822  
FNUS75 KBYZ 191204  
FWSBYZ  
 
SPOT FORECAST FOR NORTH CANYON...USDA FOREST SERVICE  
NATIONAL WEATHER SERVICE BILLINGS MT  
604 AM MDT THU OCT 19 2017  
 
FORECAST IS BASED ON IGNITION TIME OF 0900 MDT ON OCTOBER 19.  
IF CONDITIONS BECOME UNREPRESENTATIVE...CONTACT THE NATIONAL WEATHER  
SERVICE.  
 
PLEASE CONTACT OUR OFFICE IF YOU HAVE QUESTIONS  
OR CONCERNS WITH THIS FORECAST.  
   
DISCUSSION
 
 
WARM AND DRY CONDITIONS EXPECTED AT THE BURN SITE TODAY UNDER WEAK HIGH  
PRESSURE WITH RELATIVE HUMIDITIES IN THE UPPER TEENS TO LOWER 20S.  
LIGHT EAST WINDS EARLY WILL BECOME SOUTHWEST 5 TO 15 MPH BY MID-MORNING.  
DRY WEATHER CONTINUES TONIGHT WITH HUMIDITIES RECOVERING INTO THE 50S. WINDS  
WILL TURN SOUTHEAST 5 TO 15 MPH...SIMILAR TO THIS MORNING'S WINDS. A STRONG  
COLD FRONT WILL REACH THE BURN SITE LATE ON FRIDAY. IT WILL BECOME MUCH WINDIER  
AS SOUTHEAST WINDS 5 TO 15 MPH EARLY IN THE MORNING, BECOME SOUTHWEST 15 TO 25 MPH  
WITH GUSTS TO AROUND 40 MPH IN THE AFTERNOON. HUMIDITIES WILL FALL INTO THE 30S AND  
LIGHT SCATTERED RAIN SHOWERS ARE POSSIBLE WITH ISOLATED THUNDERSTORMS.  
   
REST OF TODAY
 
 
SKY/WEATHER.........SUNNY.  
LAL.................1...NO THUNDERSTORMS.  
MAX TEMPERATURE.....58-63.  
MIN HUMIDITY........18-23 PERCENT.  
WIND (20 FT)........  
SLOPE/VALLEY.......LIGHT EAST WINDS EARLY, BECOMING SOUTHWEST 5 TO 15 MPH.  
RIDGETOP...........SOUTHWEST 10 TO 20 MPH.  
MIXING HEIGHT.......1100 FT AGL LATE IN THE MORNING...INCREASING TO  
3500 FT AGL IN THE AFTERNOON.  
TRANSPORT WINDS.....SOUTHWEST 10 TO 20 MPH.  
HAINES INDEX........5.  
CWR.................0 PERCENT.  
 
TIME (MDT) 10A 11A 12P 1PM 2PM 3PM 4PM 5PM  
SKY (%).........13 11 10 14 21 25 29 37  
WEATHER COV.....  
WEATHER TYPE....  
TSTM COV........  
TEMP............52 56 57 59 60 59 59 57  
RH..............42 32 32 27 23 25 21 22  
20 FT WIND DIR..W W SW SW SW SW SW SW  
20 FT WIND SPD..7 10 12 12 12 12 11 11  
20 FT WIND GUST.8 11 14 14 14 14 13 12  
   
TONIGHT
 
 
SKY/WEATHER.........PARTLY CLOUDY.  
LAL.................1...NO THUNDERSTORMS.  
MIN TEMPERATURE.....35-40.  
MAX HUMIDITY........51-56 PERCENT.  
WIND (20 FT)........  
SLOPE/VALLEY.......SOUTHEAST WINDS 5 TO 15 MPH.  
RIDGETOP...........SOUTHWEST 20 TO 35 MPH.  
MIXING HEIGHT.......3500 FT AGL IN THE EVENING...DECREASING TO 1200  
FT AGL OVERNIGHT.  
TRANSPORT WINDS.....SOUTHWEST 10 TO 20 MPH.  
CWR.................0 PERCENT.  
   
FRIDAY
 
 
SKY/WEATHER.........MOSTLY SUNNY. SCATTERED RAIN SHOWERS WITH  
ISOLATED THUNDERSTORMS IN THE AFTERNOON.  
LAL.................1...NO THUNDERSTORMS IN THE  
MORNING...INCREASING TO 2...1 TO 8 STRIKES/15  
MIN/CELL IN THE AFTERNOON.  
MAX TEMPERATURE.....52-57.  
MIN HUMIDITY........31-36 PERCENT.  
WIND (20 FT)........  
SLOPE/VALLEY.......SOUTHEAST WINDS 5 TO 15 MPH EARLY, BECOMING SOUTHWEST 15 TO 25 MPH WITH GUSTS  
TO AROUND 40 MPH IN THE AFTERNOON. GUSTY AND ERRATIC WINDS EXPECTED NEAR  
THUNDERSTORMS IN THE AFTERNOON.  
RIDGETOP...........SOUTHWEST 25 TO 40 MPH.  
MIXING HEIGHT.......1200 FT AGL IN THE MORNING...INCREASING TO 6500  
FT AGL IN THE AFTERNOON.  
TRANSPORT WINDS.....SOUTHWEST 10 TO 20 MPH IN THE  
MORNING...INCREASING TO 20 TO 35 MPH IN THE  
AFTERNOON.  
HAINES INDEX........3 IN THE LATE MORNING AND AFTERNOON.  
CWR.................LESS THAN 10 PERCENT.  
 

 
FORECASTER...ARTHUR  
REQUESTED BY...MATT HEINZ  
TYPE OF REQUEST...PRESCRIBED  
.TAG 1717525.0/BYZ  
.EMAIL MATTHEWHEINZ@FS.FED.US  
 
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