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

Thu Apr 8 12:08:47 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.

     ...Next Update Scheduled for Monday, April 12th, 2009...

Issued: 
     Thursday, April 8th, 2010 at 12:00pm.

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 and fast-movning cold front swept across western Oregon in the pre-dawn hours
     this morning and was already moving into Idaho at midday. 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.  In the wake of the front, snow levels have dropped to near
     1500 feet.

     2-7 inches of new snow were reported this morning at the ski areas in the northern and
     central Oregon Cascades.  ODOT road cameras showed packed snow over the Cascade passes,
     at midday, with pass temperatures still in the 20s.  Roadside snow was also visible along
     Oregon Highway 22 at Detroit (elevation 1670 feet).

     The strong cold front also brought rain and snow squalls to central and eastern Oregon
     this morning, along with very windy conditions.  In the wake of the cold front, Pendleton
     was still getting west winds gusting to 50 mph late this morning.  30-40 mph westerly winds
     were common east of the Cascades.  Midday temperatures were mostly in the chilly upper 30s
     and 40s in the wake of the cold front and low 50s ahead of it along the Idaho border. 

     Infrared satellite imagery showed considerable convective clouds rotating onto the
     Washington and northern Oregon coast, at midday, in a cold northwesterly flow aloft.
     Daytime heating is acting to further destabilize the atmosphere, with showers becoming
     more vigorous.  There have already been reports of small hail showers in the Willamette
     Valley this morning.  Snow levels will stay near 1500 feet this afternoon, with showers
     continuing to produce small hail along the coast and in the Willamette Valley.  Blustery
     winds will also accompany the showers.  Midday temperatures were in the mid to upper 40s
     across western Oregon.  Even with some sunbreaks, highs will struggle to reach the low 50s.

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 46%.
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