[willamette-fcst] Forecast - Wednesday, February 4th, 2009

Wed Feb 4 08:59:32 PST 2009

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: 
     Wednesday, February 4th, 2009 at 9:00am.

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

Weather Discussion:
     Willamette Valley temperatures climbed into the mid and
     upper 50s Tuesday afternoon with Aurora hitting 60 degrees. 
     Offshore winds helped coastal temperatures soar to 70
     degrees at Tillamook and Newport.  It was also very mild in
     the mountains Tuesday, with Timberline Lodge topping out at
     55 degrees.  The freezing level was at 11,000 feet Tuesday
     afternoon.  East of the Cascades, Redmond and Klamath Falls
     both had highs Tuesday of 62 degrees.  However, some valley
     locations stayed in the mid and upper 40s.

     Fair skies and light winds overnight allowed temperatures to
     drop below freezing across much of the Willamette Valley by
     early this morning, with minimums in the upper 20s common. 
     The exception was near the western end of the Comumbia
     Gorge, where brisk easterly winds kept the low-level air
     stirred up, and minimum temperatures stayed near 40 degrees.
     Offshore pressure gradients were still in place this
     morning across the state.  Easterly winds were gusting at
     high as 30-40 mph at times from Troutdale to Corbett.  Winds
     were light in the Willamette Valley, but easterly winds were
     blowing around 10 mph along the coast at Newport.

     A strong upper-level ridge of high pressure will continue
     the dry and mild weather today across the region.  The
     freezing level was between 10,000 and 11,000 feet over
     western Oregon.  The Salem sounding showed a strong
     low-level temperature inversion from the surface, where
     temperatures were near freezing, up to 2500 feet, where
     temperatures were in the upper 50s.  That will make for very
     poor ventilation conditions again today, with mixing heights
     below 1000 feet.

     Satellite imagery showed areas of fog in the southern
     Willamette Valley and the valleys of southwestern Oregon. 
     Dry offshore flow kept fog from forming across most of the
     north valley overnight.  Middle and high clouds covered most
     of the state, in response to an upper-level low pressure
     system off the California coast.  That will result in some
     filtering of the sunshine this afternoon, which should cap
     temperatures a few degrees cooler than on Tuesday.  Valley
     highs will be generally in the low to mid 50s with light
     winds.  Middle and high clouds should continue to increase
     overnight, with areas of fog forming...mainly in the central
     and south valley.  Temperatures should not be quite as
     chilly overnight with minimums close to the freezing mark.

Surface Winds:
     Var 0-5 this morning, N 0-5 this afternoon.
Transport Winds:
     N 4 this morning, N 4 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 700 feet.  Ventilation index 3.
High Temperature:
     Salem\'s high temperature today will be near 54.
Humidities:
     Minimum relative humidity will be near 52%.
Sunrise/Sunset:
     Salem sunset tonight: 5:25pm; sunrise tomorrow: 7:26am.

Extended Outlook:
     Major changes in the weather pattern are in store, beginning
     Thursday, across the Pacific Northwest.  A weather system,
     dropping southeastward from the Gulf of Alaska, will combine
     forces with the upper-level low pressure system, off the
     California coast, and bring mostly cloudy skies with
     increasing showers to western Oregon Thursday afternoon
     through Friday.  The freezing level should drop to near 6000
     feet Thursday afternoon, and down to 4000 feet Friday, with
     improving ventilation conditions.  Overnight minimums will
     be warmer, but daytime highs will progressively cool.

     A transitory ridge will likely bring a dry and farily mild
     day to the region Saturday with a stronger weather system
     bringing rain and mountain snow on Sunday.  Showers will
     continue into Monday with very low snow levels.  A warm
     front may spread light rain back across northwestern Oregon
     by Tuesday afternoon with a cold front bringing increasing
     rain and mountain snow again Wednesday.

Tomorrow (05 Feb):  Mostly Cloudy.  Chance of PM Showers.  33/50

Fri (06 Feb):  Mostly Cloudy.  Scattered Showers.  Snow Level 3000 Feet.  38/48

Sat (07 Feb):  Partly Cloudy and Mild.  Freezing Level 5-6000 Feet.  34/51

Sun (08 Feb):  Rain with Mountain Snow.  Snow Level Dropping to 2000 Feet.  34/46

Mon (09 Feb):  Decreasing Showers.  Show Level 1500 Feet.  35/46

Tue (10 Feb):  Increasing Chance of Rain.  Snow Level Rising to 3500 Feet.  33/46

Wed (11 Feb):  Rain and Mountain Snow.  Snow Level 3000 Feet.  36/46

ODA Meteorologist
weather at oda.state.or.us