[willamette-fcst] Forecast - Monday, April 5th, 2010

[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: 
     Monday, April 5th, 2010 at 9:00am.

Burn Advisory:
     Recommended burn times for agricultural burning are from now until 5:30pm.
     Straw stack burning is allowed from now until 5:00pm.

Weather Discussion:
     A powerful storm brought strong winds and dropped from
     one-half to one inch of rain across western Oregon last
     Friday along with heavy mountain snowfall.  A cold
     upper-level trough maintained showers across the region on
     Saturday with continued very low snow levels.  The latest in
     a series of strong cold fronts swept across western Oregon
     Sunday afternoon...producing a brief period of blustery
     winds and locally heavy rain.  Since the storm moved through
     the area quickly, rainfall totals were generally less than
     one-quarter of an inch, with only a few additional inches of
     new snow in the Cascades and higher elevations of the coast
     range.  Ahead of the cold front, temperatures managed to
     climb into the low to mid 50s across western Oregon early
     Sunday afternoon, which is still well below normal.

     A cold upper level trough is centered just off the
     Washington coast this morning, with satellite imagery
     showing an enhanced area of clouds moving onto the Oregon
     coast.  Doppler radar is showing several bands of showers
     rotation across western Oregon, in a brisk southwesterly
     flow aloft.  The ODA surface analysis shows tightening
     southerly pressure gradients across western Oregon, in
     association with the approaching upper-level disturbance. 
     South winds have been gusting to around 25 mph in the
     Willamette Valley.  Even with south winds, surface
     temperatures are only near 40 degrees in the lowlands of
     western Oregon. The air aloft is unseasonably cold, with the
     snow level around 2000 feet.  ODOT road cameras show snow-covered
     Cascade passes, where temperatures are below freezing.

     Cool, showery, and blustery weather is in store for today,
     as an impressive upper-level disturbance moves onshore. 
     There is even a slight chance of a thunderstorm.  Showers
     could also produce bursts of small hail.  A few inches
     inches of additional snow are likely over the Cascades and
     higher elevations of the coast range.  Cold air aloft and
     brisk southerly winds will make for excellent ventilation
     conditions today.  Coastal and valley high temperatures will
     be about 10 degrees below normal...struggling to reach 50 degrees. 

Surface Winds:
     SSE 10-20 G28 this morning, S 12-25 G35 this afternoon.
Transport Winds:
     S 25 this morning, S 30 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 4000 feet.  Ventilation index 120.
High Temperature:
     Salem\'s high temperature today will be near 49.
Humidities:
     Minimum relative humidity will be near 65%.
Sunrise/Sunset:
     Salem sunset tonight: 7:45pm; sunrise tomorrow: 6:44am.

Extended Outlook:
     Showers will taper off Tuesday, as the flow aloft turns
     northwesterly and dries out.  Wednesday looks dry and
     warmer, and may end up being the nicest day of the next
     week, as a transitory upper-level ridge moves Oregon.  The
     break in the weather will be brief, with another cold system
     forecast to come onshore early Thursday.

     An upper-level trough will keep a chance of showers over the
     region at least through Sunday, with continued fairly low snow
     levels.  Temperatures may warm close to normal on Wednesday but
     otherwise remain below normal for the extended forecast period.

Tomorrow (06 Apr):  Decreasing Showers.  Snow Level Rising to 3000 Feet.  37/53

Wed (07 Apr):  Becoming Partly Sunny and Warmer.  37/61

Thu (08 Apr):  Rain Likely with Mountain Snow.  Snow Level Dropping to 3000 Feet.  40/52

Fri (09 Apr):  Partly Cloudy.  Chance of Showers.  Snow Level 3-400 Feet.  34/54

Sat (10 Apr):  Partly Cloudy.  Chance of Showers.  Snow Level 3-4000 Feet.  35/56

Sun (11 Apr):  Partly Cloudy.  Chance of Showers.  Snow Level 4000 Feet.  37/58

Mon (12 Apr):  Partly Cloudy.  Chance of Showers.  Snow Level 4000 Feet.  37/59

ODA Meteorologist
weather at oda.state.or.us