[willamette-fcst] Forecast - Thursday, October 16th, 2008

[Willamette Valley Ag/Burning Forecast]

Daily Smoke Management Forecast




Oregon Department of Agriculture
Smoke Management Program
Weather Outlook and Field Burning Advisory for Willamette Valley Growers and Fire Districts.

Issued: 
     Thursday, October 16th, 2008 at 9:00am.

Burn Advisory:
     Agricultural burning is not recommended.
     Preparatory burning is not allowed.
     Propane flaming is not allowed.
     Stack burning is not allowed.

Weather Discussion:
     A warm front brought very light rain to the Willamette
     Valley overnight with total rainfall amounts ranging from a
     trace in the south valley to several hundredths of an inch
     in the north valley. The Stayton area picked up about
     one-tenth of an inch. The warm front is forecast to slowly
     move north today with the light rain tapering off by early
     this afternoon.

     The Salem sounding this morning showed considerable warming
     aloft since Wednesday morning, so mixing heights will be
     held to near or below 2000 feet again today.  Low-level
     southerly winds had increased, in response to the warm
     front.  The ODA surface analysis also showed increased
     southerly gradients with southerly surface winds of 5-15 mph
     in the Willamette Valley.  Cloudy and windy conditions made
     for a much warmer overnight period with morning minimums
     staying near 50 degrees. 

     Skies may partially clear later this afternoon, mainly in
     the south valley.  With the air aloft continuing to warm,
     even a little sunshine would combine with southerly winds to
     lift temperatures into the mid to upper 60s.  However, where
     the clouds persist, which is likely in the north valley,
     temperatures will not likey warm more than the low 60s. 
     Partial clearing tonight should allow temperatures to cool
     into the mid to upper 40s tonight with areas of fog forming.

Surface Winds:
     S 5-15 this morning, S 5-12 this afternoon.
Transport Winds:
     S 15 this morning, S 12 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 2000 feet.  Ventilation index 30.
High Temperature:
     Salem\'s high temperature today will be near 64.
Humidities:
     Minimum relative humidity will be near 60%.
Sunrise/Sunset:
     Salem sunset tonight: 6:25pm; sunrise tomorrow: 7:31am.

Extended Outlook:
     Partial clearing and warm air aloft Friday should help
     surface temperatures climb into the mid to upper 60s in the
     north valley and near 70 in the south valley.  If surface
     temperatures become warm enough Friday afternoon, forecast
     west-southwesterly transport winds may provide adequate
     ventilation for the burning of remaining dry fields.

     A weak cold front is forecast to bring a chance of light
     rain Friday night through Saturday morning...mainly to the
     north valley.  Transport winds are forecast to turn
     northerly Saturday.  A transitory upper-level ridge is
     forecast to move over the region Sunday.  Increasing
     southwesterly flow aloft will send a stronger cold front
     onshore Monday.

     A transitory ridge is forecast for provide a break from the
     damp weather Tuesday with some afternoon clearing.  Another
     cold front will likely bring more rain late Wednesday and Thursday.

Tomorrow (17 Oct):  Areas of AM Fog.  Increasing Clouds.  Chance of Light Rain Late.  47/67

Sat (18 Oct):  Chance of Light Rain Early...Partial Afternoon Clearing.  48/63

Sun (19 Oct):  Areas of AM Fog.  Mostly Sunny in the Afternoon.  45/65

Mon (20 Oct):  Rain Developing.  Snow Level Dropping to near 4500 Feet Late.  45/59

Tue (21 Oct):  Areas of AM Fog...Partly Sunny Afternoon.  42/62

Wed (22 Oct):  Increasing Clouds...Chance of Rain by Afternoon.  39/61

Thu (23 Oct):  Chance of Showers.  42/59

ODA Meteorologist
weather at oda.state.or.us