[willamette-fcst] Forecast - Tuesday, January 26th, 2010

[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: 
     Tuesday, January 26th, 2010 at 9:00am.

Burn Advisory:
     Agricultural burning is not recommended.
     Stack burning is not allowed.

Weather Discussion:
     A low-pressure system tracked eastward, across extreme
     southern Oregon, overnight and was centered over
     southeastern Oregon at mid-morning.  The counter-clockwise
     circulation around this system spread clouds over all of
     Oregon overnight, but precipitation fell mainly over
     southwestern Oregon and areas east of the Cascades.  There
     is cool air aloft over the region, with the freezing levels
     over Salem, Medford, and Boise measured below 5000 feet this
     morning.  Widespread light rain and snow was falling across
     central and eastern Oregon this morning, with upslope
     conditions locally enhancing the snowfall on the eastern
     slopes of the Cascades (the opposite side of the mountains
     from where upsloping snows usually occur).

     Winter weather advisories are in effect, through early this
     afternoon, for the Redmond and Bend area of central Oregon,
     where 1-3 inches of additional snow could fall, before the
     precipitation tapers off later this afternoon.  Light snow
     was also falling over the Cascade passes this morning, and
     ODOT road cameras showed generally snow-covered road
     surfaces at pass level.  Meanwhile, cloudy skies and a few
     sprinkles held western valley temperatures mostly in the low
     to mid 40s overnight.

     Skies are cloudy over the state late this morning with areas
     of fog west of the Cascades.  Doppler radar and surface
     reports showed light rain and snow from the Cascades
     eastward but little to no precipitation west of the
     Cascades.  The ODA surface analysis showed low-pressure over
     southeastern Oregon and very weak high pressure over western
     Oregon.  Winds in the Willamette Valley were generlaly 3 mph
     or less, which was contributing to the formation of fog. 
     Mid-morning temperatures ranged from the upper 30s to the
     mid 40s across western Oregon, with most areas east of the
     Cascades in the 30s.

     The low-pressure system over southeastern Oregon will
     continue to progress eastward today, with a split-flow
     westerly jet stream pattern over Oregon. Skies should remain
     mostly cloudy across the state, with areas of rain and snow,
     mainly from the Cascades eastward, slowly tapering off this
     afternoon and evening.  Not much windflow is forecast for
     western Oregon, so ventilation conditions will be poor.  Due
     to the lack of wind, morning low-level temperature
     inversions will be tough to break this afternoon.  As a
     result, high temperatures will likely be a few degrees
     cooler than on Monday.  Highs will struggle to reach 50
     degrees, which is still above average for late January.

Surface Winds:
     Var 0-5 this morning, Var 0-5 this afternoon.
Transport Winds:
     N 4 this morning, WSW 4 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 2000 feet.  Ventilation index 8.
High Temperature:
     Salem\'s high temperature today will be near 51.
Humidities:
     Minimum relative humidity will be near 63%.
Sunrise/Sunset:
     Salem sunset tonight: 5:12pm; sunrise tomorrow: 7:37am.

Extended Outlook:
     A transitory ridge of high pressure will bring dry weather
     Wednesday and most of Thursday, with rising freezing levels.
      The western valleys should get a good dose of fog overnight
     tonight and Wednesday night with only partial afternoon
     clearing.  Overnight minimums will be cooler, and high
     temperatures will vary, depending on the local duration of
     fog.  The next weather system is forecast to bring rain to
     the coast and the western valleys on Friday, with snow
     levels lowering back down to near pass level in the
     Cascades.  The next weather system is forecast to come
     onshore about next Tuesday.

Tomorrow (27 Jan):  Partly Sunny After AM Fog.  Snow Level Rising to 5-6000 Feet.  34/49

Thu (28 Jan):  Increasing Clouds After AM Fog.  Snow Level 6-7000 feet.  35/50

Fri (29 Jan):  Rain Developing.  Mild.  Snow Level Dropping to 4500 Feet.  37/52

Sat (30 Jan):  Chance of Showers.  Snow Level 4000 Feet.  37/49

Sun (31 Jan):  Partly Cloudy.  Snow Level 3500 Feet.  35/50

Mon (01 Feb):  Mostly Cloudy.  Snow Level 4000 Feet.  36/50

Tue (02 Feb):  Mostly Cloudy.  Chance of Rain.  Snow Level 4000 Feet.  38/50

ODA Meteorologist
weather at oda.state.or.us