[willamette-fcst] Forecast - Monday, March 9th, 2009
Willamette Valley Ag/Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Mon Mar 9 08:02:38 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.
Monday, March 9th, 2009 at 9:00am.
Agricultural burning is allowed. Suggested burn times are from now until 4:00pm.
Straw stack burning is allowed from now until 4:00pm.
A weather system dropped straight down the British Columbia
Coastline and directly into Washington and Oregon Saturday.
that brought light rain to western Oregon with rainfall
amounts ranging from a few hundredths to about one-quarter
of an inch. Snow levels never rose above about 2000 feet,
with a few inches of new snow falling in the Cascades. A
very cold upper-level trough followed the cold front
Saturday night and Sunday, with instability showers falling
as snow all the way down to sea level. Accumulations were
light, on the valley floor, with most areas just seeing a
light dusting that did not stick on the road surfaces.
Another 3-7 inches of snow fell in the Cascades Sunday, with
a couple of inches also reported over the coastal mountain
passes. Total snowfall over the weekend locally exceeded a
foot in sections of the Cascades. With some rain-shadow
effects over the western valleys, much of the Willamette
Valley had at least a little sunshine Sunday afternoon.
However, with the very cold air mass in place across the
region, high temperatures were only in the low to mid 40s
(about 10-12 degrees below normal).
Another upper-level disturbance, in a cold
north-northwesterly flow aloft, was dropping sothward, from
sotuhern British Columbia, this morning. It was acting to
increase shower activity across western Washington and
northwestern Oregon, with snow levels continuing near sea
level. Scattered light rain and snow showers were falling,
across the Willamette Valley this morning, with some snow
mixing with the rain even along the northern and central
Oregon Coast. Showers will increase later this morning, as
the upper-level disturbance drops into northern Oregon.
Daytime heating will lift the snow level to around 500-1000
feet by this afternoon, but snow could continue to mix down
to sea level with heavier showers. Some showers could also
produce small hail.
Expect winter driving conditions over the coast range and
Cascade passes, through early Tuesday. ODOT reports showed
snow over all the mountain passes this morning. Another
couple of inches of snow are likely over the coastal passes
today with 3-6 inches of new snow over the Cascade passes.
Snow accumulations should be less than 1 inch in the
Willamette Valley this morning, before the showers at least
mix with rain this afternoon.
Valley temperatures were near their minimums at mid-morning
(in the low to mid 30s). Doppler radar showed one line of
showers just moving through the valley and another, stronger
line of showers, coming over the coast range. The Portland
Airport was reporting light rain, with a temperature of 36
degrees, but McMinnville and Salem were seeing light snow
showers, with temperatures just above freezing. Some light
snow showers were beginning to move into the south valley,
from Corvallis to Eugene, where temperatures were near the
The ODA surface analysis showed a weak trough of low
pressure just moving onto the coastline and inducing
southerly winds, around 10-20 mph, in the Willamette Valley.
That trough, along with the associated upper-level
disturbance, is forecast to move into northeastern Oregon
this afternoon. That will turn surface and transport winds
more westerly, with showers beginning to decrease this
evening across western Oregon.
An Arctic cold front was hleping to enhance the light
snowfall along a line from Spokane to Seattle, Washington,
at mid-morning. Northerly winds, on the north side of that
front, were ushering below freezing air into the northern
third of Washington. That front is expected to stall and
weaken, across central Washington, later today.
S 5-15 G20 this morning, WSW 10-20 this afternoon.
SW 15 this morning, W 20 this afternoon.
Atmospheric Ventilation Conditions:
Maximum mixing height today will be near 5000 feet. Ventilation index 100.
Salem\'s high temperature today will be near 44.
Minimum relative humidity will be near 60%.
Salem sunset tonight: 7:11pm; sunrise tomorrow: 7:33am.
Rain and snow showers should taper off tonight with
gradually clearing skies across western Oregon. That will
allow Willamette Valley temperatures to drop into the 20s
with local record cold minimums possible. An upper-level
ridge is forecast to bring a dry and cool northwesterly flow
aloft to Oregon Tuesday.
As the ridge builds into the coastline Wednesday,
temperatures will begin to moderate, after another chilly
morning, with near-record low temperatures. Surface winds
will turn offshore Wednesday and strongly offshore Thursday,
as the upper-level ridge builds directly over Oregon.
Afternoon temperatures will continue to warm ,under mostly
sunny skies, Thursday and Friday, but mornings will continue
to be quite chilly.
The next weather system will bring a chance of showers back
to the region Saturday, under a cooler northwesterly flow
aloft. Another Upper-level ridge is forecast to bring
mostly sunny skies and moderating temperatures Sunday and Monday.
Tomorrow (10 Mar): A Frosty Morning...Partly Sunny and Cool. 27/47
Wed (11 Mar): Near Record-Cold Morning. Mostly Sunny in the Afternoon. 25/50
Thu (12 Mar): Mostly Sunny and Warmer. 30/55
Fri (13 Mar): Mostly Sunny and Warmer. 31/58
Sat (14 Mar): Chance of Showers. Snow Level 3-4000 Feet. 35/50
Sun (15 Mar): Partly Cloudy. 35/55
Mon (16 Mar): Mostly Sunny and Warmer. 36/59
weather at oda.state.or.us
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