[willamette-fcst] Forecast - Wednesday, March 18th, 2009

Willamette Valley Ag/Burning Forecast willamette-fcst at listsmart.osl.state.or.us
Wed Mar 18 12:11:04 PDT 2009




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: 
     Wednesday, March 18th, 2009 at 12:00pm.

...Next Update Not Scheduled Until Monday, March 23rd at 9:00am...

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from now until 4:30pm.
     Straw stack burning is allowed from now until 4:30pm.

Forecast Today:  Filtered Sunshine and Mild.  Salem high near 60.

Weather Discussion:
     Showers tapered off across northwest Oregon Tuesday evening,
     but skies remained cloudy overnight, in response to a warm
     front moving into northwest Washington.  Rainfall amounts
     Tuesday ranged from about one-quarter of an inch along the
     north coast to only a few hundredths of an inch in the
     southern Willamette Valley.  Temperatures generally stayed
     in the low 40s overnight, across western Oregon, with a few
     spots dipping into the upper 30s.  Pressure gradients
     relaxed overnight, and valley winds became calm.

     The late-morning ODA surface analysis and satellite imagery showed a cold
     front moving into northern Vancouver Island, British Columbia and trailing
     offshore to about 300 miles off the northern Oregon Coast.  A warm front
     was producing rain as far south as the northern Washington Coast with lots
     of middle and high clouds extending south over Oregon.  Weak upper-level
     ridging over Oregon is forecast to lift the warm front into southern
     British Columbia this afternoon, with the cold front slowly sagging into
     northwestern Washington this evening.  Oregon should stay dry with filtered
     sunshine and mild south winds this afternoon.

     Warmer air aloft pushed the freezing level over Medford to 8000 feet early
     this morning (up from 4900 feet Tuesday morning).  The freezing level over
     Salem had not climbed as much and was measured at 4500 feet this morning.
     The air aloft should continue to warm today, with the freezing level
     over northern Oregon rising to about 6000 feet.  Light southerly winds and
     warmer air aloft should help temperatures reach 60 degrees across the Willamette
     Valley this afternoon.

Surface Winds:
     S 3-7 this afternoon.
Transport Winds:
     SSW 7 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 5000 feet.  Ventilation index 35.
High Temperature:
     Salem\'s high temperature today will be near 60.
Humidities:
     Minimum relative humidity will be near 45%.
Sunrise/Sunset:
     Salem sunset tonight: 7:22pm; sunrise tomorrow: 7:17am.

Extended Outlook:
     A cold front will weaken as it sags southward, across
     northwestern Oregon, Thursday.  That will maintain mostly
     cloudy and mild conditions with some light rain possible at
     times...mainly in the north valley.  The front will act to
     maintain good ventilation conditions across western Oregon
     with south-southwesterly transport winds.  A stronger system
     is forecast to swing onshore Friday afternoon, with snow
     levels dropping back below the Cascade passes by Friday evening.

     An upper-level trough will swing onshore Saturday, but the
     main jet stream energy will be focused south of the region,
     over California. Skies should stay mostly cloudy over Oregon,
     with rain at times, and continued farily low snow levels. 
     Showers should taper off Sunday, as the upper-level trough
     moves eastward into the Rockies.

     The long-range computer models have greatly differing
     solutions beginning early next week, so confidence in the
     forecast beyond Sunday is low.  A weakening cold front may bring
     some light rain to western Oregon by Monday afternoon.  A ridge is
     forecast to bring some drying Tuesday, but it is uncertain how long
     the dry weather will last.

Thu (19 Mar):  Mostly Cloudy.  Chance of Rain...Mainly North.  Snow Level 6000 Feet.  40/59

Fri (20 Mar):  Rain and Mountain Snow.  Snow Level Dropping to 4-5000 Feet.  44/54

Sat (21 Mar):  Rain at Times with Mountain Snow.  Snow Level 3-4000 Feet.  40/53

Sun (22 Mar):  Decreasing Showers.  Snow Level 3000 Feet.  37/52

Mon (23 Mar):  Increasing Chance of Light Rain.  Snow Level 4000 Feet.  35/57

Tue (24 Mar):  Becoming Partly Sunny.  Snow Level Rising to 6000 Feet.  39/59

Wed (25 Mar):  Increasing Clouds and Mild.  Snow Level 6-7000 Feet.  40/62

ODA Meteorologist
weather at oda.state.or.us



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