[willamette-fcst] Forecast - Wednesday, November 25th, 2009

[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.

...Next Update Scheduled for Monday, November 30th, 2009 at 9:00am...

Issued: 
     Wednesday, November 25th, 2009 at 8:45am.

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

Weather Discussion:
     A transitory upper-level ridge of high pressure allowed fog
     to form overnight across much of the Willamette Valley. 
     Visibilities this morning were locally less than one-quarter
     of a mile. Fortunately, temperature generally stayed just
     above freezing mark.  A fairly impressive frontal system
     extends southwestward, from Vancouver Island, British
     Columbia, to about 300 miles off of the Oregon Coast this
     morning.  The cloud-shield stretches all the way to just
     north of Hawaii.

     Doppler radar showed rain spreading across the extreme
     northwestern tip of Washington, with satellite imagery
     showing clouds extending across most of western Washington
     and as far south as the northwestern corner of Oregon.  The
     front should remain north and west of Oregon today but will
     be close enough to help break up the fog by around midday. 
     A mild southerly flow, both at the surface and aloft, will
     lift western Oregon temperatures well into the 50s again
     this afternoon, with some filtered sunshine.  Salem\'s high
     Tuesday was 59 degrees, Corvallis hit 60.  Normal valley
     high temperatures, for late November, are around 50 degrees.

Surface Winds:
     SSE 3-8 this morning, SSE 5-10 this afternoon.
Transport Winds:
     S 6 this morning, S 10 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 1700 feet.  Ventilation index 17.
High Temperature:
     Salem\'s high temperature today will be near 56.
Humidities:
     Minimum relative humidity will be near 53%.
Sunrise/Sunset:
     Salem sunset tonight: 4:35pm; sunrise tomorrow: 7:24am.

Extended Outlook:
     After areas of morning fog, clouds will increase across
     western Oregon Thanksgiving Day, as a cold front slowly sags
     southeastward into the state.  Rain will spread, from
     northwest to southeast, across western Oregon by Thursday
     evening.  Rain Thursday night should turn to showers Friday,
     with the snow level dropping to the Cascade passes.  A warm
     front will bring lots of clouds Saturday, but the bulk of
     the rainfall should stay north of Oregon.  Some light rain
     may spread as far south as the central Willamette Valley. 
     The snow level will lift to near or above the Cascade passes
     by Saturday night.

     A building upper-level ridge of high pressure will bring dry
     and mild weather to the region Sunday, with areas of valley
     fog giving way to partly sunny skies.  A cool weather system
     is forecast to drop southward, from the Gulf of Alaska, on
     Monday...possibly extending far enough south to bring rain
     and mountain snow back to much of Oregon.  A dry and cool
     northwesterly flow aloft is forecast Tuesday and Wednesday,
     with valley minimums possibly dropping below the freezing mark.

Tomorrow (26 Nov):  Areas AM Fog.  Rain Developing By Evening.  39/55

Fri (27 Nov):  Showers...Decreasing Late.  Snow Level Dropping to 3000 Feet.  40/48

Sat (28 Nov):  Mostly Cloudy.  Chance of Rain...Mainly North.  36/47

Sun (29 Nov):  Areas of AM Fog.  Partly Sunny in the Afternoon.  34/51

Mon (30 Nov):  Chance of Rain...Mainly North.  Snow Level Dropping to 3000 Feet.  36/46

Tue (01 Dec):  Areas of AM Fog.  Partly Sunny in the Afternoon.  32/48

Wed (02 Dec):  Areas of AM Fog...Mainly South.  Mostly Sunny in the Afternoon.  30/50

ODA Meteorologist
weather at oda.state.or.us