[willamette-fcst] Forecast - Tuesday, November 18th, 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: 
     Tuesday, November 18th, 2008 at 9:00am.

Burn Advisory:
     Agricultural burning is not recommended.
     Stack burning is not allowed.

Weather Discussion:
     Increasing southerly flow aloft helped to clear the fog and
     low clouds from sections of the southern Willamette Valley
     Monday afternoon and mix down very warm air aloft to the
     surface.  Eugene tied a daily record high temperature with
     70 degrees (previously set in 1932).  In central Oregon,
     Redmond shattered their previous daily record high, for
     November 17th, by soaring to 75 degrees (old record 66 
     degrees set in 1976).

     Eastern Oregon temperatures also got into the record books
     Monday.  Meacham, in northeast Oregon, set a daily record with
     a high of 58 degrees (old record 57 set in 1949).  Monday was
     also unseasonably warm along the coast.  Tillamook hit the
     70-degree mark and Newport climbed to 66.

     There was quite a contrast in afternoon temperatures across
     the Willamette Valley Monday.  While much of the south
     valley warmed well into the 60s, including a 66-degree high
     at Corvallis, fog was slow to clear in areas of the north
     valley.  McMinnville only managed 51 degrees, and Salem
     split the difference with a high of 58.

     A weakening cold front moved onto the north coast early this
     morning, but it was not strong enough to keep areas of
     rather dense fog from forming over sections of the Willamette
     Valley...mainly from about Aurora to Corvallis.  The front will
     fall apart, as it drifts southeastward, across western Oregon,
     today.  Southwesterly flow aloft will maintain mostly cloudy
     skies, above the fog layer.

     The Salem sounding showed significant cooling aloft since
     Monday, so temperatures should be more uniform across the
     valley this afternoon.  Most areas should see highs today
     in the mid to upper 50s with light winds.  There is a slight
     chance of sprinkles over extreme northwest Oregon, otherwise
     it should remain dry across the state today.

Surface Winds:
     Var 0-5 this morning, N 0-5 this afternoon.
Transport Winds:
     Var 3 this morning, N 3-6 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 1200 feet.  Ventilation index 4.
High Temperature:
     Salem\'s high temperature today will be near 55.
Humidities:
     Minimum relative humidity will be near 66%.
Sunrise/Sunset:
     Salem sunset tonight: 4:40pm; sunrise tomorrow: 7:16am.

Extended Outlook:
     The upper-level ridge is forecast to rebuild Wednesday, with
     areas of dense fog reforming...mainly in the central and
     south valley.  A developing offshore flow, from the Columbia
     Gorge, should help to keep dense fog out of the extreme
     north valley.  Skies will remain partly to mostly cloudy,
     above the fog layer.  A stronger cold front should increase
     the offshore flow enough to keep widespread fog from forming
     Wednesday night.

     Rain will likely spread across western Oregon Thursday
     morning, with cooler air aloft improving ventilation
     conditions.  Rain will be heaviest in the north valley,
     where amounts could top one-half inch.  Valley temperatures
     will be near normal, even with significant cooling aloft. 
     Snow levels may drop enough, by Thursday afternoon, for some
     accumulating snow over the Cascade passes.

     A warm front, from the next system, will spread clouds across
     western Oregon Friday, but rainfall should stay mostly north
     of the state.  The cold front could extend far enough south
     to bring light rain to much of western Oregon Saturday.

     A strong upper-level ridge will likely bring a return of dry
     weather Sunday through Tuesday with a little sunshine.  Low-level
     temperature inversions will make for poor ventilation conditions
     and lead to valley fog formation. Outflow, from the Columbia Gorge,
     should help keep widespread fog from forming in the north valley,
     but it could become persistent in the central and south valley.

Tomorrow (19 Nov):  Areas of Fog.  Increasing Clouds.   Chance of Rain Late.  39/56

Thu (20 Nov):  Rain Likely.  Snow Level Dropping to 4-5000 Feet.  43/52

Fri (21 Nov):  Mostly CLoudy.  Chance of Light Rain North. Snow Level 7000 Feet.  36/52

Sat (22 Nov):  Mostly Cloudy.  Chance of Light Rain.  Snow Level 4-5000 Feet.  40/52

Sun (23 Nov):  Areas of Fog...Mainly Central and South Valley.  Partly Sunny.  37/52

Mon (24 Nov):  Areas of Fog...Mainly Central and South Valley.  Partly Sunny.  37/52

Tue (25 Nov):  Areas of Fog...Mainly Central and South Valley.  Partly Sunny.  37/52

ODA Meteorologist
weather at oda.state.or.us