[willamette-fcst] Forecast - Monday, November 23rd, 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: 
     Monday, November 23rd, 2009 at 9:00am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from 11:00am until 2:30pm.
     Straw stack burning is allowed, for dry stacks, from 11:00am until 2:30pm.

Weather Discussion:
     A potent storm system moved onshore Saturday evening, bringing another round of strong
     southerly winds to southwestern Washington and much of western Oregon Saturday night and
     early Sunday.  Southerly wind gusts of 50-70 mph hit most of the Oregon Coast, with some 
     beaches and exposed headlands getting gusts to around 90 mph.  Mt. Hebo, in the north
     coast range, recorded a gust of 93 mph.  Another usual windy spot, Cape Blanco, on the
     south coast, had a gust of 92 mph.  Newport recorded gusts of 74 mph with Pacific City
     getting gusts to 70 mph.

     It also became quite windy in the Willamette Valley Saturday night, as the low-pressure
     center came inland and moved across western Washington.  That is a favorable storm-track
     for strong winds in the western valleys.  South winds gusted between 45 and 50 mph from
     southwestern Washington to the southern Willamette Valley.  The Porland Airport recorded
     one of the stronger gusts in the Willamette Valley at 51 mph.

     Freezing levels remained low enough for heavy snow to fall in the mountains over the
     weekend.  One to three feet of new snow fell in the northern and central Oregon Cascades,
     with the higher elevations on Mt. Hood seing the greatest totals.  17 inches of new snow
     fell as far south as Willamette Pass, with a foot of new snow over Santiam Pass.  The snow,
     wind, and rain tapered off Sunday, as the cold front pushed east of the region.  A
     transitory ridge of high pressure helped bring an end to the shower activity by Sunday
     evening, but the freezing level remained only in the 4-5000 foot range.

     A weak warm front was off of the Washington Coast this morning, with Doppler radar showing
     some light rain moving across mainly the northwestern section of the Evergreen State.
     Satellite imagery showed mostly cloudy skies across northwestern Oregon, at mid-morning,
     but there were no reports of rainfall.  The ODA surface analysis showed southeasterly
     gradients beginning to increase across western Oregon, with SSE winds generally at 10 mph
     or less.  Willamette Valley temperatures ranged from the freezing mark, in Eugene, to the
     low 40s in Salem.  Coastal temperatures were in the low to mid 40s.

     Skies should remain mostly cloudy over the northwestern corner of Oregon today.  Most of
     the rain, however, from the approaching warm front is forecast to stay north of Oregon. 
     Some sprinkles may fall along the north coast and in the extreme northern Willamette
     Valley.  After areas of morning fog, the central and southern valley will likely see some
     sunbreaks today.  Warmer air aloft had lifted the freezing level over Medford to 9000 feet
     by early this morning, but the Salem freezing level was still at just 4100 feet.  Freezing
     levels should continue to climb today, as a transitory upper-level ridge moves over the
     state.  Willamette Valley highs should climb to around 50 degrees, which is normal for
     late November.

Surface Winds:
     SSE 5-15 this morning, SSE 5-15 this afternoon.
Transport Winds:
     S 15 this morning, S 17 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 2000 feet.  Ventilation index 34.
High Temperature:
     Salem\'s high temperature today will be near 51.
Humidities:
     Minimum relative humidity will be near 66%.
Sunrise/Sunset:
     Salem sunset tonight: 4:36pm; sunrise tomorrow: 7:22am.

Extended Outlook:
     A weak cold front is forecast to sag southward, over extreme northern Oregon, tonight
     and early Tuesday, bringing an increasing chance of light rain...mainly to the
     northwestern corner of the state.  High pressure is forecast to build back over the region
     Tuesday, with the chance of rain decreasing. 

     Dry and mild conditions should prevail from late Tuesday through midday Thursday, with
     another weather system movning onshore Thanksgiving evening.  The rain should turn to
     showers Friday, with snow over the mountain passes.  Travel conditions are forecast to
     improve Sasturday and Sunday, as a ridge of high pressure brings dry and mild weather
     to the region.

Tomorrow (24 Nov):  Mostly Cloudy.  Chance of Light Rain Early...Decreasing late.  40/52

Wed (25 Nov):  Areas of AM Fog.  Partly Sunny and Mild.  37/55

Thu (26 Nov):  Rain Developing in the Evening.  39/54

Fri (27 Nov):  Showers.  Snow Level 3000 Feet.  39/49

Sat (28 Nov):  Mostly Cloudy.  35/48

Sun (29 Nov):  Mostly Cloudy.  36/50

Mon (30 Nov):  Partly Sunny.  35/53

ODA Meteorologist
weather at oda.state.or.us