[willamette-fcst] Forecast - Tuesday, October 20th, 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: 
     Tuesday, October 20th, 2009 at 9:00am.

Burn Advisory:
     Agricultural burning is not recommended.
     Stack burning is not allowed.

Weather Discussion:
     A transitory ridge or high pressure will build over
     Washington and Oregon today for dry and stagnant weather
     conditions.  Visible satellite imagery showed considerable
     fog and low clouds along the coast and across the Willamette
     Valley, with surface reports showing visibilities locally
     only about one-quater of a mile.  The ODA surface analysis
     showed weak high pressure centered over eastern Oregon with
     light offshore gradients beginning to develop across western Oregon.

     The low clouds and fog held overnight temperatures in the
     40s across western Oregon, with mid-morning readings mostly
     from the mid 40s to the low 50s.  The morning fog and low
     clouds will likely give way to at least partly sunny skies
     this afternoon across western Oregon with highs climbing to
     near-normal (low 60s).

Surface Winds:
     Var 0-5 this morning, SE 2-6 this afternoon.
Transport Winds:
     S 3 this morning, SE 4 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 1700 feet.  Ventilation index 7.
High Temperature:
     Salem\'s high temperature today will be near 63.
Humidities:
     Minimum relative humidity will be near 56%.
Sunrise/Sunset:
     Salem sunset tonight: 6:18pm; sunrise tomorrow: 7:36am.

Extended Outlook:
     A weak weather system push mainly into southern British
     Columbia Wednesday, with the cold front bringing some light
     rain to western Oregon.  Rainfall amounts should be between
     one-tenth and one-quarter of an inch in the Willamette
     Valley and along the south coast.  The north coast may pick
     up a little over one-quater of an inch...especially near Astoria.

     Another transitory ridge of high pressure will bring a
     return of dry weather Thursday with fairly widespread areas
     of fog that should give way to partly sunny skies in the
     afternoon.  The next weather system is also forecast to push
     mainly into the southern British Columbia on Friday, but the
     trailing cold front should bring at least some light rain to
     western Oregon late in the day.  A shower or two may linger
     over northwestern Oregon into Saturday morning, with some
     clearing Saturday afternoon.

     The timing of weather systems, beyond a couple of days out,
     is difficult, but it appears as if the next weather system
     will come onshore by Sunday evening.  That system is
     forecast to have a stronger jet stream associated with it,
     with the main storm track sagging southward to move over
     Washington and Oregon.  That could lower the snow level to
     the Cascade passes by Monday afternoon.

Tomorrow (21 Oct):  Light Rain Likely.  47/60

Thu (22 Oct):  AM Fog and Low Clouds.  Partly Sunny in the Afternoon.  45/64

Fri (23 Oct):  Areas of AM Fog.  Increasing Clouds.  A Little Rain Likely Late.  43/64

Sat (24 Oct):  Slight Chance AM Shower.  Partly Sunny in the Afternoon.  45/62

Sun (25 Oct):  Areas of AM Fog.  Increasing Clouds.  Chance of Rain by Afternoon.  42/60

Mon (26 Oct):  Rain at Times.  Snow Level Dropping to 4000 Feet.  43/59

Tue (27 Oct):  Showers and Cool.  Snow level 3000 Feet.  42/55

ODA Meteorologist
weather at oda.state.or.us