[willamette-fcst] Forecast - Friday, July 13th, 2007
Willamette Valley Ag/Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Fri Jul 13 08:49:53 PDT 2007
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, July 13th, 2007 at 9:00am.
Agricultural burning is allowed. Suggested burn times are from 11:00am until 6:00pm.
Preparatory burning is not allowed.
Propane flaming is not allowed.
Stack burning is not allowed.
The strong upper-level ridge of high pressure, that has been
responsible for the hot weather this week, has shifted
eastward to over Idaho. Oregon is on the western flank of
this ridge and under the influence of south to southeasterly
flow aloft. That is circulating middle and high level
moisture into the region, which has combined with daytime
heating to produce shower and thunderstorm development the
past three nights in parts of the Willamette. Last night
the storms were focused on the north valley, near Portland,
producing considerable lightning and about a tenth of an
inch of rainfall.
Not much change is expected in the overall weather pattern
today, with the southerly flow aloft continuing to feed warm
and unstable air into the region, with above normal
tempertures a risk of a valley thunderstorm today. This
pattern also inhibits the seabreeze from developing, so
transport winds will be extremely light today, with a south
to southeast flow at the top of the mixing layer. On the
other hand, winds could become locally strong and gusty near
The flow aloft will become more southwesterly tonight, which
will likely confine thunderstorm activity to the Cascades
and points eastward.
SW 3 this morning, W 5 this afternoon.
SW 3 this morning, SW 5 this afternoon.
Atmospheric Ventilation Conditions:
Maximum mixing height today will be near 5000 feet. Ventilation index 25.
Salem\'s high temperature today will be near 87.
Relative humidity drops to 50% by 2pm.
Minimum relative humidity will be near 35%.
Salem sunset tonight: 8:57pm; sunrise tomorrow: 5:39am.
A series of weather systems will make their way into the
Pacific Northwest over the next seven days. A southwesterly
flow aloft will swing a weak cold front onto the Pacific
Coastline Saturday night. This system will increase the
onshore flow across Western Oregon Sunday for significant
cooling and bring a slight chance of light shower activity
to the northern valley. A transitory ridge of high pressure
will bring warmer and dry conditions Monday.
The long-range computer models are now more consistent in
their solution for next week. They show the next
upper-level low pressure area approaching the coastline
Monday night. That will turn the flow aloft southerly to
southeasterly again Tuesday and Wednesday, which brings a
renewed chance of thunderstorm development to Western Oregon
and decreases the likelyhood of a burn opportunity on those
days. Southwesterly flow aloft is forecast to keep
tempertures cooler than normal with onshore surface flow
next Thursday and Friday.
Tomorrow (14 Jul): Partly Cloudy. 57/85
Sun (15 Jul): Mostly Cloudy and Cooler. Slight Chance of Showers. 57/77
Mon (16 Jul): Morning Clouds...Sunny Afternoon. 52/85
Tue (17 Jul): Increasing Clouds. Chance of Showers and Thunderstorms. 57/80
Wed (18 Jul): Mostly Cloudy. Chance of Showers and Thunderstorms. 56/75
Thu (19 Jul): Partly Sunny. 52/72
Fri (20 Jul): Partly Sunny. 50/75
weather at oda.state.or.us
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