[willamette-fcst] Forecast - Monday, October 5th, 2009
Willamette Valley Ag/Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Mon Oct 5 08:52:08 PDT 2009
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, October 5th, 2009 at 9:00am.
Agricultural burning is allowed. Suggested burn times are from 9:00am until 5:00pm.
Propane flaming is allowed from 1:00pm until 5:00pm.
Stack burning is not allowed.
The strong upper-level trough that brought showery and cool
weather the Oregon over the weekend had shifted east, to
over Idaho, this morning. Satellite imagery showed mostly
cloudy skies over southeastern Oregon, where a few showers
were still indicated by Doppler radar. Clearing skies over
the remainder of the state allowed temperatures to drop well
into to the 30s with some areas of the Willamette Valley
flirting with the freezing mark. McMinnville dropped to 32
degrees this morning, and Hillsboro dipped down to 34. Corvallis
and Eugene both dropped to 36 degrees, and Salem hit 38.
As is typical for October, low-level cooling and light winds
overnight led to formation of fairly extensive fog and low
clouds across the Willamette Valley this morning. Visibilities
were locally reduced to around one-quarter of a mile. The
mid-morning ODA surface analysis showed high pressure extending
from western Washington southward across western Oregon with
very weak pressure gradients and light soth-southeasterly winds
across the Willamette Valley. Low pressure over Idaho was
maintaining brisk north-northwesterly winds across much of
central and eastern Oregon...keeping fog from forming.
A strong upper-level ridge of high pressure, over the
eastern Pacific Ocean, will slowly build inland today, with
a drying northeasterly flow aloft over Oregon. The morning
fog and low clouds, blanketing most of the Willamette
Valley, should give way to plenty of sunshine this
afternoon, as the low-level flow backs from southeasterly to
north-northeasterly. The air mass is still chilly, with the
freezing level over Salem measured at just 6800 feet this
morning, so highs today will likely only manage to climb
into the mid 60s (about 5 degrees below average).
SSE 3-8 this morning, N 5-12 this afternoon.
SE 5 this morning, NE 8 this afternoon.
Atmospheric Ventilation Conditions:
Maximum mixing height today will be near 3000 feet. Ventilation index 24.
Salem\'s high temperature today will be near 66.
Relative humidity drops to 50% by 2pm.
Minimum relative humidity will be near 40%.
Salem sunset tonight: 6:45pm; sunrise tomorrow: 7:17am.
A dry and cool northeasterly flow aloft will allow
Willamette Valley temperatures to cool into the 30s again
Tuesday morning with local pockets of frost possible. The
upper-level ridge is forecast to build slightly more into
the coastline Tuesday. After areas of morning fog, mostly
sunny skies should warm temperatuers close to normal.
A weather system moving over the top of the ridge will drop
southward, into Montana, on Wednesday...keeping the
upper-level ridge from building over Oregon. That will
maintain a dry and cool north-northeasterly flow aloft.
Overnight minimums will likely moderate a few degrees, but
afternoon highs will still struggle to hit 70 degrees...even
with plenty of sunshine.
The flow aloft is forecast to turn north-northwesterly, over
Oregon, Thursday and Friday, as a reinforcing surge of cool
Canadian air brings some early autumn snow to the northern
Rockies. The air aloft will stay cool enough to keep
Willamette Valley temperatures slightly below normal, even
with plenty of afternoon sunshine. By Saturday, the
upper-level ridge is forecast to build more directly over
the west coast, with warmer air aloft and increasingly
offshore surface winds combining to warm valley temperatures
into the 70s (slightly above normal).
The ridge is forecast to shift east, to over Idaho, Sunday,
with increasing westerly flow aloft introducing some Pacific
moisture back into Oregon. A weak cold front could bring
some light rain to the north coast by Sunday afternoon, with
increasing clouds and onshore flow cooling Willamette Valley
temperatures back into the 60s. A more potent system is
forecast to bring widespread rain onshore next Monday.
Tue (06 Oct): Areas of AM Fog. Chilly in the Morning. Sunny and a Touch Warmer. 36/68
Wed (07 Oct): Areas of AM Fog. Sunny. 40/68
Thu (08 Oct): Areas of AM Fog. A Few High Clouds in the Afternoon. 41/68
Fri (09 Oct): Mostly Sunny. 39/68
Sat (10 Oct): Sunny. 41/71
Sun (11 Oct): Increasing Clouds. 43/68
Mon (12 Oct): Rain Likely. 44/64
weather at oda.state.or.us
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