[willamette-fcst] Forecast - Friday, April 17th, 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.

...No noon update today...

Issued: 
     Friday, April 17th, 2009 at 9:00am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from now until 6:30pm.
     Straw stack burning is allowed from now until 6:30pm.

Weather Discussion:
     Clouds increased Thursday evening across western Washingtona
     and western Oregon in response to an approaching cold front.
     Rain moved onto the northern Oregon coast shortly before
     midnight and into the northern Willamette Valley in the
     pre-dawn hours this morning. Cloudy skies overnight held
     temperatures in the mid to upper 40s across western Oregon.

     Rainfall amounts were fairly impressive across the
     northwestern corner of Oregon, but rapidly tapered off to
     the south.  Astoria has received over one-half inch of rain,
     with about one-quarter of an inch falling in the northern
     Willamette Valley, not of about Aurora.  Further to the
     south, about one-tenth of an inch of rain has fallen from
     Salem to Eugene with only a trace to a few hundredths across
     the interior of southwestern Oregon.

     The mid-morning ODA surface analysis showed a weak cold
     front just pushing onto the Oregon Coast with southerly
     gradients across western Oregon.  Satellite imagery showed
     cloudy skies covering most of Washington and the western
     half of Oregon.  Doppler radar indicated areas of rain
     across most most Washington and northwestern Oregon.  The
     freezing level was measured over Salem at 7200 feet this
     morning, so rain has been falling over the Cascade passes.

     There is not much cold air forecast in the wake of the
     front, so any port-frontal showers will be light and should
     taper off rapidly later this afternoon.  Valley highs will
     climb to near 60 degrees with southerly winds turning more
     westerly this afternoon.  There is also a chance for partial
     clearing this afternoon.

Surface Winds:
     S 5-15 this morning, W 5-15 this afternoon.
Transport Winds:
     SSW 25 this morning, W 17 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 5000 feet.  Ventilation index 125.
High Temperature:
     Salem\'s high temperature today will be near 60.
Humidities:
     Minimum relative humidity will be near 47%.
Sunrise/Sunset:
     Salem sunset tonight: 8:00pm; sunrise tomorrow: 6:22am.

Extended Outlook:
     A strong upper-level ridge is forecast to begin building
     over the Pacific Northwest Saturday, with the next storm
     system being directed north into southern British Columbia
     Saturday night and Sunday.  Low-level winds will turn
     northerly Saturday afternoon through Sunday, with
     significant warming and drying of the air mass. Temperatures
     should climb to well above normal.  The upper-level ridge is
     forecast to build directly over Oregon Monday, which should
     be the warmest day of the early-season hot spell.

     The upper-level ridge is forecast to shift east of the state
     by Tuesday, with increasing onshore flow likely beginning a
     cool-down.  The long-range computer models are beginning to
     show different tracks of a fairly strong upper-level trough
     forecast to drop into the Pacific Northwest for the second
     half of next week.  Some of the models are keeping this
     system farther offshore, which would not bring as much
     cooling to the region as earlier forecasts.  I will only
     make minor upward temperature adjustments to the second half
     of the extended forecast at this time.

     By the next update, on Monday, the computer models will
     likely have a much better handle how much cooling and
     precipitation we will get during the second half of next
     week.  Reminder...there will be no noon update today.

Tomorrow (18 Apr):  Becoming Mostly Sunny and Warmer.  36/70

Sun (19 Apr):  Sunny and Warmer.  41/76

Mon (20 Apr):  Sunny and Very Warm.  45/80

Tue (21 Apr):  Mostly Sunny. A Little Cooler.  46/73

Wed (22 Apr):  Increasing Clouds and Cooler.  Chance of Rain.  44/63

Thu (23 Apr):  Showers Likely with More Cooling.  Snow Level 4-5000 feet. 44/60

Fri (24 Apr):  Showery and Cool.  Snow Level 3-4000 Feet.  40/55

ODA Meteorologist
weather at oda.state.or.us