[willamette-fcst] Forecast - Tuesday, June 16th, 2009

[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, June 16th, 2009 at 9:00am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from 2:00pm until 7:00pm.
     Preparatory burning is not allowed.
     Propane flaming is not allowed.
     Straw stack burning is allowed from 2:00pm until 7:00pm.

Weather Discussion:
     Western North America remains under a split-flow jet stream
     pattern this morning, with the northern branch cutting
     across British Columbia and the southern branch directed at
     southern California.  A frontal system, about 300 miles off
     the Oregon Coast, was encountering the split in the jet
     stream and weakening.  Satellite imagery showed middle and
     high clouds had advanced across the western half of both
     Washington and Oregon.  In addition, low clouds and fog had
     moved into the central and southern Oregon Coast.  Skies
     were mostly clear over eastern Washington, eastern Oregon
     and Idaho. Doppler radar was not showing any precipitation
     across the Pacific Northwest.

     The mid-morning ODA surface analysis showed a weak trough
     extending from eastern Washington to southwestern Oregon. 
     Pressure gradients were weak over western Oregon and winds
     were generally less than 5 mph.  Temperatures were mostly in
     the upper 50s and low 60s across Western Oregon and ranged
     from the upper 50s to upper 60s east of the Cascades.

     As a weak weather system approches the coastline today,
     considerable middle and high clouds will continue to spread
     across western Oregon.  Onshore flow will increase this
     afternoon with weak westerly transport winds developing. 
     High temperatures should climb into the mid to upper 70s
     across the Willamette Valley.  The weather system will move
     onshore this evening and could produce a sprinkle or two
     overnight.  Cloudy skies will keep overnight temperatures
     from dropping below about 50-55 degrees in the Willamette Valley.

Surface Winds:
     Var 3-6 this morning, W 5-10 this afternoon.
Transport Winds:
     NE 6 this morning, WNW 8 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 4200 feet.  Ventilation index 34.
High Temperature:
     Salem\'s high temperature today will be near 77.
Humidities:
     Relative humidity drops to 50% by 2pm.
     Minimum relative humidity will be near 45%.
Sunrise/Sunset:
     Salem sunset tonight: 9:01pm; sunrise tomorrow: 5:25am.

Extended Outlook:
     Slightly stronger onshore flow will cool temperatures a few
     degrees Wednesday, even with a drier northwestery flow aloft
     leading to some afternoon sunbreaks.  A weak ridge will
     build over the region Thursday for warming temperatures. 
     Weak onshore flow will maintain some morning cloudiness
     across western Oregon and keep temperatures from getting too
     much above normal.

     Another weak weather system is forecast to move onshore
     Friday, with more middle and high clouds and slightly cooler
     temperatures.  A stronger upper-level trough is forecast by
     all of the long-range computer models to move onshore this
     weekend.  it may be strong enough to bring some showers to
     the region...especially by Sunday.

Tomorrow (17 Jun):  Mostly Cloudy.  Clearing Late. 55/75

Thu (18 Jun):  Morning Clouds.  Mostly Sunny in the Afternoon.  55/80

Fri (19 Jun):  Increasing Middle and High Clouds.  54/77

Sat (20 Jun):  Mostly Cloudy.  Increasing Chance of Showers. 51/75

Sun (21 Jun):  Mostly Cloudy.  Chance of Showers.  51/71

Mon (22 Jun):  Mostly Cloudy.  Chance of Showers.  50/73

Tue (23 Jun):  Mostly Cloudy.  Slight Chance of Showers.  50/75

ODA Meteorologist
weather at oda.state.or.us