[willamette-fcst] Forecast - Monday, September 22nd, 2008

[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.

...Corrected Stack Burning Areas...

Issued: 
     Monday, September 22nd, 2008 at 9:00am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from 1:00pm until 6:30pm.
     Preparatory burning is not allowed.
     Propane flaming is not allowed.
     Straw stack burning is allowed, for dry stacks, from Albany northward from 1:00pm until 6:30pm.
     Straw stack burning is not allowed south of Albany.

Weather Discussion:
     Summer finished on a damp note with most of the Willamette
     Valley picking up between one-tenth and one-quarter inch of
     rain overnight. Autumn officially began this mornig at
     8:44am.  Morning satellite imagery showed cloudy skies over
     the Willamtte Valley with what appeared to be the southern
     end of a dissipating cold front moving across NW Oregon. 
     Doppler radar showed areas of light rain over the eastern
     valley with a few showers rolling onshore in the wake of the
     weak cold front.  The ODA surface analysis showed high
     pressure building into the Central Oregon Coast with weak
     onshore pressure gradients across the Willamette Valley.

     A cool upper-level trough will swing over NW Oregon this
     morning with a few more showers likely...mainly in the
     north.  It will slide east of the region this afternoon with
     the flow aloft drying out and becoming northwesterly. 
     Showers will taper off this afternoon with a few sunbreaks. 
     Temperatures will be below normal with highs in the mid 60s.
      Fields will need time to dry before they can be burned.

     Cool air aloft will help mixing heights climb to near 5000
     feet this afternoon.  Transport winds will likely stay
     northwesterly, in the north valley, which will allow for the
     burning of dry stacks, from Albany northward.  Transport
     winds are forecast to become northerly this afternoon south
     of Albany.  The cool air mass will continue to dry overnight
     with partial clearing allowing valley temperatures to drop
     into the low 40s by Tuesday morning.

Surface Winds:
     Light this morning, NW 5-12 Albany North...N 8-15 South of Albany this afternoon.
Transport Winds:
     NW 6 this morning, NW 10 Albany north...N 10 South of Albany this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 5000 feet.  Ventilation index 50.
High Temperature:
     Salem\'s high temperature today will be near 65.
Humidities:
     Relative humidity drops to 50% by 4pm.
     Minimum relative humidity will be near 45%.
Sunrise/Sunset:
     Salem sunset tonight: 7:08pm; sunrise tomorrow: 7:01am.

Extended Outlook:
     A transitory ridge of high pressure is forecast to bring
     some sunshine early Tuesday with middle and high clouds
     increasing late, from the the next weather system, in a
     westerly flow aloft.  The lastest computer model guidance is
     suggesting that transport winds may become favorable for
     burning by late Tuesday but more likely Wednesday.  The
     models are generally holding off the rain until late
     Wednesday, which would allow for burning Wednesday
     afternoon.  Damp fields may require fluffing to take
     advantage of this potential burning opportunity.

     An upper-level trough will keep a chance of showers in the
     forecast through Thursday evening...with most of the rain in
     the north valley.  Another one-tenth to one-quarter of an
     inch of rain is possible from late Wednesday through
     Thursday...especially on the east side of the north valley. 
     Showers should taper off by Thursday evening.  A weak
     upper-level trough is forecast to approach the coastline
     Friday, which may create another burning opportunity Friday
     afternoon.

     The long-range models are coming into agreement on building
     a ridge of high pressure over the Pacific Northwest this
     weekend.  The low-level winds are forecast to become
     northerly by Saturday afternoon and perhaps offshore by
     Sunday, which would bring increasing amounts of sunshine and
     near to above normal temperatures.  That pattern would
     effectively dry any remaining damp fields in preparation for
     a burn opportunity around Wednesday of next week.

Tomorrow (23 Sep):  Partly Cloudy.  Increasing High Clouds in the Afternoon.  41/71

Wed (24 Sep):  Mostly Cloudy.  Increasing Chance of Light Rain.  47/71

Thu (25 Sep):  Chance of Showers...Decreasing Late.  50/68

Fri (26 Sep):  Mostly Cloudy.  Increasing Chance of Showers.  48/73

Sat (27 Sep):  Becoming Mostly Sunny in the Afternoon.  48/73

Sun (28 Sep):  Sunny and Warmer.  47/77

Mon (29 Sep):  Sunny and Warm.  47/79

ODA Meteorologist
weather at oda.state.or.us