[willamette-fcst] Forecast - Monday, August 10th, 2009
Willamette Valley Ag/Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Mon Aug 10 08:54:18 PDT 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.
Monday, August 10th, 2009 at 9:00am.
Agricultural burning is not recommended.
Preparatory burning is not allowed.
Propane flaming is not allowed.
Stack burning is not allowed.
An impressive Pacific frontal system, for mid-August, was
spreading rain into northwestern Washington this morning
with high clouds extending as far south as northwestern
Oregon. The front is forecast to very slowly sag southward
today, with rain possibly spreading into extreme
northwestern Oregon this afternoon. High and mid-level
clouds will increase over the Willamette Valley...especially
north. Temperatures will remain warm, with highs climbing
into the upper 70s in the north valley and low 80s in the
Ahead of the frontal system, surface gradients are weak
southerly across western Oregon with even a slight offshroe
component across northwestern Oregon. Low-level southerly
flow, ahead of the frontal system, produced some warming
aloft overnight, so it will take until about noon for mixing
heights to climb to 3000 feet. Transport winds are
south-southwesterly this morning and should slowly increase
in speed and veer to southwesterly this afternoon. That
should provide adequate ventilation for open burning, in the
southern Willamette Valley. However, open burning in the
north valley will depend on how much of a westerly component
develops in the transport winds this afternoon. Surface
heating and very slight cooling aloft should help mixing
mixing heights climb to near 5000 feet by late this afternoon.
S 5-10 this morning, W 5-10 this afternoon.
SSW 10 this morning, SW 15 this afternoon.
Atmospheric Ventilation Conditions:
Maximum mixing height today will be near 5000 feet. Ventilation index 75.
Salem\'s high temperature today will be near 81.
Relative humidity drops to 50% by 12pm.
Minimum relative humidity will be near 37%.
Salem sunset tonight: 8:26pm; sunrise tomorrow: 6:10am.
A weakending cold front will continue to sag aoutheastward,
into extreme northwestern Oregon, Tuesday. Light rain could
extend as far south as the northern Willamette Valley
Tuesday afternoon, but forecast rain amounts are only a few
hundredths of an inch, at most. The south valley will
likely only see an increase in mid and high-level clouds
Tuesday a a couple of degrees of cooling. It is possible
that mixing heights and transport winds may be favorable for
open burning Tuesday afternoon, especially in the south valley.
The frontal boundary is forecast to continue to weaken and
sag further south, over the Willamette Valley, Wednesday
afternoon. That will bring lots of clouds to the region but
little to no rainfall. If the front becomes weak enough,
that pattern can produce a burning opportunity. On the
other hand, if the front is a little stronger thatn
forecast, it could also produce light rain...especially over
the north valley.
An upper-level trough is forecast to swing onshore Thursday
and activate the surface cold front over western Oregon.
That will likely cool temperatures and increase the chance
for showers across the Willamette Valley...especially north.
If conditions stay dry enough, that could also create a burning
opportunity. A drier northwesterly flow aloft is forecast to
move over western Oregon Friday through this weekend. Windflow
at the surface and aloft is forecast to become northerly by
Sunday, with more sunshine and slightly warmer temperatures.
The flow is forecast to turn offshore by early next
week...resulting in sunny skies and seasonal temperatures.
Tomorrow (11 Aug): Mostly Cloudy North...Chance of Light Rain. Partly Cloudy South. 56/78
Wed (12 Aug): Mostly Cloudy. 56/78
Thu (13 Aug): Mostly Cloudy. Chance of Light Showers...Mainly North. 53/77
Fri (14 Aug): Morning Clouds...Partly Sunny in the Afternoon. 50/79
Sat (15 Aug): Morning Clouds. Partly Cloudy in the Afternoon. 52/80
Sun (16 Aug): Mostly Sunny. 53/83
Mon (17 Aug): Sunny. 54/84
weather at oda.state.or.us
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