[willamette-fcst] Forecast - Thursday, July 26th, 2007
Willamette Valley Ag/Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Thu Jul 26 08:36:49 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.
Thursday, July 26th, 2007 at 9:00am.
Agricultural burning is allowed. Suggested burn times are from 1:00pm until 6:00pm.
Preparatory burning is not allowed.
Propane flaming is allowed from 1:00pm until 6:00pm.
Stack burning is not allowed.
No major changes have occured in the overall weather
pattern. An upper-level ridge of high pressure is centered
over the Rocky Mountains, with a large trough of low pressure
in the Northern Gulf of Alaska. That is giving the Pacific
Northwest a fairly dry southwesterly flow aloft and onshore
flow at the surface.
The upper-air sounding, over Salem this morning, showed
significanly more onshore flow, in the lowest 2000 feet, than
was present yesterday. As a result, marine low clouds were
able to penetrate the western valleys of Oregon this
Daytime heating will evaporate the low cloud deck with sunny skies
expected over the Willamette Valley this afternoon. However,
tempertures will likely be a couple of degress cooler than on
Wednesday. 3000-foot mixing heights will not be reached until
about 1pm, so burn start-times were adjusted accordingly.
The transport winds are still northerly this morning, so
prep and stack burning are not allowed. They are forecast
to become more northwesterly later this afternoon, which we
will closely monitor for the slight chance of a burn opportunity.
The chances for a burn opportunity increase some, Friday afternoon,
as the transport winds turn a bit more westerly.
N 6 this morning, NNW 8 this afternoon.
N 7 this morning, NNW 10 this afternoon.
Atmospheric Ventilation Conditions:
Maximum mixing height today will be near 5000 feet. Ventilation index 50.
Salem\'s high temperature today will be near 84.
Relative humidity drops to 50% by 1pm.
Minimum relative humidity will be near 36%.
Salem sunset tonight: 8:46pm; sunrise tomorrow: 5:52am.
The upper-level trough, in the Northern Gulf of Alaska, will
move close enough to Pacific Coastline to spin a weak cold
front across Washington and Northern Oregon Saturday night
and early Sunday. That will increase the onshore flow and
cool tempertures to near or slightly below seasonal
High pressure is forecast to rebuild over the region early
next week. Northerly transport winds are forecast for
Monday, with the flow aloft, and at the surface, becoming
more westerly as the week progresses.
The long-range computer models are consistent in swinging
another, somewhat stronger, weather system onto the
coastline sometime between Wednesday and Friday of next
week. If that system materializes, it would create
the next significant burn opportunity.
Tomorrow (27 Jul): Morning Clouds...Afternoon Sun. 53/85
Sat (28 Jul): Morning Clouds...Afternoon Sun. 54/84
Sun (29 Jul): MOrning Clouds...Slight Chance Shower. Partly Sunny. 56/78
Mon (30 Jul): Areas Morning Clouds....Sunny with North Winds. 51/84
Tue (31 Jul): Morning Clouds...Afternoon Sun. 53/85
Wed (01 Aug): Sunny. 55/88
Thu (02 Aug): Increasing Clouds. 55/82
weather at oda.state.or.us
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