[willamette-fcst] Forecast - Wednesday, March 11th, 2009
Willamette Valley Ag/Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Wed Mar 11 08:04:14 PST 2009
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, March 11th, 2009 at 9:00am.
Agricultural burning is allowed. Suggested burn times are from 12:00pm until 4:00pm.
Stack burning is not allowed.
A cold northwesterly flow aloft helped a weakening Arctic
cold front usher drier and cold air into the region
overnight. Clouds slowly cleared across Oregon with
temperatures dropping well below freezing on both sides of
the Cascades. Willamette Valley minimums were generally in
the mid to upper 20s this morning. Eugene dropped down to
at least 24 degrees. Hillsboro was also one of the colder
spots with a low of 25. Salem and Portland dipped to at
It was quite cold east of the Cascades this morning, with
many areas in the teens or colder. Meacham, in the blue
Mountains of northeastern Oregon, dropped to 11 degrees
below zero and was still at -10 degrees at mid-morning.
Sub-zero temperatures were also experienced across eastern
Washington, where Deer Park, near Spokane, dropped to 12
degrees below zero. The cold air mass stretching from
eastern Washington across Montana is one of the coldest ever
on record for so late in the season. Minimums dropped to
more than 25 degrees below zero across sections of Montana
Satellite imagery showed areas of fog in the central and
southern Willamette Valley this morning. Offshore flow kept
the north valley clear overnight. Increasing offshore flow
will continue to dry the air mass today, resuting in sunny
skies across all of the region by this afternoon. even with
a full day of March sunshine, temperatures will stay below
normal, but to cold outflow from the Columbia Gorge and the
near-record cold air mass in the Columbia Basin. Valley
highs will only climb into the upper 40s (normal would be in
the mid 50s). Stack burning was not allowed today due to
north-northeasterly transport winds.
N 5-12 this morning, NNE 8-17 this afternoon.
NNE 12 this morning, NE 15 this afternoon.
Atmospheric Ventilation Conditions:
Maximum mixing height today will be near 3000 feet. Ventilation index 45.
Salem\'s high temperature today will be near 48.
Minimum relative humidity will be near 46%.
Salem sunset tonight: 7:13pm; sunrise tomorrow: 7:30am.
An upper-level ridge is forecast to build into the west
coast Thursday and Friday. That will bring adry conditions
with moderating temperatures, although overnight minimums
will remain chilly. After another frosty morning, on
Thursday, sunny skies and offshore winds will help afternoon
temperatures climb into the low to mid 50s. Afternoon
temperatures will jump up about 5 degrees, on Friday, with
another full day of sunshine and offshore flow at the surface.
The next weather system will bring rain back to the region
early Saturday with snow levels quickly dropping below the
Cascade passes. The rain will turn to showers by late
Saturday, but a warm front is forecast to bring more rain
Sunday, especially in the north. Snow levels may lift above
the Cascade passes by late Sunday, with increasing westerly
flow aloft and southerly winds at the surface.
The latest computer guidance is suggsting that a strong
upper-level trough of low-pressure will develop over the
eastern Pacific Ocean with southwesterly flow aloft over
Oregon. The jet stream may be far enough south to keep
Washington and western Oregon under cloudy skies with a good
chance of rain. However, the latest computer guidance gives
several possible jet stream positions, so the jury is still
out as to how wet it will be next week. A slight northward
shift of the jet stream would bring spring-like conditions
to the region, but a more southern track would bring
increasing amounts of rain. In any case, it should be mild,
with southwesterly flow aloft. My forecast reflects a
middle-of-the-road solution for now.
Tomorrow (12 Mar): Another Cold Start. Sunny and Warmer in the Afternoon. 25/53
Fri (13 Mar): Frosty Morning. Sunny and Warmer in the Afternoon. Clouds Late. 28/57
Sat (14 Mar): Rain Turning to Showers. Snow Level 3-4000 Feet. 37/50
Sun (15 Mar): Mostly Cloudy. Light Rain Likely...Mainly North. Snow Level 5000 Feet. 38/53
Mon (16 Mar): Mostly Cloudy. Chance of Rain...Mainly North. 40/57
Tue (17 Mar): Mostly Cloudy. Chance of Rain...Mainly North. 40/57
Wed (18 Mar): Mostly Cloudy. Chance of Rain. 40/55
weather at oda.state.or.us
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