[willamette-fcst] Forecast - Monday, February 22nd, 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: 
     Monday, February 22nd, 2010 at 9:00am.

Burn Advisory:
     Recommended burn times for agricultural burning are from 11:00am to 4:00pm.
     Stack burning is not allowed.

Weather Discussion:
     An upper-level ridge of high pressure, centered just off the
     west coast, brought a dry northerly flow aloft to Oregon
     over the weekend, resulting in sunny mild days and clear
     cool nights.  Willamette Valley highs ranged from the mid
     50s to the low 60s on Saturday.  It was slightly cooler
     Sunday, with valley highs in the mid to upper 50s.

     The early-season warmth brought many trees and plants out of
     dormancy, which raises some concerns of possible frost
     damage.  The dry air mass has been also allowing overnight
     temperatures to dip well below freezing, with this morning
     being the coldest in the series.  Calm winds helped minimums
     drop into the mid to upper 20s across much of the Willamette
     Valley this morning.  Hillsboro dipped to 25 degrees, with
     McMinnville and Salem both dropping to 26 degrees.  Eugene
     fell to 27 degrees.  Fortunately, these cold temperatures
     will not persist for long.  Sunny skies and warm air aloft
     will combine to quickly lift valley temperatures back above
     the freezing mark this morning.

     The upper-level ridge has moved inland this morning and is
     centered over British Columbia.  The flow aloft over Oregon
     has turned more easterly, with the air mass warming several
     degrees since Sunday.  That will allow surface temperatures
     to climb to near 60 degrees in the Willamette Valley this
     afternoon, with sunshine being filtered by high clouds.

     The ODA surface analysis showed continued offshore flow across
     the state, with easterly winds along the coast and at the western
     end of the Columbia Gorge gusting to around 15 mph.  Winds were
     light in the Willamette Valley.

     Satellite imagery showed high clouds moving onshore, in
     response to an increasing westerly flow aloft moving towards
     the coastline.  However, skies should remain mostly sunny for
     one more day, with just some increase in high clouds.

Surface Winds:
     NNE 0-5 this morning, NNE 3-8 this afternoon.
Transport Winds:
     NNE 3 this morning, NE 10 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 4000 feet.  Ventilation index 40.
High Temperature:
     Salem\'s high temperature today will be near 59.
Humidities:
     Minimum relative humidity will be near 31%.
Sunrise/Sunset:
     Salem sunset tonight: 5:50pm; sunrise tomorrow: 7:00am.

Extended Outlook:
     The upper-level ridge is forecast to shift eastward, to over
     Idaho, by Tuesday with the first in a series of weather
     systems coming onshore in the afternoon.  Increasing clouds
     will keep Tuesday morning temperatures from being as cold as
     they were this morning, but afternoon highs will be
     considerably cooler with a chance of rain.

     Another system is forecast to maintain the chance of rain
     Wednesday, with the snow level low enough for some
     accumulating snow over the Cascade passes.  A trasitory
     ridge of high pressure will bring some drying on Thursday,
     with another system coming onshore Friday. A ridge of high
     pressure may bring another spell of dry and mild weather,
     over the weekend, with the next weather system slated to
     return the chance or rain to western Oregon by Monday afternoon.

Tomorrow (23 Feb):  Increasing Clouds.  Chance of Light Rain.  32/52

Wed (24 Feb):  Chance of Rain.  Snow Level near 4000 Feet.  38/53

Thu (25 Feb):  Mostly Cloudy.  Snow Level 4-5000 Feet.  36/56

Fri (26 Feb):  Rain Likely.  Snow Level near 5000 Feet.  40/55

Sat (27 Feb):  Mostly Cloudy.  38/55

Sun (28 Feb):  Partly Cloudy and Mild.  38/60

Mon (01 Mar):  Increasing Clouds.  Chance of Rain.  Snow Level 6000 feet.  40/57

ODA Meteorologist
weather at oda.state.or.us