[willamette-fcst] Forecast - Monday, September 21st, 2009

[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.

...State Fire Marshal Conditions may be met, due to low humidities and wind, this afternoon...

Issued: 
     Monday, September 21st, 2009 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:
     An unseasonably strong upper-level ridge of high pressure is
     building over the region today. With the exception of a few
     high clouds, skies were clear this morning over the entire
     Pacific Northwest. At the surface, high pressure was
     centered over northeastern Oregon, with a building thermal
     trough along the southern Oregon Coast. That was resulting
     in a very dry offshore flow across western Oregon.

     East-northeasterly winds were gusting to around 20 mph along
     the Oregon Coast and through the coastal range passes, with
     east winds gusting to around 30 mph at the western end of
     the Columbia Gorge. Winds were light in most of the
     Willamette Valley, away from the Columbia Gorge, due to a
     strong low-level temperature inversion. However,
     north-northeasterly winds will increase later this morning,
     as daytime heating promotes stirring of the air.

     Warm air aloft, a full day of late-summer sunshine, and
     down-sloping northeasterly winds will combine to warm
     Willamette Valley temperatures to well above normal this
     afternoon. Some locations could see highs in excess of 90
     degrees. Low humidities and increasing offshore winds may
     put much of the valley into State Fire Marshal conditions by
     early this afternoon. 

Surface Winds:
     NE 5-14 this morning, NE 8-18 G25 this afternoon.
Transport Winds:
     NE 14 this morning, NE 15 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 2500 feet.  Ventilation index 38.
High Temperature:
     Salem\'s high temperature today will be near 91.
Humidities:
     Minimum relative humidity will be near 15%.
Sunrise/Sunset:
     Salem sunset tonight: 7:11pm; sunrise tomorrow: 7:00am.

Extended Outlook:
     Tuesday and Wednesday will likely be the warmest days, of
     this hot spell, in the Willamette Valley.  Record high
     temperatures are possible (mid 90s).  The strong upper-level
     ridge is forecast to shift over Idaho Thursday, with a weak
     trough moving onto the coastline in the afternoon.   Onshore
     flow should bring significant cooling to western Oregon,
     with temperatures dropping back close to normal (mid 70s). 
     The upper-level ridge is forecast to rebuild over the region,
     beginning Friday, with temperatures warming back up again.

Tomorrow (22 Sep):  Sunny.  Record Warmth Possible.  NE Winds.  53/95

Wed (23 Sep):  Sunny.  Record Warmth Possible.  NNW Winds.  55/93

Thu (24 Sep):  Mostly Sunny and Cooler.  Increasing Onshore Flow.  49/77

Fri (25 Sep):  Patchy AM Clouds...Sunny.  North Winds.  47/83

Sat (26 Sep):  Sunny.  North Winds.  46/85

Sun (27 Sep):  Sunny.  North Winds.  47/86

Mon (28 Sep):  Sunny.  NW Winds.  47/77

ODA Meteorologist
weather at oda.state.or.us