074
FNUS73 KDMX 271308
FWSDMX

Spot Forecast for CBG - Switchgrass...Polk County Conservation
National Weather Service Des Moines IA
708 AM CST Thu Feb 27 2025

Forecast is based on ignition time of 1200 CST on February 27.
If conditions become unrepresentative...contact the National Weather
Service.

An initial observation at ignition and a mid burn observation are required.

Please relay them to the National Weather Service for each prescribed burn.


...Very Windy with Low RH on Friday...

.DISCUSSION...

Mostly sunny and mild today, with highs in the mid-50s.  Winds will become
breezy out of the northwest, sustained 10 to 18 mph with a few winds gusts
around 25 mph. Similar values of RH to yesterday, with MinRH values bottoming
out near 40 percent by mid-afternoon.  It will remain a bit breezy overnight
with moderate to good RH recovery. It will become very windy on Friday,
with peak sustained northwest winds of 20-30 mph with winds gusts to 45 mph.
RH values will be about 10% lower than today, approaching critical values.
Temperatures will remain mild with highs around 60F.

Have a safe burn!



.REST OF TODAY...

Sky/weather.........Sunny (0-5 percent).
Max temperature.....Around 55.
Min humidity........40 percent.
Wind (20 ft)........Northwest winds 10 to 16 mph with gusts to 25 mph.
Mixing height.......4400 ft AGL.
Transport winds.....Northwest 20 to 26 mph.
Smoke dispersal.....Good (37000 knot-ft) early in the morning
                    increasing to excellent (100800 knot-ft) in the
                    afternoon.
GFDI................8.

TIME (CST)      12P 1PM 2PM 3PM 4PM 5PM
Sky (%).........3   3   2   1   1   3
Weather cov.....
Weather type....
Tstm cov........
Temp............48  50  53  55  55  54
RH..............51  48  46  44  42  43
20 FT wind dir..NW  NW  NW  NW  NW  W
20 FT wind spd..15  15  15  16  14  10
20 FT wind gust.25  25  23  23  18  14
Mix hgt (kft)...2.9 3.7 4.1 4.4 4.4 2.2
Transp wind dir.NW  NW  NW  NW  NW  W
Transp wind spd.24  25  26  26  25  20
GFDI............10  11  12  11  6   4
Vrate kt-ft/1K..62  81  94  101 97  37
Ventrate Cat....GD  GD  GD  VGD GD  PR
SDspl kt-ft/100062  81  94  101 97  37

.TONIGHT...

Sky/weather.........Mostly clear (15-25 percent).
Min temperature.....Around 37.
Max humidity........73 percent.
Wind (20 ft)........West winds 6 to 10 mph shifting to the southwest
                    6 to 15 mph in the late evening and overnight.
Mixing height.......400 ft AGL.
Transport winds.....West 10 to 13 mph shifting to the southwest 14
                    to 22 mph late in the evening.
Smoke dispersal.....Fair (14000 knot-ft) early in the evening
                    decreasing to poor (3800 knot-ft) late in the
                    night.
GFDI................4.

TIME (CST)      6 PM   8 PM   10 PM  MIDNGT 2 AM   4 AM
Sky (%).........3      4      6      12     25     35
Weather cov.....
Weather type....NONE   NONE   NONE   NONE   NONE   NONE
Tstm cov........
Temp............52     45     41     39     40     40
RH..............48     63     70     71     70     67
20 ft wind......W 7    SW 6   SW 7   SW 10  SW 13  SW 15
20 ft wind gust.8                           14     21
Mix hgt (ft)....600    500    400    500    600    700
Transport wind..W 12   W 10   SW 13  SW 17  SW 20  SW 21
GFDI............3      1      1      2      3      5
Vrate kt-ft/1K..6      4      5      8      10     13
Ventrate Cat....POOR   POOR   POOR   POOR   POOR   POOR
SDspl kt-ft/10006      4      5      8      10     13

.FRIDAY...

Sky/weather.........Mostly sunny (30-40 percent).
Max temperature.....Around 59.
Min humidity........30 percent.
Wind (20 ft)........Breezy. West winds 16 to 22 mph with gusts to
                    around 33 mph shifting to the northwest 23 to
                    28 mph with gusts to around 45 mph late in the
                    morning.
Mixing height.......6200 ft AGL.
Transport winds.....West 21 to 26 mph increasing to northwest 31 to
                    40 mph in the late morning and early afternoon,
                    then increasing to 38 to 43 mph late in the
                    afternoon decreasing to around 33 mph late in
                    the afternoon.
Smoke dispersal.....Fair (15000 knot-ft) early in the morning
                    increasing to excellent (131800
                    knot-ft) in the afternoon.
GFDI................11 increasing to 24 late in the morning, then
                    increasing to 39 early in the afternoon
                    increasing to 49 early in the afternoon
                    decreasing to 34.

TIME (CST)      6AM 7AM 8AM 9AM 10A 11A 12P 1PM 2PM 3PM 4PM 5PM
Sky (%).........30  30  36  32  50  53  40  21  16  14  23  38
Weather cov.....
Weather type....
Tstm cov........
Temp............42  43  45  49  52  54  57  57  58  58  56  53
RH..............58  58  56  50  45  42  40  38  36  34  37  40
20 FT wind dir..W   W   W   W   W   NW  NW  NW  NW  NW  NW  NW
20 FT wind spd..16  17  18  20  22  23  25  26  28  28  26  24
20 FT wind gust.24  25  25  30  33  37  41  43  44  45  40  38
Mix hgt (kft)...0.8 0.8 0.9 1.5 2.5 3.2 4.3 4.9 5.6 6.2 5.2 4.1
Transp wind dir.W   W   W   NW  NW  NW  NW  NW  NW  NW  NW  NW
Transp wind spd.22  22  21  26  31  35  36  40  43  41  38  33
GFDI............8   9   10  14  21  26  37  41  47  51  38  29
Vrate kt-ft/1K..16  15  16  35  69  97  132 173 205 225 173 122
Ventrate Cat....PR  PR  PR  PR  GD  GD  VGD EXL EXL EXL EXL VGD
SDspl kt-ft/100016  15  16  35  69  97  132 173 205 225 173 122

$$
Forecaster...Fowle
Requested by...Lael Neal
Type of request...PRESCRIBED
.TAG 2504175.0/DMX
.DELDT 02/27/25
.FormatterVersion 2.0.0
.EMAIL lael.neal@polkcountyiowa.gov