[willamette-fcst] Forecast - Wednesday, July 25th, 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: 
     Wednesday, July 25th, 2007 at 9:00am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from 11:00am until 7:00pm.
     Preparatory burning is not allowed.
     Propane flaming is allowed from 12:00pm until 7:00pm.
     Stack burning is not allowed.

Weather Discussion:
     With a drier air mass in place, overnight tempertures
     dropped into the upper 40s and lower 50s in the Willamette
     Valley...leading to widespread areas of ground fog early
     this morning.  Low clouds were limited mainly to coastal
     regions this morning, with northerly surface gradients and
     very weak onshore flow across Western Oregon.  

     Sunshine will prevail, over the Willamette Valley, through
     Friday, with high pressure firmly in place across the
     region.  North winds will not be as strong today, as
     pressure gradients have relaxed somewhat from yesterday.
 
     Weak southwesterly flow aloft will prevent the surface
     thermal trough, currently in Northern California, from building
     northward into the Willamete Valley this week, so
     temperatures will not rise much above seasonal normals.

     No preparatory burning is allowed today, because of
     northerly transport winds, and open field burning is
     unlikely.  The transport winds are forecast to become more
     northwesterly tomorrow and Friday.  We will closely monitor
     this for possible field burning opportunities.

Surface Winds:
     N 7 this morning, N 10 this afternoon.
Transport Winds:
     N 10 this morning, N 15 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 4900 feet.  Ventilation index 74.
High Temperature:
     Salem\'s high temperature today will be near 85.
Humidities:
     Relative humidity drops to 50% by 12pm.
     Minimum relative humidity will be near 31%.
Sunrise/Sunset:
     Salem sunset tonight: 8:47pm; sunrise tomorrow: 5:51am.

Extended Outlook:
     A weak weather system is still forecast to slide into
     Western Washington late Saturday, which will increase the
     onshore flow across Western Oregon.  That will cool high
     temperatures to near or slightly below seasonal normals
     Sunday and Monday.  There is also a slight chance of
     showers, especially in the Northern Willamette Valley,
     Saturday night and Sunday morning.

     Computer models are indicating that surface gradients will be
     northerly on Monday, which would not be conducive to
     burning.  By Tuesday and Wednesday, the onshore flow
     decreases and the transport winds are forecast to become
     northwesterly...which increases the burning potential.

Tomorrow (26 Jul):  Sunny.  53/87

Fri (27 Jul):  Mostly Sunny.  55/86

Sat (28 Jul):  Areas of Morning Clouds...Mostly Sunny Afternoon.  56/83

Sun (29 Jul):  Slight Chance of Morning Showers.  Partly Sunny Afternoon.  56/78

Mon (30 Jul):  Morning Clouds...Mostly Sunny Afternoon.  51/82

Tue (31 Jul):  Mostly Sunny.  53/85

Wed (01 Aug):  Mostly Sunny.  54/85

ODA Meteorologist
weather at oda.state.or.us