[willamette-fcst] Forecast - Monday, February 8th, 2010

[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: 
     Monday, February 8th, 2010 at 9:00am.

Burn Advisory:
     Recommended burn times for agricultural burning are from 10:00am to 3:30pm.
     Stack burning is not allowed.

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

Weather Discussion:
     After a mostly sunny and unseasonably mild Friday, with
     Eugene and Salem both setting new daily record high
     temperatures of 62 degrees, light rain returned to western
     Oregon on Saturday.  Conditions dried out again Sunday,
     although skies stayed mostly cloudy.  Temperatures remained
     above normal over the weekend, with valley highs in the low
     to mid 50s.  Partial clearing and light winds last night
     allowed temperatures to cool into the 30s across most of
     western Oregon by early this morning.  That led to
     widespread fog formation, with visibilities still locally at
     or below one-quarter of a mile, along the coast and in the
     Willamette Valley at mid-morning.

     Visible satellite imagery showed low clouds and fog covering
     most of Washington and Oregon this morning.  The exception
     was over the Cascades of both states, where mostly sunny
     skies prevailed.  There were also some breaks in the
     overcast along the coast and over the coastal range.  The
     ODA surface analysis showed weak high pressure centered over
     and just east of the Willamette Valley, where winds were
     mostly calm at mid-morning.  That was a light easterly drift
     to the wind along the coastal strip.  Mid-morning
     temperatures, west of the Cascades, ranged from just below
     freezing, at Troutdale, to the low 40s in Corvallis and
     along much of the Oregon coast.

     A westerly split-flow jet stream pattern, forced by a strong
     El Nino event in the tropical Pacific Ocean, will continue
     the mild early February weather across western Oregon this
     week.  Infrared satellite imagery showed the main
     cloud-band, associated with an approaching weather system,
     still about 200 miles offshore, although some middle and
     high clouds were already spreading onshore.  Daytime heating
     will help break up the fog and low clouds across Western
     Oregon today.

     The air aloft remains mild for this time of year, with the
     freezing level measured over Salem this morning at 4500
     feet.  That is warm enough to support valley temperatures
     warming into the upper 50s this afternoon, but considerable
     fog, low clouds, and lack of wind will likely combine to cap
     valley temperatures in the low 50s.  Ventilation conditions
     will only briefly improve to fair this afternoon, so stack
     burning was not allowed.

Surface Winds:
     ESE 0-6 this morning, NE 2-6 this afternoon.
Transport Winds:
     SE 6 this morning, ESE 5 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 2500 feet.  Ventilation index 15.
High Temperature:
     Salem\'s high temperature today will be near 52.
Humidities:
     Minimum relative humidity will be near 60%.
Sunrise/Sunset:
     Salem sunset tonight: 5:30pm; sunrise tomorrow: 7:21am.

Extended Outlook:
     The next weather system will weaken as it encounters the
     split-flow in the jet stream just offshore.  The bulk of the
     moisture is forecast to dive southweastward, into
     California, on Tuesday.  Some clouds will sweep across
     western Oregon tonight and Tuesday but with only a chance of
     light rain and higher elevation snow.  A transitory ridge of
     high pressure should provide a dry and mild Wednesday with
     areas of morning fog.  Clouds will be on the increase, by
     Wednesday evening, as the next in a series of weather
     systems approaches the coastline.

     A warm front is forecast to bring lots of clouds and a
     chance of light rain to western Oregon Wednesday night and
     Thursday morning.  Snow levels should rise above the passes
     Thursday, as warmer air aloft moves over the region.  The
     trailing cold front is likely to bring some light rain
     Thursday night through Friday morning, with snow levels
     dropping back to the Cascade passes.

     The warm front from the next system will push mainly north of the region on
     Saturday.  Sunday should be another mild day, ahead of a cold front
     forecast to bring more rain to western Oregon Sunday night. A few showers may
     linger well into Monday.

Tomorrow (09 Feb):  Mostly Cloudy.  Chance of Light Rain.  Snow Level 4000 Feet.  36/53

Wed (10 Feb):  Areas of AM Fog.  Partial Clearing...Increasing Clouds Late.  34/52

Thu (11 Feb):  Chance of Light Rain.  Snow Level Rising to 5-6000 Feet.  41/52

Fri (12 Feb):  Rain Likely.  Snow Level Dropping to 4000 Feet.  42/53

Sat (13 Feb):  Chance of Light Rain...Mainly North.  Snow Level 5-6000 Feet.  42/55

Sun (14 Feb):  Mostly Cloudy and Mild.  Rain Likely Late.  41/56

Mon (15 Feb):  Rain Early...Turning to Showers.  Snow Level 3-4000 Feet.  36/53

ODA Meteorologist
weather at oda.state.or.us