[willamette-fcst] Forecast - Thursday, April 10th, 2008
Willamette Valley Ag/Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Thu Apr 10 15:55:14 PDT 2008
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, April 10, 2008 at 4:45 pm.
Burn Advisory For Friday, April 11, 2008:
Agricultural burning is allowed. Suggested burn times are from 11:00 am until 6:00 pm.
Stack burning is not allowed.
A dissipating warm front kept skies cloudy most of the day
over Northwest Oregon with areas of light rain persisting
until early this afternoon over the north valley and the
Northern Cascade Foothills. Meanwhile, skies were mostly
sunny today from Central through Southwest Oregon. Skies
were also beginning to clear over the eastern portion of the
state, as the light rain and snow showers across that region
earlier today moved into Idaho.
The air aloft is slowly warming and drying, with an
upper-level ridge building into the west coast. The
freezing levels were still quite low this morning, at 3-4000
feet over the state, with a couple of inches of new snow
falling at pass levels in the Cascades earlier today.
Doppler radar showed a few remaining showers over the
Nothern Cascades, but even those shoud be dying off in the
next few hours. With some late-afternoon sunshine, valley
temperatures ended up a couple of degrees warmer than on
Wednesday with highs in the mid to upper 50s.
Temperatures east of the Cascades were generally in the
upper 40s and 50s this afternoon with low 60s across
Southwest Oregon. The late-afternoon ODA surface analysis
showed that high pressure had built far enough into Western
Oregon to switch pressure gradients from southerly to
westerly across the Willamette Valley where west winds were
blowing at 5-10 mph. Pressure gradients were becoming
northwesterly across Central and Eastern Oregon with wind
speeds of 15-25 mph common.
High pressure will continue to build into the Pacific
Northwest overnight with clearing skies leading to colder
minimum temperatures. Willamette Valley lows will dip into
the mid 30s with local pockets of frost. Frost-sensitive
crops in normally cold regions may need protection.
The weather forecast models all strongly build a ridge of
high pressure over the Pacific Northwest Friday for sunny
and warmer conditions. Surface gradients will turn
northerly Friday morning and weakly offshore Friday
afternoon. Northerly transport winds are not conducive to
good valley ventilation, so stack burning is not allowed
Friday. With rapid warming of the air mass aloft, valley
temperatures should top out into the upper 60s Friday
afternoon with the freezing level rapidly climbing to near
N 5-10 Friday morning, NNE 10-15 G20 south valley Friday afternoon.
NNE 5-10 Friday morning, NNE 15 Friday afternoon.
Atmospheric Ventilation Conditions:
Maximum mixing height Friday will be near 2800 feet. Ventilation index 14.
Salem\'s high temperature Friday will be near 69.
Minimum relative humidity will be near 39%.
Salem sunset tonight: 7:52 pm; sunrise Friday: 6:34 am; sunset Friday night: 7:53 pm.
Saturday will be the warmest day during this dry stretch,
with the upper-level ridge shifting east of the region, to
over Idaho, by Saturday night. By Sunday afternoon, the
upper-level ridge is forecast to be over Montana with
increasing southwesterly flow aloft over Oregon. The
surface thermal trough will shift into Central Oregon by
Sunday morning and progrees to Eastern Oregon Sunday
afternoon, for the warmest day there. That will bring
cooler onshore flow to Western Oregon Sunday.
A cold front is forecast to bring a good chance of rain to
Western Oregon Sunday night or early Monday with onshore
flow penetrating east of the Cascades and into Idaho. A
cool upper-level trough is forecast to either move over the
region or set up camp just offshore. In either case, it
will be close enough for at least a chance of showers
through much of next week.
...The updated ODA Long-Range Climate Forecast, covering the
period from April through July, is available on the web at
either PowerPoint or PDF formats...
Fri (11 Apr): Mostly Sunny and Warmer. 34/69
Sat (12 Apr): Sunny and Warm. Increasing High Clouds Late. 40/74
Sun (13 Apr): Increasing Clouds and a Touch Cooler. Chance of Rain Late. 44/70
Mon (14 Apr): Rain Likely and Much Cooler. Snow Level Dropping to 4-5000 Feet. 42/59
Tue (15 Apr): Chance of Showers and Cool. Snow Level 4-5000 Feet. 38/58
Wed (16 Apr): Chance of Showers and Cool. Snow Level 4000 Feet. 37/57
Thu (17 Apr): Chance of Showers and Cool. Snow Level 3-4000 Feet. 37/58
Fri (18 Apr): Chance of Showers and Cool. Snow Level 3000 Feet. 37/56
weather at oda.state.or.us
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