[willamette-fcst] Forecast - Wednesday, January 7th, 2009

Wed Jan 7 12:00:54 PST 2009

Daily Smoke Management Forecast

Oregon Department of Agriculture
Smoke Management Program
Weather Outlook and Field Burning Advisory for Willamette Valley Growers and Fire Districts.

NOON UPDATE

Issued: 
     Wednesday, January 7th, 2009 at 12:00pm.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from now until 3:00pm.
     Straw stack burning is allowed from now until 3:00pm.

Weather Discussion:
     A very moist frontal system brought heavy rain to western
     Washington and extreme northwestern Oregon last night
     through this morning.  24-hour rainfall amounts from 1-3
     inches were common across western Washington.  There were
     sections of the extreme northern Oregon coastal range that
     have received just over two an one-half inches of rain in
     the past 24 hours.  Along the coast, Astoria has picked up
     just over two inches of rain in the past 24 hours.  Rainfall
     amounts fall off quickly to the south, with Tillamook only
     reporting around one-half inch of rain in the past 24 hours.
     Rain has been even lighter in the Willamette Valley, with 24-hour
     amounts generally less than one-quarter of an inch.

     Strong southerly winds have been gusting to near 40 mph all
     day from the Oregon Coast to the Willamette Valley with
     temperatures staying in the low to mid 50s.  Rain and wind
     will continue to increase across western Oregon this
     afternoon, as the frontal boundary sags southward.  High
     wind warnings have been issued for later this afternoon and
     tonight along the the northern and central coast, and for
     the northern coast range.  Southerly winds will increase
     with gusts between 60 and 70 mph possible.  Southerly winds
     in the Willamette Valley will continue to gust to near 40
     mph with increasing rain.

     Additional rainfall amounts of 2-4 inches are possible along
     the northern and central coast, with even greater amounts
     possible in the coastal range.  The Willamette Valley could
     receive 1-2 inches of rain by Thursday evening.  The
     freezing levels over Oregon are near 10,000 feet.  Numerous
     flood watches and warnings have been issued for western
     Oregon due to melting snow and increasing rain. The latest
     flood advisories can be viewed at: http://www.wrh.noaa.gov/pqr/

Surface Winds:
     S 15-25 G 35 this afternoon.
Transport Winds:
     SSW  40 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 2500 feet.  Ventilation index 88.
High Temperature:
     Salem\'s high temperature today will be near 54.
Humidities:
     Minimum relative humidity will be near 89%.
Sunrise/Sunset:
     Salem sunset tonight: 4:48pm; sunrise tomorrow: 7:49am.

Extended Outlook:
     A strong cold front will move onshore early Thursday morning
     with locally heavy rain and strong winds continuing.  South
     winds could gust to around 60 mph along the coastal
     headlands and beaches, and to near 70 mph in the northern
     coastal range, until the cold front pushes east.  Southerly
     winds will continue to gust to near 40 mph in the Willamette
     Valley through early Thursday.  Cooler air aloft will drop
     the snow level to near 3000 feet by Thursday evening with
     the precipitation becoming more showery and focused mainly
     on the western slopes of the coast range and Cascades.

     Showers will taper off Thursday night, as an upper-level
     ridge of high pressure begins building over the region. 
     Cooler overnight temperatures and moist low-level air will
     likely lead to areas of fog in the western valleys by Friday
     morning.  Freezing levels will jump back above the Cascade
     passes, but dry weather should help river levels drop and
     ease flooding concerns.

     The upper-level ridge will initially be rather flat. 
     Westerly flow aloft will allow another Pacific storm to slide
     into western Washington Saturday.  Some rain could make it
     south into northwestern Oregon late in the day.  The
     upper-level ridge is forecast to amplify Sunday with the
     flow aloft becoming northwesterly and drying out.  The ridge
     is forecast to move over the region early next week with dry
     weather expected and freezing levels rising to more than
     10,000 feet.  Ventilation conditions will become stagnant. 
     Some easterly outflow from the Columbia Gorge will help to
     clear skies in the north valley, but the south valley may
     have fairly persistent fog Monday through Wednesday.

Thu (08 Jan):  Rain and Windy...Turning to Showers.  Snow Level Dropping to 3000 Feet.  48/50

Fri (09 Jan):  Areas of AM Fog.  Becoming Partly Sunny.  34/46

Sat (10 Jan):  Areas AM Fog.  Mostly Cloudy.  Increasing Chance of Light Rain North.  32/46

Sun (11 Jan):  Areas of AM Fog.  Partial Clearing.  34/48

Mon (12 Jan):  Areas of AM Fog.  Partly Sunny.  33/50

Tue (13 Jan):  Areas of AM Fog...Mainly South.  Partly Sunny.  34/51

Wed (14 Jan):  Areas of AM Fog...Mainly South.  Partly Sunny.  34/51

ODA Meteorologist
weather at oda.state.or.us