[willamette-fcst] Forecast - Friday, January 22nd, 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: 
     Friday, January 22nd, 2010 at 9:00am.

Burn Advisory:
     Recommended burn times for agricultural burning are from 10:00am to 3:00pm.

     ...The rules for stack burning have changed...

     In 2010, a total of 1000 acres can be stack-burned in the
     Willamette Valley.  Pre-registration is now required, and
     stack burning permits must be obtained from an ODA staff member. 
     
Weather Discussion:
     Two strong low-pressure areas dominated the weather scene
     along the west coast on Thursday.  One circulation center
     brought rain windy conditions to much of California, while
     the other weakened and moved slowly north, along the Oregon
     coast.  The latter system brought very mild southerly winds
     to western Oregon Thursday afternoon with very little
     rainfall, except over the extreme southwestern corner of the
     state. Temperatures climbed into the balmy mid to upper
     50s...more than 10 degrees above normal.  Salem was one of
     the warmest spots in western Oregon with a high of 58
     degrees.  Warm southeasterly winds also reached east of the
     Cascades, with downtown Pendleton recording a high Thursday
     of 62 degrees.

     The low-pressure center off the Oregon coast weakened and
     drifted northwestward overnight.  It was well off the
     Washington coast this morning and not much of a factor. 
     Meanwhile, the California system swept northeastward, across
     Nevada, overnight and was moving into southern Idaho this
     morning.  The counterclockwise circulation around it was
     spreading clouds and light precipitation across all of
     Oregon this morning.  

     The freezing levels over Oregon and western Idaho had
     dropped below 4000 feet by early this morning, with areas of
     light snow extending westward from eastern Oregon to the
     Oregon Cascade passes.  Very light snow was falling this
     morning from the Bend/Redmond area, to Klamath Falls, to
     Burns.  After pushing over 60 degrees Thursday afternoon,
     Pendleton was in the upper 20s this morning and could see a
     few snowflakes today.

     Satellite imagery showed cloudy skies also extending over
     western Oregon, with Doppler radar and surface reports
     showing widespread areas of light rain.  Temperatures along
     the coast and in the western valleys were generally in the
     low to mid 40s.  Cascade pass temperatures were just below
     freezing, as well most areas in central and eastern Oregon.
 
     As the weather system over Idaho exits eastward, another
     weak upper-level disturbance is forecast to rotate onshore
     into southwestern Oregon and northwestern California.  That
     will keep skies generally cloudy across Oregon today with
     areas of light rain and higher elevation snow.  Willamette
     Valley temperatures will be markedly cooler today, with
     highs struggling to reach 50 degrees...much closer to
     normal.  Pressure gradients are not very strong today, with
     light southerly winds forecast to continue across western Oregon.

Surface Winds:
     S 5-10 this morning, S 5-12 this afternoon.
Transport Winds:
     S 10 this morning, SSW 12 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 3000 feet.  Ventilation index 36.
High Temperature:
     Salem\'s high temperature today will be near 49.
Humidities:
     Minimum relative humidity will be near 68%.
Sunrise/Sunset:
     Salem sunset tonight: 5:06pm; sunrise tomorrow: 7:41am.

Extended Outlook:
     A transitory upper-level ridge will likely bring some drying
     by Saturday afternoon. A warm front is forecast to bring
     rain back onshore by Sunday night, along with rising snow
     levels.  The trailing cold front has the potential to bring
     strong southerly winds to mainly the coastal strip Sunday
     night.  It appears as if energy from this storm may get
     split apart, as it comes onshore, with the bulk of the
     moisture heading both north and south of Oregon.  However,
     it should bring more rain to the Willamette Valley than the
     past couple of weaker weather systems.  

     Rain will slowly taper off late Monday and Tuesday, with a
     split-flow jet stream pattern developing.  Another mild
     storm is forecast to come onshore late Wednesday and
     Thursday, with showers and lowering snow levels on Friday.

Sat (23 Jan):  Mostly Cloudy.  Decreasing Chance of Showers.  Snow Level 3000 Feet.  35/49

Sun (24 Jan):  Increasing Rain and Wind Late.  Snow Level Rising to 4000 Feet.  34/47

Mon (25 Jan):  Rain Decreasing.  Snow Level 4500 Feet.  41/50

Tue (26 Jan):  Mostly Cloudy.  Slight Chance of Showers.  Snow Level 4000 Feet.  38/50

Wed (27 Jan):  Increasing Clouds.  Snow Level Rising to 5-6000 Feet.  37/50

Thu (28 Jan):  Rain Likely and Mild.  Snow Level 6000 feet.  42/54

Fri (29 Jan):  Rain Turning to Showers.  Snow Level 4500 Feet.  37/50

ODA Meteorologist
weather at oda.state.or.us