[willamette-fcst] Forecast - Wednesday, October 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.

       The October Update of the ODA Seasonal Climate Forecast is Available at:
           http://oregon.gov/ODA/NRD/weather.shtml#Weather_forecasts

NOON UPDATE

Issued: 
     Wednesday, October 21st, 2009 at 12:00pm.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from now until 4:30pm.
     Straw stack burning is allowed from now until 4:30pm.

Weather Discussion:
     Rain and thunderstorms spread across western Oregon during
     the pre-dawn hours this morning, ahead of a cold front that
     was moving onshore late this morning.  There was
     considerable lightning and thunder from Corvallis, to
     Eugene, to Roseburg and around North Bend, on the south
     coast.  Rainfall amounts were greatest along the north
     coast, with nearly two-thirds of an inch (.63 inches)
     falling at Astoria.  Between one-tenth and one quarter of an
     inch fell along the central and south coast and the
     Willamette Valley.  Portland picked up just over one-quarter
     (.27 inches) of an inch.  

     The showers weakened as they advanced across the Cascades. 
     Redmond received .07 inches, while Pendleton only managed to
     get .01 inches.  Meacham, in the Blue Mountains, received
     only a trace of rain this morning.  Lightning detection was
     still indicating an isolated strike or two over
     south-central Oregon late this morning, but otherwise things
     had settled down.  Pockets of light rain were showing up on
     radar, across central and eastern Oregon, but surface
     reports were not showing much rainfall.

     Doppler radar showed the areas of light rain were tapering
     off across northwestern Oregon late this morning.  The cold
     front is forecast to push east of the Cascades by late this
     afternoon, with showers tapering off across western Oregon. 
     Some sunbreaks were appearing along the coast at midday and
     could make their way into the Willamette Valley this
     afternoon.  Additional rainfall amounts across the valley
     should be a couple hundredths of an inch, at most.

     The air aloft is still warm enough to support high
     temperatuers climbing into the lower 60s this
     afternoon...especially if there are many breaks in the
     clouds.  The freezing level was measured over Salem this
     morning at 10,700 feet and is forecast to only drop to about
     8000 feet this afternoon.  Southerly winds should turn more
     westerly, in the wake of the cold front, by late this
     afternoon.  Higher mixing heights and brisk transport winds
     will make for much-improved ventilation conditions today.

Surface Winds:
     W 5-12 this afternoon.
Transport Winds:
     W 12 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 4500 feet.  Ventilation index 68.
High Temperature:
     Salem\'s high temperature today will be near 63.
Humidities:
     Minimum relative humidity will be near 65%.
Sunrise/Sunset:
     Salem sunset tonight: 6:17pm; sunrise tomorrow: 7:37am.

Extended Outlook:
     Another transitory ridge of high pressure will bring a
     return of dry weather Thursday with widespread morning fog
     giving way to partly sunny skies in the afternoon.  The next
     weather system is forecast to spread more rain across
     western Oregon Friday.  Rainfall amounts should be similar
     to today, with the greatest totals on the north coast and
     the northern Willamette Valley.  A shower or two may linger
     into Saturday morning, with some clearing Saturday afternoon.

     The next weather system is forecast to swing more rain onshore
     Sunday afternoon.  The storm track is forecast to sag southward,
     over Washington and Oregon, late Sunday through Tuesday.  Colder
     air aloft will drop the snow level down to the northern Cascade
     passes by Monday afternoon. Strong northwesterly flow aloft is
     forecast next Tuesday and Wednesday, which will dry things out
     but keep temperatures below normal.

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

Fri (23 Oct):  Areas of AM Fog.  Increasing Clouds.  PM Rain Developing.  43/62

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.  42/61

Mon (26 Oct):  Rain Turning to Showers.  Snow Level Dropping to 4000 Feet.  43/57

Tue (27 Oct):  Decreasing Chance of Showers and Cool.  Snow level 3-4000 Feet.  40/55

Wed (28 Oct):  Areas of AM Fog.  Partly Sunny and Cool.  39/57

ODA Meteorologist
weather at oda.state.or.us