[willamette-fcst] Forecast - Friday, June 19th, 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: 
     Friday, June 19th, 2009 at 9:00am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from 12:00pm until 8:00pm.
     Preparatory burning is not allowed.
     Propane flaming is not allowed.
     Straw stack burning is allowed from 12:00pm until 8:00pm.

Weather Discussion:
     A weak cold front was moving onto the Oregon Coast this
     morning.  Clouds advanced inland, well ahead of the front,
     Thursday night, with light rain falling as far south as
     North Bend along the coast and Eugene in the western
     interior.  Showers also spread across north-central and into
     northeastern Oregon overnight.  Rainfall amounts locally
     topped one-tenth of an inch along the north coast and in the
     northern Willamette Valley...tapering off to just a trace in
     Eugene.  Showers only dropped a few hundredths of an inch of
     rain east of the Cascades.

     Mid-morning satellite imagery showed one area of clouds and
     showers had sheared away from the surface cold front and
     stretched from northern Idaho, across northeastern Oregon,
     to south-central Oregon.  What was left of the cold front
     was enhancing the low cloud-deck covering most of western
     Washington and western Oregon.  Surface reports confirmed
     areas of light rain extended from northeastern Oregon to
     south-central Oregon with some light rain also falling along
     the north coast.  Doppler radar also showed areas of light
     precipitation over the north coast range and along the
     western slopes of the northern Oregon Cascades.

     The ODA surface analysis showed weak high pressure building
     into the southern Oregon Coast with lower pressure over much
     of Washington state.  That was resulting in southerly
     pressure gradients across western and northeastern Oregon. 
     South winds were blowing in the 5-10 mph range across the
     Willamette Valley.  Skies remained mostly cloudy across
     Oregon, but there were a few sunbreaks...mainly just east of
     the coast range and the Cascades, due to downsloping
     westerly winds aloft.

     Minimum temperatures were mostly in the mild 50s across
     Oregon overnight, due to considerable cloudiness.  Lakeview
     was the cold spot with a low of 41.  Mid-morning readings
     were mostly in the upper 50s and low 60s on both sides of
     the Cascades.  The Salem sounding this morning showed
     westerly flow aloft with significant cooling from the
     surface all the way up to 35,000 feet.  As the weak cold
     front and associated upper-level trough move across the
     state today, continued cooling aloft is forecast.  Daytime
     heating of the surafce will destabilize the atmosphere
     today...with scattered showers developing.  There is also a
     chance of a thunderstorm from the Cascades eastward.

     Cool onshore flow and mostly cloudy skies will keep temperatures
     from climbing above the upper 60s across the Willamette Valley
     this afternoon.  Transport winds will be mainly westerly today,
     so when mixing heights climb above 3000 feet this afternoon, 
     ventilation conditions will be favorable for both agricultural
     and stack burning.

Surface Winds:
     SSW 6-15 this morning, WSW 8-15 this afternoon.
Transport Winds:
     SSW 12 this morning, WNW 17 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 3700 feet.  Ventilation index 63.
High Temperature:
     Salem\'s high temperature today will be near 68.
Humidities:
     Minimum relative humidity will be near 60%.
Sunrise/Sunset:
     Salem sunset tonight: 9:02pm; sunrise tomorrow: 5:26am.

Extended Outlook:
     Another weather system will bring a reinforcing shot of cool
     and moist air into western Oregon later Saturday and across all
     of Oregon Sunday.  It will also renew the showers activity across
     the state.  An upper-level trough is forecast to remain over the
     region during the first half of next week, with temperatures staying
     below normal.  Onshore flow will maintain considerable morning
     clouds along the coast and in the Willamette Valley, but the shower
     threat should significantly decrease after Monday.

     The jet stream is forecast to push just north of Oregon late
     next week, with a strong westerly flow aloft forcast to move
     across Washington and southern British Columbia.  That will
     maintain onshore flow across western Oregon with plenty of
     morning marine clouds keeping temperatures near-normal.

Tomorrow (20 Jun):  Mostly Cloudy.  Chance of Showers...Increasing Late. 51/67

Sun (21 Jun):  Cloudy and Quite Cool.  Scattered Showers.  50/65

Mon (22 Jun):  Mostly Cloudy.  Slight Chance of Showers.  Partial Afternoon Clearing.  48/69

Tue (23 Jun):  AM Clouds. Partly Sunny in the Afternoon.  Warmer.  48/76

Wed (24 Jun):  AM Clouds. Partly Sunny PM.  Slight Chance of Showers...Mainly North.  53/74

Thu (25 Jun):  AM Clouds...Afternoon Clearing.  52/75

Fri (26 Jun):  AM Clouds...Afternoon Clearing.  52/75

ODA Meteorologist
weather at oda.state.or.us