124
FNUS76 KPDT 070430
FWSPDT

Spot Forecast for Grande Ronde Rappellers Mountain Week...USFS
National Weather Service Pendleton OR
930 PM PDT Wed May 6 2026

Forecast is based on ignition time of 0700 MDT on May 07.
***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.

.DISCUSSION...Excellent (80-90%) overnight humidity recoveries
this morning will lead to slightly cooler (-2) temperatures and
drier (-3%) afternoon conditions today. A weak cold front will
move in early Friday which will increase cloud cover and cause
elevated, breezy west winds Friday afternoon.

.THURSDAY...

Sky/weather.........Mostly sunny (10-20 percent).
CWR.................0 percent.
Chance of lightning.0 percent.
Max temperature.....75-78.
Min humidity........11-16 percent.
Wind (20 ft)........Light winds 2 to 6 mph becoming west 4 to 8
                    mph after 0900 and shifting from the
                    northwest around 1500.
Ridgetop wind.......Light winds 3 to 7 mph becoming west 5 to 10
                    mph after 0900 and shifting from the
                    northwest around 1500.
Mixing height.......7100 ft AGL.
Transport winds.....West 9 to 14 mph.
Ventilation Index...Low (140) increasing to very high (760) in the
                    afternoon.

TIME (MDT)      8AM 9AM 10A 11A 12P 1PM 2PM 3PM 4PM 5PM 6PM 7PM
Chc of ltng (%).0   0   0   0   0   0   0   0   0   0   0   0
Temp............42  46  51  60  66  68  72  73  74  75  73  72
RH..............79  67  50  35  25  21  19  17  15  15  16  18
20 FT wind dir..W   W   W   W   W   W   W   NW  NW  NW  NW  NW
20 FT wind spd..3   4   4   5   5   7   8   8   8   8   6   5
20 FT wind gust.            11  12  13  14  15  14  14  12  11

.THURSDAY NIGHT...

Sky/weather.........Partly cloudy (30-40 percent).
CWR.................0 percent.
Chance of lightning.0 percent.
Min temperature.....Around 40.
Max humidity........59-64 percent.
Wind (20 ft)........Northwest winds 4 to 8 mph, becoming light
                    and downsloping 1 to 4 mph after 2000.
Ridgetop wind.......Northwest winds 5 to 10 mph, becoming light
                    and downsloping 1 to 4 mph after 2000.
Mixing height.......4500 ft AGL early in the evening then 500 ft
                    AGL overnight.
Transport winds.....Northwest 6 to 10 mph.
Ventilation Index...Low (180) decreasing (30) overnight.

.FRIDAY...

Sky/weather.........Partly sunny (55-65 percent) then becoming
                    sunny (5-15 percent) after 1700.
CWR.................0 percent.
Chance of lightning.0 percent.
Max temperature.....74-77.
Min humidity........11-16 percent.
Wind (20 ft)........Light downsloping winds becoming west after
                    0500 and increasing to 6 to 12 mph with
                    gusts up to 18 mph after 1300.
Ridgetop wind.......Light downsloping winds becoming west after
                    0500 and increasing to to 7 to 14 mph with
                    22 mph after 1300.
Mixing height.......7800 ft AGL.
Transport winds.....West 8 to 17 mph.
Ventilation Index...Low (120) increasing to very high (930) in the
                    afternoon.

$$
Forecaster...Callihan
Requested by...Cutler Christensen
Type of request...PRESCRIBED
.TAG 2612123.3/PDT
.DELDT 05/07/26
.FormatterVersion 2.0.0
.EMAIL christensen.cutler@gmail.com