SILVERTON HILLS FIELD BURNING FORECAST

OREGON DEPARTMENT OF FORESTRY WEATHER OFFICE

11:50 AM PDT MON JUL 14, 2025

 

WEATHER DISCUSSION:

 

It was a hot weekend, with valley temperatures climbing into the mid-90s on Saturday and upper-90s on Sunday.  State Fire Marshal Burn-Ban conditions were reached Sunday afternoon, due to hot temperatures, brisk north winds, and low humidity.

 

Salem’s temperature is within a degree or two of 24 hours ago, and the air mass remains very dry.  Humidity levels have already dropped below 45% and will likely fall to near or below 30% later this afternoon.  Despite cooler temperatures, due to an incoming dry cold front, the combination of wind and low humidity may, once again, put the valley in State Fire Marshal Burn-Ban Conditions later this afternoon.

 

BURN ADVISORY:

 

Agricultural burning is not recommended.

 

Prep burning is not allowed.

 

Field burning is a possibility today, depending on weather conditions.

 

(See “Notes” below for difference between field burning and Agricultural burning)

 

TODAY’S FORECAST:

 

Sunny but cooler.  Turning breezy this afternoon and early evening with low humidity.

 

Salem's high temperature today will be near 88°F (average is 84°F).

Relative humidity: Dropping to near or below 30% by 5 p.m.

Surface winds: NW-N 10-15 mph; possible gusts to 20 mph.

Transport winds: NW-N 15-20 mph.

Mixing height: Above 3000 at midday; rising to 5000 feet by 5 p.m.

Salem’s sunset tonight: 8:56 p.m.

 

(Salem Airport data for Friday, July 11th: High 91°F; Rainfall: .00”)

(Salem Airport data for Saturday, July 12th: High 93°F; Rainfall: .00”)

(Salem Airport data for Sunday, July 13th: High 98°F; Rainfall: .00”)

 

(Maximum Ventilation Index expected today: 100)

                                                                           

EXTENDED DISCUSSION:

 

High pressure rapidly rebuilds over Oregon Tuesday and Wednesday with temperatures climbing back into the mid-to-upper 90s in the central Willamette Valley.

 

Another dry upper-level trough will bring some cooling on Thursday, but high temperatures will likely remain near 90°F with little in the way of clouds and continued low humidity.

 

Upper-level winds are expected to turn SW on Friday, with increasing onshore flow starting to raise humidity levels slightly.  However, skies should remain mostly sunny with high temperatures holding near 90°F.

 

A weak upper-level trough may bring a few clouds and cool temperatures into the 80s over the weekend, but no precipitation is expected.

 

The National Weather Service’s digital forecast is available at:

http://forecast.weather.gov/MapClick.php?lat=44.90549606158295&lon=-122.8106689453125&site=pqr&unit=0&lg=en&FcstType=text

 

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.  Ventilation Index is the height of the mixing layer (ft) times

         the transport wind speed (mph) divided by 1000.

                                                            

     4.  Surface wind direction is the general expected wind direction. 

         At a specific point surface winds are highly dependent on local

         terrain conditions.

 

     5.  In accordance with OAR 837-110-0090, all field burning shall be

         banned when any two of the following criteria are present:

         A. Temperature of 95 degrees Fahrenheit or above

         B. Relative humidity of 30 percent or below        

         C. Wind speed of 15 miles per hour or higher

                                                            

     6.  Agricultural burning: Burning of any agricultural waste generated

         by an agricultural operation that uses or intends to use land

         primarily for the purpose of obtaining profit by raising,

         harvesting, and selling crops or animals. Prohibited materials

         such as tires cannot be burned, even in an agricultural setting.

         If you make your primary living from an agricultural operation,

         you are considered an agricultural operator and can agricultural

         burn. If you don't make your primary living from the agricultural

         operation, you are a backyard burner and subject to the rules of

         backyard burning.  Contact your local fire district for

         information about backyard burning.

                                             

     7.  Open field burning: Burning of any grass seed or cereal grain  

         crops, or associated residue, including steep terrain and species

         identified by the Director of Agriculture, or any “emergency” or

         “experimental” burning (ORS 603-077-0105(29)).

                                                    

     8.  Preparatory (prep) burning: A type of field burning where

         controlled burning of portions of selected fields is conducted

         for the specific purpose of reducing the fire hazard potential

         or other conditions which would otherwise inhibit rapid ignition

         burning when the field is subsequently open burned

         (ORS 603-077-0105(34)).

 

     9.  Test fires: A type of field burning where individual field burns

         are specifically authorized by the Department for the purpose of

         determining or monitoring atmospheric dispersion conditions (ORS

         603-077-0105(54)).

 

This forecast is provided under an agreement between the Oregon Department

of Agriculture (ODA) and the Oregon Department of Forestry (ODF).  For

information contact ODA at 503-986-4701.

 

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Pete Parsons

ODF Meteorologist