[willamette-fcst] Forecast - Tuesday, March 10th, 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: 
     Tuesday, March 10th, 2009 at 9:00am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from 12:00pm until 4:00pm.
     Straw stack burning is allowed from 12:00pm until 4:00pm.

Weather Discussion:
     A cold northwesterly flow aloft helped a weakening Arctic
     cold front slowly sag southward, across most of Washington,
     overnight.  An unseasonably cold air mass is on the north
     side of that frontal boundary.  All but extreme southwestern
     Washington was well below freezing this morning with north
     or northeasterly winds.  To the south of the front, onshore
     flow keep skies cloudy overnight across western Oregon with
     southerly winds helping to hold temperatures in the mid 30s
     across the Willamette Valley.

     Satellite imagery showed mostly cloudy skies along and south
     of the Arctic cold front, covering the southern third of
     Washington and most of Oregon.  Doppler radar was indicating
     areas of very light precipitation near the frontal zone
     across extreme southern Washington and northern Oregon.  The
     snow level is at the surface east of the Cascades and around
     500 feet over northwest Oregon this morning, so a few
     snowflakes are possible even at low elevations again this morning.

     Expect winter driving conditions over the coast range and
     Cascade passes today.  ODOT reports showed icy areas over
     the coast range and packed snow over the Cascade passes this
     morning.  The air mass aloft is very cold, with Cascades
     pass temperatures only in the upper teens this morning.  A
     Winter Weather Advisory remains in effect until 10am for the
     Cascades, where another inch or two of snow could fall this morning.  

     The Arctic frontal boundary is expected to continue to
     weaken and slowly sag south to over northern Oregon this
     afternoon.  that should keep skies mostly cloudy today
     across the Willamette Valley with a slight chance of
     sprinkles or flurries.  Light southerly winds will taper off
     this afternoon and become northerly tonight, as colder and
     drier air begins filtering into western Oregon.  Afternoon
     temperaturs will struggle into the mid 40s (about 10 degrees
     below average).  Partial clearing and the influx of colder
     air will drop valley temperatures well down into the 20s
     tonight with local record low temperatures possible.

Surface Winds:
     S 5-10 this morning, S 3-8 this afternoon.
Transport Winds:
     WSW 10 this morning, WSW 8 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 5000 feet.  Ventilation index 50.
High Temperature:
     Salem\'s high temperature today will be near 44.
Humidities:
     Minimum relative humidity will be near 58%.
Sunrise/Sunset:
     Salem sunset tonight: 7:12pm; sunrise tomorrow: 7:31am.

Extended Outlook:
     After a frosty morning on Wednesday, with near-record low
     temperatures, mostly sunny skies will help afternoon
     temperatures moderate into the upper 40s. Surface winds will
     turn offshore Wednesday and strongly offshore Thursday, as
     an upper-level ridge builds into the coastline and brings a
     dry northerly flow aloft.  Afternoon temperatures will
     continue to warm, under mostly sunny skies, Thursday and
     Friday, but mornings will continue to be quite chilly.

     The next weather system will bring rain back to the region
     Friday night with showers continuing on Saturday.  The air
     aloft will be cold enough to support snow down to Cascade
     pass levels Saturday.  A flat upper-level ridge is forecast
     to build over the region early next week.  There may still
     be some light rain over northwestern Oregon Sunday, but
     Monday is looking dry and warmer.  It may become spring-like
     early next week, with increasing offshore flow yielding
     afternoon temperatures in the low to mid 60s.

Tomorrow (11 Mar):  Near Record-Cold Morning.  Mostly Sunny in the Afternoon.  24/48

Thu (12 Mar):  Another Cold Start.  Mostly Sunny and Warmer in the Afternoon.  27/53

Fri (13 Mar):  Mostly Sunny and Warmer.  Increasing Clouds Late.  31/57

Sat (14 Mar):  Rain Turning to Showers. Snow Level 3-4000 Feet.  35/50

Sun (15 Mar):  Mostly Cloudy.  Chance of light Rain North.  Snow Level 5000 Feet.  38/53

Mon (16 Mar):  A Brief Shot of Spring-like Conditions.  Mostly Sunny.  39/63

Tue (17 Mar):  Increasing Cloudy and Mild.  42/63

ODA Meteorologist
weather at oda.state.or.us