[willamette-fcst] Forecast - Monday, October 12th, 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, October 12th, 2009 at 9:00am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from 1:00pm until 4:30pm.
     Propane flaming is not allowed.
     Stack burning is not allowed.

Weather Discussion:
     Unseasonably cold and dry air poured southward into eastern
     Washington and northeastern Oregon, over the weekend, in
     reponse to a strong northerly jet stream.  Numerous record
     low temperatures were tied or broken across that region on
     Saturday...including record shattering minimums of 8 degrees
     in Pullman, Washington and 10 degrees in Omak, Washington
     (the old records were 20 and 24 degrees respectively). 
     Spokane, Washington also crushed their low temperature
     record Saturday with a minimum of 19 degrees (the old record
     was 24 degrees).  On Sunday, Spokane not only broke their
     record low temperature for the date, with 20 degrees, they
     also tied their coldest maximum for the date, with a high of
     only 40 degrees.  In northeastern Oregon, Pendleton
     shattered their daily low temperature record Saturday with
     19 degrees (the old record was 25 degrees).  Redmond also
     blew away their old daily record low of 23 degrees Saturday, 
     with a minimum of 15 degrees.

     Enough cold air also poured into northwestern Washington for
     Olympia to tie their daily record low Sunday of 28 degrees. 
     Drier air continued to southward, into the Willamette Valley
     Sunday, leading to some chilly temperatures this morning
     with areas of frost.  Corvallis dropped down to at least 30
     degrees this morning and Eugene hit 31.  Salem dropped to 35
     degrees.  Easterly outflow, from the Columbia Gorge, kept
     the air stirred up enough in the extreme north valley to
     keep most areas above freezing, even though dew-point
     temperatures locally in the teens.

     Satellite imagery showed high and mid-level clouds covering
     much of Washington and Oregon this morning, with the weather
     pattern undergoing a transition from the dry and cool
     northerly flow, of the past week, to a wet westerly flow. 
     The ODA surface analysis showed cold high pressure
     persisting over eastern Washington and northeastern Oregon
     with very dry offshore flow extending to the coast. 
     Mid-morning temperatures were only in the 20s and low 30s
     east of the Cascades with 30s to low 40s across the interior
     valleys of western Oregon.  Even the coast was only in the
     mid 40s.  Offshore winds were generally less than 10 mph
     west of the Cascades, except for gusts to around 20 mph near
     the western end of the Columbia Gorge.

     Today will be the last day of the week-long dry spell across
     western Oregon, with middle and high clouds filtering the
     autumn sunshine.  The increase in cloud-cover will likely
     reduce high temperatures a degree or two from Sunday, but it
     will still be a pleasant day.  An increasing westerly flow
     aloft will open the door for a series of Pacific storms to
     bring the first real soaking rains of this autumn season to
     western Oregon, beginning tomorrow. Rain will likely move
     onshore tonight and spread across all of western Oregon
     Tuesday, along with blustery winds. Coastal regions will
     likely pick up between one-half and one inch of rain Tuesday,
     with the greatest totals in the south.  The western valleys
     will generally received from one-quarter to one-half inch of
     rain Tuesday...also with the greater amounts to the south.   

     With increasing cloud-cover, temperatures should stay well
     above freezing tonight across western Oregon.  However,
     daytime highs Tuesday will be cooler (in the 50s), with rain
     replacing the partly sunny skies of today. 

Surface Winds:
     Var 0-6 this morning, Var 4-8 this afternoon.
Transport Winds:
     SSE 3 this morning, SSE 4 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 2500 feet.  Ventilation index 10.
High Temperature:
     Salem\'s high temperature today will be near 61.
Humidities:
     Minimum relative humidity will be near 26%.
Sunrise/Sunset:
     Salem sunset tonight: 6:32pm; sunrise tomorrow: 7:26am.

Extended Outlook:
     Westerly flow aloft will bring rain to western Oregon
     Tuesday and Wednesday with a transitory ridge bringing some
     drying on Thursday.  Another weather system may bring more
     rain onshore as early as Friday afternoon.  The wet weather
     pattern appears as if it will last into next week.

Tomorrow (13 Oct):  Rain.  A Bit Blustery at Times.  Quite Cool.  38/56

Wed (14 Oct):  Rain.  47/60

Thu (15 Oct):  Moslty Cloudy.  Chance of Showers. 48/63

Fri (16 Oct):  Mostly Cloudy.  Chance of Rain Late.  48/68

Sat (17 Oct):  Rain Turning to Showers.  48/64

Sun (18 Oct):  Mostly Cloudy.  Increasing Rain Late.  46/63

Mon (19 Oct):  Rain Turning to Showers.  47/62

ODA Meteorologist
weather at oda.state.or.us