[willamette-fcst] Willamette Valley Ag Forecast

[Willamette Valley Ag/Burning Forecast]

Oregon Department of Agriculture
Smoke Management Program
Weather Outlook and Field Burning Advisory for Willamette 
Valley Growers and Fire Districts.

Issued:
      Monday, October 13th, 2008 at 9:00am.

Burn Advisory:
      Agricultural burning is not recommended.
      Preparatory burning is not allowed.
      Propane flaming is not allowed.
      Stack burning is not allowed.

Weather Discussion:
      A cold and dry northerly flow aloft led to record 
low
      temperatures across sections of Western Oregon 
Saturday
      morning.  Astoria, McMinnville, and Eugene all 
recorded new
      daily record cold minimums and Salem missed a 
long-standing
      record by just one degree.

      Saturday Morning Record Minimums:

      Astoria      32 degrees...old record 33 set in 1969

      McMinnville  28 degrees...old record 29 set in 1924

      Salem        31 degrees...record 30 set in 1919 and 
1894

      Eugene       28 degrees...old record 30 set in 2002

      Sunshine warmed temperatures into the low 60s 
Saturday
      afternoon with north winds helping to dry damp 
fields.  As
      the upper-level ridge built over the region, a weak 
warm
      front kept temperatures warmer Sunday morning and 
brought a
      few sprinkles to the Northern Willamette Valley. 
 Once again,
      high temperatures climbed into the low 60s Sunday 
afternoon.

      Satellite imagery showed low clouds, associated with 
another
      weak warm front, across Western Washington and NW 
Oregon.
      Surface observations confirmed areas of light rain 
across
      Western Washington and along the Nrothern Oregon 
Coast, at
      Astoria.  There were no reports of rain in the 
Willamette
      Valley as of mid-morning.  The warm front may bring 
a few
      sprinkles in the extreme north valley before pushing 
north
      and the region this afternoon.

      The Salam sounding this morning showed considerable 
warming
      aloft since Sunday.  That will keep mixing heights 
below about
      1000 feet until surface temperatures climb to near 
60 degrees.
      Valley temperaturs were only in the upper 40s and 
low 50s at
      mid-morning, so mixing heights will stay quite low 
through early
      afternoon.  Partial clearing and warmer south winds 
should combine
      to lift valley temperatures into the mid 60s later 
this afternoon,
      with mixing heights climbing to near 3000 feet.

      Clouds, associated with a cold front, stretched from 
Vancouver
      Island, British Columbia southwestward to about 400 
miles west of
      the Northern Oregon Coast this morning.  That system 
will slowly
      push southeastward today and may improve ventilation 
conditions
      enough to allow for open burning of dry north valley 
fields later
      this afternoon.  We plan to begin pibal readings at 
1pm.

      The cold front will bring a chance of light rain to 
Western
      Oregon overnight...mainly north. Total rainfall 
amounts
      should be less than one-tenth of an inch with 
sections of
      the south valley likely seeing little to no 
rainfall.

Surface Winds:
      SSE 4-8 this morning, S 4-8 this afternoon.
Transport Winds:
      SW 7 this morning, WSW 7 this afternoon.
Atmospheric Ventilation Conditions:
      Maximum mixing height today will be near 3000 feet. 
 Ventilation index 21.
High Temperature:
      Salem\'s high temperature today will be near 65.
Humidities:
      Minimum relative humidity will be near 56%.
Sunrise/Sunset:
      Salem sunset tonight: 6:30pm; sunrise tomorrow: 
7:27am.

Extended Outlook:
      A transitory ridge of high pressure is forecast to 
build over
      Oregon Tuesday and Wednesday with partial clearing 
and northerly
      transport winds.  A warm front may bring some 
sprinkles or very
      light rain, mainly to the north valley, Thursday.  A 
cold front
      is forecast to bring a chance of light rain by 
Friday night.  A
      weak westerly flow is forecast over the weekend with 
a stronger
      system moving onshore Sunday night.

Tomorrow (14 Oct):  Chance of Light Rain Early...Becoming 
Partly Cloudy.  46/63

Wed (15 Oct):  Areas of AM Fog.  Partly Sunny.  39/60

Thu (16 Oct):  Mostly Cloudy/Foggy.  Chance of 
Sprinkles...Mainly North.  41/65

Fri (17 Oct):  Areas of AM Fog.  Increasing Clouds. 
 Chance of Light Rain Late.  45/67

Sat (18 Oct):  Mostly Cloudy.  Decreasing Chance of 
Showers.  46/62

Sun (19 Oct):  Increasing Clouds.  Chance of Rain Late. 
 43/65

Mon (20 Oct):  Chance of Rain.  44/60

ODA Meteorologist
weather at oda.state.or.us