[willamette-fcst] Forecast - Thursday, September 25th, 2008
Willamette Valley Ag/Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Thu Sep 25 08:01:34 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.
Thursday, September 25th, 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 slow-moving cold front dropped generally from one-tenth to
one-third of an inch of rain across most of the Willamette
Valley Wednesday evening. Heavier amounts fell in some of
the Cascade Foothills. An upper-level trough will maintain
a chance of showers today...mainly in the north valley.
Temperatures will be cooler today with valley highs in the
65-70 degree range.
Satellite imagery showed the low-pressure center near
Vancouver Island, British Columbia this morning with the
cold front moving across Eastern Oregon. There were some
breaks in the overcast west of the Cascades with Doppler
radar indicating a few light showers north of about Salem.
Valley temperatures were running in the low to mid 50s with
south to southwest winds 5-10 mph.
The Salem sounding showed considerable cooling aloft since
Wednesday, so mixing heights should climb to 3000 feet when
surface temperatures warm to about 64 degrees and climb as
high as 4000 feet this afternoon, due to the passage of a
cool upper-level trough to our north. Transport winds are
forecast to be west-southwesterly this afternoon and much
lighter than yesterday, so ventilation conditions may be
conducive to allow for open burning of dry fields. Fluffing
of damp fields is required to take advantage of this
potential burning opportunity.
SW 5-15 this morning, W 5-15 this afternoon.
SW 13 this morning, WSW 10 this afternoon.
Atmospheric Ventilation Conditions:
Maximum mixing height today will be near 4000 feet. Ventilation index 52.
Salem\'s high temperature today will be near 67.
Minimum relative humidity will be near 54%.
Salem sunset tonight: 7:03pm; sunrise tomorrow: 7:05am.
A weaker upper-level trough is forecast to approach the
Southern British COlubia Coast late Friday with westerly
flow aloft over Oregon. That may may create a
late-afternoon burning opportunity for dry fields, but
forecast soundings indicate that low-level winds may be too
northerly. The system will move into Southern British
Columbia early Saturday with precipitation forecast to stay
mostly north of Oregon. It could produce some sprinkles or
light showers in the extreme north valley. Depending on the
timing and strength of that system, it may also create a
burning opportunity Saturday afternoon, but forecast
soundings are calling for northerly low-level winds
returning by Saturday afternoon.
The long-range models are still forecasting an upper-level
ridge to amplify over Eastern Oregon and Idaho Sunday,
putting Western Oregon under weak southwesterly flow aloft.
Offshore surface flow and warmer air aloft may help valley
temperatures approach 80 degrees, which will aid in the
drying of damp fields. The ridge is forecast to slowly
slide eastward, early next week, opening the door for a
series of progressively wetter weather systems to come
onshore beginning late Tuesday or Wednesday. This
transition may create a burning opportunity about Tuesday or
Wednesday of next week, if transport winds are not too
southerly. The outlook is for wet conditions late next week
Tomorrow (26 Sep): Mostly Sunny. 45/75
Sat (27 Sep): Mostly Sunny. 46/76
Sun (28 Sep): Sunny and Warm. 46/81
Mon (29 Sep): Increasing High Clouds and Warm. 49/82
Tue (30 Sep): Increasing Clouds. 50/76
Wed (01 Oct): Mostly Cloudy. Increasing Chance of Rain. 51/69
Thu (02 Oct): Rain Likely. 50/66
weather at oda.state.or.us
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