[willamette-fcst] Forecast - Tuesday, April 1st, 2008
Willamette Valley Ag/Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Tue Apr 1 06:59:46 PST 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.
Tuesday, April 1, 2008 at 9:00 am.
Agricultural burning is allowed. Suggested burn times are from now until 5:30 pm.
Stack burning is not allowed.
Another upper-level disburbance, from British Columbia,
brought scattered showers to Washington and the northern
third of Oregon Monday afternoon and evening. Snow levels
were quite low (2000 feet) over Northern Oregon, but
not much additional snow fell in the mountains due to the
lack of moisture. Rainfall amounts were generally only a
couple hundredths of an inch across extreme Northern Oregon
with a trace of rain falling as far south as Salem.
The upper-level disturbance moved into Northeastern Oregon
overnight with clearing skies and a cold air mass bringing
near-record cold temperatures to Western Oregon this
morning. Valley minimums ranged from 25-30 degrees.
Official low temperatures will not be available until 11 am,
but preliminary readings show that Aurora, Salem, Corvallis,
and Eugene all dropped down to at least 30 degrees.
McMinnville dipped to at least 27 and Hillsboro to at least 25.
As you would expect, it was much colder east of the Cascades
this morning. Meacham, in Northeastern Oregon, was one of
the coldest spots...dropping to at least 5 degrees. Redmond
dropped to at least 10 degrees and Lakeview to at least 19.
Clouds and snow flurries kept temperatures from falling
quite as low over extreme Eastern Oregon, but it was still
plenty cold. Baker City fell to at least 23 degrees with
some very light snow overnight.
Northerly flow aloft will continue over the Pacific
Northwest today. The air mass will slowly dry and warm, as an
upper-level ridge builds closer to the coastline. Temperatures
will warm, both at the surface and aloft, with sunny skies helping
afternoon temperatures climb into the mid and upper 50s across
Western Oregon. Northerly surface and transport winds are not
favorable for good valley ventilation, so stack burning is not
allowed again today.
The next upper-level disturbance will drop down from British
Columbia across Eastern Washington, Northern Idaho, and
Northeast Oregon tonight. That is too far east to bring
much in the way of cloud-cover to Western Oregon, but it
will help to maintain the unseasonably cold air mass over
the region. Light northerly winds and mostly clear skies
will allow for another very cold night, across Oregon, with
near record low temperatures likely again in the Willamette
Valley. Frost sensitive crops may need protection.
This is a very typical early spring La Nina weather pattern.
In fact, my top analog year to this year (1971) had a
similar cold spell at this same time of year. April of 1971
went on to be colder than normal across the state, with
near-normal precipitation (slightly wet west of the Cascades
and slightly dry east). I am expecting this April to be
similar. My seasonal climate outlook for April-June is
available in either PowerPoint or PDF format on the web at
N 5-10 this morning, N 10-15 this afternoon.
NNE 10 this morning, NNE 15 this afternoon.
Atmospheric Ventilation Conditions:
Maximum mixing height today will be near 4500 feet. Ventilation index 68.
Salem\'s high temperature today will be near 56.
Minimum relative humidity will be near 33%.
Salem sunset tonight: 7:41pm; sunrise tomorrow: 6:50am.
Further warming is expected Wednesday and Thursday, as the
upper-level ridge continues to build into the west coast.
Northerly flow will prevail, both at the surface and aloft.
The dry air mass and fair skies will allow morning minimums
to dip near or below the freezing mark across the valley.
Afternoon highs should reach near 60 Wednesday and into the
The weather system slated to move into the region Friday
shows up stronger on the latest computer model projections.
It now appears strong enough to bring a significant threat
of showers to Western Oregon, as it pushes through the
upper-level ridge and turns the surface flow onshore. That
should help to keep minimums above the freezing mark Friday
morning and cool afternoon temperaures back into the 50s.
A transitory ridge is still forecast to rebuild over the
region for some drying and warming Saturday. The long-range
models are all over the board after Saturday, so my
confidence in the forecast for early next week is low. The
models want to maintain some form of onshore flow, which
would give mostly cloudy skies and at least a chance of
showers to Western Oregon. Temperatures are most likely
going to stay near or slightly below normal.
Tomorrow (02 Apr): Sunny and Warmer. Winds N 5-15. 29/59
Thu (03 Apr): Mostly Sunny. 31/63
Fri (04 Apr): Mostly Cloudy. Good Chance of Showers. 35/58
Sat (05 Apr): Becoming Partly Cloudy. 35/61
Sun (06 Apr): Mostly Cloudy. Chance of Rain. Snow Dropping to 4000 Feet. 38/57
Mon (07 Apr): Mostly Cloudy. Chance of Showers. Snow Level 4000 Feet. 38/56
Tue (08 Apr): Mostly Cloudy. Chance of Showers. Snow Level 4000 Feet. 39/57
weather at oda.state.or.us
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