777
FNUS76 KOTX 102258
FWSOTX
SPOT FORECAST FOR UPPER SMITH SOUTH...CDA DISPATCH
NATIONAL WEATHER SERVICE SPOKANE WA
358 PM PDT THU SEP 10 2026
FORECAST IS BASED ON FORECAST START TIME OF 1800 PDT ON SEPTEMBER 10.
DISCUSSION
QUIET WEATHER IS FORECAST FOR THURSDAY NIGHT WITH TERRAIN DRIVEN WINDS.
ON FRIDAY THE ATMOSPHERE WILL BECOME MODERATELY UNSTABLE WITH A 30
PERCENT CHANCE OF AN AFTERNOON SHOWER AND A 10 PERCENT CHANCE OF A
THUNDERSTORM. FRIDAY NIGHT INTO SATURDAY AN APPROACHING WEATHER
SYSTEM WILL BRING AN INCREASE IN NORTHEAST WINDS ESPECIALLY ON
RIDGETOPS WITH GUSTS UP TO 25 MPH. THEN THE WEATHER SYSTEM PASSAGE
SATURDAY NIGHT INTO SUNDAY WILL BRING AN 85 PERCENT CHANCE OF A
WETTING RAIN. THERE IS A 70% CHANCE OF GREATER THAN 0.50 INCHES OF
RAIN WITH A 30% CHANCE OF GREATER THAN AN INCH.
IF CONDITIONS BECOME UNREPRESENTATIVE, CONTACT THE NATIONAL WEATHER
SERVICE.
***************************************************************
FORECASTS FOR 20 FOOT WIND SPEEDS (VALLEYS AND RIDGE TOPS) ARE
10 MINUTE AVERAGES REFLECTING RAWS WIND.
***VENTILATION INDEX IS DERIVED FROM TRANSPORT WIND
MULTIPLIED BY THE MIXING HEIGHT DIVIDED BY 100.
CATEGORIES: LOW (< 200), MODERATE (200-500),
HIGH (500-800), AND VERY HIGH (> 800).
***************************************************************
TONIGHT
SKY/WEATHER.........MOSTLY CLOUDY.
CWR.................0 PERCENT.
CHANCE OF LIGHTNING.5 PERCENT.
MIN TEMPERATURE.....38-45.
MAX HUMIDITY........MID SLOPES TO RIDGETOPS..........60-70 PERCENT
VALLEY BOTTOM AND LOWER SLOPES...75-85 PERCENT.
WIND (20 FT)........RIDGETOPS...WEST-NORTHWEST WINDS 4-8 MPH
IN THE EVENING SHIFTING TO THE EAST WITH SIMILAR
SPEEDS AFTER 2100 HOURS.
VALLEY BOTTOM AND SLOPES...UPSLOPE/UPVALLEY 2
TO 5 MPH SHIFTING TO DOWNSLOPE/DOWNVALLEY 1 TO
3 MPH NEAR 1900.
MIXING HEIGHT.......4000 FT AGL FALLING NEAR SURFACE NEAR 1900.
TRANSPORT WINDS.....WEST AROUND 5 MPH SHIFTING TO THE EAST IN
THE EVENING.
VENTILATION INDEX...MODERATE (291) DECREASING TO LOW (34)
OVERNIGHT.
FRIDAY
SKY/WEATHER.........PARTLY CLOUDY. 30 PERCENT CHANCE OF RAIN SHOWERS
AND A 10 PERCENT CHANCE OF THUNDERSTORMS IN THE
AFTERNOON.
CWR.................5 PERCENT.
CHANCE OF LIGHTNING.10 PERCENT.
MAX TEMPERATURE.....MID SLOPES TO RIDGETOPS..........47-56.
VALLEY BOTTOM AND LOWER SLOPES...57-64.
MIN HUMIDITY........MID SLOPES TO RIDGETOPS..........48-55 PERCENT.
VALLEY BOTTOM AND LOWER SLOPES...42-48 PERCENT.
WIND (20 FT)........RIDGETOPS.......NORTHEAST 3 TO 6 MPH SHIFTING TO
SOUTHWEST 2 TO 5 MPH IN THE AFTERNOON.
VALLEY BOTTOM AND SLOPES...DOWNSLOPE/DOWNVALLEY
1 TO 3 MPH SHIFTING TO UPSLOPE/UPVALLEY 2 TO 5
MPH NEAR 1100.
MIXING HEIGHT.......NEAR SURFACE THROUGH 0900 INCREASING TO 5000 FT
AGL IN THE AFTERNOON.
TRANSPORT WINDS.....EAST 5 TO 10 MPH.
VENTILATION INDEX...MODERATE (263).
FRIDAY NIGHT
SKY/WEATHER.........CLOUDY. SLIGHT CHANCE OF RAIN SHOWERS IN THE
EVENING.
CWR.................10 PERCENT.
CHANCE OF LIGHTNING.5 PERCENT.
MIN TEMPERATURE.....37-44.
MAX HUMIDITY........80-95 PERCENT.
WIND (20 FT)........RIDGETOPS: NORTHEAST 2 TO 5 MPH IN THE EVENING
INCREASING TO 5 TO 12 MPH WITH GUSTS UP TO 20
MPH NEAR 2200.
VALLEY BOTTOM AND SLOPES: DOWNSLOPE/DOWNVALLEY
3 TO 7 MPH.
MIXING HEIGHT.......FALLING TO NEAR SURFACE AT 1900.
TRANSPORT WINDS.....NORTHEAST 5 TO 15 MPH.
VENTILATION INDEX...LOW (115).
SATURDAY
SKY/WEATHER.........MOSTLY CLOUDY.
CWR.................0 PERCENT.
CHANCE OF LIGHTNING.0 PERCENT.
MAX TEMPERATURE.....MID SLOPES TO RIDGETOPS..........47-56.
VALLEY BOTTOM AND LOWER SLOPES...57-64.
MIN HUMIDITY........MID SLOPES TO RIDGETOPS..........50-57 PERCENT.
VALLEY BOTTOM AND LOWER SLOPES...44-50 PERCENT.
WIND (20 FT)........RIDGETOPS: NORTHEAST 8 TO 15 MPH WITH GUSTS UP
TO 25 MPH.
VALLEY BOTTOM AND SLOPES: NORTHEAST 3 TO 9 MPH.
MIXING HEIGHT.......NEAR SURFACE THROUGH 0900 INCREASING TO 4000 FT
AGL IN THE AFTERNOON.
TRANSPORT WINDS.....NORTHEAST 5 TO 15 MPH.
VENTILATION INDEX...MODERATE (251) INCREASING TO MODERATE (421) IN
THE AFTERNOON.
FORECASTER...JW
REQUESTED BY...STEPHANIE
TYPE OF REQUEST...WILDFIRE
.TAG 2620106.21/OTX
.DELDT 09/10/26
.FORMATTERVERSION 2.0.0
.EMAIL JEDIDIAH.ADAMS@USDA.GOV,IDCDC@FIRENET.GOV
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