[willamette-fcst] Forecast - Tuesday, July 3rd, 2007
Willamette Valley Ag/Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Tue Jul 3 08:51:10 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.
Tuesday, July 3rd, 2007 at 9:00am.
Agricultural burning is allowed. Suggested burn times are from 11:00am until 6:00pm.
Straw stack burning is allowed from 11:00am until 6:00pm.
A strong upper-level ridge of high pressure is expanding
northward, into the Pacific Northwest, from the four-corners
region of the United States. That will bring an extended
period of warm and dry weather to the region. The ridge
axis is forecast to position itself east of Oregon, over
Idaho and extreme Western Montana, which will not allow for
a surface thermal trough to develop west of the Oregon
Cascades. That will prevent excessive heat from making its
way into Western Oregon this week, due to a continuation of
onshore surface winds.
The ODA morning surface analysis showed very little pressure
gradient across the region with light winds being reported
statewide. Weak onshore flow was producing some areas of
low clouds along sections of the coastal strip and coast
range, with sunny skies elsewhere. A dissapating surface
cold front was stretching from the NW tip of Washington to
well off of the Oregon Coastline. This feature will
continue to weaken, as surface high pressure builds north
along the Oregon and Washington Coast today, helping to
provide an afternoon seabreeze in the Willamette Valley.
The Salem upper-air sounding was available this morning and
and showed light south winds at the surface becoming
southwesterly above 5000 feet. Our friends at REMAX
launched a hot-air balloon, just west of the Dept. of Ag.
building this morning, which visually confirmed a light
south low-level wind. It would be nice, if they did that
I calculated a maximum mixing height of 6000 feet today,
based on the Salem sounding. However, we should experience
some warming aloft today, due to the building ridge of high
pressure, so mixing heights are not likely to climb much
above 4500 feet. I have adjusted my forecast accordingly.
S 3 this morning, NW 4-8 this afternoon.
SSW 3 this morning, WNW 8 this afternoon.
Atmospheric Ventilation Conditions:
Maximum mixing height today will be near 4500 feet. Ventilation index 36.
Salem\'s high temperature today will be near 86.
Relative humidity drops to 50% by 2pm.
Minimum relative humidity will be near 32%.
Salem sunset tonight: 9:02pm; sunrise tomorrow: 5:31am.
An upper-level ridge will continue to build northward over
the region Wednesday but will stay centered over Idaho and
Western Montana. That will result in surface thermal trough
development near the Idaho border with 100 degree
temperatures in the Eastern Oregon valleys Wednesday and
Thursday. Weak onshore gradients will help cap mid-week
high temperatures near 90 degrees in the Willamette
The upper-level ridge will begin to flatten and shift into
Eastern Idaho Thursday evening, with the surface thermal
trough moving into Idaho. That will increase onshore
gradients across Oregon and usher in cooler marine air. The
region will stay dry and warm through the extended forecast
period, under the influence of a stable west-southwesterly
Tomorrow (04 Jul): Sunny and Hot. 55/90
Thu (05 Jul): Sunny and Hot. 57/91
Fri (06 Jul): Sunny. 54/85
Sat (07 Jul): Patchy Morning Clouds...Sunny. 51/83
Sun (08 Jul): Patchy Morning Clouds...Sunny. 50/83
Mon (09 Jul): Sunny. 51/86
Tue (10 Jul): Mostly Sunny. 54/85
weather at oda.state.or.us
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