[willamette-fcst] Forecast - Thursday, October 2nd, 2008

Thu Oct 2 08:04:39 PDT 2008

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: 
     Thursday, October 2nd, 2008 at 9:00am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from 8:00am until 5:00pm.
     Preparatory burning is not allowed.
     Propane flaming is not allowed.
     Straw stack burning is allowed from 12:00pm until 5:00pm.

Weather Discussion:
     The early-autumn dry and warm spell was broken overnight, as
     the first in a series of Pacific Storms moved onshore. The
     first of several bands of showers rolled nrothward across
     the Willamette Valley overnight.  National Weather Servie
     and CoCORaHS reports indicate that only a couple hundredths
     of an inch fell over most of the valley with the greatest
     totals on the west side of the valley in Benton and Polk
     Counties.  It is possible that some fields in Eastern Marion
     County have received little to no rain so far.

     Doppler radar was showing another area of showers extending
     from the central Coast to near Eugene, moving north up
     mainly the west side of the Willamette Valley at
     mid-morning.  Surface reports confirm areas of light rain
     raeching the valley floor, but amounts have generally been
     only a few hundredths of an inch.  The cold front and
     associated upper-level trough from this first system were
     still offshore this morning and are forecast to weaken as
     they move inland late today.  That will increase the light
     shower acticity over Western Oregon with most of the valley
     likely getting at least a few hundredths of an inch of rain.

     The Salem sounding from late Wednesday afternoon showed a
     strong temperature inversion from 1500 feet to 3500 feet,
     but significant cooling aloft overnight had eliminated it by
     this morning.  Continued cooling aloft should raise mixing
     heights to around 3500 feet by mid-afternoon with forecast
     south-southwesterly transport winds.  In the unlikely event
     that any north-valley fields should stay dry, ventilation
     conditions may allow for open burning this afternoon.  We
     will continue to monitor the rainfall coverage and transport
     winds today.

     The cloudy and showery and conditions will finally cool
     temperatures below normal across Western Oregon today with
     valley highs only climbing into the mid 60s.  The showers
     should taper off tonight, as the weak upper-level trough
     moves east of the region.

Surface Winds:
     SSE 3-8 this morning, SSW 7-12 this afternoon.
Transport Winds:
     SSW 10 this morning, SW 16 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 3800 feet.  Ventilation index 61.
High Temperature:
     Salem\'s high temperature today will be near 66.
Humidities:
     Minimum relative humidity will be near 65%.
Sunrise/Sunset:
     Salem sunset tonight: 6:50pm; sunrise tomorrow: 7:13am.

Extended Outlook:
     Things will briefly dry out early Friday, ahead of a very
     impressive weather system forecast to bring increasing rain
     to Western Oregon Friday afternoon.  The low pressure center
     with this strom is forecat to become quite strong and may
     track close enough to the coastline to bring strong
     southerly winds to the coastal strip Friday night, along
     with locally heavy rain to much of Western Oregon.night and
     Saturday.

     This strom has the potential, depending on it\'s track, to
     bring damaging winds to the coast by early Saturday morning.
      It will likely turn blustery in the Willamette Valley
     Saturday with continued showers.  Total rainfall amounts
     from this system could exceed one inch in the Willamette
     Valley, between midday Friday and Saturday night.  The
     showers and winds are forecast to taper off Saturday night,
     as the low pressure system weakens and moves north to near
     Vancouver Island, British Columbia.

     A transitory ridge of high pressure is forecast to bring
     some drying Sunday with the next system now slated to come
     onshore late Monday.  That system may create a burning
     opportunity, Monday afternoon, in the unlikely event that
     fields are dry enough.   The cold front is forecast to come
     onshore early Tuesday with a cool upper-level trough
     bringing showers to the region through early Wednesday. A
     ridge of high pressure is forecast to dry things out Thursday.

     The long-range computer models are showing a stronger ridge
     of high pressure building over the Pacific Northwest next
     weekend, which could bring a more prolonged period of dry
     and warmer weather.

Tomorrow (03 Oct):  Mostly Cloudy.  Increasing Rain and Wind Late.  Wind: SSE 10-20.  52/66

Sat (04 Oct):  Rain Turning to Showers and Blustery...Decreasing Late.  54/63

Sun (05 Oct):  Mostly Cloudy.  Slight Chance of a Shower.  48/65

Mon (06 Oct):  Mostly Cloudy.  Chance of Rain Late.  46/68

Tue (07 Oct):  Light Rain Turning to Showers.  51/60

Wed (08 Oct):  Decreasing Showers.  45/62

Thu (09 Oct):  Partly Sunny.  42/67

ODA Meteorologist
weather at oda.state.or.us