[willamette-fcst] Forecast - Thursday, October 15th, 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, October 15th, 2009 at 9:00am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from now until 4:30pm.
     Straw stack burning is allowed, for dry stacks, from 11:00am until 4:30pm.

Weather Discussion:
     After a very windy Wednesday, things are much more calm this
     morning across western Oregon.  A weak warm front was
     pushing bands of rain northward across northwestern Oregon,
     with light rain falling from Portland to Salem, in the
     Willamette Valley, at mid-morning.  Skies were cloudy, but
     it was mostly dry in the south valley.  Skies should stay
     mostly cloudy today, with a chance of light rain at
     times...mainly north.  Partial clearing is possible,
     especially south.  The ODA surface analysis showed weak
     offshore pressure gradients across western Oregon, and
     surface reports showed east-southeasterly winds blowing at
     less than 10 mph, except for gusts to around 25 mph at the
     western end of the Columbia Gorge.

     Temperatures were very mild overnight with minimums mostly
     in the upper 40s.  The air mass aloft is also cntinuing to
     warm.  The freezing level over Salem rose from 7200 feet
     Wednesday morning to 9000 feet this morning.  The air to the
     south is even warmer, with the freezing level over Medford
     measured at 11,300 feet early this morning.  Southerly winds
     aloft will transport that warmer air northward, to over
     northwestern Oregon, today.  The combination of warm air
     aloft and light southeasterly winds should help temperatures
     climb into the mid to upper 60s this afternoon.  Areas that
     see some partial clearing may break the 70-degree mark,
     especially in the south valley.  Average highs, for
     mid-October, are around 65 degrees in the Willamette Valley.

Surface Winds:
     ESE 3-8 this morning, SE 5-10 this afternoon.
Transport Winds:
     SE 8 this morning, S 10 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 3300 feet.  Ventilation index 33.
High Temperature:
     Salem\'s high temperature today will be near 68.
Humidities:
     Minimum relative humidity will be near 59%.
Sunrise/Sunset:
     Salem sunset tonight: 6:27pm; sunrise tomorrow: 7:30am.

Extended Outlook:
     south-southwesterly flow aloft will make for a very mild
     overnight period, with temperatures likely remaing above 50
     degrees.  Warming southerly winds should push Willamette
     Valley temperatures well into the 60s Friday afternoon, with
     the freezing level in the northern Cascades rising above
     10,000 feet.  A slow-moving cold front is forecast to swing
     onshore by Friday evening and stall over northwestern Oregon
     Friday night and Saturday. That could bring soaking rains to
     the region, with more than an inch possible from the coast
     to the Cascades.

     The steady rain should turn to showers by Saturday night,
     with some showers lingering into Sunday.  Another weather
     system is forecast to spread some light rain back across
     western Oregon Monday.come onshore Monday.  There may be a
     brief break from the rain late Monday and early Tuesday,
     ahead of another potent storm Tuesday afternoon and Wednesday.

Tomorrow (16 Oct):  Mostly Cloudy but Warmer.  Chance of Rain Late.  51/71

Sat (17 Oct):  Rain...Possible 1+ Inch totals in the Valley.  53/65

Sun (18 Oct):  Mostly Cloudy.  Chance of Showers.  Increasing Rain Late.  47/62

Mon (19 Oct):  Light Rain Turning to Showers.  46/61

Tue (20 Oct):  Areas of AM Fog. Increasing Clouds...Rain Late.  45/66

Wed (21 Oct):  Showers Likely.  44/66

Thu (22 Oct):  Mostly cloudy.  Chance of Showers.  44/62

ODA Meteorologist
weather at oda.state.or.us