[willamette-fcst] Forecast - Wednesday, July 11th, 2007
Willamette Valley Ag/Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Wed Jul 11 09:02:04 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.
Wednesday, July 11th, 2007 at 9:00am.
Agricultural burning is not recommended.
Preparatory burning is not allowed.
Propane flaming is not allowed.
Stack burning is not allowed.
A strong upper-level ridge is still over the Pacific
Northwest this morning but showing signs of slowly
progressing eastward. Southerly flow aloft has spread
middle and high cloudiness over most of Oregon this morning.
That will block some sunshine today and prevent
temperatures from getting as warm as Wednesday\'s 100-degree
readings in the Willamette Valley. Somewhat cooler surface
temperatures, combined with very warm air aloft, may keep
mixing heights below 3000 feet this afternoon.
The ODA morning surface analysis showed the surface thermal
trough over the Willamette Valley, with onshore flow
stretching northward along the entire Oregon Coastline.
Morning winds will be light in the valley. As the thermal
trough shifts north and east this afternoon, some marine air
will begin the filter into the Southern Willamette Valley.
The flow aloft will become south to southeasterly this
afternoon, with more middle and high level moisture being
drawn into the region. That increases the likelihood of
thunderstorm development and reduces the westerly component
of the transport winds...making for poor burning conditions.
S 3 this morning, SW 6 this afternoon.
SW 3 this morning, W 10 this afternoon.
Atmospheric Ventilation Conditions:
Maximum mixing height today will be near 3000 feet. Ventilation index 30.
Salem\'s high temperature today will be near 93.
Relative humidity drops to 50% by 11.
Minimum relative humidity will be near 27%.
Salem sunset tonight: 8:58pm; sunrise tomorrow: 5:37am.
The upper-level ridge is forecast to progress eastward to
over Idaho Thursday. Southerly to southeasterly flow aloft
will further raise the thunderstorm threat for all of
Oregon, which is not conducive to burning. The thermal
trough will shift into Eastern Oregon, with increasing
onshore surface flow and cooling into the Willamette
The upper-level flow will become southwesterly Friday
afternoon, which will likely put an end to the thunderstorm
threat west of the Cascades. The marine air will have
already infiltrated the Willamette Valley by then, so I do
not anticipate a field-burn opportunity, but I will keep you
Long-range computer models are all consistent with the
development of a rather strong upper-level low pressure
area, for this time of the year, in the Eastern Pacific
Ocean. That will spin a series of weather systems across
the Pacific Northwest beginning this weekend through the
middle of next week.
Tomorrow (12 Jul): Partly Cloudy. Chance of Thunderstorms. 61/90
Fri (13 Jul): Chance of Morning Thunderstorms...Partly Cloudy. 60/85
Sat (14 Jul): Partly Cloudy. 58/84
Sun (15 Jul): Mostly Cloudy. Chance of Showers. 54/79
Mon (16 Jul): Mostly Cloudy. Chance of Showers. 54/76
Tue (17 Jul): Mostly Cloudy. Chance of Showers. 54/72
Wed (18 Jul): Partly Cloudy. 50/70
weather at oda.state.or.us
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