FNUS71 KBOX 181301 FWSBOX Spot Forecast for Cuttyhunk_Rx_Fire_20260518...MassWildlife National Weather Service Boston/Norton MA 901 AM EDT Mon May 18 2026 Forecast is based on ignition time of 0931 EDT on May 18. If conditions become unrepresentative, contact the National Weather Service. .DISCUSSION... Sunny conditions will prevail today with high temperatures reaching the middle 60s today on Cuttyhunk Island. Due to the marine environment, temperatures will end up quite a bit cooler than over the mainland, with minimum relative humidities around 65-70 percent. In addition, mixing heights end up being very shallow and lead to very limited vertical mixing, even with the prescribed burn location being just away from the coast. Due to our forecast database's resolution, it will show very low mixing heights (around 400 ft) as it will treat some of the Island as "water". A more optimistic peak mixing height given the more inland location would be around 900 to 1000 ft during the late morning to midafternoon, but not likely to be any deeper than that. East-southeast winds around 10 to 15 mph will begin to turn to southeast by early afternoon and then south by mid to late afternoon. Expect modest transport off towards the northwest and north. .REST OF TODAY... Sky/weather.........Mostly sunny. CWR.................1 percent. Max temperature.....Around 65. Min humidity........70 percent. Dewpoint............52. Max apparent temp...61. Surface winds (mph).East winds 12 to 13 mph shifting to the south around 12 mph late in the afternoon. Wind (20 ft)........East winds around 12 mph shifting to the south late in the afternoon. Mixing height.......900 ft AGL. Transport winds.....Southeast 12 to 13 mph shifting to the south 12 to 14 mph late in the afternoon. Smoke dispersal.....Poor (3600 knot-ft). LVORI...............4. ADI.................13 to 15. CEILING (KFT).......25 decreasing to 11. TIME (EDT) 9AM 10A 11A 12P 1PM 2PM 3PM 4PM 5PM Sky (%).........31 23 26 16 27 25 38 35 33 Weather cov..... Weather type.... Tstm cov........ CWR.............0 0 0 0 0 0 0 0 0 Temp............57 61 61 61 61 61 60 60 59 Dewpoint........51 51 52 52 53 53 53 53 54 RH..............80 70 72 72 75 75 78 78 83 Heat index (F)..57 61 61 61 61 61 60 60 59 20 FT wind dir..E E E SE SE SE SE S S 20 FT wind spd..12 12 13 12 12 12 12 12 12 20 FT wind gust.14 16 17 17 17 17 17 17 16 Surface wnd dir.E E E SE SE SE SE S S Surface wnd spd.12 12 13 12 12 12 12 12 12 Surface wnd gst.14 16 17 17 17 17 17 17 16 Mix hgt (kft)...0.4 0.4 0.5 0.7 0.8 0.9 0.9 0.9 0.6 Transp wind dir.E E E E SE SE SE S S Transp wind spd.13 13 13 13 12 12 12 12 14 LVORI...........4 4 4 4 4 4 4 4 4 ADI.............14 14 14 14 13 13 13 13 15 Vrate kt-ft/1K..4 5 4 4 4 4 4 4 5 Ventrate Cat....PR PR PR PR PR PR PR PR PR Ceiling (kft)...25 25 25 25 25 25 15 13 11 .TONIGHT... Sky/weather.........Partly cloudy then becoming mostly cloudy. Patchy fog. CWR.................1 percent. Min temperature.....Around 55. Max humidity........100 percent. Dewpoint............54. Max apparent temp...58. Surface winds (mph).Southwest winds 12 to 17 mph. Wind (20 ft)........Southwest winds 12 to 17 mph. Mixing height.......300 ft AGL. Transport winds.....Southwest 14 to 21 mph. Smoke dispersal.....Poor (4400 knot-ft). LVORI...............5. ADI.................13 to 21. CEILING (KFT).......11 decreasing to 1.5, then decreasing to 0.8 increasing to 3.5 increasing to 7.0 increasing to 8.0 after midnight increasing to 11. TIME (EDT) 6 PM 8 PM 10 PM MIDNGT 2 AM 4 AM Sky (%).........35 57 55 65 73 77 Weather cov.....PATCHY PATCHY PATCHY PATCHY PATCHY PATCHY Weather type....FOG FOG FOG FOG FOG FOG Tstm cov........ CWR.............0 0 0 0 0 0 Temp............58 57 56 56 56 57 Dewpoint........54 54 55 55 55 55 RH..............86 90 96 96 96 93 Heat index (F)..58 57 56 56 56 57 20 ft wind......S 12 S 12 SW 13 SW 14 SW 15 SW 16 20 ft wind gust.16 14 15 16 17 18 Surface wind....S 12 S 12 SW 13 SW 14 SW 15 SW 16 Surface wnd gst.16 14 15 16 17 18 Mix hgt (ft)....400 400 400 400 400 400 Transport wind..S 14 S 15 S 17 SW 17 SW 20 SW 21 LVORI...........4 5 5 5 5 5 ADI.............15 13 15 15 18 19 Vrate kt-ft/1K..5 5 6 6 7 8 Ventrate Cat....POOR POOR POOR POOR POOR POOR Ceiling (kft)...11 12 1.5 3.5 8.0 11 .TUESDAY... Sky/weather.........Partly sunny. Patchy fog in the morning. Patchy fog early in the afternoon. CWR.................1 percent. Max temperature.....Around 72. Min humidity........75 percent. Dewpoint............56. Max apparent temp...65. Surface winds (mph).Southwest winds 17 to 23 mph. Wind (20 ft)........Southwest winds 17 to 23 mph. Mixing height.......500 ft AGL. Transport winds.....Southwest 20 to 24 mph. Smoke dispersal.....Poor (6900 knot-ft). LVORI...............6. ADI.................1 to 27. CEILING (KFT).......11 decreasing to 8.0 early in the morning, then decreasing to 6.0 early increasing to 10 late in the morning increasing to 14 increasing to 20 early decreasing to 16 decreasing to 9.9 late in the afternoon decreasing to 3.8. TIME (EDT) 6 AM 8 AM 10 AM NOON 2 PM 4 PM Sky (%).........73 52 37 52 53 63 Weather cov.....PATCHY PATCHY PATCHY PATCHY PATCHY Weather type....FOG FOG FOG FOG FOG NONE Tstm cov........ CWR.............0 0 0 0 0 0 Temp............57 58 58 59 65 63 Dewpoint........55 56 56 56 57 56 RH..............93 93 93 90 75 78 Heat index (F)..57 58 58 59 65 63 20 ft wind......SW 17 SW 17 SW 18 SW 21 SW 22 SW 23 20 ft wind gust.20 20 23 25 26 28 Surface wind....SW 17 SW 17 SW 18 SW 21 SW 22 SW 23 Surface wnd gst.20 20 23 25 26 28 Mix hgt (ft)....400 400 500 400 400 500 Transport wind..SW 21 SW 21 SW 21 SW 22 SW 24 SW 24 LVORI...........5 5 5 4 4 6 ADI.............23 23 23 24 27 1 Vrate kt-ft/1K..7 7 8 8 9 11 Ventrate Cat....POOR POOR POOR POOR POOR POOR Ceiling (kft)...11 6.0 14 20 22 9.9 $$ Forecaster...Loconto Requested by...Alex Entrup Type of request...PRESCRIBED .TAG 2613843.1/BOX .DELDT 05/18/26 .FormatterVersion 2.0.0 .EMAIL alex.entrup@mass.gov