[willamette-fcst] Forecast - Monday, March 16th, 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, March 16th, 2009 at 9:00am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from now until 4:30pm.
     Straw stack burning is allowed, for dry stacks, from now until 4:30pm.

Weather Discussion:
     A strong cold front brought high winds, locally heavy rain,
     and mountain snow to Washington and Oregon  over the
     weekend.  Ahead of the cold front, the air mass was just
     cold enough for wet snow to fall across much of northwestern
     Washington early Sunday.  A couple of inches fell in the
     Seattle area Sunday morning, with one-half inch of snow
     falling at Sea-Tac Airport.  That brought their 2008-9
     winter-season snow total up to 23.3 inches...which ties for
     the 6th snowiest winter on record.  The snowiest winter was
     1968-9, when Sea-Tac Airport received 67.5 inches of snow.

     Significant amounts of rain and wind battered the lowlands
     of western Oregon over the weekend.  Most of the coastline
     received about two inches of rain with southerly winds
     gusting as high as 70 mph at Cape Foulweather, north of
     Newport, and 60 mph at Depoe Bay.  The Willamette Valley
     picked up between three-quarters and 1.5 inches of rain with
     southerly winds, gusting as high as 45 mph, downing some trees.

     Heavy snow fell in the mountains, above about 3000 feet,
     along with blustery winds.  Timberline Lodge, at the
     6000-foot mark on Mt. Hood, reported 20 inches of new snow
     in the past 72 hours.  Mt. Hood Meadows received 13 inches
     of snow in the past 24 hours.  16 inches of new snow fell at
     Mt. Bachelor, in central Oregon, and 13 inches over
     Willamette Pass.  Snow levels dropped low enough over the
     weekend for some wet snow at times over the higher coastal
     mountain passes.

     ODOT road reports showed spots of ice, but mostly just wet
     pavement, over the coastal passes this morning.  The Cascade
     passes were snow-packed with locally heavy snow and gusty
     winds making for very difficult traveling.  Pass
     temperatures were in the mid to upper 20s.  The National
     Weather Service still has a Winter Weather Advisory in
     effect for the Cascades, where another 4-8 inches of snow
     are likely today.  The wintry travel conditions will likely
     continue through tonight with continued snow showers.

     A strong west-southwesterly flow aloft will continue to
     circulate bands of showers onshore across Washington and
     Oregon today.  The air mass is quite cool, with the freezing
     levels over Salem and Medford measured at just 3200 feet and
     5200 feet respectively.  That puts the snow level at just
     2000 feet in the north and 4000 feet across extreme southern
     Oregon.  Daytime heating could make the atmophere unstable
     enough for a thundershower and/or small hail this afternoon.
      Mid-morning temperatures were in the low 40s across western
     Oregon, and afternoon highs will only climb into the upper
     40s. Southerly winds will not be as strong today but
     blustery near showers.

Surface Winds:
     S 5-15 G25 this morning, SW 10-20 G30 this afternoon.
Transport Winds:
     SW 25 this morning, SW 30 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 5000 feet.  Ventilation index 150.
High Temperature:
     Salem\'s high temperature today will be near 49.
Humidities:
     Minimum relative humidity will be near 68%.
Sunrise/Sunset:
     Salem sunset tonight: 7:20pm; sunrise tomorrow: 7:20am.

Extended Outlook:
     Little change in the overall weather pattern is expected
     Tuesday, followed by a slight northward shift of the jet
     stream on Wednesday, in response to an approaching frontal
     system.  That will lift snow levels a bit, with the showery
     precipitation turning to a more steady rainfall...mainly
     north.  The jet stream will migrate further north Thursday,
     with the main storm track shifting into western Washington. 
     The jet stream is forecast to drop back southward to over
     Oregon Friday, with increasing rain and mountain snow.

Tomorrow (17 Mar):  Showers.  Snow Level 2500-3500 feet.  38/51

Wed (18 Mar):  Rain Likely.  Snow Level Lifting to 4-5000 Feet.  40/53

Thu (19 Mar):  Mostly Cloudy.  Chance of Rain...Mainly North.  Snow Level 6000 Feet.  42/56

Fri (20 Mar):  Increasing Rain and Mountain Snow.  Snow Level 4-5000 Feet.  43/54

Sat (21 Mar):  Showers.  Snow Level 3000 Feet.  40/52

Sun (22 Mar):  Showers.  Snow Level 2500 Feet.  39/51

Mon (23 Mar):  Showers.  Snow Level 2500 Feet.  37/53

ODA Meteorologist
weather at oda.state.or.us