[willamette-fcst] Forecast - Wednesday, February 18th, 2009
Willamette Valley Ag/Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Wed Feb 18 09:04:08 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, February 18th, 2009 at 9:00am.
Agricultural burning is allowed. Suggested burn times are from now until 3:30pm.
Stack burning is not allowed.
Satellite imagery showed an impressive low-pressure system,
an associated cloud-shield, centered several hundred miles
off the northern California coastline this morning.
Precipitation from that system should stay offshore today
with an upper-level ridge continuing to build over Oregon
and Washington. The freezing level over Salem rose from
4300 feet Tuesday afternoon to 5200 feet early this morning
and should continue to slowly climb today.
With the expection of valley low clouds and fog thsi
morning, skies were generally fair over Washington and
Oregon this morning. Clearing skies overnight allowed
temperatures to drop below freezing across most of the
Willamette Valley overnight.McMinnville was one of the
colder spots, dipping to just 28 degrees. Calm winds even
helped the, normally warmer, Portland Airport drop briefly
below the freezing mark this morning (31 degrees).
The ODA surface analysis showed very weak offshore pressure
gradients across western Oregon, and morning winds were
mostly calm at mid-morning. Temperatures were generally in
the low to mid 30s with some sunbreaks beginning to make it
through the widespread valley fog. The fog should give way
to at least partly sunny skies today with valley
temperatures climbing mostly into the mid 50s (a little
above normal). Surface winds will remain lightly offshore.
Stack burning is not allowed today due to light northerly
transport winds combined with mixing heights at or below
2000 feet. Offshore gradients are forecast to slowly
increase tonight and Thursday, as the offshore low-pressure
system drifts closer to the California coastline.
Var 0-5 this morning, N 2-7 this afternoon.
N 3 this morning, N 5 this afternoon.
Atmospheric Ventilation Conditions:
Maximum mixing height today will be near 2000 feet. Ventilation index 10.
Salem\'s high temperature today will be near 56.
Minimum relative humidity will be near 38%.
Salem sunset tonight: 5:45pm; sunrise tomorrow: 7:06am.
Middle and high clouds will likely increase Thursday and
Friday, as the storm off the California coastline slowly
moves eastward. However, it should remain mostly dry in the
Willamette Valley, with some light rain possibly making it
into southwestern Oregon by Friday. Surface winds will
remain light offshore with mild afternoon temperatures.
Ventilation conditions may deteriorate slightly, as the air
aloft continues to warm.
The sry conditions may hold through Saturday with a good
chance of light rain moving into western Oregon by Sunday.
Ventilation conditions are expected to improve early next
week, with an increasing chance of rain and lowering snow
Tomorrow (19 Feb): Areas of AM Fog. Becoming Partly Sunny. 31/56
Fri (20 Feb): Areas of AM Fog. Partly Sunny. 33/57
Sat (21 Feb): Areas of AM Fog. Partly Sunny. 34/57
Sun (22 Feb): Chance of Rain. 38/53
Mon (23 Feb): Rain Likely at Times. Snow Level Dropping to 3500 Feet. 40/52
Tue (24 Feb): Showers. Mountain Snow. Snow Level 2500 Feet. 38/50
Wed (25 Feb): Showers. Mountain Snow. Snow Level 1500 Feet. 36/49
weather at oda.state.or.us
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