840  
FNUS75 KRIW 191245  
FWSRIW  
 
SPOT FORECAST FOR SVF UNIT 1...USFS-BTF  
NATIONAL WEATHER SERVICE RIVERTON WY  
645 AM MDT THU MAR 19 2026  
 
FORECAST IS BASED ON IGNITION TIME OF 0900 MDT ON MARCH 19.  
IF CONDITIONS BECOME UNREPRESENTATIVE, CONTACT THE NATIONAL WEATHER  
SERVICE  
   
DISCUSSION
 
 
WARM AND DRY WEATHER WILL CONTINUE TODAY WITH A MAINLY CLEAR SKY  
AND ONLY A FEW PASSING MID AND HIGH LEVEL CLOUDS. WIND SHOULD BE  
SIMILAR TO YESTERDAY WITH LARGELY LIGHT AND DIURNAL WIND UNTIL  
AROUND 1200 THEN A WEST WIND DEVELOPING WITH GUSTS TO AROUND 15  
MPG UNTIL AROUND 1800. HUMIDITY WILL BE SIMILAR TO YESTERDAY,  
DROPPING TO AROUND 20 PERCENT IN THE AFTERNOON. MIXING AND SMOKE  
DISPERSAL WILL BE POOR UNTIL INVERSIONS BREAK AROUND NOON AND THEN  
BECOMING FAIR AND POSSIBLY GOOD AFTER 1300. HIGHER MIXING HEIGHTS  
ON FRIDAY MAY BRING BETTER SMOKE DISPERSAL IN THE AFTERNOON.  
   
..THUNDERSTORMS IMPLY STRONG GUSTY AND ERRATIC WINDS
 
 
   
REST OF TODAY
 
 
SKY/WEATHER.........SUNNY (0-10 PERCENT).  
CWR.................0 PERCENT.  
CHANCE OF PCPN......0 PERCENT.  
CHANCE OF THUNDER...0 PERCENT.  
MAX TEMPERATURE.....AROUND 67.  
MIN HUMIDITY........22 PERCENT.  
WIND (20 FT)........LIGHT WINDS UNTIL 1200, THEN WEST 7 TO 8 MPH  
WITH GUSTS TO AROUND 13 MPH.  
RIDGETOP WIND.......SOUTH 10 TO 15 MPH UNTIL 1400, THEN WEST.  
MIXING HEIGHT.......2500 FT AGL UNTIL 1300, THEN 4000 FT AGL.  
TRANSPORT WINDS.....SOUTHWEST 9 TO 13 MPH UNTIL 1300, THEN WEST 14  
TO 16 MPH.  
SMOKE DISPERSAL.....POOR UNTIL 1200, THEN FAIR TO POSSIBLY GOOD.  
 
TIME (MDT) 9AM 10A 11A 12P 1PM 2PM 3PM 4PM 5PM  
SKY (%).........0 0 0 0 0 0 0 0 0  
WEATHER COV.....  
WEATHER TYPE....  
TSTM COV........  
CWR.............0 0 0 0 0 0 0 0 0  
CHC OF PCPN (%).0 0 0 0 0 0 0 0 0  
CHC OF THDR (%).0 0 0 0 0 0 0 0 0  
TEMP............47 52 58 61 65 67 67 67 67  
RH..............60 45 40 35 30 25 24 25 28  
20 FT WIND DIR..S S S SW SW W W W W  
20 FT WIND SPD..4 4 4 5 6 7 7 8 8  
20 FT WIND GUST.6 6 6 7 10 11 11 13 13  
RIDGE WIND DIR..S S S SW SW W W W W  
RIDGE WIND SPD..10 10 10 10 15 15 15 15 15  
MIX HGT (KFT)...1.0 1.5 2.0 2.5 3.5 4.0 4.0 4.0 3.5  
TRANSP WIND DIR.S S SW SW W W W W W  
TRANSP WIND SPD.9 9 9 13 14 16 16 16 15  
SDSPL KT-FT/10009 10 15 30 43 59 59 55 42  
   
TONIGHT
 
 
SKY/WEATHER.........CLEAR (0-10 PERCENT).  
CWR.................0 PERCENT.  
CHANCE OF PCPN......0 PERCENT.  
CHANCE OF THUNDER...0 PERCENT.  
MIN TEMPERATURE.....AROUND 40.  
MAX HUMIDITY........61 PERCENT.  
WIND (20 FT)........WEST WINDS AROUND 7 MPH UNTIL 1900, THEN LIGHT.  
RIDGETOP WIND.......SOUTHWEST 10 TO 15 MPH UNTIL 2100, THEN LIGHT  
UNTIL 2300, THEN SOUTHEAST AROUND 10 MPH.  
MIXING HEIGHT.......1000 FT AGL.  
TRANSPORT WINDS.....WEST 8 TO 14 MPH UNTIL 0100, THEN SOUTH.  
SMOKE DISPERSAL.....POOR.  
 
TIME (MDT) 6PM 7PM 8PM 9PM 10P 11P MID 1AM 2AM 3AM 4AM 5AM  
SKY (%).........0 5 5 5 10 10 10 10 10 10 10 10  
WEATHER COV.....  
WEATHER TYPE....  
TSTM COV........  
CWR.............0 0 0 0 0 0 0 0 0 0 0 0  
CHC OF PCPN (%).0 0 0 0 0 0 0 0 0 0 0 0  
CHC OF THDR (%).0 0 0 0 0 0 0 0 0 0 0 0  
TEMP............64 60 55 52 49 48 45 44 44 43 43 41  
RH..............34 40 49 52 55 55 58 55 55 58 59 61  
20 FT WIND DIR..W SW SW S S S SE SE SE SE SE SE  
20 FT WIND SPD..7 6 4 2 2 3 4 4 4 4 4 4  
20 FT WIND GUST.11 8 6 6 6 6 6 6 6  
RIDGE WIND DIR..W SW SW S S S SE SE SE SE SE SE  
RIDGE WIND SPD..15 10 10 5 5 10 10 10 10 10 10 10  
MIX HGT (KFT)...2.5 1.5 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0  
TRANSP WIND DIR.W W W W SW SW SW SW S S S S  
TRANSP WIND SPD.14 12 9 8 8 8 9 9 9 9 9 9  
SDSPL KT-FT/100027 13 9 8 8 8 9 9 9 9 9 9  
   
FRIDAY
 
 
SKY/WEATHER.........SUNNY (5-15 PERCENT).  
CWR.................0 PERCENT.  
CHANCE OF PCPN......0 PERCENT.  
CHANCE OF THUNDER...0 PERCENT.  
MAX TEMPERATURE.....AROUND 68.  
MIN HUMIDITY........25 PERCENT.  
WIND (20 FT)........LIGHT WINDS UNTIL 1500, THEN WEST AROUND 7 MPH.  
RIDGETOP WIND.......SOUTH AROUND 10 MPH UNTIL 1200, THEN SOUTHWEST.  
MIXING HEIGHT.......2500 FT AGL UNTIL 1200, THEN 5500 FT AGL.  
TRANSPORT WINDS.....SOUTHWEST 8 TO 17 MPH.  
SMOKE DISPERSAL.....POOR UNTIL 1100, BECOMING GOOD AFTER 1400.  
 
TIME (MDT) 6AM 7AM 8AM 9AM 10A 11A 12P 1PM 2PM 3PM 4PM 5PM  
SKY (%).........15 10 10 5 5 5 5 10 10 10 10 15  
WEATHER COV.....  
WEATHER TYPE....  
TSTM COV........  
CWR.............0 0 0 0 0 0 0 0 0 0 0 0  
CHC OF PCPN (%).0 0 0 0 0 0 0 0 0 0 0 0  
CHC OF THDR (%).0 0 0 0 0 0 0 0 0 0 0 0  
TEMP............40 41 42 46 51 57 61 64 66 67 68 68  
RH..............61 59 57 54 50 45 39 33 28 25 25 26  
20 FT WIND DIR..SE S S S S SW SW SW W W W W  
20 FT WIND SPD..4 4 3 3 4 4 4 6 6 7 7 7  
20 FT WIND GUST.6 6 6 6 6 8 10 11 11 11  
RIDGE WIND DIR..SE S S S S SW SW SW W W W W  
RIDGE WIND SPD..10 10 10 10 10 10 10 10 15 15 15 15  
MIX HGT (KFT)...1.0 1.0 1.0 1.0 1.5 2.5 3.5 4.0 5.0 5.5 4.5 3.5  
TRANSP WIND DIR.S S S S S SW SW SW SW SW SW SW  
TRANSP WIND SPD.9 9 8 8 9 10 13 14 16 17 16 15  
SDSPL KT-FT/10009 9 8 7 12 22 38 50 68 84 65 49  
   
FORECAST DAYS 3 THROUGH 5
 
   
SATURDAY
 
 
MOSTLY CLEAR. LOWS IN THE LOWER 40S. HIGHS IN THE MID 60S. LIGHT  
WINDS.    
SUNDAY
 
 
COOLER. PARTLY CLOUDY. LOWS IN THE MID 30S. HIGHS IN THE MID 50S.  
LIGHT WINDS.    
MONDAY
 
 
PARTLY CLOUDY. LOWS IN THE MID 30S. HIGHS IN THE UPPER 50S. LIGHT  
WINDS.  
 

 
FORECASTER...HATTINGS  
REQUESTED BY...MICHAEL MCEWEN  
TYPE OF REQUEST...PRESCRIBED  
.TAG 2605908.1/RIW  
.DELDT 03/19/26  
.FORMATTERVERSION 2.0.0  
.EMAIL MICHAEL.MCEWEN@USDA.GOV  
 
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