879
FNUS76 KPDT 212327
FWSPDT

Spot Forecast for SPRING CREEK FIRE...WALLA WALLA COUNTY FIRE DISTRICT 4
National Weather Service Pendleton OR
427 PM PDT Tue Jul 21 2026

Forecast is based on forecast start time of 1800 PDT on July 21.
***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 transport wind
   multiplied by the mixing height in 100`s of ft.
   Categories are a generalized indicator only:
   low (< 200), moderate (200-500), high (500-700),
   and very high (> 700).                           ***

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

...HEAT ADVISORY IN EFFECT UNTIL 9 PM PDT THURSDAY...

.DISCUSSION...Generally dry conditions are expected through Thursday.

There is a low (<15 percent) chance of afternoon thunderstorms on Thursday.

Winds will mainly be 10 mph or less.

MIN RH values will be around 20 percent on Wednesday and 25 to 30 percent
on Thursday with moderate overnight recoveries.

.TONIGHT...

Sky/weather.........Partly cloudy (35-45 percent). Patchy smoke.
CWR.................0 percent.
Chance of lightning.0 percent.
Min temperature.....66-69.
Max humidity........40-45 percent.
Wind (20 ft)........Northwest winds 5 to 7 mph shifting to the
                    southeast in the late evening and overnight.
Ridgetop wind.......North winds 5 to 10 mph.
Mixing height.......500 ft AGL in the evening and overnight.
Transport winds.....Northwest around 5 mph shifting to the
                    southeast 5 to 7 mph early in the evening.
Ventilation Index...Low (30).

TIME (PDT)      6PM 7PM 8PM 9PM 10P 11P MID 1AM 2AM 3AM 4AM 5AM
Chc of ltng (%).0   0   0   0   0   0   0   0   0   0   0   0
Temp............97  93  88  75  76  74  72  72  72  69  70  69
RH..............24  27  34  44  41  43  44  43  43  45  44  45
20 FT wind dir..NW  NW  W   SE  SE  SE  SE  SE  SE  SE  SE  SE
20 FT wind spd..5   5   5   5   6   6   5   5   6   6   6   6
20 FT wind gust.

.WEDNESDAY...

Sky/weather.........Mostly sunny (25-35 percent). Patchy smoke in
                    the morning and early afternoon, then areas of
                    smoke late in the afternoon.
CWR.................0 percent.
Chance of lightning.1 percent.
Max temperature.....100-103.
Min humidity........17-22 percent.
Wind (20 ft)........Southeast winds 5 to 7 mph early in the morning
                    becoming light, then becoming west 5 to 7 mph
                    late in the morning shifting to northwest.
Mixing height.......6500 ft AGL.
Ridgetop wind.......North winds 5 to 10 mph, becoming west 5 to 10 mph
                    in the afternoon.
Mixing height.......7500 ft AGL early in the morning.
Transport winds.....Southeast around 6 mph early in the morning
                    becoming light, then becoming northwest 5 to 6
                    mph late in the morning.
Ventilation Index...Low (30) increasing to moderate (290) in the
                    afternoon.

.WEDNESDAY NIGHT...

Sky/weather.........Partly cloudy (25-35 percent). Areas of smoke
                    early in the evening, then patchy smoke early
                    in the evening.
CWR.................0 percent.
Chance of lightning.2 percent.
Min temperature.....Around 70.
Max humidity........43-48 percent.
Wind (20 ft)........North winds 5 to 7 mph shifting to the east 5
                    to 8 mph early in the evening, then shifting to
                    the south overnight.
Ridgetop wind.......West winds 5 to 10 mph, becoming south by daybreak.
Mixing height.......6500 ft AGL.
Mixing height.......500 ft AGL.
Transport winds.....North around 6 mph shifting to the east around
                    5 mph early in the evening, then shifting to
                    the south late in the evening.
Ventilation Index...Low (90) decreasing to low (40) overnight.

.THURSDAY...

Sky/weather.........Sunny (15-25 percent). Patchy smoke early in
                    the morning. A low (<15 percent chance of
                    thunderstorms in the afternoon).
CWR.................0 percent.
Chance of lightning.9 percent.
Max temperature.....99-102.
Min humidity........26-31 percent.
Wind (20 ft)........South winds 5 to 8 mph shifting to the west 5
                    to 10 mph late in the morning.
Ridgetop wind.......South winds 5 to 10 mph, becoming west in the afternoon.
Transport winds.....Southwest 9 to 10 mph shifting to the west late
                    in the afternoon.
Ventilation Index...Low (90) increasing to moderate (370) in the
                    afternoon.

$$
Forecaster...Nierenberg
Requested by...BRANDON MCKINNEY
Type of request...WILDFIRE
.TAG 2617669.6/PDT
.DELDT 07/21/26
.FormatterVersion 2.0.0
.EMAIL jgolden@wwfire4.com,spotweather@wwfire4.com