[willamette-fcst] Forecast - Wednesday, November 4th, 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.

Issued: 
     Wednesday, November 4th, 2009 at 9:00am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from 12:00pm until 3:00pm.
     Straw stack burning is allowed from 12:00pm until 3:00pm.

Weather Discussion:
     The upper-level ridge of high pressure that brought mostly
     sunny skies to the region on Tuesday had shifted eastward to
     over Idaho by this morning.  Increasing southwesterly flow
     aloft was spreading considerable middle and high clouds
     across Washington and most of western Oregon.  Overnight
     cooling and light winds combined to help fog form in the
     central and southern Willamette Valley this morning. 
     Visibilities are locally below one-quarter of a mile,
     especially in the south valley.  Dry easterly outflow, from
     the Columbia Gorge, kept fog from forming across much of the
     north valley.

     Areas of the north valley exposed to the easterly winds
     stayed in the upper 40s and low 50s overnight, but calm
     regions of the Willamette Valley dropped to near the
     freezing mark.  Eugene dipped down to 32 degrees and Salem
     dropped to 33.  Mid-morning temperatures ranged from the
     foggy mid 30s in the south valley to around 50, under mostly
     sunny skies, in the north valley.

     The ODA surface analysis showed strong easterly pressure
     gradients across western Oregon, with easterly winds blowing
     through the coast range passes to the beaches.  East winds
     were continuing to gust over 30 mph at the western end of
     the Gorge, with light and variable winds across most of the
     Willamette Valley.

     Areas of morning valley fog will give way to high and
     mid-level clouds, in the afternoon, with increasing
     southwesterly flow aloft over Washington and Oregon. Highs
     should, once again, climb into the upper 50s and low 60s.

Surface Winds:
     Var 0-5 this morning, ESE 3 this afternoon.
Transport Winds:
     SE 5 this morning, SSE 6 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 1700 feet.  Ventilation index 10.
High Temperature:
     Salem\'s high temperature today will be near 60.
Humidities:
     Minimum relative humidity will be near 46%.
Sunrise/Sunset:
     Salem sunset tonight: 4:56pm; sunrise tomorrow: 6:56am.

Extended Outlook:
     The upper-level ridge is forecast to continue shifting
     eastward on Thursday, with the first of several potent
     weather systems forecast to come onshore by the afternoon. 
     The first cold front is forecast to push across western
     Oregon Friday morning.  Precipitation will turn showery
     Friday afternoon, with the snow level dropping to around to
     Cascade passes.

     A colder system is forecast to come onshore Saturday, with
     locally heavy rain and mountain snows...followed by slow
     drying on Sunday.  A warmer system is forecast to come
     onshore late Monday, with snow levels likely lifting above
     the Cascade passes.  A cool upper-level trough will drop the
     snow level back below the passes Tuesday and Wednesday.

Thu (05 Nov):  Increasing Clouds.  Rain Developing in the Afternoon.  South Winds.  40/60

Fri (06 Nov):  Rain Turning to Showers.  Snow Level Dropping to 4-5000 feet.  48/54

Sat (07 Nov):  Rain.  Possibly Heavy Mountain Snow.  Snow Level 3-4000 Feet.  44/51

Sun (08 Nov):  Decreasing Showers.  Snow Level 4000 Feet.  42/54

Mon (09 Nov):  Rain Developing Late.  Snow Level Risning to 5-6000 Feet.  40/56

Tue (10 Nov):  Showers.  Snow Level 3-4000 Feet.  40/54

Wed (11 Nov):  Showers.  Snow Level 3000 Feet.  40/53

ODA Meteorologist
weather at oda.state.or.us