502
FNUS73 KLSX 161012
FWSLSX

Spot Forecast for Canaan Fields burn...Missouri department of Conservation
National Weather Service Saint Louis MO
512 AM CDT Wed Sep 16 2026

Forecast is based on ignition time of 0700 CDT on September 16.
If conditions become unrepresentative, contact the
National Weather Service.

...HEAT ADVISORY IN EFFECT UNTIL 8 PM CDT FRIDAY...

.DISCUSSION...
A weak cold front that is slowly pushing south this morning has
passed through the burn area within the last few hours. Surface
winds will be light to somewhat variable generally out of the
northeast this morning, potentially becoming light and southerly
by the afternoon. Scattered to broken low/mid-level clouds will
move in from the northwest around sunrise with gradual dispersion
of this cloud cover anticipated throughout the day. There may be
some additional low-level clouds that develop later today with a
20-30% chance for an isolated shower or sub-severe thunderstorm
this afternoon and evening. Aside from those low precipitation
chances, dry conditions should prevail while the more widespread
rain this morning stays to the north across northern MO. Minimum
relative humidity values today should reach the mid 50s briefly
this afternoon with slightly lower values in the mid 40s possible
Thursday afternoon. Mixing heights could be slower to increase
this morning with lighter surface winds and especially if cloud
cover is more prevalent. Assuming an afternoon high in the low
90s, mixing heights briefly reach around 5kft before quickly
lowering below 1kft after sunset. Relatively steep low-level lapse
rates this afternoon will allow for efficient vertical mixing of
smoke. However, any scattered mid/low-level clouds that move past
the burn area will temporarily lower that efficiency. Thursday
should feature more sunshine, warmer afternoon temperatures (highs
mid 90s), possibly leading to slightly higher afternoon mixing
heights (>5kft) along with light and variable surface winds.


.REST OF TODAY...

Sky/weather.........Mostly sunny (30-40 percent). Slight chance of
                    showers and thunderstorms early in the morning.
                    Slight chance of showers and thunderstorms in
                    the afternoon.
CWR.................11 percent.
Chance of thunder...23 percent.
Temperature.........75 at ignition...Max 92.
RH..................87 percent at ignition...Min 56 percent.
Eye level winds.....Light and generally southerly.
Wind (20 ft)........Winds east at 4 mph at ignition...otherwise
                    Light winds becoming southeast around 5 mph
                    late in the morning, then becoming light late
                    in the morning. Gusty and erratic winds
                    expected near thunderstorms early in the
                    morning. Gusty and erratic winds expected near
                    thunderstorms in the afternoon.
Mixing height.......1200 ft AGL at ignition...otherwise max 5600 ft
                    AGL.
Transport winds.....East 7 to 8 mph shifting to the southwest 6 to
                    9 mph in the late morning and afternoon.
Smoke dispersal.....Poor /1080 m/s-m/ at ignition. Max...marginal
                    /5810 m/s-m/.

TIME (CDT)      7AM 8AM 9AM 10A 11A 12P 1PM 2PM 3PM 4PM 5PM 6PM
Sky (%).........56  46  35  21  16  10  13  13  29  53  59  52
Weather cov.....SCH SCH             SCH SCH SCH SCH SCH SCH CHC
Weather type....RW  RW              RW  RW  RW  RW  RW  RW  RW
Tstm cov........SCH SCH             SCH SCH SCH SCH SCH SCH CHC
CWR.............10  10  10  10  10  10  10  10  10  10  10  10
Chc of thdr (%).20  20  10  10  10  20  20  20  20  20  20  30
Temp............75  75  79  82  86  88  90  92  92  92  91  89
RH..............87  90  82  77  70  63  62  56  56  56  56  61
20 FT wind dir..E   E   SE  SE  S   S   SW  SW  S   S   E   SE
20 FT wind spd..4   4   4   5   4   4   4   4   3   3   4   4
20 FT wind gust.8   8   8   9   8   8   8   8   7   7   7   7
Eye lvl wnd dir.E   E   SE  SE  S   S   SW  SW  S   S   E   SE
Eye lvl wnd spd.2   2   2   2   2   2   2   2   1   1   2   2
Eye lvl wnd gst.4   4   4   4   4   4   4   4   3   3   3   3
Mix hgt (kft)...1.2 1.0 1.2 1.4 2.5 3.2 4.4 5.3 5.6 4.7 2.6 1.0
Transp wind dir.E   E   SE  S   SW  SW  SW  SW  SW  S   S   SE
Transp wind spd.7   8   8   7   9   9   8   8   6   6   7   7
Vrate kt-ft/1K..7   7   8   9   20  25  31  37  28  24  16  6
Ventrate Cat....PR  PR  PR  PR  PR  PR  PR  PR  PR  PR  PR  PR

.TONIGHT...

Sky/weather.........Mostly cloudy (55-65 percent) then becoming
                    partly cloudy (20-30 percent). Chance of
                    showers and thunderstorms early in the evening.
CWR.................12 percent.
Chance of thunder...27 percent.
Temperature.........Min 76.
RH..................Max 79 percent.
Eye level winds.....Light and generally southerly.
Wind (20 ft)........Light winds. Gusty and erratic winds expected
                    near thunderstorms early in the evening.
Mixing height.......Min 400 ft AGL.
Transport winds.....South 7 to 10 mph shifting to the southwest 10
                    to 12 mph after 3 am.
Smoke dispersal.....Poor (420 m/s-m).

.THURSDAY...

Sky/weather.........Sunny (10-20 percent). Slight chance of showers
                    and thunderstorms early in the afternoon.
CWR.................6 percent.
Chance of thunder...22 percent.
Temperature.........Max 95.
RH..................Min 48 percent.
Eye level winds.....Light and southerly in the morning turning
westerly around the middle of the day and
northerly by the afternoon.
Wind (20 ft)........Light winds. Gusty and erratic winds expected
                    near thunderstorms early in the afternoon.
Mixing height.......Max 6500 ft AGL.
Transport winds.....Southwest 10 to 13 mph shifting to the
                    northwest 6 to 12 mph in the afternoon.
Smoke dispersal.....Poor (690 m/s-m) early in the morning
                    increasing to fair max (7320 m/s-m) in the
                    afternoon.

$$
Forecaster...Peine
Requested by...Ryan Westcott
Type of request...PRESCRIBED
.TAG 2621976.0/LSX
.DELDT 09/16/26
.FormatterVersion 2.0.0