[willamette-fcst] Forecast - Friday, July 18th, 2008
Willamette Valley Ag/Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Fri Jul 18 08:10:17 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, July 18th, 2008 at 9:00am.
Agricultural burning is allowed. Suggested burn times are from 12:00pm until 8:00pm.
Preparatory burning is allowed from 12:00pm until 2:00pm with a 100 acre limit.
Propane flaming is allowed from 12:00pm until 5:00pm.
Stack burning is not allowed.
An upper-level trough, moving across Southern British
Columbia, helped turn the transport winds from northerly to
north-northwesterly late Thursday, but not before surface
winds became too strong for open burning. Sunny skies
helped valley temperatures climb into the low to mid 80s.
Increased onshore flow overnight brought a thick blanket of
low clouds into the coastline with some clouds penetrating
into the extreme northern valley this morning. Visible
satellite imagery showed low clouds over most of Western
Washington, along the Oregon Coast, and in the Northern
Willamette Valley (from about Salem northward). Some
drizzle was also falling along section of the north coast.
With the exception of the north valley, skies were sunny
across the interior of Oregon.
The morning ODA surface analysis showed high pressure had
built into Western Washington and Western Oregon with
onshore flow now extending across both states. Strong
gradiant-stacking and Medford-Draw conditions exist and will
likely persist today with the transport winds remaining more
The Salem sounding this morning showed very slight cooling
below about 8000 feet, so afternoon temperatures should only
climb to about 80 today across the valley. Valley minimums
this morning were in the mid 40s to mid 50s. Mid-morning
temperatures were in the mid to upper 50s with generally
northwest winds about 4-8 mph.
As the upper-level trough slides into Northern Idaho, the
flow aloft will turn west-northwesterly this afternoon.
Weak subsidence aloft will slightly warm the air mass this
afternoon. Valley temperatures should top out near 80
degrees with afternoon sunshine. Transport winds were
northeasterly this morning and will turn northerly this
afternoon with a slight northwesterly component possible in
the north valley.
Mixing heights should climb to near 3000 feet after about 2
pm. Daytime heating will probably not alleviate the
significant gradient-stacking and Medford-Draw conditions,
and transport winds will be mostly northerly. That makes
open burning unlikely this afternoon.
NW 5-10 this morning, N 8-15 this afternoon.
NNE 10 this morning, N 10 this afternoon.
Atmospheric Ventilation Conditions:
Maximum mixing height today will be near 4700 feet. Ventilation index 47.
Salem\'s high temperature today will be near 80.
Relative humidity drops to 50% by 12pm.
Minimum relative humidity will be near 31%.
Salem sunset tonight: 8:53pm; sunrise tomorrow: 5:44am.
A weak upper-level low pressure area will approach the
Northern California Coast Saturday and turn the flow aloft
southwesterly over Oregon. That should bring a little
warming to the region but also a slight chance of shower or
thundershowers to the southern mountains.
The long-range computer models have been very inconsistent
in their handling of the weak upper-level low pressure area
slated to move onshore Sunday. It appears as if it will be
too weak to produce much in the way of shower activity but
should maintain the onshore flow pattern across Western
Oregon. A westerly flow aloft is forecast Monday through
Friday for seasonal conditions.
Tomorrow (19 Jul): Mostly Sunny and Warmer. Wind: N 10-20 mph. 49/84
Sun (20 Jul): Mostly Sunny. 50/85
Mon (21 Jul): Morning Clouds. Mostly Sunny. 53/85
Tue (22 Jul): Morning Clouds. Mostly Sunny. 54/83
Wed (23 Jul): Morning Clouds...Sunny & Warmer. 52/82
Thu (24 Jul): Mostly Sunny. 53/84
Fri (25 Jul): Mostly Sunny. 53/82
weather at oda.state.or.us
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