JEFFERSON COUNTY FIELD-BURNING FORECAST
OREGON DEPARTMENT OF FORESTRY WEATHER OFFICE
9:30 AM PDT TUE SEP 30, 2025
TODAY’S DISCUSSION:
Today will have somewhat of a break between fronts with showers holding off until later in the afternoon and evening. An upper-level low offshore is sending rounds of rain through this week with amounts generally under 0.10” daily. Winds today are starting light from S and will increase, turning from SSW-SW with higher gusts this afternoon. The morning aircraft sounding shows a much cooler atmosphere than yesterday, which will allow mixing heights to rise high today.
TODAY’S FORECAST:
Partly cloudy with a few showers late, surface winds from S at 8-12 mph early, then SSW-SW 10-14 mph in the afternoon and gusts to 25 mph
Madras’ Forecast High Today: 70°F (Monday High: 70°F; Rainfall: 0.08”)
Transport Winds: S 16-20 mph late this morning; then SSW-SW 18-22 mph this afternoon
Mixing Heights: Rising to 5000 feet this morning;
then up to 8000 feet this afternoon
Relative Humidity: Near 50% by 11 a.m.; down to 32% this afternoon
EXTENDED DISCUSSION:
Gusty S-SW winds continue on Wednesday as the upper-level low approaches the region. Showers are likely with mostly light rainfall amounts. Mixing heights will rise high. The weakening low will still bring a chance of showers on Thursday though winds will be lighter from SW-W. Friday and the weekend look to be mostly dry and sunny with winds from NW-N during the afternoon.
National Weather Service’s digital forecast is
available at:
Notes:
1. Mixing height, as used here, is the lowest height at which the
potential temperature exceeds the potential temperature at the
surface. As a practical matter it is the approximate height to
which a smoke plume will rise assuming good ignition, dry fuels, and
winds less than about 15 mph.
2. Transport winds are a layer average through the mixing height,
weighted slightly toward the winds at the top of the layer.
3. Surface wind direction is the general expected wind direction.
at a specific point surface winds are highly dependent on local
terrain conditions.
4. Ventilation Index (if you want to calculate it) is the height of the
mixing layer times the transport wind speed divided by 1000.
This forecast is provided under an agreement between the Oregon Department of
Agriculture (ODA) and the Oregon Department of Forestry (ODF). For more information, contact ODA at 503-986-4701.
Sherri Pugh
ODF Meteorologist