[willamette-fcst] Forecast - Friday, February 20th, 2009
Willamette Valley Ag/Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Fri Feb 20 11:59:31 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.
...Next update not scheduled until Tuesday, February 24th at 9am...
Friday, February 20th, 2009 at 12:00pm.
Agricultural burning is not recommended.
Stack burning is not allowed.
Fair skies and light winds overnight, once again, allowed
most Willamette Valley temperatures to drop below freezing.
Hillsboro dipped to 25 degrees; Eugene fell to 27. Salem and
Corvallis dropped to 28. Portland bottomed out at the
freezing mark (32 degrees). Minimums along the coast were in
the mid 30s. Areas of fog and low clouds formed in sections
of the valley this morning...mainly from Salem south to Eugene.
A nearly stationary upper-level low pressure center
continues to sit and spin, well off the northern California
coastline, with a mild southwesterly flow aloft over Oregon and
Washington. The freezing level has steadily risen over the past
few days and jumped above 8000 feet yesterday. The upper-level
ridge axis is slowly shifting eastward, and the freezing level
over Salem slipped back to 7000 feet this morning.
Midday visible satellite imagery showed a few areas of low
clouds and fog rapidly shrinking in the central and southern
valley. Elsewhere across western Oregon, skies were mostly
sunny. Bone-chilling low clouds and fog extended from eastern
Washington, down the Columbia basin of northeastern Oregon, to
near The Dalles. Temperatures under that fog and cloud-cover
were near freezing. Elsewhere across central and eastern Oregon,
areas of morning fog had given way to mostly sunny skies.
Temperaures were already in the upper 40s in Redmond and La Grande.
Infrared satellite imagery showed middle and high clouds
circulating northward, mainly offshore, with shower activity
well offshore. Warm air aloft will keep mixing heights at
or below about 1500 feet again today. The ODA surface analysis
showed weak northeaseterly pressure gradients across western
Oregon at midday. Wind speeds were generally about 5 mph or less,
except for easterly winds gusting to more than 30 mph at the
western end of the Columbia Gorge.
Midday temperatures had already warmed int the mid to upper
50s along much of the coastline. Willamette Valley readings
were mostly in the mid to upper 40s. There were still pockets
of low clouds, like in Corvallis, holding temperatures in the
low 40s. Under mostly sunny skies this afternoon, Willamette
Valley temperatures should climb well into the 50s. Many coastal
areas will see the low 60s today. Light northeasterly surface
winds will continue across western Oregon through the afternoon.
NE 3-7 this afternoon.
NNE 7 this afternoon.
Atmospheric Ventilation Conditions:
Maximum mixing height today will be near 1500 feet. Ventilation index 11.
Salem\'s high temperature today will be near 57.
Minimum relative humidity will be near 49%.
Salem sunset tonight: 5:48pm; sunrise tomorrow: 7:03am.
Clouds will increase over Oregon Saturday, as an offshore
weather system slowly moves towards the coastline. The flow
aloft will turn more southerly with offshore surface
gradients increasing. Rain may move onshore as soon as
Saturday afternoon, with rain likely spreading across
western Oregon Saturday night and Sunday.
South-southweseterly flow aloft will keep snow levels above
the Cascade passes Sunday. Valley temperatures will remain
mild with southerly surface winds improving ventilation
conditions. As the upper-level low pressure system moves
onshore late Monday, colder air aloft should drop the snow
level down to the Cascade passes with increasing rain and
mountain snow. Showers will continue Tuesday, before tapering
off Wednesday, as the flow aloft becomes northwesterly.
There is significant uncertainty in the forecast for late next
Week. It is possible that a cool system could drop into the
region, from the Gulf of Alaska, on Thursday, or things could
dry out Thursday and Friday. Computer models are more consistent
in showing a very cool system dropping into the region next
weekend, with increasing showers and very low snow levels.
Tomorrow (21 Feb): Areas of AM Fog. Mostly Cloudy and Mild. Chance of Rain Late. 32/55
Sun (22 Feb): Rain Likely. Snow Level 5-6000 Feet. 38/53
Mon (23 Feb): Rain Likely at Times. Snow Level 5000 Feet...Dropping late. 40/50
Tue (24 Feb): Showers. Mountain Snow. Snow Level 3000 Feet. 38/50
Wed (25 Feb): Decreasing Showers. Snow Level 3000 Feet. 37/49
Thu (26 Feb): Chance of Showers. Snow Level 3000 Feet. 35/49
Fri (27 Feb): Chance of Showers. Snow Level 2-3000 Feet. 35/49
weather at oda.state.or.us
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