[willamette-fcst] Forecast - Tuesday, July 17th, 2007

[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, July 17th, 2007 at 9:00am.

Burn Advisory:
     Agricultural burning is not recommended.
     Preparatory burning is not allowed.
     Propane flaming is not allowed.
     Stack burning is not allowed.

Weather Discussion:
     A strong uppper-level low pressure area, centered about 400
     miles west of the Oregon Coast, is spreading clouds and
     light rain across Western Oregon and Western Washington this
     morning.  The moist southerly flow aloft will continue to
     circulate showers into the region today under cloudy skies.
 
     The morning ODA surface analysis showed weak onshore
     gradients across Washington and Oregon, with gradient
     stacking east of Salem.  This pattern is not conducive to
     good ventilation, in the Willamette Valley, even with mixing
     heights near 5000 feet this afternoon.

     The upper-level low pressure area is forecasat to slowly
     move to near the Southern Oregon Coast by late Wednesday,
     which will continue the southerly flow aloft of moist and
     increasingly unstable air over Oregon.  Therefore, cool and
     damp conditions will persist through Wednesday.

Surface Winds:
     Var 3 this morning, WNW 5-10 this afternoon.
Transport Winds:
     SW 3 this morning, SSW 7 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 5000 feet.  Ventilation index 35.
High Temperature:
     Salem\'s high temperature today will be near 74.
Humidities:
     Minimum relative humidity will be near 51%.
Sunrise/Sunset:
     Salem sunset tonight: 8:54pm; sunrise tomorrow: 5:43am.

Extended Outlook:
     An upper-level trough of low pressure is forecast, by
     computer models, to be directly over Western Oregon Thursday
     morning, which should continue the showers across the
     region.  It is expected to lift northeastward, into Eastern
     Washington, Thursday afternoon, with showers tapering
     off in the Willamette Valley.

     Another upper-level low pressure area is forecast to set up
     camp over the Eastern Pacific, beginning Friday, with an
     unseasonably strong jet stream directing a series of weather
     systems into Southern British Columbia.  The first of these
     weather fronts may extend far enough south to bring showers
     to Western Oregon Friday afternoon.  It appears that the jet
     stream will move just far enough northward, over the
     weekend, for drier and warmer weather to return to the
     region, with southwesterly flow aloft and weak onshore flow
     at the surface.

Tomorrow (18 Jul):  Cloudy and Cool with Showers.  Chance of a Thunderstorm.  59/74

Thu (19 Jul):  Morning Showers.  Becoming Partly Cloudy.  58/76

Fri (20 Jul):  Increasing Clouds.  Chance of Showers Late.  55/79

Sat (21 Jul):  Partly Cloudy.  58/82

Sun (22 Jul):  Mostly Sunny.  58/85

Mon (23 Jul):  Mostly Sunny.  58/88

Tue (24 Jul):  Mostly Sunny.  60/85

ODA Meteorologist
weather at oda.state.or.us