[willamette-fcst] Forecast - Thursday, October 29th, 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 29th, 2009 at 9:00am.

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

Weather Discussion:
     A warm front spread light rain onshore and into the
     Willamette Valley Wednesday evening.  Light rain continued
     to fall overnight along the northern and central coast and
     across the Willamette Valley.  Rainfall totals have been
     greatest to the north.  By mid-morning, rainfall amounts
     ranged from just a few hundredths of an inch, in the south
     valley and along the central coast, to more than one-quarter
     of an inch from the north valley to the north coast.

     Satellite imagery showed clouds covering virtually all of
     Washington and Oregon, with a very moist northwesterly flow
     aloft.  Doppler radar showed areas of precipitation
     extending south and east across all of Oregon.  The ODA
     surface analysis showed the warm front just off the
     Washington and northern Oregon coastline.  Ahead of the
     front, south-southeasterly winds were gusting to 25 mph from
     the coast to the Willamette Valley.  Temperatures were
     mostly in the mid 40s.

     Warmer air aloft is rapidly lifting freezing levels, from
     west to east, across Oregon.  The freezing level over Salem
     jumped from 4200 feet Wednesday evening to 11,200 feet this
     morning.  However, the air mass is cold enough this morning,
     east of the Cascades, to support areas of light snow. 
     Meacham, John day, and Burns were reporting light snow at
     mid-morning, with temperatures in the upper 20s and low 30s.
     Enough warm air aloft had moved over the Cascade passes,
     and north-central Oregon, to turn to the light snow to rain,
     by mid-morning, with surface temperatures just above freezing.

     Rain will continue across the Willamette Valley today, as
     the warm front moves onshore.  Total rainfall amounts will
     likely range from around one-quarter of an inch south to
     more than one-half inch in the north valley.  Continued
     warming aloft should lift the snow level to the highest
     peaks in the Cascades and turn the snow to rain across
     eastern Oregon this afternoon.  Surface temperatures will
     slowly rise today, across western Oregon, with warming southerly
     winds helping temperatures climb into the mid 50s by midnight.

Surface Winds:
     SSE 7-17 G25 this morning, S 7-17 G25 this afternoon.
Transport Winds:
     S 22 this morning, S 22 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 2000 feet.  Ventilation index 44.
High Temperature:
     Salem\'s high temperature today will be near 56.
Humidities:
     Minimum relative humidity will be near 72%.
Sunrise/Sunset:
     Salem sunset tonight: 6:04pm; sunrise tomorrow: 7:48am.

Extended Outlook:
     The steady rain will likely taper off by Friday morning with
     possible areas of fog forming.  Friday will be spent in the
     warm-sector of the storm, with mostly cloudy skies and the
     best chance of rain across the northwestern corner of the
     state.  Warming southerly breezes will likely lift
     temperatures into the low to mid 60s.  A cold front is
     forecast to bring rain onshore Friday night, with showers
     continuing into Saturday afternoon.

     The air mass behind this cold front is not nearly as cold as
     the one earlier this week, with the snow level only forecast
     to drop to about 6-7000 feet Saturday afternoon.  The
     showers will likely begin tapering off, as the
     trick-or-treaters head out Saturday night.  A flat and broad
     ridge of high pressure is forecast to bring a mostly dry day
     on Sunday...followed by a weak system on Monday.  The ridge
     may build enough over the region to keep things dry next
     Tuesday through Thursday.

Tomorrow (30 Oct):  AM Fog Patches.  Chance of Rain...Mainly North. Mild South Winds.  52/63

Sat (31 Oct):  Rain Early...Decreasing Showers.  49/59

Sun (01 Nov):  Partly Sunny.  43/58

Mon (02 Nov):  Mostly Cloudy.  Chance of Light Rain...Mainly North.  42/57

Tue (03 Nov):  Mostly Cloudy.  42/58

Wed (04 Nov):  Mostly Cloudy.  41/56

Thu (05 Nov):  Mostly Cloudy.  42/56

ODA Meteorologist
weather at oda.state.or.us