[willamette-fcst] Forecast - Tuesday, April 22nd, 2008
Willamette Valley Ag/Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Tue Apr 22 08:10:52 PDT 2008
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, April 22nd, 2008 at 9:00am.
Agricultural burning is allowed. Suggested burn times are from now until 6:00pm.
Straw stack burning is allowed from now until 6:00pm.
The very cold upper-level low pressure system that brought
rain, hail, and snow showers to the region over the weekend
backed off the Washington Coastline Monday and combined
forces with another system off the Oregon coast. Strong
westerly flow aloft continued to circulate cold showers into
the region with snow levels slowly rising to about 1500 feet
by Monday evening.
The Showers changed to a steady rain across Western Oregon
overnight in response to a potent warm front from the
offshore system. As a surface low pressure area approached
the Central Oregon Coast overnight, the resultant offshore
flow kept cool air in place across Oregon with snow levels
remaining near 1500 feet across Northern Oregon. Warmer air
aloft had lifted snow levels to near 4000 feet over Southern
Oregon by early this morning.
The clouds and rain kept valley temperatures from dropping
below about 40 degrees overnight, even though the air aloft
remains unseasonably cold. Total rainfall amounts in the 24
hours ending at 5 am today ranged from around one-tenth to
one-third of an inch in the Willamette Valley with just
under one-half inch falling along the Oregon Coast. Spotty
light rain and snow fell east of the Cascades, under cloudy
skies, with precipitation amounts less than one-tenth of an inch.
There was some concern that the air mass would be cold
enough overnight and early this morning for a rare April
snowfall in the Upper Hood River Valley and perhaps the
eastern end of the Columbia Gorge. However, The Dalles had
light rain and 40 degrees at mid-morning, so it appears
slightly too warm for snow in the lowest elevations there.
Some wet snow is still possible in that region, above about
1000 feet this morning.
This is a very cold storm that would have produced
widespread snow over Western Oregon, had this pattern set up
during the winter season. It did produce snow overnight in
the northern coastal range and in the Cascades above about
1500 feet. The northern coastal passes were covered in snow
and slush early this morning with near-freezing
temperatures. Packed snow covered the Cascade Passes this
morning, where temperatures were in the mid 20s.
Not much in the way of rain or snow made it into Central and
Eastern Oregon overnight, but skies had turned cloudy. As
the storm progresses eastward, precipitation should push
into Central Oregon later this morning mainly as snow. The
National Weather Service has issued a snow advisory for The
Bend and Redmond areas for up to a couple of inches of snow
later this morning. Areas of light rain and snow will
spread eastward across the state today and tonight, but
significant snow accumulations are not expected.
The ODA surface analysis showed a low pressure center about
150 miles west of Newport with a warm front extending
eastward to near Newport. Ahead of the warm front, winds in
the Northern Willamette Valley and along the north coast
were northeasterly at 5-15 mph. On the south side of the
warm front, southeasterly winds of 5-15 were blowing along
and south of a Newport to Eugene line. Temperatures ranged
from from near 40 in the north valley, and the north coast,
to the upper 40s along the southern coast.
The warm front is forecast to weaken and slowly progress
northward today with rain at times continuing and
southeasterly winds moving northward across Western Oregon.
The warmer air aloft over Southern Oregon will filter
northward this afternoon with the snow level over Northern
Oregon creeping up to around 3000 feet. The snow level over
Southern Oregon will stay near 4000 feet. Clouds and rain
will help hold valley temperatures in the low 50s (about 10
degrees below average).
SE 5-15 this morning, SE 5-15 this afternoon.
S 25-30 this morning, S 20-25 this afternoon.
Atmospheric Ventilation Conditions:
Maximum mixing height today will be near 4000 feet. Ventilation index 100.
Salem\'s high temperature today will be near 52.
Minimum relative humidity will be near 69%.
Salem sunset tonight: 8:07pm; sunrise tomorrow: 6:13am.
The cold front from the slow-moving offshore storm system
will finally move inland tonight. The associated cold
upper-level trough will move over the region Wednesday and
Thursday for showers and a return of quite low snow levels.
High pressure will build into the coastline Friday and begin
to dry out the air mass. That may lead to cool temperatures
over sections of the valley Friday and/or Saturday mornings
with daytime temperatures shooting above normal Saturday.
The next weather system is forecast to move onshore Sunday
night and Monday.
Tomorrow (23 Apr): Showers. Chance T-Storm. Snow Level Dropping to 1500 Feet. 42/52
Thu (24 Apr): Mostly Cloudy. Chance of Showers. Snow Level Rising to 3000 Feet. 37/56
Fri (25 Apr): Mostly Cloudy. Decreasing Chance of Showers. Snow Level 4000 Feet. 36/58
Sat (26 Apr): Becoming Mostly Sunny and Warmer. 34/67
Sun (27 Apr): Increasing Clouds. Rain Likely Late. 40/63
Mon (28 Apr): Rain Likely and Cooler. 44/58
Tue (29 Apr): Showers. Snow Level 2500 Feet. 40/55
weather at oda.state.or.us
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