[willamette-fcst] Forecast - Tuesday, October 7th, 2008

[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: 
     Tuesday, October 7th, 2008 at 9:00am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from now until 5:00pm.
     Preparatory burning is not allowed.
     Propane flaming is not allowed.
     Straw stack burning is allowed, for dry stacks, from now until 5:00pm.

Weather Discussion:
     A weak cold front swept across Western Oregon overnight...dropping
     about one-tenth to one-third of an inch.  The heavier amounts were
     in the Coast Range and Cascades.  Most of the Willamette Valley
     received about one-tenth of an inch.  Mostly cloudy skies held
     temperatures up overnight with morning minimums staying in the low
     to mid 50s.

     The cold front had moved east of the Cascades be mid-morning
     with a cool westerly flow aloft continuing to circuate a few
     showers across Western Oregon.  Doppler radar showed
     scattered light showers, moving from WNW to ESE, across
     Western Washington and NW Oregon.  There was some enhancement
     of the showers, as they bumped up against the Cascades.

     The Salem sounding this morning showed considerable cooling
     aloft with the freezing level at 9300 feet.  Futher cooling
     aloft is forecast today, so surface temperatures will
     struggle into the low 60s this afternoon.  High mixing
     heights and northwesterly transport winds will make for good
     ventilation conditions for stack burning today, but fields
     will likely be too damp for open burning.

Surface Winds:
     WSW 5-12 this morning, NW 5-15 this afternoon.
Transport Winds:
     W 10 this morning, NW 12 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 4500 feet.  Ventilation index 54.
High Temperature:
     Salem\'s high temperature today will be near 63.
Humidities:
     Minimum relative humidity will be near 58%.
Sunrise/Sunset:
     Salem sunset tonight: 6:40pm; sunrise tomorrow: 7:20am.

Extended Outlook:
     Showers should taper off Wednesday with continued cool
     onshore flow.  Ventilation conditions will remain good over
     Western Oregon.  A cold upper-level trough is forecast to
     drop, from the Gulf of Alaska, into the region Thursday. 
     That will increase the showers over Western Oregon with most
     of the Willamette Valley likely picking up another one-tenth
     of an inch of rain with locally greater amounts...especially
     in the north valley near the Cascade Foothills.

     Snow levels will drop the near or below 4000 feet by
     Thursday afternoon.  The Northern Cascade Mountain Passes
     will likely get their first snowfall of this season.  A
     strong upper-level ridge of high pressure is still forecast
     to build over the west coast, beginning Friday, for what
     should be several days of dry weather.  Offshore flow may
     develop over the weekend, which will aid in the drying of
     damp fields.

     How long the protective ridge of high pressure will last is
     in question, but the latest guidance is suggesting a
     transition back to a damp westerly flow during the first
     half of next week.  That transition may present a
     late-season burning opportunity, if fields are dry enough.

Tomorrow (08 Oct):  Mostly Cloudy.  Chance of Showers...Mainly North.  41/61

Thu (09 Oct):  Increasing Showers and Very Cool.  Snow Level Dropping to 4000 feet.  39/56

Fri (10 Oct):  Showers Ending...Becoming Partly Sunny.  Continued Cool.  37/59

Sat (11 Oct):  Chilly Start with areas of AM Fog...Becoming Mostly Sunny.  35/62

Sun (12 Oct):  Areas of AM Fog...Mainly South...Sunny.  38/65

Mon (13 Oct):  Mostly Sunny.  Increasing Clouds Late.  41/67

Tue (14 Oct):  Mostly Cloudy.  Chance of Rain.  43/64

ODA Meteorologist
weather at oda.state.or.us