[willamette-fcst] Forecast - Friday, August 22nd, 2008
Willamette Valley Ag/Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Fri Aug 22 07:59:46 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.
Friday, August 22nd, 2008 at 9:00am.
Agricultural burning is allowed. Suggested burn times are from 12:00pm until 7:00pm.
Preparatory burning is not allowed.
Propane flaming is not allowed.
Stack burning is not allowed.
Showers tapered off early on Thursday across Western Oregon,
with the flow aloft turning northwesterly, in the wake of a
strong upper-level trough that brought soaking rains to the
Willamette Valley Tuesday and Wednesday. Rainfall amounts
in the 24 hours ending at 5am today were generlaly less than
one-tenth of an inch across the valley. With some sunbreaks
Thursday afternoon, valley high temperatures reached the low
70s, after staying in the upper 60s Wednesday. Relative
humidties dropped below 50% Thursday afternoon in the
valley, which aided the drying of damp fields.
The ODA surface analysis showed high pressure centered over
NE Oregon and a weak thermal low pressure trough building
northward into Western Oregon. Gradients were weak
north-northeasterly across the Willamette Valley with
surface winds light and variable at mid-morning. Clearing
skies overnight allowed temperatures to drop into the mid to
upper 40s across much of the valley this morning with areas
of ground fog. Mid-morning temperatures had recovered into
the mid to upper 50s.
A flat upper-level ridge of high pressure was moving over
the region this morning. The Salem sounding showed
considerable warming and drying aloft since Thursday
morning. Satellite imagery showed both low and mid-level
clouds over the Willamette Valley with some breaks in the
overcast. Fields will get an opportunity to further dry out
today, as the air mass continues to warm up and dry out.
Skies will become mostly sunny this afternoon with northerly
winds and lower humidities. Afternoon highs should reach 80
degrees, which is about normal for late August.
Var 3-8 this morning, N 5-15 this afternoon.
NE 14 this morning, NNE 10 this afternoon.
Atmospheric Ventilation Conditions:
Maximum mixing height today will be near 4000 feet. Ventilation index 56.
Salem\'s high temperature today will be near 80.
Relative humidity drops to 50% by 1pm.
Minimum relative humidity will be near 33%.
Salem sunset tonight: 8:06pm; sunrise tomorrow: 6:24am.
The ridge will move over Montana Saturday, with increasing
southwesterly flow aloft over Oregon. Valley temperatures
should warm into the mid 80s under mostly sunny skies. The
southwesterly flow aloft is forecast to further strengthen
Sunday, as a broad upper-level trough in the Gulf of Alaska
slowly shifts eastard.
Rain from a fairly active cold front is forecast to move onto
the Washington Coast Sunday afternoon and slowly sag south and
east into the Willamette Valley Sunday night and Monday. Rainfall
totals from this system will likely range from one-tenth to
one-quarter of an inch, with locally greater amounts, near the
Cascade foothills, in the north.
Showers will taper off Monday night with the flow aloft is
becoming northwesterly. The latest computer forecast
guidance is suggesting that a building ridge of high
pressure will shift the jet stream north into Southern
British Columbia Tuesday through Friday, of next week, with
dry and warmer weather returning to Oregon. Surface winds
are forecast to be mostly northerly.
Tomorrow (23 Aug): Sunny and Warm. 52/85
Sun (24 Aug): 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): Becoming Mostly Sunny. 49/76
Wed (27 Aug): Sunny and Warmer. 49/81
Thu (28 Aug): Sunny and Warm. 52/84
Fri (29 Aug): Sunny and Warm. 54/84
weather at oda.state.or.us
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