[willamette-fcst] Forecast - Tuesday, January 19th, 2010

[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.

Issued: 
     Tuesday, January 19th, 2010 at 9:00am.

Burn Advisory:
     Agricultural burning is Recommended with suggested burn times from now until 3:00pm.

  The rules for stack burning have changed.  In 2010, the total number of acres that can
     be stack-burned in the Willamette Valley is 1000 acres.  Pre-registration is now required,
     and stack burning permits must be obtained from an ODA staff member.   

Weather Discussion:
     A very typical \"El Nino\" weather pattern has set up across
     the Pacific Ocean.  A strong jet stream is directing a
     series of potent storms into California, with an extremely
     mild south-southwesterly flow aloft over Washington and
     Oregon.  The bulk of the rainfall from the incoming weather
     systems will stay south of the Willamette Valley, this week,
     but some rain and blustery winds can be expected at
     times...mainly south.

     At the surface, low-pressure centers have been approaching
     the northern California coastline and then turning north,
     and moving across the offshore waters of the Oregon Coast. 
     The latest in a series of low-pressure systems moved
     northward off of the Oregon Coast overnight and was centered
     about 300 miles west of Astoria at mid-morning.  It brought
     blustery winds to western Oregon in the early morning hours
     but stayed a little too far offshore to produce damaging
     winds.  Southerly winds, gusting to about 45 mph, swept
     across the coast and into much of the Willamette Valley
     shortly after midnight.  Winds had turned southeasterly and
     decreased by mid-morning.

     Another low-pressure wave was forming along the frontal zone
     and was bringing farily strong southerly winds to
     southwestern Oregon this morning.  Medford was getting gusts
     to just over 50 mph at mid-morning.  Some increase in
     southerly winds is likely this afternoon, along the coast
     and in the Willamette Valley, as this low-pressure wave
     continues northward.  More showers will also rotate
     northward, across western Oregon, but rainfall amounts are
     not expected to be significant in the Willamette Valley. 
     The bulk of the rain is expected to remain south of the
     Oregon/California border.

     The air aloft remains unseasonably mild.  The freezing
     levels over Salem and Medford were measured at 5300 and 5800
     feet respectively this morning.  ODOT road cameras showed a
     mixture and rain and snow over the Cascade passes, with pass
     temperatures near freezing.  As a broad upper-level trough
     slowly approaches the coastline, the air aloft will
     cool...lowering the snow level to below the passes by
     tonight.  However, significant snow accumulations are not
     likely, due to the lack of precipitation.

     Slight cooling aloft and southerly transport winds will make
     for good ventilation conditions today.  Skies should remain
     mostly cloudy across western Oregon with a few showers and
     some increase in the southerly winds this afternoon. 
     Temperatures will remain unseasonably mild, with afternoon
     highs climbing into the mid 50s (about 10 degrees above normal).

Surface Winds:
     Var 0-10 this morning, SSE 5-15 G20 this afternoon.
Transport Winds:
     SE 15 this morning, S 20 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 2500 feet.  Ventilation index 50.
High Temperature:
     Salem\'s high temperature today will be near 55.
Humidities:
     Minimum relative humidity will be near 55%.
Sunrise/Sunset:
     Salem sunset tonight: 5:02pm; sunrise tomorrow: 7:43am.

Extended Outlook:
     The next low-pressure system, in the latest series of
     storms, is forecast to approach the northern California
     coastline on Wednesday.  That should keep skies mostly
     cloudy across western Oregon and induce an offshore
     low-level flow.  Rain will likely spread northward, at least
     into the southern Willamette Valley, by Wednesday afternoon.

     Once again, the bulk of the rain from this system is
     forecast to push into California.  As the low-pressure
     system tracks northward, near the Oregon Coast, Wednesday
     night and early Thursday, it may bring a burst of strong
     southerly winds to sections of western Oregon.  Depending on
     the track of this system, it has the potential to produce
     locally damaging winds, especially along the coast and
     across southwestern Oregon.

     The parent upper-level trough is forecast to move inland
     Friday, with showers and slightly lower snow levels.  A
     transitory upper-level ridge will likely bring some drying
     over the weekend.  The next weather system is forecast to come
     onshore Sunday night.  Some drying will move onshore by Tuesday.

Tomorrow (20 Jan):  Mostly Cloudy. Rain Spreading North. Snow Level 4000 Feet.  39/50

Thu (21 Jan):  Rain and Windy Early...Turning to Showers.  Snow Level 3500 Feet.  38/50

Fri (22 Jan):  Showers.  Snow Level 3000 Feet.  36/48

Sat (23 Jan):  Mostly Cloudy.  Chance of Showers.  Snow Level 3000 Feet.  35/49

Sun (24 Jan):  Increasing Clouds.  Rain Late.  Snow Rising to 4000 Feet.  34/48

Mon (25 Jan):  Rain Likely.  Snow Level 4500 Feet.  39/50

Tue (26 Jan):  Mostly Cloudy.  37/50

ODA Meteorologist
weather at oda.state.or.us