[willamette-fcst] Forecast - Thursday, January 8th, 2009

[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: 
     Thursday, January 8th, 2009 at 9:00am.

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:
     The strong Pacific storm that has brought heavy rain and
     strong winds to western Washington and northwestern Oregon,
     over the past two days, finally pushed east of the region
     this morning.  The cold front stretched from eastern
     Washington through eastern oregon at mid-morning and was
     accompanied by areas of rain and brisk westerly and
     southwesterly winds gusting to around 40 mph. Steady rain
     had turned showery west of the Cascades with some glimpses
     of sunshine.

     Brisk southerly winds held temperatures in the low 50s
     across western Oregon overnight, with cooler
     west-southwesterly winds ushering cooler air onshore this
     morning.  Most areas west of the Cascades recorded their
     high temperatures for today shortly after midnight. 
     Mid-morning temperatures had cooled into the upper 40s along
     the coast and in the Willamette Valley.  Temperatures will
     likely hold steady or slowly fall through this afternoon
     with continued shower activity.

     The cold front had pushed east of Salem by the time the
     morning sounding was taken.  It showed considerable cooling
     aloft, with the upper level winds shifting from
     southwesterly to westerly.  The freezing level over Salem
     had dropped from 8000 feet Wednesday afternoon to only 4600
     feet early this morning.  Heavy rain had turned to snow over
     the northern and central Cascade passes by mid-morning. 
     ODOT cameras showed packed snow at Government Camp, Santiam
     Pass and Willamette Pass with snow continuing to
     accumulate.

     The lowering snow levels and decreasing rain will help to
     ease the flooding west of the Cascades, which has been most
     significant across western Washington, and to a lesser
     degree in extreme northwestern Oregon, where numerous flood
     warnings remain in effect.  Many of the rivers and streams
     in this region crested Wednesday night or will crest this
     morning.  Near-record flooding is occuring this morning near
     Chehalis, Washington, where a 20-mile stretch of Interstate
     5 is closed due to high water.

     Lees Camp, on highway 6 in the northern Oregonm coastal
     range, has received 4.8 inches of rain in the past 24 hours
     and 6.7 inches of rain in the past 48 hours.  The Astoria
     airport has received 4.01 inches of rain in the past 24
     hours and nearly 5 inches in the past 48 hours.  Rainfall
     have also been very impressive across western Washington. 
     3-7+ inches of rain have falled in the past 48 hours from
     Kelso (just over 3.5 inches), to Olympia (more than 6
     inches), to Shelton (more than 7 inches).  In contrast,
     rainfall amounts taper off quickly, as you move south and
     east into the Willamette Valley, where 48-hour rainfall has
     been generally from one-half to one inch.

     Cooler air aloft will drop the snow level to near 2500 feet
     by this evening with the showers decreasing and becoming
     mainly focused on the western slopes of the coast range and
     Cascades.  3-6 inches of snow is possible over the Cascade
     passes, with the greatest amounts in the north.  Showers
     will taper off tonight, as an upper-level ridge of high
     pressure begins building over the region. Partial clearing
     and colder air aloft will allow valley temperatures to fall
     into the low to mid 30s by Friday morning with areas of fog.


Surface Winds:
     SW 10-20 this morning, W 10-20 this afternoon.
Transport Winds:
     WSW 20 this morning, W  20 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 2500 feet.  Ventilation index 50.
High Temperature:
     Salem\'s high temperature today will be near 51.
Humidities:
     Minimum relative humidity will be near 86%.
Sunrise/Sunset:
     Salem sunset tonight: 4:49pm; sunrise tomorrow: 7:49am.

Extended Outlook:
     After areas of morning valley fog, some sunbreaks are likely
     Friday. 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 much of next week.

Tomorrow (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):  Mostly Cloudy.  Chance of Sprinkles North.  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

Thu (15 Jan):  Areas of AM Fog...Mainly South.  Partly Sunny.  34/51

ODA Meteorologist
weather at oda.state.or.us