[willamette-fcst] Forecast - Wednesday, March 3rd, 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: 
     Wednesday, March 3rd, 2010 at 9:00am.

Burn Advisory:
     Recommended burn times for agricultural burning are from now until 4:00pm.
     Stack burning is not allowed.

Weather Discussion:
     A spoke of upper-level energy rotated across northwestern
     Oregon Tuesday afternoon, activating a surface front that
     was moving onshore.  Bands of showers developed right over
     northwestern Oregon.  Some sections of the valley escaped
     with little to no rain, while others picked up from a tenth
     to a quarter of an inch in a very short time period.  The
     showers rapidly tapered off Tuesday evening, with mostly
     clouds skies overnight holding valley minimums mostly above
     the 40 degree mark.

     Satellite imagery showed the main cloud band from the next
     weather system stretching from Newport to Klamath Falls
     southward, into northern and central California.  The main
     punch from this system is headed towards California, with
     the low-pressure center off the northern California
     coastline.  However, Doppler radar was showing some light
     rain extending northward into the central Willamette Valley.

     The ODA surface analysis showed almost flat pressure
     gradients across western Oregon, with computer models
     forecast northeasterly transport winds this morning to
     switch to light south-southwesterly this afternoon.  Skies
     should remain mostly cloudy today, with the best chance of
     rain from Salem south.  Valley highs will likely be a few
     degrees cooler than on Tuesday, with some light snow above
     about 3500 feet in the Cascades.

Surface Winds:
     Var 3-10 this morning, S 5-10 this afternoon.
Transport Winds:
     NE 10 this morning, SSW 6 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 2000 feet.  Ventilation index 20.
High Temperature:
     Salem\'s high temperature today will be near 53.
Humidities:
     Minimum relative humidity will be near 66%.
Sunrise/Sunset:
     Salem sunset tonight: 6:02pm; sunrise tomorrow: 6:44am.

Extended Outlook:
     A transitory ridge of high pressure will dry things out on
     Thursday.  The next weather system, on Friday, will also
     encounter the split-flow pattern in the jet stream offshore
     and move mainly into California.  A weak ridge of high
     pressure will likely bring dry and mild conditions for at
     least the first half of the weekend.

     A weak cold front is forecast to come onshore Sunday afternoon,
     which appears as if it will be strong enough to spread some rain
     and higher elevation snow back across western Oregon.  Some
     computer models are indicating a possible change in the weather
     pattern, beginning the middle of next week, that could bring
     some much needed snow to the mountains.

Tomorrow (04 Mar):  Partly Sunny.  35/55

Fri (05 Mar):  Mostly Cloudy.  Chance of Rain...Mainly South.  Snow Level 4000 Feet.  40/55

Sat (06 Mar):  Partly Sunny.  35/58

Sun (07 Mar):  Increasing Clouds.  Chance of Rain PM.  Snow Level 4000 Feet.  37/53

Mon (08 Mar):  Decreasing Chance of Showers.  Snow Level 3-4000 Feet.  37/53

Tue (09 Mar):  Increasing Clouds.  Chance of Rain Late.  36/55

Wed (10 Mar):  Rain Likely...Snow Level Possibly Lowering to Near 3000 Feet.  38/52

ODA Meteorologist
weather at oda.state.or.us