290 
FNUS76 KPDT 092142
FWSPDT

Spot Forecast for Black Rock - H1...COIMT3
National Weather Service Pendleton OR
242 PM PDT Tue Sep 9 2025

Forecast is based on forecast start time of 0600 PDT on September 10. 
***Thunderstorms imply gusty and erratic winds***
***Winds are 20 foot 10-minute averages***
***CWR-Chance of wetting rain 0.10 or greater***
***Ventilation Index is derived from the
   transport wind multiplied by the mixing
   height in 100's of feet. Index categories
   are a generalized indicator only.***

If you have questions or concerns with this forecast, please
contact our office at (541) 276-8134.

.DISCUSSION...Shower and thunderstorm chances will continue for
the region as a low pressure system continues to move into the
Pacific Northwest. Rain chances will be at their greatest during
the overnight period Wednesday night into Thursday, before showers
generally shift eastward. Isolated storms are possible, but are
expected to be wetting in nature. Winds will start out terrain-
driven, before shifting more westerly as this weather system moves
through. 

.WEDNESDAY...

Sky/weather.........Partly cloudy (45-55 percent). Chance of rain 
                    showers and thunderstorms. (30-40 percent)
CWR.................8 percent. 
Chance of lightning.29 percent. 
Max temperature.....82-85. 
Min humidity........36-41 percent. 
Wind (20 ft)........Upvalley winds 5 to 8 mph. Gusty and 
                    erratic winds expected near thunderstorms. 
Ridgetop wind.......North winds 7 to 14 mph.   
Mixing height.......6300 ft AGL. 
Transport winds.....North around 9 mph. 
Ventilation Index...Poor (60) increasing to fair (280) in the 
                    afternoon. 

TIME (PDT)      6 AM   8 AM   10 AM  NOON   2 PM   4 PM   
Chc of ltng (%).0      0      0      10     20     20     
Temp............58     62     70     76     79     81     
RH..............81     73     58     51     45     41     
20 ft wind......SW 6   SW 6   SW 6   N 6    N 7    N 7    
20 ft wind gust.                     8      11     11     

.WEDNESDAY NIGHT...

Sky/weather.........Mostly cloudy (65-75 percent). Showers likely 
                    (50-60 percent) with a chance of thunderstorms
                    (20-30 percent). 
CWR.................11 percent increasing to 22 percent early in 
                    the morning. 
Chance of lightning.29 percent. 
Min temperature.....59-62. 
Max humidity........71-76 percent. 
Wind (20 ft)........Drainage winds around 5 mph. Gusty and erratic 
                    winds expected near thunderstorms. 
Ridgetop wind.......West-Northwest winds 5 to 10 mph.  
Mixing height.......1900 ft AGL. 
Transport winds.....West around 8 mph. 
Ventilation Index...Fair (240) decreasing to poor (130) overnight. 

.THURSDAY...

Sky/weather.........Mostly cloudy (55-65 percent). Chance of showers
                    and thunderstorms early (40-50 percent), 
                    decreasing throughout the day.  
CWR.................22 percent decreasing to 4 percent late in the 
                    morning. 
Chance of lightning.20 percent. 
Max temperature.....79-82. 
Min humidity........41-46 percent. 
Wind (20 ft)........West winds 5 to 10 mph. Gusty and 
                    erratic winds expected near thunderstorms. 
Ridgetop wind.......Northwest winds 7 to 14 mph.  
Mixing height.......6100 ft AGL. 
Transport winds.....West-Northwest around 9 mph. 
Ventilation Index...Poor (100) increasing to fair (250) in the 
 afternoon. 

$$
Forecaster...Evans
Requested by...Kathy Reed
Type of request...WILDFIRE
.TAG 2521661.0/PDT
.DELDT 09/09/25
.FormatterVersion 2.0.0
.EMAIL katherine.reed@usda.gov