAY  
LEAVING A MOSTLY DRY DAY AS A COLD FRONT MOVES THROUGH.  
 
MINIMUM RELATIVE HUMIDITIES RANGE FROM 45 TO 65 PERCENT THIS  
AFTERNOON AND 55 TO 70 PERCENT ON FRIDAY.  
 
OUTLOOK...SATURDAY THROUGH WEDNESDAY...  
 
MOSTLY DRY THIS WEEKEND BUT MUCH COOLER AIR RETURNS. THE NEXT CHANCE  
OF RAIN COMES LATE SUNDAY INTO EARLY NEXT WEEK.  
   
REST OF TONIGHT
 
 
SKY/WEATHER.........MOSTLY CLOUDY (50-60 PERCENT).  
CWR.................0 PERCENT.  
MIN TEMPERATURE.....AROUND 54.  
MAX HUMIDITY........86 PERCENT.  
DEWPOINT............52.  
MAX APPARENT TEMP...55.  
SURFACE WINDS.......LIGHT WINDS.  
WIND (20 FT)........LIGHT WINDS.  
MIXING HEIGHT.......100 FT AGL.  
TRANSPORT WINDS.....WEST AROUND 6 MPH.  
SMOKE DISPERSAL.....POOR (800 KNOT-FT).  
LVORI...............6.  
ADI.................3.  
HAINES INDEX........4 LOW POTENTIAL FOR LARGE PLUME DOMINATED FIRE  
GROWTH.  
CEILING (KFT).......20.  
 
TIME (EDT) 5AM  
SKY (%).........55  
WEATHER COV.....  
WEATHER TYPE....  
TSTM COV........  
CWR.............0  
TEMP............61  
DEWPOINT........52  
RH..............86  
HEAT INDEX (F)..55  
20 FT WIND DIR..NW  
20 FT WIND SPD..2  
20 FT WIND GUST.12  
SURFACE WND DIR.NW  
SURFACE WND SPD.2  
SURFACE WND GST.12  
MIX HGT (KFT)...0.1  
TRANSP WIND DIR.W  
TRANSP WIND SPD.6  
LVORI...........6  
ADI.............3  
HAINES INDEX....4  
VRATE KT-FT/10001  
CEILING (KFT)...20  
   
TODAY
 
 
SKY/WEATHER.........PARTLY SUNNY (50-60 PERCENT) THEN BECOMING  
SUNNY (20-30 PERCENT).  
CWR.................0 PERCENT.  
MAX TEMPERATURE.....AROUND 73.  
MIN HUMIDITY........53 PERCENT.  
DEWPOINT............53.  
MAX APPARENT TEMP...71.  
SURFACE WINDS.......LIGHT SOUTHWEST WINDS 3 TO 5 MPH EARLY IN THE MORNING  
THEN BECOMING SOUTHWEST 5 TO 15 MPH IN THE LATE  
MORNING AND AFTERNOON, GUSTING TO 23 MPH.  
WIND (20 FT)........LIGHT SOUTHWEST WINDS 5 TO 7 MPH EARLY IN THE MORNING  
THEN BECOMING SOUTHWEST 7 TO 15 MPH IN THE LATE  
MORNING AND AFTERNOON, GUSTING TO 23 MPH.  
MIXING HEIGHT.......100 FT AGL INCREASING TO 2500-2900 FT AGL  
EARLY, THEN DECREASING TO 800 FT AGL LATE IN  
THE AFTERNOON.  
TRANSPORT WINDS.....SOUTHWEST 5 TO 10 MPH INCREASING TO 18 TO 20  
MPH LATE IN THE AFTERNOON.  
SMOKE DISPERSAL.....POOR TO GOOD (500-47400 KNOT-FT) INCREASING TO  
FAIR TO GOOD (18700-50600 KNOT-FT) LATE IN THE  
AFTERNOON.  
LVORI...............4.  
ADI.................7 INCREASING TO 29, THEN INCREASING TO 50 EARLY  
INCREASING TO 60 EARLY IN THE AFTERNOON  
DECREASING TO 43 DECREASING TO 26 LATE IN THE  
AFTERNOON.  
HAINES INDEX........4 TO 6 OR LOW POTENTIAL FOR LARGE PLUME  
DOMINATED FIRE GROWTH TO HIGH POTENTIAL FOR  
LARGE PLUME DOMINATED FIRE GROWTH THROUGH EARLY  
AFTERNOON.  
CEILING (KFT).......20 INCREASING TO 25.  
 
TIME (EDT) 6AM 7AM 8AM 9AM 10A 11A 12P 1PM 2PM 3PM 4PM 5PM  
SKY (%).........59 58 64 45 43 24 34 35 19 13 14 14  
WEATHER COV.....  
WEATHER TYPE....  
TSTM COV........  
CWR.............0 0 0 0 0 0 0 0 0 0 0 0  
TEMP............61 60 60 61 65 68 70 71 71 71 70 69  
DEWPOINT........51 51 51 52 53 53 53 53 53 54 54 55  
RH..............86 86 80 72 65 59 55 53 53 55 57 61  
HEAT INDEX (F)..55 55 57 61 65 68 70 71 71 71 70 69  
20 FT WIND DIR..SW SW SW SW SW SW SW SW SW SW SW SW  
20 FT WIND SPD..2 3 3 5 7 8 9 12 13 13 13 12  
20 FT WIND GUST.10 10 9 10 12 14 16 17 21 21 21 22  
SURFACE WND DIR.SW SW SW SW SW SW SW SW SW SW SW SW  
SURFACE WND SPD.2 3 3 5 7 8 9 12 13 13 13 12  
SURFACE WND GST.10 10 9 10 12 14 16 17 21 21 21 22  
MIX HGT (KFT)...M M 0.1 M M 2.5 M M 2.9 M M 0.8  
TRANSP WIND DIR.M M SW M M SW M M SW M M SW  
TRANSP WIND SPD.M M 5 M M 10 M M 18 M M 20  
LVORI...........6 5 4 4 3 1 1 1 1 1 1 2  
ADI.............3 5 5 11 29 51 49 59 64 55 43 26  
HAINES INDEX....M M 4 M M 5 M M 5 M M 6  
VRATE KT-FT/10001 1 1 7 20 36 41 47 51 40 29 19  
CEILING (KFT)...20 25 25 25 25 25 25 25 25 25 25 25  
   
TONIGHT
 
 
SKY/WEATHER.........PARTLY CLOUDY (30-40 PERCENT).  
CWR.................0 PERCENT.  
MIN TEMPERATURE.....AROUND 58.  
MAX HUMIDITY........90 PERCENT.  
DEWPOINT............57.  
MAX APPARENT TEMP...68.  
SURFACE WINDS.......SOUTHWEST WINDS 12 TO 14 MPH.  
WIND (20 FT)........SOUTHWEST WINDS 12 TO 14 MPH.  
MIXING HEIGHT.......300 FT AGL UNTIL JUST AFTER MIDNIGHT.  
TRANSPORT WINDS.....SOUTHWEST 14 TO 16 MPH UNTIL JUST AFTER  
MIDNIGHT.  
SMOKE DISPERSAL.....POOR TO FAIR (4200-14100 KNOT-FT).  
LVORI...............4.  
ADI.................13.  
HAINES INDEX........4 TO 5 OR LOW POTENTIAL FOR LARGE PLUME  
DOMINATED FIRE GROWTH TO MODERATE POTENTIAL FOR  
LARGE PLUME DOMINATED FIRE GROWTH UNTIL JUST  
AFTER MIDNIGHT.  
CEILING (KFT).......20 INCREASING TO 25 EARLY IN THE EVENING, THEN  
DECREASING TO 20 EARLY INCREASING TO 25 IN THE  
LATE EVENING AND EARLY MORNING DECREASING TO 20  
DECREASING TO 13 EARLY IN THE MORNING.  
 
TIME (EDT) 6 PM 8 PM 10 PM MIDNGT 2 AM 4 AM  
SKY (%).........19 36 29 18 15 38  
WEATHER COV.....  
WEATHER TYPE....NONE NONE NONE NONE NONE NONE  
TSTM COV........  
CWR.............0 0 0 0 0 0  
TEMP............68 65 62 62 62 62  
DEWPOINT........56 59 58 58 59 59  
RH..............65 81 87 87 90 90  
HEAT INDEX (F)..68 65 62 62 62 62  
20 FT WIND......SW 12 S 12 SW 12 SW 13 SW 14 SW 14  
20 FT WIND GUST.23 24 21 23 24 24  
SURFACE WIND....SW 12 S 12 SW 12 SW 13 SW 14 SW 14  
SURFACE WND GST.23 24 21 23 24 24  
MIX HGT (FT)....M 300 M M 300 M  
TRANSPORT WIND..M S 14 M M SW 16 M  
LVORI...........3 4 4 4 5 5  
ADI.............13 11 15 16 15 14  
HAINES INDEX....M 5 M M 5 M  
VRATE KT-FT/100014 6 5 5 5 5  
CEILING (KFT)...20 20 25 25 20 15  
   
FRIDAY
 
 
SKY/WEATHER.........MOSTLY SUNNY (30-40 PERCENT).  
CWR.................0 PERCENT.  
MAX TEMPERATURE.....AROUND 72.  
MIN HUMIDITY........66 PERCENT.  
DEWPOINT............59.  
MAX APPARENT TEMP...71.  
SURFACE WINDS.......SOUTHWEST WINDS 9 TO 13 MPH.  
WIND (20 FT)........SOUTHWEST WINDS 9 TO 13 MPH.  
MIXING HEIGHT.......600 FT AGL INCREASING TO 3500-4300 FT AGL  
EARLY, THEN DECREASING TO 1600 FT AGL LATE IN  
THE AFTERNOON.  
TRANSPORT WINDS.....SOUTHWEST 15 TO 21 MPH THROUGH EARLY AFTERNOON.  
SMOKE DISPERSAL.....POOR TO GOOD (7500-53300 KNOT-FT) INCREASING TO  
FAIR TO EXCELLENT (27800-68300 KNOT-FT) IN THE  
AFTERNOON, THEN DECREASING TO FAIR (13400  
KNOT-FT) LATE IN THE AFTERNOON.  
LVORI...............3.  
ADI.................17 INCREASING TO 36 LATE IN THE MORNING, THEN  
INCREASING TO 46 INCREASING TO 59 EARLY  
INCREASING TO 68 DECREASING TO 53 EARLY IN THE  
AFTERNOON DECREASING TO 38 DECREASING TO 20  
LATE IN THE AFTERNOON.  
HAINES INDEX........3 TO 4 OR VERY LOW POTENTIAL FOR LARGE PLUME  
DOMINATED FIRE GROWTH TO LOW POTENTIAL FOR  
LARGE PLUME DOMINATED FIRE GROWTH THROUGH EARLY  
AFTERNOON.  
CEILING (KFT).......10 INCREASING TO 14 IN THE LATE MORNING AND  
AFTERNOON.  
 
TIME (EDT) 6 AM 9 AM NOON 3 PM  
SKY (%).........49 47 39 28  
WEATHER COV.....  
WEATHER TYPE....NONE NONE NONE NONE  
TSTM COV........  
CWR.............0 0 0 0  
TEMP............62 65 70 70  
DEWPOINT........59 60 60 59  
RH..............90 86 70 67  
HEAT INDEX (F)..62 65 70 70  
20 FT WIND......SW 13G23 SW 12G20 SW 12G18 SW 10G17  
SURFACE WIND....SW 13G23 SW 12G20 SW 12G18 SW 10G17  
MIX HGT (FT)....M M M M  
TRANSPORT WIND..M M M M  
LVORI...........5 4 3 1  
ADI.............13 36 61 54  
HAINES INDEX....M M M M  
VRATE KT-FT/10008 25 53 46  
CEILING (KFT)...12 12 15 15  
 

 
FORECASTER...BRW  
REQUESTED BY...ALEX ENTRUP  
TYPE OF REQUEST...PRESCRIBED  
.TAG 2119862.0/BOX  
.DELDT 10/21/21  
.EMAIL ALEX.ENTRUP@MASS.GOV  
 
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