[willamette-fcst] Forecast - Thursday, September 17th, 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: 
     Thursday, September 17th, 2009 at 8:50am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from 1:00pm until 6:00pm.
     Preparatory burning is not allowed.
     Propane flaming is allowed from 1:00pm until 6:00pm.
     Stack burning is not allowed.

Weather Discussion:
     A narrow but slow-moving cold front brought light rain to
     the Willamette Valley Wednesday afternoon and early evening.
     Most of the valley received between a trace and one-tenth of
     an inch, with the greatest amounts in the north. As much as
     one-third of an inch fell in sections of Multnomah County.

     The cold front continued eastward, across central and
     eastern Oregon, overnight, with partial clearing west of the
     Cascades allowing temperatures to drop into the 40s and low
     50s. That helped areas of dense fog to form across the
     Willamette Valley by early this morning.

     The mid-morning ODA surface analysis showed high pressure
     centered over western Washington and northwestern Oregon
     with very weak northerly gradients across the Willamette
     Valley.  High pressure will continue to build over the
     region today.  Areas of morning fog giving way to sunny
     skies and light northery winds this afternoon. Valley highs
     should recover into the mid 70s...about normal for
     mid-September.

Surface Winds:
     N 0-7 this morning, N 5-12 this afternoon.
Transport Winds:
     NE 6 this morning, N 10 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 3500 feet.  Ventilation index 35.
High Temperature:
     Salem\'s high temperature today will be near 77.
Humidities:
     Relative humidity drops to 50% by 2pm.
     Minimum relative humidity will be near 37%.
Sunrise/Sunset:
     Salem sunset tonight: 7:18pm; sunrise tomorrow: 6:55am.

Extended Outlook:
     Further warming and drying is likely on Friday.  Another
     weather system is forecast to swing mainly into southern
     British Columbia and Washington Saturday, but the trailing
     cold front will likely bring some light rain and cooler
     temperatures to the Willamette Valley.  Rainfall amounts
     could be as little as a few hundredths of an inch in the
     south valley but should exceed one-tenth of an inch in the
     north valley.

     Showers will quickly taper off, in the wake of the cold
     front, Saturday evening, with areas of fog forming by Sunday
     morning.  A strong upper-level ridge is forecast to build
     over the west coast next week.  Increasing offshore flow
     will combine with sunny skies to send temperatures well
     above normal.

Tomorrow (18 Sep):  Sunny and Warmer.  49/84

Sat (19 Sep):  Light Rain Likely...Mainly North.  Clearing Late.  55/73

Sun (20 Sep):  Areas AM Fog...Becoming Sunny and Warmer.  Offshore Flow Developing.  49/80

Mon (21 Sep):  Sunny and Very Warm.  Strong Offshore Flow.  52/91

Tue (22 Sep):  Sunny and Very Warm.  Strong Offshore Flow.  55/93

Wed (23 Sep):  Sunny and Very Warm.  Light Winds.  55/88

Thu (24 Sep):  Sunny and Continued Very Warm.  North Winds.  52/86

ODA Meteorologist
weather at oda.state.or.us