[willamette-fcst] Forecast - Tuesday, October 14th, 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 14th, 2008 at 9:00am.

Burn Advisory:
     Agricultural burning is not recommended.
     Preparatory burning is not allowed.
     Propane flaming is not allowed.
     Stack burning is not allowed.

Weather Discussion:
     Mixing heights near 4000 feet and westsouthwesterly
     transport winds allowed for the open burning of remaining
     Northern Willamette Valley fields Monday afternoon. 
     Although mixing heights will be fairly high again today,
     conditions are not favorable for stack burning, due to
     northeasterly transport winds.

     A very weak cold front moved across Western Oregon early
     this morning with only trace amounts of rain in the north
     valley.  The north coast did pick up a few hundredths of an
     inch of rain.  The frontal zone had pushed east of the
     Cascades, by mid-morning, and stretched from NE to SW
     Oregon.  It is mostly a cloud-maker and will continue to
     weaken, as it pushes into Idaho, today.

     The ODA surface analysis showed high pressure building into
     Western Oregon with surface winds in the Willamette Valley
     becoming northerly.  Satellite imagery showed areas of low
     clouds but also a fair amount of clearing across the valley.
     Skies should be partly sunny today across Western Oregon,
     with a lack of any storm activity in a westerly flow aloft.
 
     The Salem sounding this morning showed cooling aloft, since
     Monday afternoon, so high temperatures will be about 5
     degrees cooler today, even with some sunshine.

     The cool air mass and clearing skies will allow temperatures
     to drop well into the 30s, across the Valley, overnight.  It
     is not impossible that isolated pockets could drop to the
     freezing mark, but widespread freezing temperatures are not
     expected.

Surface Winds:
     N 5-12 this morning, N 7-14 this afternoon.
Transport Winds:
     NE 10 this morning, NNE 10 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 3600 feet.  Ventilation index 36.
High Temperature:
     Salem\'s high temperature today will be near 64.
Humidities:
     Relative humidity drops to 50% by 2pm.
     Minimum relative humidity will be near 46%.
Sunrise/Sunset:
     Salem sunset tonight: 6:28pm; sunrise tomorrow: 7:28am.

Extended Outlook:
     A transitory ridge of high pressure is forecast to build
     over Oregon Wednesday morning with areas of early morning
     fog givning way to increasing high clouds in the afternoon. 
     Low-level temperatures inversions will increase with surface
     temperatures likely cooling a few degrees from Tuesday.

     A warm front will spread considerable clouds over the region
     Wednesday night and Thursday with a chance of very light
     rain...mainly in the north valley.  Southeasterly winds will
     mix the air near the surface and likely warm temperatures a
     few degrees from Wednesday.

     A little clearing and slightly warmer temperatures are
     likely Friday, ahead of a cold front forecast to bring a
     chance of light rain by Friday night.  A weak westerly flow
     is forecast Saturda with an increasing southwesterly flow
     aloft Sunday.  A stronger cold front is forecast to come
     onshore Sunday night and Monday.

Tomorrow (15 Oct):  Areas of AM Fog.  Increasing High Clouds.  Chance of Light Rain.  35/61

Thu (16 Oct):  Cloudy.  Chance of Sprinkles/Light Rain...Mainly North.  41/64

Fri (17 Oct):  Increasing Clouds.  Chance of Light Rain Late.  47/67

Sat (18 Oct):  Becoming Partly Sunny.  46/65

Sun (19 Oct):  Increasing High Clouds and Mild.  Chance of Rain Late.  44/67

Mon (20 Oct):  Rain Likely.  Snow Level Dropping to near 4000 Feet.  47/59

Tue (21 Oct):  Showers Ending...Becoming Partly Sunny.  46/62

ODA Meteorologist
weather at oda.state.or.us