[willamette-fcst] Forecast - Thursday, March 12th, 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.

Issued: 
     Thursday, March 12th, 2009 at 9:00am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from 11:00am until 4:00pm.
     Stack burning is not allowed.

Weather Discussion:
     A north-northwesterly flow aloft helped a modifying Arctic
     air slowly settle southward across Oregon Wednesday.  Even
     with clearing skies allowing for a full day of warming March
     sunshine, afternoon temperatures only climbed into the upper
     40s across most of the Willamette Valley.  Corvallis did
     manage to hit 50 degrees, for the warm spot in the valley,
     but that was still about 5 degrees below average.

     Clear skies and a dry air mass allowed for rapid cooling of
     the low-level air mass overnight across the entire state. 
     Willamette Valley minimums dipped as low as the mid 20s this
     morning, with windy areas staying near freezing. It was
     quite cold, again, east of the Cascades this morning, with
     many areas in the teens or colder.  Meacham, in the blue
     Mountains of northeastern Oregon, dropped to 11 degrees
     below zero for the second consecutive morning.  The
     unseasonalby cold Arctic air mass stretched from Oregon and
     Washington, eastward across much of the country this
     morning.  Below zero temperatures extended from northeastern
     Oregon and eastern Washington to the center of the cold
     dome, in Minnesota.

     Satellite imagery showed clear skies over Oregon this
     morning.  Strong offshore flow was keeing dry air over the
     region, along with blustery north-northeasterly winds. 
     Temperatures ranged from the upper 20s to the mid 30s across
     western Oregon, at mid-morning, with all areas east of the
     Cascades still well below freezing.  The air aloft is warmer
     this morning, with the freezing level over Salem measure at
     7600 feet.  That will help high temperatures climb into the
     50s across the Willamette Valley this afternoon under sunny skies.

Surface Winds:
     N 5-15 this morning, NNE 7-17 this afternoon.
Transport Winds:
     NNE 15 this morning, NE 17 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 3000 feet.  Ventilation index 51.
High Temperature:
     Salem\'s high temperature today will be near 54.
Humidities:
     Minimum relative humidity will be near 32%.
Sunrise/Sunset:
     Salem sunset tonight: 7:15pm; sunrise tomorrow: 7:28am.

Extended Outlook:
     An upper-level ridge is forecast to build over Oregon Friday
     for another sunny day.  After a frosty morning, high
     temperatures should climb to near normal (mid 50s).  Clouds
     will increase Friday evening, ahead of what appears will be
     a very damp weekend.  A couple of weather systems, dropping
     into the region from the Gulf of Alaska, will bring
     substantial rain and mountain snow to Oregon Saturday and
     Saturday night.  A warm front will continue the rain and
     snow Sunday, with snow levels lifting above the Cascade
     passes by the afternoon.  Southerly winds may become
     blustery Sunday afternoon and evening, especially along the
     coast, with mild temperatures.

     The long-range computer model forecasts are still not
     consistent on their forecast storm track position for early
     next week, but the trend is for a strong west-southwesterly
     jet stream to take aim at Washington and northwest Oregon. 
     That has the potential to bring significant precipitation to
     the region throug Monday...especially across western
     Washington.  Southerly surface winds should keep
     temperatures mild, mainly in the overnight periods. The
     storm track is forecast to weaken and shift slightly north
     late Tuesday and Wednesday.  A weaker system is forecast to
     move onshore Thursday.

Tomorrow (13 Mar):  Frosty Morning.  Sunny and Warmer in the Afternoon. Clouds Late.  28/57

Sat (14 Mar):  Rain...Possibly Heavy at Times. Snow Level 3-4000 Feet.  37/49

Sun (15 Mar):  Rain. Increasing Southerly Winds. Snow Level Lifting to 5000 Feet Late. 42/53

Mon (16 Mar):  Rain Likely...Mainly North.  Snow Level 4000 Feet.  43/57

Tue (17 Mar):  Mostly Cloudy.  Chance of Rain...Mainly North.  42/55

Wed (18 Mar):  Mostly Cloudy.  Slight Chance of Rain.  Snow Level 6000 Feet.  39/55

Thu (19 Mar):  Increasing Chance of Rain.  Snow Level 5000 Feet.  40/54

ODA Meteorologist
weather at oda.state.or.us