[willamette-fcst] Forecast - Monday, February 9th, 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: 
     Monday, February 9th, 2009 at 9:00am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from now until 3:30pm.
     Straw stack burning is allowed from now until 3:30pm.

Weather Discussion:
     A Pacific cold front dropped between one and two-tenths of
     an inch of rain along the coast Sunday with lighter amounts
     inland.  Snow levels dropped to about 2000 feet Sunday
     afternoon, with about 1-3 inches of new snow falling in the
     Cascades.  Cloudy skies held Willamette Valley highs in the
     mid to upper 40s Sunday, after a mostly sunny Saturday with
     highs in the low to mid 50s.

     The cold front pushed east of the Cascades Sunday night with
     clearing skies and a cool air mass allowing temperatures to
     drop below freezing across most of western
     Oregon...including along the coast.  Hillsboro was one of
     the colder spots, in the Willamette Valley, droping at least
     down to 26 degrees.  McMinnville and Eugene both dipped to
     28.  Along the coast, Astoria fell to 30 degrees and
     tempertures fell to the freezing mark as far south as North
     Bend and Brookings.  Meanwhile, cloudy skies and areas of
     very light snow kept central and eastern Oregon temperatures
     mostly in the 20s overnight, with a few areas dropping in
     the teens.

     Satellite and Radar showed an impressive line of showers,
     associated with an upper-level trough, just moving onto the
     coastline at mid-morning. The air mass with these showers is
     quite cold, and Astoria was even reporting light snow with
     temperatures in the low 30s. The upper-level trough, and
     associated showers, will move across western Oregon later
     this morning through early this afternoon.  The snow level
     will be between 500 and 1000 feet, but wet snow could mix to
     the valley floor at times.  High temperatures will only
     climb into the low to mid 40s.  A transitory ridge of high
     pressure will bring some partial clearing overnight with
     temperatures, once again, dropping to near or below the
     freezing mark across most of western Oregon.

     The Salem sounding this morning showed significant cooling
     from near the surface to 30,000 feet, with southerly
     low-level winds becoming northwesterly above about 2000
     feet.  The freezing level was measured at just 2100 feet. 
     Ventilation conditions across western Oregon should be good
     today, as the upper-level trough moves onshore.  Low-level
     winds are southerly this morning but are forecast to turn
     more westerly, in the wake of the upper-level trough, later
     this afternoon.

Surface Winds:
     S 5-10 this morning, WSW 5-12 this afternoon.
Transport Winds:
     S 10 this morning, W 12 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 3000 feet.  Ventilation index 36.
High Temperature:
     Salem\'s high temperature today will be near 43.
Humidities:
     Minimum relative humidity will be near 62%.
Sunrise/Sunset:
     Salem sunset tonight: 5:32pm; sunrise tomorrow: 7:20am.

Extended Outlook:
     Another cold Pacific storm is forecast to spread clouds and
     precipitation back onshore Tuesday morning.  The air mass
     will initially be quite cold, so the precipitation will
     begain as snow down to very low elevations...perhaps even on
     the valley floors.  The low-pressure center is forecast drop
     southward, off the Oregon Coast, late Tuesday.  That will
     keep the low-level winds offshore and maintain very low snow
     levels across all of western Oregon...especially near the
     Columbia Gorge.

     The National Weather Service has issues a Winter Storm
     Watch, for possible significant snow Tuesday, in the coastal
     range, the Columbia Gorge, the Cascade foothills (above 1000
     feet), and for the Cascades. Wet snow could fall on the
     valley floors, but significant accumulations are not
     expected at the very lowerest elevations.  This system will
     need to be watched closely for the potetial to produce
     sticking snow even at sea level, especially in the extreme
     northern Willamette Valley, due to the persistent offshore
     flow, from the Columbia Gorge, keeping the low-level air
     mass cold.

     The rain and snow should taper off late Tuesday, as the
     low-pressure center moves inland into northern California. 
     A few showers or flurries are still possible into
     Wednesday...especially in the south valley.  Wednesday
     morning temperatures will be near freezing with afternoon
     highs warming a few degrees from Tuesday.  The next system
     is forecast to take more of a southerly track, mainly into
     northern California, with some light rain and snow possibly
     spreading as far north as about Portland Thursday night and
     Friday.  Some drying is expected Saturday, under a cold
     northerly flow aloft.

Tomorrow (10 Feb):  Rain/Snow Mix.  Significant Snow Above 1000 Feet.  31/42

Wed (11 Feb):  Decreasing areas of light Rain/Snow.  Partial PM Clearing.  32/46

Thu (12 Feb):  Increasing Clouds.  Chance of Rain/Snow Mix.  32/45

Fri (13 Feb):  Mostly Cloudy.  Chance of Rain/Snow Mix.  32/45

Sat (14 Feb):  Gradual Clearing and Cool.  30/47

Sun (15 Feb):  Mostly Sunny and Cool.  28/48

Mon (16 Feb):  Mostly Sunny and Cool.  28/48

ODA Meteorologist
weather at oda.state.or.us