[willamette-fcst] Forecast - Wednesday, February 10th, 2010

Wed Feb 10 09:09:36 PST 2010

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 10th, 2010 at 9:00am.

Burn Advisory:
     Recommended burn times for agricultural burning are from 12:00pm to 3:30pm.
     Straw stack burning is allowed from 12:00pm until 3:30pm.

      ...The rules for stack burning have changed.  Stack burning
     permits must be obtained from ODA Smoke Management Personnel...

Weather Discussion:
     A drying northwesterly flow aloft helped to clear the low
     clouds from the Willamette Valley late Tuesday afternoon. 
     Clearing skies allowed temperatures to drop to the freezing
     mark in the Willamette Valley overnight, with areas of fog
     reforming.  Aurora was one of the colder spots with a low of
     30 dgrees.  Salem and McMinnville both dipped to 32. By
     early this morning, however, clouds began to increase, from
     an approaching storm system, with the fog lifting and
     temperatures climbing into the upper 30s and lower 40s.

     Satelite imagery showed a solid band of low clouds moving
     onshore at mid-morning, with middle and high clouds
     extending across the Cascades over much of central and
     eastern Oregon.  Doppler radar showed light precipitation
     along the coast and extending into the central and southern
     Willamette Valley.  The ODA surface analysis showed
     increasing southeasterly pressure gradients, with winds in
     the 5-15 mph range greatly improving ventilation conditions
     across western Oregon. Light rain was being reported at
     Astoria and should spread across the Willamette Valley
     during the next couple of hours.

     Cloudy skies and occasional light rain will keep high
     temperatures in the mid to upper 40s across the Willamette
     Valley today, with low 50s possible along the coast. 
     Southeasterly winds will continue to increase slightly and
     turn more southerly this afternoon, making for good
     ventilation conditions over the valley.  The freezing level
     was measured at just over 5000 feet this morning, so snow
     levels will be near the Cascade passes today, where a couple
     of inches of new snow are possible.  The frontal system is
     forecast to stall over western Oregon today and become
     activated by an approaching warm front tonight.  That will
     likely lift snow levels above the Cascade passes by Thursday
     morning, with increasing rain across western Oregon.

Surface Winds:
     SE 7-15 this morning, S 10-20 this afternoon.
Transport Winds:
     S 15 this morning, SSW 20 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 2500 feet.  Ventilation index 50.
High Temperature:
     Salem\'s high temperature today will be near 47.
Humidities:
     Minimum relative humidity will be near 74%.
Sunrise/Sunset:
     Salem sunset tonight: 5:33pm; sunrise tomorrow: 7:19am.

Extended Outlook:
     Thursday should be quite wet and mild across western Oregon,
     with a morning warm front followed by a fairly strong cold
     front Thursday evening.  Southerly winds will increase late
     Thursday, with possible gusts to around 60 mph along the
     coast Thursday night.  The cold front should drop snow
     levels back to the Cascade passes by Friday morning, as the
     steady rain turns showery and begins to taper off.

     A colder weather system is forecast to spread more rain
     onshore Friday, with the snow level staying near or slightly
     below the Cascade passes.  Southeasterly winds should make
     for good ventilation conditions.  A transitory ridge of high
     pressure may dry things out Saturday, especially south, as a
     warm front brushes by to our north.  It there is enough
     mixing of the air mass, temperatures could become quite mild
     Saturday afternoon.  A weak cold front may bring some light
     rain Sunday, with snow levels likely remaining near or above
     the Cascade passes.  Another warm front will bring a chance
     of rain Monday, with snow levels lifting above the Cascade
     passes.  A weak cold front is forecast to come onshore Tuesday.

Thu (11 Feb):  Rain Likely.  Blustery Along the Coast Late.  Snow Level 5500 Feet.  42/53

Fri (12 Feb):  Rain Likely...Turning to Showers.  Snow Level Dropping to 4000 Feet.  40/52

Sat (13 Feb):  Chance of Light Rain...Mainly North.  Mild.  Snow Level 6000 Feet.  40/58

Sun (14 Feb):  Mostly Cloudy and Mild.  Chance of Light Rain.  Snow Level 5500 Feet.  41/53

Mon (15 Feb):  Chance of Light Rain...Mainly North.  Snow Level 6000 Feet.  39/54

Tue (16 Feb):  Chance of Rain.  Snow Level 5000 Feet.  37/54

Wed (17 Feb):  Partly Sunny.  36/57

ODA Meteorologist
weather at oda.state.or.us