[willamette-fcst] Forecast - Friday, August 1st, 2008

[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: 
     Friday, August 1st, 2008 at 9:00am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from 2:00pm until 7:00pm.
     Preparatory burning is allowed from 2:00pm until 5:00pm with a 100 acre limit.
     Propane flaming is allowed from 2:00pm until 5:00pm.
     Straw stack burning is allowed from 2:00pm until 7:00pm.

Weather Discussion:
     A weakening cold front was moving onto the Northern Oregon
     Coastline this morning and will likely stall over the
     Willamette Valley this afternoon.  The front dumped up to
     one-half of an inch of rain along the Northern Washington
     Coast, since yesterday morning, with one-tenth to one-third
     of an inch falling in the northern interior of Western Washington.

     The front is drying out as it slowly moves southward with
     only spotty light rain expected today across NW Oregon.  The
     north valley could see a few hundredths of an inch of rain,
     with only a chance of showers in the south valley.  Some
     light rain was reported this morning along the Northern and
     Central Oregon Coast and in the extreme Northern Willamette
     Valley.  Aurora picked up .01 inches with trace amounts as
     far south as Salem.

     The Salem sounding this morning showed cooling aloft, so
     mixing heights will likely reach 3000 feet later this
     afternoon, even with much cooler temperatures today.  Cloudy
     skies should hold valley highs in the low 70s (about 10
     degrees cooler than Thursday).  Open burning is unlikely today 
     due to marginal mixing heights and gradient-stacking issues.

     Ahead of the cold front, surface winds across the valley
     were southerly this morning at about 5-10 mph.  Transport
     winds were southwesterly this morning and are expected to
     turn more westerly this afternoon, which is favorable for
     valley ventilation.  Therefore, propane and prep burning is
     allowed later today.  Some fields may get light rain between
     now and when burning is allowed this afternoon.  Please note
     that burning is allowed only for fields that stay dry.

Surface Winds:
     S 5-10 this morning, W 5-10 this afternoon.
Transport Winds:
     SW 12 this morning, WSW 12 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 3500 feet.  Ventilation index 42.
High Temperature:
     Salem\'s high temperature today will be near 72.
Humidities:
     Minimum relative humidity will be near 51%.
Sunrise/Sunset:
     Salem sunset tonight: 8:38pm; sunrise tomorrow: 5:59am.

Extended Outlook:
     An upper-level trough will swing onshore this evening, in
     the wake of the cold front.  Strong onshore flow will keep
     skies mostly cloudy tonight through much of Saturday.  The
     trough will slowly weaken over the weekend, with onshore
     flow becoming more northerly and temperatures recoving to
     near normal by Sunday.

     A ridge of high pressure is forecast to build over the
     Pacific Northwest early next week.  The low-level winds will
     turn north-northeasterly with valley temperatures possibly
     warming to near 90 degrees.  Increasing south to
     southwesterly flow aloft is forecast for the second half of
     next week with an increased threat of thundershowers...mainly
     from the Cascades eastward.  Increasing onshore flow may
     create a burn opportunity during the second half of next week,
     if the flow aloft is not too southerly.

Tomorrow (02 Aug):  Morning Clouds...Afternoon Clearing.  53/76

Sun (03 Aug):  Patchy Morning Clouds...Sunny and Warmer in the Afternoon.  49/82

Mon (04 Aug):  Sunny and Warm.  52/85

Tue (05 Aug):  Mostly Sunny and Very Warm.  54/90

Wed (06 Aug):  Partly Cloudy.  Slight Chance of T-Storms Near the Cascades.  54/89

Thu (07 Aug):  Partly Cloudy and Cooler. Slight Chance Showers/T-Storms.  56/84

Fri (08 Aug):  Partly Cloudy.  Slight Chance of a Shower.  55/84

ODA Meteorologist
weather at oda.state.or.us