[willamette-fcst] Forecast - Wednesday, August 26th, 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: 
     Wednesday, August 26th, 2009 at 9:00am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from 2:00pm until 7:00pm.
     Preparatory burning is not allowed.
     Propane flaming is allowed from 2:00pm until 5:00pm.
     Straw stack burning is allowed from 2:00pm until 7:00pm.

Weather Discussion:
     An upper-level ridge of high pressure will rebuild over
     Oregon today, with southwesterly flow aloft decreasing and
     becoming more southerly. Satellite imagery showed mostly
     clear skies over Oregon this morning, except for some high
     clouds over mainly the northwestern corner of the state.
     Mid-morning temperatures were mostly in the low to mid 50s,
     across western Oregon, with light north to northeasterly
     surface winds.  With warmer air aloft, and sunny skies today,
     Willamette Valley highs should climb into the mid to upper 80s.

Surface Winds:
     NE 0-5 this morning, NNW 5-10 this afternoon.
Transport Winds:
     NE 8 this morning, SSW 6 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 4000 feet.  Ventilation index 32.
High Temperature:
     Salem\'s high temperature today will be near 87.
Humidities:
     Relative humidity drops to 50% by 12pm.
     Minimum relative humidity will be near 22%.
Sunrise/Sunset:
     Salem sunset tonight: 7:59pm; sunrise tomorrow: 6:29am.

Extended Outlook:
     The flow aloft will continue to weaken, and turn almost due
     southerly on Thursday, as a strong upper-level ridge builds
     over Idaho and western Montana.  Temperatures should warm a
     few more degrees over the interior of western Oregon, under
     mostly sunny skies.  Transport winds will likely be too
     southerly for open burning.  

     A weakening Pacific cold front is forecast push into the
     strong ridge and make it onshore Friday, with enough
     moisture to likely bring some light rain to the Oregon
     Coast.  Some light rain could make it inland into the
     Willamette Valley Friday afternoon, but that is questionable
     at this time.  Depending on the timing of this system, it
     may create a burning opportunity Friday afternoon.  However,
     the flow aloft is forecast to remain southerly, which does
     not vavor open burning chances.

     A weak cut-off upper-level low-pressure area is forecast to
     remain over Wahington and Oregon Saturday, before moving
     into Idaho Sunday.  A broad and strong upper-level ridge
     will remain anchored over the remainder of western North
     America.  Temperatures will slowly climb back above normal
     by Sunday, across western Oregon, with increasing amounts of
     sunshine.

     Increasing southwesterly flow aloft will develop Monday, as
     a trough drops southeastward, from the Gulf of Alaska.  That
     may create a burning opportunity Monday afternoon, if the
     system approaches the coastline quickly enough.  High
     temperatures may warm a degree or two more, on Monday,
     before onshore flow increases late in the day.  Onshore flow
     will likely increase Tuesday and Wednesday, as the
     upper-level trough approaches the coastline.  If the winds
     aloft are not too southerly, that may also create a burning
     opportunity.

Tomorrow (27 Aug):  Sunny and Warm.  53/90

Fri (28 Aug):  Increasing Clouds and Cooler.  Chance of PM Sprinles or Light Rain.  56/79

Sat (29 Aug):  Partly Cloudy.  54/81

Sun (30 Aug):  Mostly Sunny and Warmer.  53/85

Mon (31 Aug):  Mostly Sunny and Warm.  Increasing onshore flow in the afternoon.  54/86

Tue (01 Sep):  Mostly Sunny.  A Little Cooler.  54/82

Wed (02 Sep):  Partly Cloudy.  52/79

ODA Meteorologist
weather at oda.state.or.us