[willamette-fcst] Forecast - Tuesday, May 20th, 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: 
     Monday, May 19th, 2008 at 4:45 pm.

Burn Advisory For Tuesday, May 20th, 2008:
     Agricultural burning is allowed.  Suggested burn times are from 9:00am until 6:30pm.
     Straw stack burning is allowed from 9:00am until 6:30pm.

Weather Discussion:
     The cooling trend that began Sunday across Oregon continued
     today, as the strong upper-level high pressure ridge
     flattened and pushed east of the region.  High clouds spread
     over much of the state by midday and were thickening up
     across Western Oregon this afternoon.  With very warm air
     aloft, the high clouds did not keep temperatures from
     climbing well above normal again this afternoon across the
     interior regions of the state.  Mid-afternoon temperatures
     in the Willamette Valley were in the low to mid 80s. 
     Temperatures east of the Cascades were in the mid to upper
     80s.  It was much cooler along the coast, where onshore
     winds kept temperatures in the mid 60s.

     The ODA surface analysis showed a very weak trough extending
     from Central Washington through SW Oregon with weak onshore
     flow from the coastal strip to the coast range and very weak
     winds in the western valleys.  The onshore flow will
     increase later this evening, bringing cooler ocean air into
     the western valleys, in response to an approaching cold
     front about 200 miles offshore.  Clouds will increase
     tonight, making for a mild overnight period with low
     temperatures in the mid 50s.

     A fairly strong cold front is forecast to move onshore early
     Tuesday morning and rapidly sweep across the state during
     the day.  Rain is likely for most of Western Oregon with
     numerous showers making it east of the Cascades.  The
     cool-down will be significant with high temperatures
     dropping about 20 degrees from today across the state. 
     Temperatures west of the Cascades will fall to below normal
     and the snow level should drop to about 5000 feet.  Strong
     onshore flow will make for locally windy conditions east of
     the Cascades.

Surface Winds:
     SW 10 Tuesday morning, WSW 10-15 Tuesday afternoon.
Transport Winds:
     WSW 15 Tuesday morning, W 18 Tuesday afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height Tuesday will be near 5000 feet.  Ventilation index 90.
High Temperature:
     Salem\'s high temperature Tuesday will be near 62.
Humidities:
     Minimum relative humidity will be near 58%.
Sunrise/Sunset:
     Salem sunset tonight: 8:40pm; sunrise Tuesday: 5:37am.

Extended Outlook:
     A cold upper-level trough will move over the Pacific
     Northwest Tuesday night and Wednesday for continued cool
     temperatures and the threat of showers.  High pressure will
     slowly push closer to the coastline Thursday and Friday with
     the flow aloft turning more northerly and drying out some. 
     the long-range models are indicating the possibility of a
     weak disturbance dropping into the region, via the northerly
     flow aloft, for a renewed slight chance of showers on
     Friday.  A cool but relatively dry upper-level trough will
     likely pitch a tent and set up camp over the region this
     holiday weekend with the next significant chance of rain
     moving onshore Tuesday.

Tue (20 May):  Rain AM...Showers PM.  Much Cooler.  Snow Level Dropping to 5000 Feet.  54/62

Wed (21 May):  Mostly Cloudy and Cool.  Chance of Showers.  Snow Level 5000 Feet.  46/60

Thu (22 May):  Partly Sunny.  A Little Warmer.  43/66

Fri (23 May):  Partly Cloudy.  Slight Chance of a Shower.  43/65

Sat (24 May):  Partly Cloudy.  A Little Warmer.  41/70

Sun (25 May):  Partly Cloudy.  42/70

Mon (26 May):  Mostly Sunny.  44/74

Tue (27 May):  Chance of Showers.  47/69

ODA Meteorologist
weather at oda.state.or.us