[willamette-fcst] Forecast - Friday, February 12th, 2010

[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: 
     Friday, February 12th, 2010 at 9:00am.

Burn Advisory:
     Recommended burn times for agricultural burning are from now to 3:30pm.
     Straw stack burning is allowed from now until 3:30pm.

     ...The rules for stack burning have changed.  Stack burning
     permits must be obtained from ODA Smoke Management Personnel...

Weather Discussion:
     A quick-hitting weather system came onshore late Thursday
     and dumped between one-quarter and one-half inch of rain
     along the coast and across the Willamette Valley.  Southerly
     winds also became quite blustery for a few hours, Thursday
     evening, gusting to nearly 70 mph along the exposed
     headlands at the coast and to near 40 mph in the northern
     Willamette Valley.  Cape Foulweather and Garibaldi both
     recorded peak gusts of 69 mph, with gusts to 54 mph at
     Newport and 53 mph at Lincoln City.  In the Willamette
     Valley, McMinnville had a gust to 39 mph and Salem recorded
     a peak gust of 35 mph.

     The rain and wind tapered off overnight, with the passage
     of the cold front.  The snow level was up to nearly 6000
     feet ahead of the front but had dropped to near the Cascade
     passes by this morning.  The break from the rain was brief,
     with another, somewhat colder, weather system moving onshore
     at mid-morning.  Satellite imagery showed a fairly narrow
     but impressive-looking cloud band rotating onto the Oregon
     coast and inland over western Oregon.  Doppler radar and
     surface reports show that rain has indeed spread back over
     much of western Oregon.

     The ODA surface analysis showed increasing southerly
     pressure gradients, with gusts to around 35 mph along the
     coast, from Astoria to North Bend.  Blustery south winds
     were beginning to make it into the Willamette Valley. 
     McMinnville was getting gusts to around 25 mph.  Southerly
     winds were keeping temperatures around the 50 degree mark
     across most of western Oregon.

     Rain and blustery southerly winds will continue through this
     morning with the precipitation turning showery later this
     afternoon.  Colder air aloft will lower the snow level to at
     or below 4000 feet this afternoon, so several inches of snow
     are likely over the Cascade passes by this evening.  The air
     mass will also become increasingly unstable this afternoon,
     with a chance of thunderstorms along the coast and a slight
     chance inland.  Clouds and rain will keep temperatures from
     climbing about about 55 degrees in the valley, after locally
     warming to 60 degrees on Thursday.  Southerly winds will not
     be quite as brisk today as they were last night but will
     make for excellent ventilation conditions across the valley.

Surface Winds:
     S 10-20 G30 this morning, S 12-22 G30 this afternoon.
Transport Winds:
     S 35 this morning, SSW 30 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 53.
Humidities:
     Minimum relative humidity will be near 70%.
Sunrise/Sunset:
     Salem sunset tonight: 5:36pm; sunrise tomorrow: 7:16am.

Extended Outlook:
     A warm front will bring a chance of light rain Saturday morning, with a transitory ridge
     of high pressure drying things out Saturday afternoon.  Temperatures could become quite
     mild, with some afternoon sunbreaks...mainly south.  Freezing levels will jump well
     above the Cascade passes by Saturday afternoon.
  
     A weak cold front will likely spread light rain back across western Oregon by Sunday
     afternoon, with snow levels likely remaining above the Cascade passes.  Monday looks
     mostly cloudy but mild, with a warm front bringing some sprinkles to northern sections
     of western Oregon by Monday evening.  A cold front is forecast to swing onshore Monday
     night and early Tuesday.  Snow levels may drop back to the Cascade passes Tuesday.

     A building upper-level ridge of high pressure is still forecast to bring mostly sunny
     and mild weather to the region Wednesday through Friday of next week, with offshore flow.

Sat (13 Feb):  Chance of AM Light Rain...Mainly North. Snow Level Rising to 6000 Feet.  44/60

Sun (14 Feb):  Light Rain Developing by the Afternoon.  Snow Level 5500 Feet.  44/55

Mon (15 Feb):  Increasing Chance of Light Rain...Mainly North.  Snow Level 6000 Feet.  38/57

Tue (16 Feb):  Chance of Rain...Mainly North.  Snow Level 4-5000 Feet.  42/53

Wed (17 Feb):  Areas of AM Fog.  Becoming Mostly Sunny & Mild.  36/57

Thu (18 Feb):  Mostly Sunny and Spring-Like.  35/62

Fri (19 Feb):  Mostly Sunny and Mild.  35/60

ODA Meteorologist
weather at oda.state.or.us