FNUS73 KOAX 081354 FWSOAX Spot Forecast for St. Marys Island...Iowa DNR National Weather Service Omaha/Valley NE 854 AM CDT Wed May 8 2024 Forecast is based on ignition time of 1100 CDT on May 08. If conditions become unrepresentative, contact the National Weather Service. .DISCUSSION... Temperatures today mainly will be in the 70s. West to southwest winds at 10 to 15 mph with gusts up to 20 mph are expected. Isolated showers this morning may bring gusty winds as high as 55 mph. There has already been a 55 mph wind gust recorded at Harlan earlier this morning. Strongest Possible Wind Speeds on Day of Burn: 20 mph. Gusts up to 50 mph possible under any shower or thunderstorm that develops today. Lowest Possible Relative Humidity on Day of Burn: 40% .REST OF TODAY... Sky/weather.........Mostly sunny (45-55 percent). Slight chance of showers and thunderstorms late in the afternoon. Temperature.........66 at ignition...Max 75. RH..................58 percent at ignition...Min 38 percent. Eye level winds.....Southeast winds up to 6 mph shifting to the northeast around 4 mph late in the afternoon, then shifting to the west up to 6 mph late in the afternoon. Surface winds (mph).Southeast winds around 10 mph decreasing to 8 to 9 mph early in the afternoon, then shifting to the northeast around 8 mph late in the afternoon shifting to the west 8 to 10 mph late in the afternoon. Wind (20 ft)........Winds southeast at 8 mph at ignition...otherwise Southeast winds around 9 mph decreasing to 6 to 8 mph early in the afternoon, then shifting to the northeast around 6 mph late in the afternoon shifting to the west 7 to 9 mph late in the afternoon. Gusty and erratic winds expected near thunderstorms late in the afternoon. Mixing height.......1900 ft AGL at ignition...otherwise 7500 ft AGL. Transport winds.....Southeast 12 to 17 mph shifting to the south around 7 mph early in the afternoon, then shifting to the west 8 to 10 mph late in the afternoon. Smoke dispersal.....Fair /24200 knot-ft/ at ignition. Max...excellent /60000 knot-ft/. GFDI................0. Haines Index........6 or high potential for large plume dominated fire growth at ignition...max 6. TIME (CDT) 11A 12P 1PM 2PM 3PM 4PM 5PM Sky (%).........29 53 34 59 52 50 67 Weather cov..... SCH SCH SCH Weather type.... RW RW RW Tstm cov........ SCH SCH SCH Temp............66 70 72 74 74 75 73 RH..............58 51 44 43 41 38 41 20 FT wind dir..SE SE SE SE NE W W 20 FT wind spd..8 7 6 6 6 6 8 20 FT wind gust.13 12 10 10 10 10 13 Eye lvl wnd dir.SE SE SE SE NE W W Eye lvl wnd spd.6 5 4 4 4 4 6 Eye lvl wnd gst.10 9 8 7 7 8 10 Surface wnd dir.SE SE SE SE NE W W Surface wnd spd.10 9 8 8 8 8 10 Surface wnd gst.16 15 13 12 12 13 16 Mix hgt (kft)...1.9 3.9 5.5 6.8 7.5 7.5 6.1 Transp wind dir.SE SE SE S W NW W Transp wind spd.17 16 12 7 8 8 10 GFDI............0 0 0 0 0 0 0 Haines index....6 6 5 5 5 5 5 SDspl kt-ft/100024 42 55 60 59 53 42 .TONIGHT... Sky/weather.........Mostly cloudy (50-60 percent) then becoming mostly clear (15-25 percent). Chance of showers and thunderstorms early in the evening, then slight chance of showers and thunderstorms early in the evening. Temperature.........Min 49. RH..................Max 96 percent. Eye level winds.....Northwest winds up to 6 mph. Surface winds (mph).Northwest winds 6 to 10 mph. Wind (20 ft)........Northwest winds 5 to 9 mph. Gusty and erratic winds expected near thunderstorms early in the evening. Mixing height.......400 ft AGL. Transport winds.....Northwest 10 to 12 mph shifting to the north overnight. Smoke dispersal.....Fair (28800 knot-ft) early in the evening decreasing to poor (3500 knot-ft) late in the night. GFDI................0. Haines Index........5 or moderate potential for large plume dominated fire growth. TIME (CDT) 6 PM 8 PM 10 PM MIDNGT 2 AM 4 AM Sky (%).........58 35 21 16 8 22 Weather cov.....CHANCE S CHC Weather type....RNSHWR RNSHWR NONE NONE NONE NONE Tstm cov........CHANCE S CHC Temp............73 67 60 56 53 51 RH..............40 49 60 72 83 89 20 ft wind......W 8 NW 7 NW 6 N 6 N 6 NW 6 20 ft wind gust.13 Eye level wind..W 6 NW 5 NW 4 N 4 N 4 NW 4 Eye lvl wnd gst.10 5 Surface wind....W 10 NW 9 NW 8 N 8 N 8 NW 8 Surface wnd gst.16 Mix hgt (ft)....4300 500 500 500 400 500 Transport wind..W 10 NW 10 NW 12 N 12 N 12 N 10 GFDI............0 0 0 0 0 0 Haines index....5 5 5 5 5 5 SDspl kt-ft/100029 10 5 4 4 4 .THURSDAY... Sky/weather.........Mostly sunny (45-55 percent). Chance of rain showers. Slight chance of thunderstorms in the afternoon. Temperature.........Max 66. RH..................Min 56 percent. Eye level winds.....North winds up to 9 mph. Surface winds (mph).North winds 8 to 15 mph. Wind (20 ft)........North winds 6 to 13 mph. Gusty and erratic winds expected near thunderstorms in the afternoon. Mixing height.......3700 ft AGL. Transport winds.....North 12 to 17 mph. Smoke dispersal.....Poor (4100 knot-ft) early in the morning increasing to good (57300 knot-ft) in the afternoon. GFDI................0. Haines Index........3 to 5 or very low to moderate potential for large plume dominated fire growth. TIME (CDT) 6 AM 8 AM 10 AM NOON 2 PM 4 PM Sky (%).........37 42 49 43 50 57 Weather cov..... CHANCE CHANCE CHANCE CHANCE CHANCE Weather type....NONE RNSHWR RNSHWR RNSHWR RNSHWR RNSHWR Tstm cov........ S CHC S CHC Temp............49 51 58 62 63 64 RH..............96 96 80 70 67 63 20 ft wind......NW 6 NW 7 N 9 N 10 N 12 N 12 20 ft wind gust. 8 12 14 16 18 Eye level wind..NW 4 NW 5 N 7 N 8 N 9 N 9 Eye lvl wnd gst. 6 9 10 12 13 Surface wind....NW 8 NW 9 N 11 N 13 N 15 N 15 Surface wnd gst. 10 15 17 20 22 Mix hgt (ft)....500 1200 2200 3000 3500 3700 Transport wind..NW 12 N 16 N 16 N 16 N 16 N 17 GFDI............0 0 0 0 0 0 Haines index....5 3 3 3 3 3 SDspl kt-ft/10004 14 31 46 56 55 .FORECAST DAYS 3 THROUGH 5... .FRIDAY... Partly cloudy. Chance of showers and slight chance of thunderstorms. Lows in the upper 40s. Highs in the mid 70s. Northwest winds around 8 mph. .SATURDAY... Mostly clear. Lows in the upper 40s. Highs in the mid 70s. Northwest winds around 12 mph. .SUNDAY... Partly cloudy. Slight chance of showers and thunderstorms. Lows in the lower 50s. Highs in the lower 80s. Southwest winds around 8 mph. $$ Forecaster...Darrah Requested by...Matt Dollison Type of request...PRESCRIBED .TAG 2413479.0/OAX .DELDT 05/08/24 .FormatterVersion 2.0.0 .EMAIL matt.dollison@dnr.iowa.gov