[willamette-fcst] Forecast - Monday, August 11th, 2008

[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, August 11th, 2008 at 9:00am.

Burn Advisory:
     Agricultural burning is not recommended.
     Preparatory burning is allowed from 12:00pm until 5:00pm with a 100 acre limit.
     Propane flaming is allowed from 12:00pm until 5:00pm.
     Stack burning is not allowed.

Weather Discussion:
     A cold front brought some light rain to the Oregon Coast and
     the Willamette Valley Saturday, along with well below normal
     temperatures.  Rainfall amounts were generally only a couple
     hundredths of an inch, but Hillsboro did pick up just over
     one-tenth of an inch.  Dry weather returned Sunday with
     temperatures warming close to normal.

     An upper-level ridge is forecast to move over Washington and
     Oregon today for further warming and drying of the air mass.
     Morning satellite imagery showed low clouds along much of
     the Oregon Coast, the Northern Willamette Valley, and in
     extreme North-Central Oregon.  The remainder of the state
     was under mostly sunny skies.  The areas of low clouds
     should give way to sunshine by this afternoon, even along
     the coast, as the low-level flow dries out and turns northerly.

     The ODA surface analysis showed very weak pressure gradients
     across Oregon.  Valley winds were 3 mph or less this
     morning.  The Salem sounding showed considerable warming
     aloft since Sunday morning, so temperatures will be about 5
     degrees warmer today than on Sunday.  Valley highs should
     climb into the mid 80s.  Warming aloft will decrease maximum
     mixing heights, which climbed to more than 5000 feet Sunday
     afternoon, but they should still exceed 3000 feet by midday.
     However, forecast northerly transport winds, for this
     afternoon, makes open burning unlikely.  

Surface Winds:
     Var 0-4 this morning, N 5-15 this afternoon.
Transport Winds:
     NW 2 this morning, N 8 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 85.
Humidities:
     Relative humidity drops to 50% by 1pm.
     Minimum relative humidity will be near 35%.
Sunrise/Sunset:
     Salem sunset tonight: 8:24pm; sunrise tomorrow: 6:11am.

Extended Outlook:
     A weak trough is forecast to move across Washington and
     Northern Oregon late Tuesday with little more than a few
     high clouds for the Willamette Valley.  However, it may be
     strong enough to back the transport winds, from northerly to
     northwesterly. enough to allow for limited open burning.  A
     strong ridge is forecast to rebuild over the Pacific
     Northwest during the second half of the week with the surface
     flow turning northerly again Wednesday and offshore Thursday.

     The ridge is forecast to shift eastward, to over Idaho, by
     late Friday.  A weak upper-level disturbance is forecast to
     approach the Oregon Coast and may bring a bring a chance of
     thundershowers to the state Friday...mainly from the
     Cascades eastward.  If the system arrives soon enoungh, it
     may create another burning opportunity, but that is too far
     out to call at this time.  Another very weak trough is
     forecast to clip the region Sunday and cool temperatures to
     near normal.

Tomorrow (12 Aug):  Mostly Sunny and Warm.  Wind: NW 5-15 mph.  55/85

Wed (13 Aug):  Patchy Morning Clouds.  Mostly Sunny.  Wind: N 5-15 mph.  55/86

Thu (14 Aug):  Sunny and Hot.  Wind: NE 5-15 mph.  56/95

Fri (15 Aug):  Mostly Sunny and Hot.  Wind: Becoming NW 5-15 late.  57/95

Sat (16 Aug):  Mostly Sunny and Warm.  Wind: NW 5-15 mph.  57/90

Sun (17 Aug):  Mostly Sunny & Cooler.  56/85

Mon (18 Aug):  Mostly Sunny.  55/84

ODA Meteorologist
weather at oda.state.or.us