[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.

...Next Forecast Update Not Until Tuesday, October 20th, at 9:00am...

NOON UPDATE

Issued: 
     Thursday, October 15th, 2009 at 12:00pm.

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

Weather Discussion:
     Conditions were drying out across western Oregon late this
     morning.  A weak warm front pushed a band of rain northward
     across most of the Willamette Valley earlier this morning. 
     Rainfall amounts were generally less than one-tenth of an
     inch.  Doppler Radar showed the rain-band had moved mainly
     in southwestern Washington by midday.  Satellite imagery
     still showed considerable clouds over the Willamette Valley,
     but some thin sopts were beginning to emerge.  A transitory
     ridge of high pressure will likely bring some partial
     clearing to western Oregon this afternoon...especially
     south.  Temperatures were mostly in the upper 50s across the
     valley at midday.  The ODA surface analysis showed weak
     offshore pressure gradients across western Oregon, with
     winds blowing at less than 10 mph.  East winds were still
     gusting to near 20 mph at the western end of the Columbia Gorge.

     The air mass aloft is continuing to warm, with the freezing
     levels measured over Salem and Medford this morning at 9000 feet
     and 11,300 feet respectively.  Southerly winds aloft will
     continue to warm the air mass this afternoon.  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:
     SE 5-10 this afternoon.
Transport Winds:
     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 night,
     with temperatures likely remaing above 50 degrees.  Warming
     southerly winds should push Willamette Valley temperatures to
     around 70 degrees 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.  There may be a brief break from the rain late Monday
     and early Tuesday, ahead of another potent storm slated to move
     onshore Tuesday afternoon and across the state 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):  Rain Early...Turning to Showers.  44/66

Thu (22 Oct):  Areas of AM Fog.  Mostly Cloudy. 44/62

ODA Meteorologist
weather at oda.state.or.us