[willamette-fcst] Forecast - Monday, July 30th, 2007
Willamette Valley Ag/Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Mon Jul 30 08:59:36 PDT 2007
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, July 30th, 2007 at 9:00am.
Agricultural burning is allowed. Suggested burn times are from 11:00am until 7:00pm.
Preparatory burning is not allowed.
Propane flaming is allowed from 12:00pm until 7:00pm.
Stack burning is not allowed.
An upper-level low pressure area is moving eastward across
Northern British Columbia this morning, with a weak trough
extending southward into Northern Oregon. The trough will
lift northeastward through Eastern Washington this
afternoon, with high pressure building across Oregon. That
is producing north to northeast transport winds over the
Willamette Valley today, so preparatory burning is not
allowed and open burning is unlikely.
This morning\'s surface analysis showed fairly strong onshore
flow across Central and Eastern Oregon, with gradients
turning more northerly, west of the Cascades. The upper-air
sounding, over Salem, showed north to northeast winds up to
4000 feet, with a strong subsidence inversion at 5000 feet.
The decreased onshore flow greatly reduced the formation of
marine low clouds in the Willamette Valley, so a full day of
sunshine will warm tempeartures to around 80 degrees this
afternoon...or about 5 degrees warmer than on Sunday.
N 10 this morning, N 10-15 this afternoon.
NNE 15 this morning, N 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 80.
Relative humidity drops to 50% by 12pm.
Minimum relative humidity will be near 33%.
Salem sunset tonight: 8:41pm; sunrise tomorrow: 5:56am.
A transitory upper-level ridge will build over the Pacific
Northwest Tuesday and Wednesday, with continued sunny skies,
northerly transport winds, and warming temperatures for the
Willamette Valley. A weak west-southwesterly flow aloft
will allow a surface thermal trough to build into SW Oregon
by Wednesday, which should be the warmest day of the week,
west of the Cascades.
On Thursday, the flow aloft becomes southwesterly, again, as
an upper-level low pressure area approaches the coastline.
That system is forecast to shift the thermal surface trough
east of the Cascades, with a marine push likely in the
Willamette Valley. This transition is too far away to time,
but the forecast wind-shift does create a potential burning
opportunity. Right now, it appears that the most likely
time will be Thursday afternoon. We will continue to
monitor this and keep you updated.
The long-range computer models are beginning to forecast a
fairly strong upper-level low pressure area, for this time
of the year, to move into the Pacific Northwest Friday and
stay here through the weekend. That would result in strong
onshore surface flow, cool temperatures, and the chance of
drizzle or light showers across the Willamette Valley, which
is rare for early August. We will keep you updated on that
outlook, as well...
Tomorrow (31 Jul): Sunny and Warm. 51/87
Wed (01 Aug): Sunny and Hot. 55/93
Thu (02 Aug): Sunny. Increasing Clouds Late. 60/85
Fri (03 Aug): Mostly Cloudy...Much Cooler. Chance of Drizzle. 55/74
Sat (04 Aug): Mostly Cloudy and Cool. Chance of Drizzle or Light Showers. 54/73
Sun (05 Aug): Mostly Cloudy and Cool. Chance of Drizzle or Light Showers. 54/72
Mon (06 Aug): Morning Clouds...Afternoon Clearing. 54/78
weather at oda.state.or.us
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