[willamette-fcst] Forecast - Thursday, February 12th, 2009
Willamette Valley Ag/Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Thu Feb 12 09:19:06 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.
Issued:
Thursday, February 12th, 2009 at 9:00am.
Burn Advisory:
Agricultural burning is allowed. Suggested burn times are from 11:00am until 3:30pm.
Straw stack burning is allowed from 11:00am until 3:30pm.
Weather Discussion:
Clearing skies last night combined with light winds and a
cold air mass over the region to drop temperatures well
below freezing across most of western Oregon. Willamette
Valley minimums fell into the 20s, with areas of icy fog
forming. Hillsboro was at least as cold as 22 degrees this
morning, approaching their record low of 20 degrees, set in
1948. McMinnville dipped to at least 24, Salem and Aurora
hit 26 degrees, and Eugene dipped to 27. Some wet road
surfaces may have turned icy overnight, especially in foggy
areas, so travel with caution this morning. Temperatures
were still at or below freezing, across most of western
Oregon, at 8am.
Satellite imagery showed high clouds already increasing over
western Washington and western Oregon, in response to the
next in a series of cold weather systems dropping into the
region from the Gulf of Alaska. A surface low-pressure
center was developing about 300 miles west of the central
Washington coast. The associated cold front was still a
couple of hundred miles offshore and extended south to off
the northern California coast. This storm is forecast to
take a slightly more of a southerly track than the system
that moved through the region Tuesday and Wednesday, with
the bulk of the precipitation headed for California.
As the low-pressure center slowly drifts southeastward, the
associated cold front will bring increasing clouds to
western Oregon today with rain moving onto the coast later
this afternoon. Valley highs will climb into the mid 40s
with increasing south-southeasterly winds. The air mass
remains very cool over the region with the freezing levels
over Salem and Medford measured at just 2300 and 2900 feet
respectively early this morning. Increasing offshore
low-level flow will maintain quite low snow levels tonight
and Friday. Expect sticking snow, above about 1000 feet, in
the coastal range tonight with a 2-4 inches of new snow
likely. Snow totals will increase to the south.
Rain will move into the western valleys this evening with
snow levels dropping to around 500 feet in the north valley,
by early Friday, and to about 1000 feet in the south valley.
A few inches of new snow are also likely over the Cascade
passes...especially across the southern half of the state.
Some wet snow may locally mix to the valley floors tonight
and Friday, but accumulations below 500 feet are not
expected. Total precipitation amounts, tonight and Friday,
will likely be less than one-quarter of an inch across the
Willamette Valley, with most of the moisture from this
system moving into southwestern Oregon and northern
California. Cloudy and damp conditions should keep most
valley minimums slightly above freezing tonight.
Surface Winds:
SSE 0-7 this morning, SSE 5-15 this afternoon.
Transport Winds:
S 7 this morning, S 12 this afternoon.
Atmospheric Ventilation Conditions:
Maximum mixing height today will be near 1800 feet. Ventilation index 22.
High Temperature:
Salem\'s high temperature today will be near 45.
Humidities:
Minimum relative humidity will be near 59%.
Sunrise/Sunset:
Salem sunset tonight: 5:36pm; sunrise tomorrow: 7:15am.
Extended Outlook:
Clearing skies Friday night should allow valley temperatures
to, once again, drop well below freezing. Saturday will be
a break-day between storm systems with partial clearing and
just a slight chance of a shower. The next weather system
is forecast to take an even more southerly track, Sunday and
Monday, with the bulk of the moisture rotating across
southern Oregon and northern California. That storm track
will maintain a cool offshore low-level flow across western
Oregon, so snow levels will remain between 1000 and 3000 feet.
Tuesday, a weak upper-level trough over Oregon will maintain
low snow levels and a chance of showers. The chance of showers
will decrease Wednesday and Thursday with more clearing.
Temperatures should moderate closer to normal by Thursday.
Tomorrow (13 Feb): Decreasing Rain and Snow. Snow Level Near 1000 Feet. 33/44
Sat (14 Feb): Partial Clearing and Cool. Slight Chance of a Shower. 27/47
Sun (15 Feb): Chance of Showers and Cool. Snow Level Near 2000 Feet. 30/46
Mon (16 Feb): Mostly Cloudy. Slight Chance of Showers. Snow Level 2500 feet. 30/48
Tue (17 Feb): Chance of Showers. Snow Level 2-3000 Feet. 33/48
Wed (18 Feb): Slight Chance of Showers. Snow Level 3000 Feet. 33/50
Thu (19 Feb): Partly Cloudy. Slight Chance of Showers. 33/51
ODA Meteorologist
weather at oda.state.or.us
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