[willamette-fcst] Forecast - Thursday, June 18th, 2009

Willamette Valley Ag/Burning Forecast willamette-fcst at listsmart.osl.state.or.us
Thu Jun 18 09:00:56 PDT 2009




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: 
     Thursday, June 18th, 2009 at 9:00am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from 11:30am until 7:30pm.
     Preparatory burning is not allowed.
     Propane flaming is not allowed.
     Straw stack burning is allowed from 11:30am until 7:30pm.

Weather Discussion:
     A weak and transitory upper-level ridge of high pressure
     will bring dry and slightly warmer conditions to Oregon
     today.  The one exception will be possible areas of morning
     drizzle along the coast and western slopes of the coast
     range.  Visible satellite imagery showed marine low clouds
     blanketing western Washington and most of western Oregon at
     mid-morning.  The low clouds extended south to about Cape
     Blanco on the southern Oregon Coast.  Inland, low clouds
     covered the entire Willamette Valley and stretched south, to
     the southern border of Douglas County, into southwestern
     Oregon.  Skies were mostly clear east of the Cascade crest
     across both Washington and Oregon.

     The ODA surface analysis showed weak high pressure building
     into the central Oregon Coast with another high pressure
     center over northeastern Oregon.  Onshore flow extended from
     the Oregon Coastl eastward into Idaho.  Westererly winds
     were less than 10 mph across western Oregon but increased to
     around 20 mph across sections of northeast and eastern
     Oregon.  Temperatures dropped mostly into the 50s overnight
     across western Oregon with cooler 40s and 50s east of the
     Cascades.  Redmond, in central Oregon, was the cold spot in
     the state this morning with a minimum of 40 degrees.

     The Salem sounding this morning showed slight cooling,
     compared with Wednesday, below 5500 feet and warming above,
     due to the building upper-level ridge over the region. 
     Warming aloft will help to shallow the marine layer enough
     to promote a little more sunshine this afternoon than on
     Wednesday.  That will likely boost western Oregon
     temperatures into the mid 70s, after topping out in the low
     70s Wednesday.  Surface and transport winds will be mainly
     westerly this afternoon, making for favorable ventililation
     conditions for both agricultural and stack burning.

Surface Winds:
     W 3-8 this morning, W 5-12 this afternoon.
Transport Winds:
     SW 4 this morning, W 10 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 5500 feet.  Ventilation index 55.
High Temperature:
     Salem\'s high temperature today will be near 75.
Humidities:
     Relative humidity drops to 50% by 1pm.
     Minimum relative humidity will be near 45%.
Sunrise/Sunset:
     Salem sunset tonight: 9:02pm; sunrise tomorrow: 5:25am.

Extended Outlook:
     The weak upper-level ridge over the region will flatten
     tonight, with the flow aloft backing from northwesterly to
     southwesterly.  A little stronger weather system, compared
     with the one that moved across Oregon Tuesday, is forecast
     to move onshore Friday.  That will deepen the cool marine
     layer over western Oregon...resulting in more clouds, lower
     temperatures, and a pretty good chance of showers.  Scattered
     showers will spread across the entire state during the day on
     Friday, with a chance of thundershowers from the Cascades eastward.

     Another system will bring a reinforcing shot of cool and
     moist marine air into western Oregon later Saturday and
     Sunday, with a renewed chance of showers.  An upper-level
     trough is forecast to remain over the region during at least
     the first half of next week, with temperatures staying below
     normal.  Onshore flow will maintain considerable morning
     clouds along the coast and in the Willamette Valley, but the
     shower threat should significantly decrease after Monday. 
     The onshore flow is forecast to weaken late next week, with
     temperatures warming to near or above normal.

Tomorrow (19 Jun):  Mostly Cloudy and Cooler.  Chance of Showers.  54/70

Sat (20 Jun):  Mostly Cloudy.  Chance of Showers...Increasing Late. 51/67

Sun (21 Jun):  Cloudy and Quite Cool.  Scattered Showers.  50/66

Mon (22 Jun):  Mostly Cloudy.  Slight Chance of Showers.  Partial Afternoon Clearing.  48/69

Tue (23 Jun):  AM Clouds. Partly Sunny in the Afternoon.  A Little Warmer.  49/74

Wed (24 Jun):  AM Clouds. Partly Sunny PM.  Slight Chance of Showers...Mainly North.  51/73

Thu (25 Jun):  AM Clouds...Becoming Mostly Sunny and Warmer.  50/76

ODA Meteorologist
weather at oda.state.or.us



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