[willamette-fcst] Forecast - Wednesday, March 18th, 2009

Willamette Valley Ag/Burning Forecast willamette-fcst at listsmart.osl.state.or.us
Wed Mar 18 09:02:39 PDT 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.

Issued: 
     Wednesday, March 18th, 2009 at 9:00am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from 11:00am until 4:30pm.
     Straw stack burning is allowed from 11:00am until 4:30pm.

Forecast Today:  Mostly Cloudy and Mild.  Salem high near 60.

Weather Discussion:
     Showers tapered off across northwest Oregon Tuesday evening,
     but skies remained cloudy overnight, in response to a warm
     front moving into northwest Washington.  Rainfall amounts
     Tuesday ranged from about one-quarter of an inch along the
     north coast to only a few hundredths of an inch in the
     southern Willamette Valley.  Temperatures generally stayed
     in the low 40s overnight, across western Oregon, with a few
     spots dipping into the upper 30s.  Pressure gradients
     relaxed overnight, and valley winds became calm.

     The ODA surface analysis and satellite imagery showed a cold
     front moving into northern Vancouver Island, British
     Columbia and trailing offshore to about 300 miles off the
     northern Oregon Coast.  A warm front was producing rain as
     far south as the central Washington Coast with cloudy skies
     covering Washington and most of Oregon.  Weak upper-level
     ridging over Oregon is forecast to lift the warm front into
     northern Washington and southern British Columbia this
     afternoon, with the cold front slowly sagging into
     northwestern Washington late in the day.  Light rain could
     spread as far south as the northern Oregon Coast this
     morning and inland into western Washinton.  The interior of
     western Oregon will likely stay dry, although skies should
     remain mostly cloudy.

     Warmer air aloft pushed the freezing level over Medford to
     8000 feet early this morning (up from 4900 feet Tuesday
     morning).  The freezing level over Salem had not climbed as
     much and was measured at 4500 feet this morning.  The air
     aloft should continue to warm today, with the freezing level
     over northern Oregon rising to about 6000 feet.  Light
     southerly winds and warmer air aloft should help
     temperatures approach 60 degrees across the Willamette
     Valley this afternoon...especially south.

Surface Winds:
     SE 0-5 this morning, SSW 3-7 this afternoon.
Transport Winds:
     SSW 7 this morning, SSW 7 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 5000 feet.  Ventilation index 35.
High Temperature:
     Salem\'s high temperature today will be near 60.
Humidities:
     Minimum relative humidity will be near 51%.
Sunrise/Sunset:
     Salem sunset tonight: 7:22pm; sunrise tomorrow: 7:17am.

Extended Outlook:
     A cold front will weaken as it sags southward, across
     northwestern Oregon, Thursday.  That will maintain mostly
     cloudy and mild conditions with some light rain possible at
     times...mainly in the north valley.  The front will act to
     maintain good ventilation conditions across western Oregon
     with south-southwesterly transport winds.  A stronger system
     is forecast to swing onshore Friday afternoon, with snow
     levels dropping back below the Cascade passes by Friday evening.

     An upper-level trough will swing onshore Saturday, but the
     main jet stream energy will be focused south of the region,
     over California. Skies should stay mostly cloudy over Oregon
     with numerous showers and continued farily low snow levels. 
     Showers should taper off Sunday, as the upper-level trough
     moves eastward into the Rockies.

     The long-range computer models have greatly differing
     solutions beginning early next week, so confidence in the
     forecast beyond Sunday is low.  A slight north or south
     shift in the forecast jet stream position can make a huge
     difference in our weather this time of year.  Next week
     could end up being quite mild and mostly dry or on the damp
     side.  Western Washington stands a much better chance of
     being wet for much of next week, but even that is not
     certain at this time.

     A transitory ridge may hold on through most of Monday, but
     it appears that a cold front will sag south far enough to
     bring some rain to western Washington and a chance of rain
     to northwestern Oregon Tuesday and Wednesday.

Thu (19 Mar):  Mostly Cloudy.  Chance of Rain...Mainly North.  Snow Level 6000 Feet.  40/59

Fri (20 Mar):  Rain and Mountain Snow.  Snow Level Dropping to 4-5000 Feet.  44/54

Sat (21 Mar):  Showers with Mountain Snow.  Snow Level 3-4000 Feet.  40/53

Sun (22 Mar):  Decreasing Showers.  Snow Level 3000 Feet.  37/52

Mon (23 Mar):  Partly Sunny.  Freezing Level Rising to 5000 feet.  35/58

Tue (24 Mar):  Mostly Cloudy.  Chance of Rain...Mainly North.  Snow Level 6000 Feet.  40/58

Wed (25 Mar):  Mostly Cloudy.  Chance of Rain...Mainly North.  Snow Level 6000 Feet.  42/58

ODA Meteorologist
weather at oda.state.or.us



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