[willamette-fcst] Forecast - Thursday, May 15th, 2008
Willamette Valley Ag/Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Thu May 15 16:19:45 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, May 15th, 2008 at 4:45 pm.
Burn Advisory For Friday, May 16th, 2008:
Agricultural burning is allowed. Suggested burn times are from 12:00pm until 6:30pm.
Stack burning is not allowed.
High pressure aloft built strongly northward, just offshore,
Wednesday and dried out the air mass over the Pacific
Northwest. It was a mild this morning with minimums in the
low to mid 50s across Western Oregon. It was also mild
from the Cascades eastward. Timberline Lodge recording a
low temperature this morning of 49 degrees with early
morning readings across Central and Eastern Oregon in the
40s and 50s. Extensive low clouds covered most of Western
Washington and the Willamette Valley early this morning but
gave way to sunny skies by midday. The rest of the region
enjoyed a full day of sunshine...including the coastline.
A building surface thermal trough, just off the Southern
Oregon Coastline, combined with high pressure over Eastern
Washington and NE Oregon to turn the surface winds
northeasterly across Western Oregon. The offshore flow,
ample sunshine, and very warm air aloft sent Western Oregon
temperatures to their highest values so far this year. Late
afternoon readings climed into the 70s and low 80s along the
Northern and Central Oregon Coast and into the low to mid
80s across the Willamette Valley. The southwestern valleys
soared into the upper 80s to mid 90s. Temperatures were
generally in the 70s to mid 80s east of the Cascades.
The warm spot in the state today was in an unusual
place...The town of Brookings, on the extreme South Oregon
Coast was 100 degrees this afternoon due to the local
downsloping winds off the mountains just to their north.
This is known as the \"Brookings Effect\" and sometimes
occurs during the onset of a heat-wave, in the summer
season, when the winds in that regino turn
north-northeasterly. That is the one part of the state
(along the Southern Oregon Coast) that will see cooler
temperatures Friday. the rest of Oregon will see even
warmer temperatures Friday.
The upper-level ridge is forecast to continue to build over
the Pacific Northwest Friday with the surface thermal trough
remaining along the coastline for offshore flow across
Western Oregon. That will push Willamette Valley high
temperatures to daily record values...in the low to mid 90s.
Temperatures will also warm into the 90s across Central and
Eastern Oregon. Onshore flow will likely kick in along the
southern and central coast Friday afternoon, as the center
of the thermal low-pressure area moves up the coast. The
north coast will have another sunny day with highs likely
well into the 80s and perhaps hitting 90.
Very warm air aloft will cap mixing heights at or below
about 3000 feet again Friday, but ventilation will be good
enough for agricultural burning in the afternoon. However,
northeasterly transport winds are not favorable for
evacuation of smoke from the valley from stack burns, so
they are not allowed Friday. Friday night will be very warm
with valley minimums near 60 degrees.
NE 5-10 Friday morning, NE 5-10 Friday afternoon.
NE 8 Friday morning, NNE 7 Friday afternoon.
Atmospheric Ventilation Conditions:
Maximum mixing height Friday will be near 3000 feet. Ventilation index 24.
Salem\'s high temperature Friday will be near 95.
Minimum relative humidity will be near 24%.
Salem sunset tonight: 8:35pm; sunrise tomorrow: 5:42am.
It appears that Friday will be the warmest day west of the
Cascades. the upper-level ridge is forecast to shift east
of the Cascades Saturday, along with the associated surface
thermal trough. That should bring cooler onshore winds into
the Willamette Valley Saturday afternooon, in time to cap
tempertures in the mid 80s. That will shift the record hot
weather into Central and Eastern Oregon Saturday afternoon.
Cooler ocean air begin filtering into Central and much of
Eastern Oregon Sunday, with increasing onshore flow west of
the Cascades cooling temperatures back into the upper 70s
and perhaps low 80s.
A increasing southwesterly flow aloft will bring
progressively cooler temperatures early next week. A
weather system is forecast to bring a good chance of rain to
all of Western Oregon Monday night and early Tuesday with
some drying on Wednesday. The long-range models diverge
beginning next Thursday with some calling for dry and
seasonal conditions and others calling for a chance of more
rain. I am splitting the difference and calling for cool
but mostly dry weather. That is subject to major change
when I return on Monday. Have a great weekend.
Tomorrow (16 May): Sunny with Record High Temperatures. 58/95
Sat (17 May): Sunny and Very Warm. 59/87
Sun (18 May): Partly Cloudy and Cooler. 52/77
Mon (19 May): Mostly Cloudy. Chance of Rain Late. 50/70
Tue (20 May): Chance of Rain and Cooler. 46/65
Wed (21 May): Partly Sunny. 42/69
Thu (22 May): Partly Sunny. 43/72
Fri (23 May): Partly Sunny. 43/74
weather at oda.state.or.us
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