[willamette-fcst] Forecast - Thursday, April 8th, 2010

Thu Apr 8 09:10:27 PDT 2010

Daily Smoke Management Forecast

Oregon Department of Agriculture
Smoke Management Program
Weather Outlook and Field Burning Advisory for Willamette Valley Growers and Fire Districts.

     This daily Willamette Valley Agricultural Weather Forecast will become a seasonal product,
     as of Friday April 16th. The last broadcast and email of this forecast will be Thursday,
     April 15th. It will return as the \"Willamette Valley Field Burning Weather Forecast,\"
     issued daily via email and broadcast on WPOZ 585, beginning Thursday July 1st.

Issued: 
     Thursday, April 8th, 2010 at 9:00am.

Burn Advisory:
     Recommended burn times for agricultural burning are from now until 6:00pm.
     Straw stack burning is allowed from now until 5:00pm.

Weather Discussion:
     A vigorous cold front rapidly swept across western Oregon in
     the pre-dawn hours this morning and was already nearing the
     Idaho border by mid-morning.  The front dropped between
     one-quarter and one-half inch of rain along the coast and up
     to around one-quarter of an inch in the Willmatte Valley. 
     Snow levels rapidly dropped to between 2000 and 3000 feet
     with the passage of the cold front.  From 2-7 inches of new
     snow was reported this morning at the ski areas in the
     northern and central Oregon Cascades.  ODOT road cameras
     showed snow-packed Cascade passes this morning, where
     temperatures had dropped into the low to mid 20s.

     The strong cold front also brought rain and snow squalls to
     central and eastern Oregon this morning, along with very
     windy conditions.  In the immediate wake of the cold front,
     Pendleton was getting west winds gusting to 50 mph.  On the
     back side of the cold front, 30-40 mph westerly wind gusts
     were common east of the Cascades this morning, with
     post-frontal temperatures dropping into the 30s.  Ahead of
     the cold front, Ontario and Rome were in the mid to upper
     40s with a brisk south wind.

     Infrared satellite imagery showed considerable convective
     clouds rotating onto the Washington and mainly northern
     Oregon coast, in a cold northwesterly flow aloft.  Daytime
     heating will further destabilize the atmosphere today, with
     showers becoming more vigorous.  Snow levels will drop to
     around 1500 feet over northwestern Oregon this afternoon,
     with showers locally producing small hail along the coast
     and in the Willamette Valley.  Blustery winds will also
     accompany the showers.  Even with some sunbreaks, high
     temperatures will be at least 10 degrees below normal.

Surface Winds:
     W 5-15 G25 this morning, W 5-15 G25 this afternoon.
Transport Winds:
     WNW 20 this morning, WNW 20 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 5000 feet.  Ventilation index 100.
High Temperature:
     Salem\'s high temperature today will be near 49.
Humidities:
     Minimum relative humidity will be near 50%.
Sunrise/Sunset:
     Salem sunset tonight: 7:49pm; sunrise tomorrow: 6:38am.

Extended Outlook:
     A weak and transitory upper-level ridge will turn the flow
     aloft more westerly Friday and decrease the shower activity
     across the state.  After a cold morning, temperatures should
     recover into the low to mid 50s.  The air aloft will remain
     cold enough for daytime heating to increase convective
     activty and produce at least a few showers...mainly over the
     northwestern corner of the state.

     Temperatures will likely warm considerably on Saturday, as
     the flow aloft turns more southerly, in response to the next
     system digging southward to off the northern California
     coast.  However, southerly flow aloft and daytime heating
     may combine to trigger showers late in the day.  The
     offshore upper-level trough is forecast to move mainly to
     our south, Sunday and Monday, but the air aloft should
     destabilize enough for an increasing shower threat.  The
     next trough is forecast to take aim more at Oregon Tuesday
     through Thursday of next week.

Tomorrow (09 Apr):  Chance of Showers....Mainly North.  Snow Level 2-3000 Feet.  33/54

Sat (10 Apr):  Partly Cloudy and Warmer.  Chance of PM Showers.  Snow Level 5000 Feet.  33/62

Sun (11 Apr):  Increasing Chance of Showers.  Cooler.  Snow Level 4-5000 Feet.  37/59

Mon (12 Apr):  Showers Likely.  Cooler.  Snow Level 4000 Feet.  38/55

Tue (13 Apr):  Showers Likely Late.  Snow Level 4-5000 Feet.  37/56

Wed (14 Apr):  Showers Likely.  Cool.  Snow Level 3000 Feet.  37/53

Thu (15 Apr):  Partly Cloudy.  Chance of Showers.  Snow Level 4000 Feet.  37/57

ODA Meteorologist
weather at oda.state.or.us