[willamette-fcst] Forecast - Thursday, August 21st, 2008
Willamette Valley Ag/Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Thu Aug 21 07:53:33 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, August 21st, 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 upper-level trough continued to circulate vigorous
shower activity across the northern half of Oregon overnight
and centered over northern Washington this morning.
Rainfall amounts in the 24 hours ending at 5am were, for the
most part, greater than the previous 24 hours. The northern
Willamette Valley picked up around one-third of an inch of
rain with over one-tenth of an inch in the south valley.
Two-day totals were around one-quarter of an inch in the
south valley and about one-half inch in the north valley.
The upper-level trough is moving east and the flow aloft is
forecast to turn northwesterly and begin drying and warming
this afternoon. Doppler radar has shown a general decrease
in the shower activity over Western Oregon during the past
couple of hours and satellite imagery is even showing a few
breaks in the overcast skies. Additional precipitation
amounts today should be less than one-tenth of an inch with
the showers liekly ending by mid-afternoon. The Salem
sounding this morning showed even more cooling aloft, with
the freezing level clear down to 8100 feet, so temperatures
will remain quite cool today, even with a little sunshine.
The ODA surface analysis showed high pressure building into
SW Oregon with southerly gradients across Western Oregon.
Valley winds were ssw at 5-15 mph. The winds should veer to
northwesterly this afternoon, as the surface high pressure
ridge builds northward in the wake of the exiting
upper-level trough. Skies will clear tonight with areas of
ground fog likely forming due to the damp conditions.
SSW 5-15 this morning, WNW 5-15 this afternoon.
SW 20 this morning, W 12 this afternoon.
Atmospheric Ventilation Conditions:
Maximum mixing height today will be near 3500 feet. Ventilation index 70.
Salem\'s high temperature today will be near 70.
Minimum relative humidity will be near 57%.
Salem sunset tonight: 8:07pm; sunrise tomorrow: 6:23am.
A flat transitory ridge of high pressure will continue to
dry and warm the air mass Friday with surface winds becoming
northerly. The ridge will move over Montana Saturday, with
the flow aloft over Oregon turning southwesterly, in
response to a large upper-level trough approaching from the
Gulf of Alaska. Temperatures will continue to warm with
sunny skies allowing for further drying of damp fields.
The computer forecast models are becoming consistent in
moving the upper-level trough closer to the coastline Sunday
with increasing southwesterly flow aloft. An unseasonably
strong jet stream will likely drive another fairly potent
weather system onshore Sunday night with more rain spreading
across the Willamette Valley. Rainfall totals will likely
range from one-tenth to one-quarter of an inch, by Monday
morning, with locally greater amounts in the north valley.
The flow aloft is forecast to become northwesterly Tuesday
and Wednesday with weak upper-level troughs maintaining a
slight chance of showers...especially in the north. Strong
onshore flow will keep temperatures below normal. The jet
stream may push northward enough Thursday to decrease the
onshore flow and dry things out. That would enable
temperatures to recover close to normal.
Tomorrow (22 Aug): Patchy Morning Fog...Mostly Sunny & Warmer. Wind: N 5-15. 50/80
Sat (23 Aug): Sunny and Warm. 52/85
Sun (24 Aug): Mostly Sunny. Increasing Clouds with a Chance of Rain Late. 54/82
Mon (25 Aug): Rain Likely...Turning to Showers by Afternoon. Much Cooler. 58/72
Tue (26 Aug): Mostly Cloudy North...Slight Chance of Showers. Partly Cloudy South. 52/74
Wed (27 Aug): Mostly Cloudy North...Slight Chance of Showers. Partly Cloudy South. 52/74
Thu (28 Aug): Mostly Sunny. 50/78
weather at oda.state.or.us
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