[willamette-fcst] Forecast - Thursday, March 4th, 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: 
     Thursday, March 4th, 2010 at 12:00pm.

Burn Advisory:
     Recommended burn times for agricultural burning are from now until 4:00pm.
     Straw stack burning is allowed from now until 4:00pm.

Weather Discussion:
     The storm that cut across northern California and extreme southern Oregon, on Wednesday,
     was centered over extreme eastern Nevada late this morning.  Satellite imagery showed
     the counter-clockwise circulation around it continuing to drive clouds into extreme
     southeastern Oregon, but the bulk of the moisture had pushed south and east of the
     state.  Doppler radar also showed a few showers rotating from southwestern Idaho into
     the southeast corner of Oregon, where temperatures were still locally just above the
     freezing mark.  The ODOT road camera south of Burns Junction, at about 4500 feet on
     US highway 95, showed a fresh coating of roadside snow late this morning.

     Back in our neck of the woods, visible satellite imagery showed the morning low
     clouds and fog, across the western valleys, beginning to break up, with mostly sunny
     skies along the northern and central coast.  Midday temperatures ranged from the mid
     40s, in cloudy sections of the north valley, to the low 50s in the south valley, where
     the low clouds were giving way to some sunshine.

     The late-morning ODA surface analysis showed high pressure building into western Oregon,
     with flat pressure gradients across the Willamette Valley.  Brisk northwesterly winds
     were locally gusting to near 30 mph across eastern Oregon...feeding into a surface
     low-pressure center over east-central nevada.  Temperatures east of the Cascades ranged
     from the mid 30s, in the higher elevations of south-central and southeastern Oregon, to
     the mid 50s in the Columbia Basin of northeastern Oregon.

     The air aloft was fairly chilly this morning.  The freezing levels were measured at
     just 3400 feet and 4700 feet over Medford and Salem respectively.  ODOT road
     cameras showed a light dusting of new snow over the Cascade passes early this morning,
     with partial clearing warming pass temperatures mostly in the mid 30s at midday.  A
     transitory ridge of high pressure will partially clear skies across the western valleys
     this afternoon, but cold air aloft will keep some convective cloud development going.
     Along the coast, mostly sunny skies will slowly yield to increasing high clouds.  A light
     south wind was beginning to across western Oregon late this morning, ahead of the next
     weather system, still more than 300 miles offshore.  Valley highs should climb into the
     mid to upper 50s.

Surface Winds:
     S 3-8 this afternoon.
Transport Winds:
     SSW 6 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 3500 feet.  Ventilation index 21.
High Temperature:
     Salem\'s high temperature today will be near 56.
Humidities:
     Minimum relative humidity will be near 56%.
Sunrise/Sunset:
     Salem sunset tonight: 6:04pm; sunrise tomorrow: 6:43am.

Extended Outlook:
     On Friday, a weather system dropping into the region, from the Gulf of Alaska, will also
     encounter the split-flow pattern in the jet stream offshore and move mainly into California.
     Some light rain is possible...mainly along the coast and across southern Oregon.  A weak
     ridge of high pressure will dry things out for the first half of the weekend with some sun.

     A change to a stormy and cooler weather pattern is forecast for next week.  A cold front
     should spread rain back onshore Sunday afternoon, and across western Oregon by Sunday
     evening.  This system has colder air aloft associated with it, so snow levels will likely
     drop to below the Cascade passes.  Showers will taper off Monday, with the lowest snow
     levels we\'ve seen in many weeks.  After a brief break, early Tuesday, another cold weather
     system will bring more valley rain and much-needed mountain snow Tuesday night and
     Wednesday.  Yet another system is forecast to bring rain and blustery conditions onshore
     Thursday, followed by cooler and showery weather next Friday.

Fri (05 Mar):  Mostly Cloudy.  Chance of Rain...Mainly South.  Snow Level 4000 Feet.  38/57

Sat (06 Mar):  Becoming Partly Sunny and Mild.  37/60

Sun (07 Mar):  Rain Developing in the Afternoon.  Snow Level Dropping to 3-4000 Feet.  36/53

Mon (08 Mar):  Decreasing Showers.  Snow Level 2500 Feet.  35/49

Tue (09 Mar):  Increasing Clouds.  Chance of Rain Late.  Snow level 4000 Feet.  31/51

Wed (10 Mar):  Rain Turning to Showers.  Snow Level Near 3000 Feet.  38/51

Thu (11 Mar):  Rain Developing and Turning Blustery.  Snow Level Rising To 5000 Feet.  36/52

ODA Meteorologist
weather at oda.state.or.us