[willamette-fcst] Forecast - Monday, July 23rd, 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: 
     Monday, July 23rd, 2007 at 9:00am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from 1:00pm until 7:00pm.
     Preparatory burning is allowed from 1:00pm until 2:00pm with a 100 acre limit.
     Propane flaming is not allowed.
     Dry straw stack burning is allowed from 1:00pm until 7:00pm.

Weather Discussion:
     South-southwesterly flow over the weekend stalled an active
     frontal system just offshore. The Northern Oregon Coastal
     strip received over an inch of rain. Meanwhile, the
     Willamette Valley saw only very light amounts, with a trace
     to a few hundredths of an inch on Saturday. Sunday was
     generally dry.  The damp weather and high humidity levels,
     over the weekend, made for only marginal drying conditions,
     after the widespread rainfall last Wednesday across the
     valley.

     The upper-level trough, responsible for the moist conditions
     the past several days, is weakening and will begin lifting
     into Southern British Columbia today.  The associated
     surface front is also weakening and will finally push inland
     this afternoon and evening.  That system will provide some
     lift to the very moist air mass west of the Cascades, which
     could result in some areas of light rain this afternoon.

     Transport winds, which have been south-southwesterly are
     likely to shift to a more favorable west-northwesterly
     direction, for burning, this afternoon and mixing heights
     should reach about 4500 feet.  Surface gradients, which are
     weakly onshore this morning, may also become more favorable
     for open burning this afternoon.  However, changes in
     transport winds may be difficult to assess, due to low cloud
     cover, and the relative humidity may stay too high for open
     burning.  Please contact your permit agent, if you think you
     have a dry field that is ready to burn.

     Preparatory burning is only being allowed from 1pm until 2pm
     due to high humidity levels and the potential for open
     burning this afternoon.  That burning window may be
     extended, if conditions favorable for open burning are not
     likely to develop.

Surface Winds:
     W 4 this morning, NW 7-11 this afternoon.
Transport Winds:
     SSW 7 this morning, WNW 13 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 4500 feet.  Ventilation index 59.
High Temperature:
     Salem\'s high temperature today will be near 79.
Humidities:
     Minimum relative humidity will be near 50%.
Sunrise/Sunset:
     Salem sunset tonight: 8:49pm; sunrise tomorrow: 5:49am.

Extended Outlook:
     A more typical summer weather pattern is shown on today\'s
     medium and long-range computer models.  The pattern looks
     dry beginning Tuesday through this weekend.  There continues
     to be weak southwesterly flow aloft, which would continue
     onshore surface flow west of the Cascades and prevent
     temperatures from climbing much above seasonal normals.  

Tomorrow (24 Jul):  Morning Clouds...Afternoon Sunshine.  58/83

Wed (25 Jul):  Mostly Sunny and Warm.  54/88

Thu (26 Jul):  Mostly Sunny and Warm.  58/88

Fri (27 Jul):  Mostly Sunny and Warm.  58/88

Sat (28 Jul):  Mostly Sunny. A touch cooler.  58/85

Sun (29 Jul):  Partly Cloudy.  56/80

Mon (30 Jul):  Partly Cloudy. 55/80

ODA Meteorologist
weather at oda.state.or.us