231 
FNUS76 KPDT 102038
FWSPDT

Spot Forecast for Black Rock Fire...COIMT3
National Weather Service Pendleton OR
138 PM PDT Wed Sep 10 2025

Forecast is based on forecast start time of 0630 PDT on September 11. 
***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...Upper low pressure system over the region will
continue to bring scattered thunderstorm chances to the fire site,
with storms capable of heavy rain, abundant lightning, small hail,
and gusty outflow winds. Winds will generally be from the west to
northwest in the afternoons, shifting to the southwest in the
overnight periods. Afternoon RHs will be in the lower 40s Thursday,
but as the low moves out of the area, RHs will dip into the upper 20s
Friday. Overnight recovery will be good to excellent.

.THURSDAY...

Sky/weather.........Mostly sunny (40-50 percent). Chance of showers 
                    and slight chance of thunderstorms. 
CWR.................15 percent decreasing to 0 percent late in the 
                    morning. 
Chance of lightning.22 percent. 
Max temperature.....81-84. 
Min humidity........40-45 percent. 
Wind (20 ft)........South winds 5 to 8 mph shifting to the west 5 
                    to 10 mph after 1PM. Gusty and erratic winds
                    expected near thunderstorms through the
					late afternoon.
Ridgetop wind.......Southwest 5 to 8 mph shifting to the northwest
					7 to 12 mph after 2PM.
Mixing height.......5700 ft AGL. 
Transport winds.....Southwest around 7 mph shifting to the 
                    northwest 9 to 13 mph late in the afternoon. 
Ventilation Index...Poor (140) increasing to fair (310) in the 
                    afternoon. 

TIME (PDT)      6 AM   8 AM   10 AM  NOON   2 PM   4 PM   
Chc of ltng (%).20     10     10     20     20     20     
Temp............60     63     70     75     78     80     
RH..............77     73     60     55     49     44     
20 ft wind......S 8    S 8    S 8    SW 7   W 8    W 8    
20 ft wind gust.                     10     12     12     

.THURSDAY NIGHT...

Sky/weather.........Mostly clear (20-30 percent). Slight chance of 
                    rain showers in the evening. 
CWR.................0 percent. 
Chance of lightning.14 percent. 
Min temperature.....Around 60. 
Max humidity........70-75 percent. 
Wind (20 ft)........West winds 5 to 10 mph shifting to the 
                    southwest 5 to 8 mph after 11PM. 
Ridgetop wind.......Northwest winds 5 to 10 mph shifting to the west
					around 8PM, then shifting to the southwest after
					11PM. 
Mixing height.......1900 ft AGL. 
Transport winds.....Northwest 8 to 13 mph shifting to the southwest 
                    8 to 9 mph late in the evening. 
Ventilation Index...Fair (320) decreasing to poor (150) overnight. 

.FRIDAY...

Sky/weather.........Sunny (10-20 percent). 
CWR.................0 percent. 
Chance of lightning.5 percent. 
Max temperature.....85-88. 
Min humidity........28-33 percent. 
Wind (20 ft)........Southwest winds 5 to 8 mph shifting to the west 
                    around 11AM. 
Ridgetop wind.......Southwest winds 5 to 10 mph shifting to the west
					around 1PM, then shifting to the northwest after
					5PM.
Mixing height.......6200 ft AGL. 
Transport winds.....Southwest 6 to 9 mph shifting to the northwest 
                    around 8 mph late in the afternoon. 
Ventilation Index...Poor (150) increasing to fair (240) in the 
                    afternoon. 

$$
Forecaster...Lawhorn
Requested by...Kathy Reed
Type of request...WILDFIRE
.TAG 2521423.6/PDT
.DELDT 09/10/25
.FormatterVersion 2.0.0
.EMAIL katherine.reed@usda.gov