[willamette-fcst] Forecast - Tuesday, April 22nd, 2008

[Willamette Valley Ag/Burning Forecast]

Daily Smoke Management Forecast




Oregon Department of Agriculture
Smoke Management Program
Weather Outlook and Field Burning Advisory for Willamette Valley Growers and Fire Districts.

NOON UPDATE

...Next Update 9 am Wednesday, April 23, 2008...

Issued: 
     Tuesday, April 22nd, 2008 at 12:00pm.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from now until 6:00pm.
     Straw stack burning is allowed from now until 6:00pm.

Weather Discussion:
     The showers from Monday changed to a steady rain across
     Western Oregon overnight in response to a potent warm front
     from a surface low pressure area approaching the Central
     Oregon Coast.  Offshore flow kept cool air in place across
     Northern Oregon with snow levels remaining near 1500 feet
     overnight, while warming aloft lifted snow levels to near
     4000 feet over Southern Oregon by early this morning.

     The clouds and rain kept valley temperatures from dropping
     below about 40 degrees overnight, even though the air aloft
     remained unseasonably cold.  Total rainfall amounts in the
     24 hours ending at 5 am today ranged from around one-tenth
     to one-third of an inch in the Willamette Valley with just
     under one-half inch falling along the Oregon Coast.  Up to a
     tenth of an inch of additional rain fell across the region
     between 5 am and 11 am this morning.

     This is a very cold storm that would have produced
     widespread snow over Western Oregon, had this pattern set up
     during the winter season.  It did produce snow overnight in
     the northern coastal range and in the Cascades above about
     1500 feet.  The Cascade Passes remained mostly snow-packed
     late this morning with temperatures in the 30s.

     Clouds had penetrated inland across the Cascades and Central
     Oregon by late this morning with some light rain reported in
     Redmond.  Warmer air had pushed Central Oregon temperatures
     into the upper 40s with snow levels jumping above 4000 feet.
     The eastern third of the state was seeing sunshine at midday 
     with temperatures ranging from the upper 40s to mid 50s.

     The ODA surface analysis continued to show a low pressure
     center west of Newport, but a second area of low pressure is
     forming off the Southern Oregon Coast, along the surface
     cold front offshore.  A weak warm front extended from the
     low-pressure center west to Newport to the Northern Oregon
     Coast.  To the north of the warm front, winds are
     northeasterly at 5-15 mph across Western Washington and
     portions of Northwestern Oregon.  On the south side of the
     warm front, southeasterly winds of 5-15 were blowing along
     the Oregon Coast and south of about Eugene in the western
     interior.  The developing low pressure ara off the south
     coast is keeping the surface flow northeasterly over NW
     Oregon.  Temperatures across Western Oregon were in the mid
     to upper 40s with areas of rain increasing from south to north.

     The warm front is forecast to weaken and slowly progress
     northward today with rain at times continuing and
     southeasterly winds migrating slowly northward across
     Western Oregon.  The warmer air aloft over Southern Oregon
     will filter northward this afternoon with the snow level
     over Northern Oregon creeping up to around 3000 feet.  The
     snow level over Southern Oregon will stay near 4000 feet. 
     Clouds and rain will help hold valley temperatures in the
     low 50s (about 10 degrees below average).

Surface Winds:
     NE 5-15 mph north valley...SE 5-15 south valley this afternoon.
Transport Winds:
     S 20-25 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 4000 feet.  Ventilation index 100.
High Temperature:
     Salem\'s high temperature today will be near 52.
Humidities:
     Minimum relative humidity will be near 69%.
Sunrise/Sunset:
     Salem sunset tonight: 8:07pm; sunrise tomorrow: 6:13am.

Extended Outlook:
     The cold front from the slow-moving offshore storm system
     will finally move inland tonight.  The associated cold
     upper-level trough will move over the region Wednesday and
     Thursday for showers and a return of quite low snow levels.

     High pressure will build into the coastline Friday and begin
     to dry out the air mass.  That may lead to cool temperatures
     over sections of the valley Friday and/or Saturday mornings
     with daytime temperatures shooting above normal Saturday. 
     The next weather system is forecast to move onshore Sunday
     night and Monday.

Tomorrow (23 Apr):  Showers.  Chance T-Storm.  Snow Level Dropping to 1500 Feet.  42/52

Thu (24 Apr):  Mostly Cloudy.  Chance of Showers.   Snow Level Rising to 3000 Feet.  37/56

Fri (25 Apr):  Mostly Cloudy.  Decreasing Chance of Showers.  Snow Level 4000 Feet.  36/58

Sat (26 Apr):  Becoming Mostly Sunny and Warmer.  34/67

Sun (27 Apr):  Increasing Clouds.  Rain Likely Late.  40/63

Mon (28 Apr):  Rain Likely and Cooler. 44/58

Tue (29 Apr):  Showers.  Snow Level 2500 Feet.  40/55

ODA Meteorologist
weather at oda.state.or.us