[willamette-fcst] Forecast - Tuesday, July 1st, 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.

Issued: 
     Tuesday, July 1st, 2008 at 9:00am.

Burn Advisory:
_____________________________________________________________________

     Due to the Olympic Trials in Eugene, ODA will not be issuing
     buring permits from now through July 8th.

     The DEQ has issued an air polution advisory for the Willamette
     Valley due to smoke from the California Wildfires.
_____________________________________________________________________

     Agricultural burning is not recommended.
     Preparatory burning is not allowed.
     Propane flaming is not allowed.
     Stack burning is not allowed.

Weather Discussion:
     Southerly flow aloft will continue over Oregon today, so
     expect the hazy conditions to persist, as smoke from the
     California wildfires continues to get transported northward
     over Oregon.  The southerly flow is also transporting moist
     and unstable air into the region which will maintain the
     threat of thunderstorms...mainly from the Cascades eastward.

     Satellite imagery late this morning showed a line of
     thundershowers from near Hood River extending southeastward
     to near John Day.  Hazy sunshine covered the remainder of 
     Oregon, except for a blanket of marine low clouds along the
     Oregon coast.  Visible satellite imagery showed that the 
     coastal low clouds were not able to penetrate inland beyond
     the coast range, except for along the Columbia river into
     sections of the extreme north valley near Portland.

     The morning sounding over Salem showed continued to show
     southerly flow aloft with very light west-southwesterly
     transport winds below 5000 feet.  Temperatures had cooled a
     few degrees between 3000 and 5000 feet, so afternoon highs
     across the valley today should be a couple of degrees cooler
     than yesterday.

     A weak impulse in the southerly flow aloft may help trigger
     more late-day thundershowers over the Central and Southern
     Cascades, as well as sections of Central and Eastern Oregon.
     It is possible that the flow aloft may locally turn enough
     southeasterly for thunderstorms to drift off the Cascades,
     and move over the Willamette Valley, so I am leaving a
     slight chance of thunderstorms in the forecast for this
     evening and overnight.

Surface Winds:
     N 2-5 this morning, NW 5-10 this afternoon.
Transport Winds:
     WSW 4 this morning, NW 5 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 3500 feet.  Ventilation index 18.
High Temperature:
     Salem\'s high temperature today will be near 84.
Humidities:
     Relative humidity drops to 50% by 12pm.
     Minimum relative humidity will be near 34%.
Sunrise/Sunset:
     Salem sunset tonight: 9:02pm; sunrise tomorrow: 5:30am.

Extended Outlook:
     An upper-level trough will slowly approach the coastline
     Wednesday and Thursday with cooling both aloft and at the
     surface across Western Oregon.  Increasing southerly flow
     aloft will continue to circuate wildfire smoke over Oregon
     and increase the chance of showers and thundershowers.

     The upper-level trough is forecast to move onshore Friday
     with flow aloft becoming more westerly.  That should help to
     clear the smoke from the region, but it will also bring a
     chance of showers statewide.  The thundershower threat,
     however, will shift east of the Cascades, as the increased
     onshore flow stabilizes the air mass over Western Oregon.

     A more typical summer-time pattern is forecast by Saturday,
     with onshore flow bringing mostly cloudy mornings with
     increasing amounts of afternoon clearing, in the western
     valleys, through early next week.

Tomorrow (02 Jul):  Partly Cloudy and Hazy.  Chance of Showers or Thundershowers.  56/84

Thu (03 Jul):  Mostly Cloudy, Hazy, & Muggy.  Chance of Showers or Thundershowers.  59/89

Fri (04 Jul):  Mostly Cloudy and Cooler.  Chance of a Showers.  55/73

Sat (05 Jul):  Morning Clouds.  Partial Afternoon Clearing.  53/75

Sun (06 Jul):  Morning Clouds...Mostly Sunny.  53/79

Mon (07 Jul):  Morning Clouds...Mostly Sunny.  53/81

Tue (08 Jul):  Mostly Sunny.  54/83

ODA Meteorologist
weather at oda.state.or.us