[willamette-fcst] Forecast - Friday, July 20th, 2007

[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

Issued: 
     Friday, July 20th, 2007 at 12:00pm.

Burn Advisory:
     Agricultural burning is not recommended.
     Preparatory burning is not allowed.
     Propane flaming is not allowed.
     Stack burning is not allowed.

Weather Discussion:
     A southwesterly flow aloft is steering a very moist weather
     system into the Pacific Coastline this morning.  Light rain
     has been falling most of the morning along the northern coastal
     strip, with Astoria receiving just over a tenth of an inch (.13\").
     Very light rain has been falling off and on in the Northern
     Willamette Valley, with amounts ranging from a trace in Salem to
     three-hundredths (.03\") of an inch in Hillsboro.

     At midday, doppler radar was showing rain across the NW corner of the
     state, with the back edge just north and west of Salem.  More areas of
     rain will be circulating into Western Oregon this afternoon and evening,
     as the whole weather pattern slowly shifts eastward.

     Predicting rainfall amounts from this system is tricky, because Western
     Oregon is getting a glancing blow for this very moist storm.  Most of the
     rain will fall along the North Oregon Coast and across Western Washington,
     but the Willamette Valley could get a tenth to a quarter of an inch by Saturday
     morning.  The greatest amounts will be in the northern valley.

     Some warming aloft has decreased mixing heights today, but
     burning advisory decisions were based on the need for
     another drying day, more light rain forecast for this
     afternoon, and south-southwesterly transport winds. 
     Southwesterly surface winds will increase this afternoon, in
     the Willamette Valley, as a cold front approaches the Oregon
     Coast.

Surface Winds:
     SSW 13 this afternoon.
Transport Winds:
     SSW 20 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 4000 feet.  Ventilation index 80.
High Temperature:
     Salem\'s high temperature today will be near 72.
Humidities:
     Minimum relative humidity will be near 55%.
Sunrise/Sunset:
     Salem sunset tonight: 8:52pm; sunrise tomorrow: 5:46am.

Extended Outlook:
     A damp weekend is in store, as a southwesterly flow aloft
     steers a couple of very moist weather systems up the Pacific
     Coastline.  The first system, which will bring rain into the
     Willamette Valley This afternoon and evening, will move into
     the valley and weaken Saturday, and the second system is
     forecast to approach the coastline Sunday morning.

     Sunday\'s system not expected to push as far east, with the
     valley likely receiving less than a tenth of an inch of
     rain.  It will weaken considerably, as it moves inland
     Monday.  By Monday night, an upper level ridge of high
     pressure will build enough over the Pacific Northwest to
     weaken the storm track.  That will bring some drying and
     warming, but no prolonged dry or hot weather is forecast. 
     
Tomorrow (21 Jul):  Light Rain Likely at Times.  59/75

Sun (22 Jul):  Light Rain Likely at Times.  60/77

Mon (23 Jul):  Mostly Cloudy.  Chance of Showers.  60/78

Tue (24 Jul):  Partly Sunny.  56/80

Wed (25 Jul):  Mostly Cloudy.  Slight Chance of Showers.  57/75

Thu (26 Jul):  Morning Clouds...Afternoon Sun.  57/80

Fri (27 Jul):  Mostly Sunny.  55/83

ODA Meteorologist
weather at oda.state.or.us