[willamette-fcst] Forecast - Friday, August 7th, 2009
Willamette Valley Ag/Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Fri Aug 7 08:45:23 PDT 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.
Friday, August 7th, 2009 at 8:45am.
Agricultural burning is not recommended.
Preparatory burning is allowed from 12:00pm until 2:00pm with a 100 acre limit.
Propane flaming is allowed from 12:00pm until 2:00pm.
Stack burning is not allowed.
The upper-level low pressure center, that brought cloudy and
much cooler weather to western Oregon Thursday, was centered
over Idaho this morning. The counterclockwise circulation
around it was still spinning clouds back over virtually all
of Oregon this morning, with some showers continuing east of
There is a deep marine layer over the Willamette Valley this
morning...extending up to about 7500 feet, with a thick
cloud-cover and areas of drizzle/sprinkles. Mostly just
trace amounts of rain have been reported. Clouds will be
persistent across western Oregon today, even as the parent
upper-level trough pushes off to the east. There may be some
partial clearing in the late afternoon. Cooler air aloft and
cloudy skies will keep high temperatures near 70 degrees
(more than 10 degrees below normal).
With westerly transport winds today and the flow aloft
turning from northeasterly to northwesterly, smoke from area
wildfires is being evacuated from western Oregon. Willamette
Valley and western Cascade nephelometer readings are falling
back closer to normal levels this morning...an indication
that the wildfire smoke is being pushed east of the region.
Cooler air aloft should allow mixing heights to climb to near
3000 feet around noon, so limited prep burning was allowed.
Due to the deep marine layer over western Oregon, there is
about 4 millibars of gradient-stacking from Salem to Redmond
this morning. With only partial clearing expected this
afternoon, it is unlikely that west-side temperatures will
warm enough to reverse that and allow for open burning.
SW 5-10 this morning, W 5-10 this afternoon.
W 6 this morning, W 10 this afternoon.
Atmospheric Ventilation Conditions:
Maximum mixing height today will be near 4000 feet. Ventilation index 40.
Salem\'s high temperature today will be near 71.
Minimum relative humidity will be near 50%.
Salem sunset tonight: 8:30pm; sunrise tomorrow: 6:06am.
A very weak system is forecast to move across southern
British Columbia over the weekend...maintaining onshore flow
across western Oregon. Some drizzle is possible along the
coast and in the northern Cascade foothills, but the bulk of
western Oregon will stay dry with morning clouds giving way
to afternoon clearing each day. Temperatures will remain
The lastest computer guidance is backing off slightly on the
strength of a seriers of weather systems slated to come
onshore next week, which increases the chances that they
will create burning opportunities, before bringing any
rainfall to the Willamette Valley. The first system is
forecast to move across southern British Columbia Monday
with the chance for rain extending only about as far south
as the Washington/Oregon border. The next system is
forecast to move onshore late Tuesday and Wednesday. That
system has a greater potential of bringing some light rain
or showers to the Willamette Valley Tuesday night and
Wednesday. A dry and weak westerly flow aloft is forecast by
late next week.
Tomorrow (08 Aug): AM Clouds. Partly Sunny in the Afternoon. 54/77
Sun (09 Aug): AM Clouds. Mostly Sunny in the Afternoon. 56/78
Mon (10 Aug): Mostly Cloudy North...Partly Cloudy South. 55/78
Tue (11 Aug): Increasing Clouds...Chance of Light Rain Late..Mainly North. 55/79
Wed (12 Aug): Mostly Cloudy. Chance of Rain. 55/74
Thu (13 Aug): Mostly Cloudy. Chance of Showers. 55/75
Fri (14 Aug): Am Clouds. Afternoon Clearing. Warmer. 53/82
weather at oda.state.or.us
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