[willamette-fcst] Forecast - Tuesday, May 5th, 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, May 5th, 2009 at 9:00am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from now until 6:30pm.
     Straw stack burning is allowed, for dry stacks, from now until 6:30pm.

Weather Discussion:
     A strong cold front moved onshore Monday night, bringing
     locally heavy rain to western Oregon and unseasonaby strong
     winds to the Oregon Coast.  Southelry winds gusted to 77 mph
     at Cape Foulweather (north of Newport), 72 mph at Waldport
     and the Sea Lion Caves, 63 mph at Florence, 53 mph at
     Garibaldi, and 50 mph at the Astoria Aorport.  In the wake
     of locally heavy rain, associated with the cold front,
     southerly winds of 25-35 mph swept across the Willamette
     Valley overnight.

     Rainfall amounts in the past 24 hours were fairly
     impressive, for early May, with about an inch falling along
     the coastline and three-quarters to one inch of rain in the
     Willamette Valley.  The southwestern valleys also picked up
     from one-half to one inch of rain.  Snow levels were near
     7000 feet ahead of the cold front, so much of the
     precipitation from this storm fell as rain in the Cascades. 
     Rain turned to snow, above about 5000 feet, in the wake of
     the cold front overnight.  Timberline Lodge has received
     over 1.6 inches of water-equivalent precipitation in the
     past 24 hours, with over 1.1 inches at Mt Hood Meadows. 
     Much of that fell as rain, with ony 2 inches of new snow at
     Timberline overnight and 1 inch of new snow at Mt. Hood Meadows.

     The ODA surface analysis showed the cold front moving into
     eastern Oregon at mid-morning.  The front had lost a lot of
     moisture crossing the Cascades, with only partly cloudy
     skies covering much of central and eastern Oregon.  The
     exception was northeastern Oregon, where the frotn still had
     enough moisture to keep skies generally cloudy with areas of
     light rain.  The intense surface low-pressure area had
     weakened and tracked northward to the northern tip of
     Vancouver Island, British Columbia.  Tight southerly
     pressure gradients were relaxing across western Washington
     and western Oregon, but winds were still gusting to about 30
     mph along the northern Oregon Coast and to about 25 mph in
     the Willamette Valley.

     Strong onshore flow, in the wake of the cold front, was
     keeping skies mostly cloudy across western Oregon with
     Doppler radar showing bands of showers rotating onshore in a
     strong southwesterly flow aloft.  The Salem sounding from
     5am showed 50 mph southwesterly winds at just 5000 feet with
     30 mph winds extending down to about 2500 feet.  The
     freezing level had dropped to 5400 feet, from 8100 feet
     Monday afternoon.  Midday temperatures were generally in the
     low to mid 50s across westner Oregon.

     Cold air aloft, moist onshore flow, and a strong westerly
     jet stream will maintain mostly cloudy skies and scattered
     showers across western Oregon today.  Southwesterly winds
     will decrease today but continue to be blustery...especially
     near showers.  High temperatures will only climb into the
     upper 50s, more than 5 degrees below normal for early May. 
     The snow level in the Cascades will hold near 4-5000 feet,
     with rain possibly turning to wet snow over the passes.

Surface Winds:
     SW 10-20 G25 this morning, SW 10-20 G25 this afternoon.
Transport Winds:
     SW 35 this morning, SW 30 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 5000 feet.  Ventilation index 175.
High Temperature:
     Salem\'s high temperature today will be near 59.
Humidities:
     Minimum relative humidity will be near 67%.
Sunrise/Sunset:
     Salem sunset tonight: 8:23pm; sunrise tomorrow: 5:54am.

Extended Outlook:
     A fast-moving westerly flow aloft will drive the next
     weather system onshore Wednesday with rain and wind
     increasing again across western Oregon.  Winds will not be
     as strong with this system, but it will bring blustery and
     wet weather back to the region.  South wind-gusts of 30-40
     mph are possible along the coastal strip Wednesday with
     gusts to about 25 mph in the Willamette Valley.  The snow
     level should lift above the Cascade passes Wednesday, to
     around 5500 feet, but the ski areas will get some more snow.

     Showers will continue through Thursday, as an upper-level
     trough moves over the region.  A drier northwesterly flow
     aloft will take over Friday and Saturday.  A weak weather
     system may bring back some showers as early as Sunday.

Tomorrow (06 May):  Rain and Blustery.  Snow Level 5500 feet.  48/59

Thu (07 May):  Scattered Showers.  45/60

Fri (08 May):  Partly Cloudy.  39/65

Sat (09 May):  Partly Cloudy.  40/68

Sun (10 May):  Chance of Showers.  42/67

Mon (11 May):  Chance of Showers.  42/66

Tue (12 May):  Chance of Showers.  43/62

ODA Meteorologist
weather at oda.state.or.us