[willamette-fcst] Forecast - Friday, October 9th, 2009

Willamette Valley Ag/Burning Forecast willamette-fcst at listsmart.osl.state.or.us
Fri Oct 9 12:16:00 PDT 2009




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, October 9th, 2009 at 12:00pm.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from now until 4:30pm.
     Stack burning is not allowed.

Weather Discussion:
     A strong upper-level ridge of high pressure remains over the
     eastern Pacific Ocean with a cool north-northwesterly flow
     aloft over Washington and Oregon.  Satellite imagery showed
     a 150-mile-wide band of clouds extending from central
     Washington through extreme northeastern Oregon, in
     association with an Arctic cold front dropping south from
     Canada.  There was no precipitation being reported from that
     frontal system, but on the north side of it, brisk
     north-northeasterly winds were ushering unseasonably cold
     and dry air into eastern Washington.  Spokane was only in
     the upper 30s at midday with northeasterly winds gusting to
     nearly 25 mph...burrrrrr.  The dry Canadian air was also
     making it into Bellingham, near the Canadian border, in
     western Washington, where northeasterly winds were also
     gusting to nearly 25 mph, although temperatures were
     significantly warmer than east of the Cascades (mid 50s).

     Meanwhile, the areas of low clouds and fog along the coast
     and Willamette Valley had just about cleared by midday, with
     some persistent pockets of clouds near the Columbia River. 
     The ODA surface analysis showed weak northerly pressure
     gradients beginning to increase over southwestern Oregon
     with light gradients still across the Willamette Valley. 
     Fair skies and light winds allowed temperatures to drop into
     the 30s across much of the Willamette Valley this morning. 
     Eugene and McMinnville both dipped to 34 degrees.

     Cold and dry low-level Canadian air will continue pouring
     into eastern Washington this afternoon.  That will raise
     surface pressures east of the Cascades and increase the
     northerly gradients across western Oregon.  Drying northerly
     winds will help to break up the patchy fog and low clouds
     near th Columbia River this afternoon with temperatures
     recovering into the mid and upper 60s across the Willamette
     Valley.  Drier air will continue to pour into the valley
     overnight, which will make for cold minimum temperatures
     Saturday morning...locally near freezing in frost-prone areas.

Surface Winds:
     N 4-10 this afternoon.
Transport Winds:
     N 7 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 3000 feet.  Ventilation index 21.
High Temperature:
     Salem\'s high temperature today will be near 67.
Humidities:
     Relative humidity drops to 50% by 2pm.
     Minimum relative humidity will be near 45%.
Sunrise/Sunset:
     Salem sunset tonight: 6:37pm; sunrise tomorrow: 7:22am.

Extended Outlook:
     Cold air is forecast to continue to move southward, across
     northern Oregon, Saturday, which will generate a cold
     easterly outflow from the Columbia Gorge, into the
     Willamette Valley.  That will help keep skies clear but
     temperatures will be well below normal.  Overnight
     temperatures will be especially chilly by Sunday and Monday
     mornings, with frost likely in wind-sheltered areas.

     The upper-level ridge is forecast to be undercut by a strong
     westerly flow aloft next week...opening the door for a
     series of wet Pacific storms to come onshore...mainly into
     southern Oregon and northern California.  An upper-level
     ridge may bring some drying late in the week.

Tomorrow (10 Oct):  Mostly Sunny.  Increasing Offshore Flow.  34/65

Sun (11 Oct):  Sunny.  Cold and Dry Offshore Flow.  30/61

Mon (12 Oct):  Increasing High Clouds.  Strong Offshore Flow.  30/61

Tue (13 Oct):  Rain Likely.  Brisk Southeast Winds.  37/59

Wed (14 Oct):  Showers Likely.  48/62

Thu (15 Oct):  Mostly Cloudy.  Chance of Showers.  47/64

Fri (16 Oct):  AM Fog.  Partly Sunny in the Afternoon.  46/65

ODA Meteorologist
weather at oda.state.or.us



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