[willamette-fcst] Forecast - Wednesday, August 13th, 2008
Willamette Valley Ag/Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Wed Aug 13 08:03:23 PDT 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.
Wednesday, August 13th, 2008 at 9:00am.
Agricultural burning is not recommended.
Preparatory burning is not allowed.
Propane flaming is not allowed.
Stack burning is not allowed.
A strong ridge is forecast to build over the Pacific
Northwest, beginning today, with the surface flow turning
northerly and valley highs climbing into the mid to upper
80s. The Salem sounding this morning showed
north-northeasterly winds from just above the surface to
about 3000 feet. The air mass aloft had not started warming
much yet, so mixing hights should climb above 3000 feet this
afernoon. North-northeasterly transport winds are expected
to continue today. That is not conducive to good
ventialtion for most of the valley but could create a
burning opportunity for fields on the west side of the
valley later this morning.
The ODA surface analysis showed high pressure building into
Western Washington with northerly gradients developing
across Western Oregon. Valley winds were generally from the
north at less than 10 mph with temperatures in the low to
mid 60s. Satellite imgery showed mostly clear skies across
Oregon, except for patchy low clouds along the coast and in
the extreme north valley. The air mass will warm today in
response to the building ridge over the region. Valley
temperatures will climb into the upper 80s this afternoon
with increasing north winds. Coastal locations will also
see sunshine and northerly winds this afternoon with highs
in the 65-75 degree range.
N 5-10 this morning, N 10-20 this afternoon.
NNE 13 this morning, NNE 13 this afternoon.
Atmospheric Ventilation Conditions:
Maximum mixing height today will be near 3700 feet. Ventilation index 48.
Salem\'s high temperature today will be near 87.
Relative humidity drops to 50% by 11am.
Minimum relative humidity will be near 34%.
Salem sunset tonight: 8:21pm; sunrise tomorrow: 6:13am.
We are in for a heat-wave. The upper-level ridge will
amplify Thursday with warmer air aloft and offshore surface
gradients lifting temperatures into the mid 90s across the
Willamette Valley and the 70s to low 80s along the coast.
Even with high afternoon surface temperatures, mixing
heights will struggle to reach 3000 feet due to very warm
The upper-level ridge axis is forecast to shift east of the
Cascades Friday afternoon with southerly flow aloft
developing over Western Oregon. That will likely begin
transporting smoke, from California wildfires, back over
Western Oregon and make for hazy conditions. The air aloft
will continue to warm with valley temperatures approaching
daily record highs under a broad surface themal trough.
An upper-level disturbance is forecast to approach the
Oregon Coast Friday and begin to increase the moisture and
instability over the western half of the state. The thermal
trough may begin to shift east of the Cascades late
Saturday, but not before temperatures climb to near the
century mark in the valley for the second straight day.
The upper-level ridge is forecast to shift over Western
Montana Sunday with increasing southwesterly flow aloft over
Oregon. That will bring more stable air into the region and
increase the onshore flow for cooler temperatures across the
interior of Western Oregon. The onshore flow will continue
Monday with a stronger trough forecast to approach the
coastline Tuesday. That system may create a burning
opportunity Tuesday afternoon, before bringing a chance of
light rain to Western Oregon Wednesday.
Tomorrow (14 Aug): Sunny and Hot. 58/95
Fri (15 Aug): Sunny, Hot and Hazy. Slight Chance of T-Storms Late. 62/100
Sat (16 Aug): Mostly Sunny, Hot, and Hazy. Slight Chance of T-Storms. 62/98
Sun (17 Aug): Partly Cloudy and Much Cooler. 60/87
Mon (18 Aug): Mostly Sunny. 55/85
Tue (19 Aug): Mostly Sunny. 53/83
Wed (20 Aug): Mostly Cloudy and Cooler. Chance of Light Rain. 55/72
weather at oda.state.or.us
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