[willamette-fcst] Forecast - Tuesday, February 10th, 2009
Willamette Valley Ag/Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Tue Feb 10 09:01:08 PST 2009
Daily Smoke Management Forecast
Oregon Department of Agriculture
Smoke Management Program
Weather Outlook and Field Burning Advisory for Willamette Valley Growers and Fire Districts.
Tuesday, February 10th, 2009 at 9:00am.
Agricultural burning is allowed. Suggested burn times are from 8:00am until 3:30pm.
Straw stack burning is allowed from 8:00am until 3:30pm.
Satellite imagery showed the next in a series of cold
Pacific storms moving onto the coastline at mid-morning.
The leading edge of the clouds had already advanced into
central Oregon, with a solid cloud shield extending westward
close to 200 miles offshore. Dopler radar showed light
precipitation across western Washington and western Oregon
about as far south as Roseburg. The air mass aloft is very
cold, with the freezing level over Salem this morning
measured at just 900 feet. Surface temperatures are in the
low to mid 30s from Seattle to Medford, so precipitation
started falling mostly in the form of light snow...even
along the Washington and northern Oregon Coastlines.
The low-pressure center was about 450 miles west of the
central Washington coast at mid-morning and tracking slowly
to the southeast. It is forecast to be just off the central
Oregon coast by Wednesday morning. With the low-pressure
center forecast to stay offshore, cool outflow from the
Columbia Gorge will maintain very low snow levels in the
Gorge and the northern Willamette Valley, near Portland.
However, southerly winds will increase in the central and
southern valleys later this morning and this afternoon,
which should help to lift the snow level to around 1500
feet. Some light accululation (less than one inch) is
locally possible this morning, especially north of Salem.
There have already been reports of about one-half inch of
snow around McMinnville.
Precipitation will increase across western Oregon later this
morning through early this afternoon, as the main cold front
moves onshore. Precipitation will remain as snow at
elevations above about 1500 feet with 3-6 inches of snow
likely. The National Weather Service has issued Winter
Weather Advisories for the coastal range, the western
Columbia Gorge (including the immediate Portland/Vancouver
area), the western Cascade foothills (above 1000 feet), and
the Cascades. Temperatures are marginal for sticking snow
to persist in the lower elevations around Portland, because
outflow from the Columbia Gorge is not that cold. It will
likely barely stay cold enough in the Gorge for snow to
accumulate down to the Columbia River level. However, that
will need to be watched closely today, because a couple of
degrees can make the difference between wet pavement and
several inches of wet snow. At the very least, expect
winter driving conditions today over all western Oregon and
western Washington mountain passes...including the coastal
Temperatures in the valley should warm into the low 40s this
afternoon, as southerly winds increase and become rather
blustery (gusts to near 30 mph are possible). Southerly
winds will also increase along the northern and central
Oregon Coast later this morning through late afternoon,
where High Wind Warnings have been issued for gusts to near
65 mph. The brisk southerly winds will only warm coastal
temperatures into the mid 40s, so it will feel quite raw
there. Very cold air aloft will yield reasonably high
mixing heights this afternoon. That, combined with brisk
southerly transport winds, will make for good ventilation
conditions over the region today.
The latest weather advisories from the National Weather
Service are at:
The latest road conditions across Oregon may be found at:
SSE 10-20 this morning, S 12-25 this afternoon.
S 20 this morning, S 25 this afternoon.
Atmospheric Ventilation Conditions:
Maximum mixing height today will be near 3000 feet. Ventilation index 75.
Salem\'s high temperature today will be near 41.
Minimum relative humidity will be near 73%.
Salem sunset tonight: 5:34pm; sunrise tomorrow: 7:18am.
The rain and snow should taper off Wednesday, from north to
south across western Oregon, as the low-pressure center
moves inland near the southern Oregon/northern California
border. The snow level should hover around 500-1000 feet.
Wednesday morning temperatures will be near freezing with
cool northerly winds only allowing afternoon highs to warm
into the low to mid 40s. Some clearing is likely Wednesday
night and early Thursday. That will allow temperatures to
fall below the freezing mark Thursday morning. The next
system is forecast to take a slightly more of a southerly
track, but it should bring more rain and snow to western
Oregon Thursday afternoon through early Friday. The snow
level should be near the valley floors again with
significant snow accumulations possible above about 1000
feet, especially south.
Computer models are fairly consistent in forecasting a
split-flow jet stream pattern Saturday through Monday, with
weather systems moving by both north and south of Oregon.
It is unlikely that the region will stay completely dry
during that time period. Temperatures will slowly moderate
but should remain below normal until about Tuesday.
Tomorrow (11 Feb): Decreasing Areas of light Rain/Snow. Partial PM Clearing. 32/46
Thu (12 Feb): Increasing Clouds. Chance of PM Rain/Snow Mix. 28/45
Fri (13 Feb): Decreasing Rain and Snow. Snow Level Near 1000 Feet. 32/45
Sat (14 Feb): Gradual Clearing and Cool. 28/47
Sun (15 Feb): Partly Cloudy and Cool. Chance of Showers. Snow Level Near 2000 Feet. 28/48
Mon (16 Feb): Increasing Clouds. Chance of Rain Late. Snow Level 3000 feet. 32/48
Tue (17 Feb): Rain and Warmer. Snow Level 4000 Feet. 36/50
weather at oda.state.or.us
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