[willamette-fcst] Forecast - Monday, March 2nd, 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.

...Updated High Temperature For Today and Corrected Wording on Weather Discussions...

Issued: 
     Monday, March 2nd, 2009 at 9:30am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from now until 4:00pm.
     Straw stack burning is allowed from now until 4:00pm.

Weather Discussion:
     A slow moving cold front brought more than an inch of rain
     to sections of the southern and central oregon caoast
     overnight and from one-quarter to three-quarters of an inch
     of rain to the Willamette Valley.  The greatest rainfall
     amounts were in Lane County.  North Bend picked up just over
     two inches of rain in the past 24 hrs, with the southern
     Willamette valley generally receiving between one-half and
     three-quarters of an inch.  Some spots in the extreme north
     valley, like the Portland Airport, received less than
     one-quarter of an inch.

     The ODA surface analysis showed the weakening cold front
     along the Cascades at mid-morning.  Southerly flow aloft was
     keeping freezing levels near 6000 feet, with pass
     temperatures in the mid 30s.  Timberline Lodge reported 3
     inches of new snow overnight, so this front was not a big
     snow-maker for the mountains.  ODOT road cameras showed
     generally wet pavement over the passes.  Pressure greadients
     were relaxing across western Oregon, with
     south-southeasterly winds in the 5-15 mph range.

     Satellite imagery showed considerable breaks in the clouds
     across western Oregon, in the wake of the cold front.  Some
     sunbreaks will enhance daytime heating, with valley highs
     likely climbing into the mid to upper 50s (several degrees
     above normal).  With the air aloft slowly cooling today, the
     daytime heating should help to trigger some instability
     showers.  Ventilation conditions will be good today, with
     southerly transport winds and high mixing heights.

Surface Winds:
     SSE 5-15 this morning, SSE 5-15 this afternoon.
Transport Winds:
     S 20 this morning, S 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 57.
Humidities:
     Minimum relative humidity will be near 57%.
Sunrise/Sunset:
     Salem sunset tonight: 6:01pm; sunrise tomorrow: 6:46am.

Extended Outlook:
     Another organized system, in the southwesterly flow aloft,
     is forecast to come onshore overnight, which will increase
     the rainfall across western Oregon.  Snow levels will slow
     drop to the Cascade passes tonight, with 3-6 inches of new
     snow likely there by Tuesday morning.  An upper-level trough
     will stay close enough to the coastline to keep some showers
     going over western Oregon into Wednesday.

     A quite cold system is forecast to drop into the region,
     from southern British Columbia, Thursday afternoon and
     Friday.  This system will need to be watched closely for the
     potential to produce sticking snow in the coast range and
     wet snow down the Willamette Valley floor.  Showers will
     decrease Friday afternoon, with snow levels lifting to about
     1500 feet.  we may see a brief break in the weather
     Saturday, before another very cold system drops into the
     region Sunday.  That system is forecast to be even colder
     than the one Thursday night, so it also has the potential to
     bring wet snow to the lower elevations of northwestern Oregon.

Tomorrow (03 Mar):  Rain Turning to Showers.  Snow Level 3500 Feet.  41/53

Wed (04 Mar):  Showers...Decreasing Late.  35/50

Thu (05 Mar):  Rain and Colder.  Snow Level Dropping to 1000 Feet or Less.  34/46

Fri (06 Mar):  showers.  Snow Level Starting Below 1000 Feet and Slowly Rising.  32/47

Sat (07 Mar):  Partly Cloudy.  Slight Chance of Showers.  31/50

Sun (08 Mar):  Increasing Rain and Snow.  Wet Snow Possible on the Valley Floor.  33/45

Mon (09 Mar):  Very Cold Start...Becoming Partly Sunny.  29/49

ODA Meteorologist
weather at oda.state.or.us