[willamette-fcst] Forecast - Wednesday, July 2nd, 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: 
     Wednesday, July 2nd, 2008 at 9:00am.

Burn Advisory:
_____________________________________________________________________

     Due to the Olympic Trials in Eugene, ODA will not be issuing
     buring permits from now through July 8th.
_____________________________________________________________________

     Agricultural burning is not recommended.
     Preparatory burning is not allowed.
     Propane flaming is not allowed.
     Stack burning is not allowed.

Weather Discussion:
     A very slow-moving upper-level low pressure area was centered
     about 550 miles west of the Southern Oregon Coast this morning.
     The counter-clockwise circulation around it is responsible for
     the southerly flow aloft, the past few days.  That has been
     sending California wildfire smoke into Oregon and making for
     quite hazy conditions statewide.  The southerly flow aloft has
     also been responsible for thunderstorm activity the past few
     days...mainly from the Cascades eastward.

     It was a mild night around the state with morning minimums
     generally in the 50s and low 60s.  Lakeview was the cool
     spot with 45 degrees.  The Dalles the warm spot with a
     low of 67.  Satellite imagery this morning showed bands of
     high clouds circulating northward across Oregon with marine
     low clouds along the immediate coastline.  The onshore flow
     is slightly weaker this morning across Western Oregon, so
     the marine low clouds did not penetrate east of the coast
     range.  Hazy sunshine covered the interior of Oregon this
     morning with temperatures generally in the 60s across Western
     Oregon and ranging from the mid 60s to mid 70s east of the Cascades.

     The morning sounding over Salem continued to show southerly
     flow aloft with very light winds below 5000 feet.  Due to a
     weakening of the onshore flow, temperatures had warmed slightly,
     between 3000 and 6000 feet, from Tuesday morning.  The morning ODA
     surface analysis showed a broad and weak thermal trough trying to
     extend back into the Northern Willamette Valley.  It stretched from
     North-Central Oregon to SW Oregon.  Surface winds were light
     statewide.  The decreased onshore flow should help temperatures
     warm a few degrees more, across Western Oregon, than on Tuesday,
     with hazy sunshine lifting highs into the mid 80s.

     As the offshore upper-level low pressure system slowly moves
     northeastward, the flow aloft will become more moist and turn
     southeasterly.  That is a favorable windflow for increased afternoon
     and evening thundershower development in the Cascades.  There is also
     a chance of thunderstorms drifting off the Cascades, into the
     Willamette Valley, late this evening and overnight.

Surface Winds:
     Var 0-4 this morning, W 5 this afternoon.
Transport Winds:
     Var 4 this morning, SW 7 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 3500 feet.  Ventilation index 25.
High Temperature:
     Salem\'s high temperature today will be near 85.
Humidities:
     Relative humidity drops to 50% by 12pm.
     Minimum relative humidity will be near 36%.
Sunrise/Sunset:
     Salem sunset tonight: 9:02pm; sunrise tomorrow: 5:31am.

Extended Outlook:
     The offshore upper-level trough will slowly approach the
     coastline Thursday with increasing southerly flow aloft. 
     That will further increase the coverage of showers and
     thundershowers statewide and bring cooler weather to the
     region.  The southerly flow aloft will likely maintain the
     hazy conditions across the state for one more day. 

     The upper-level trough is finally forecast to move onshore
     Thursday night and early Friday with flow aloft becoming
     more westerly by Friday afternoon.  That should help to
     clear the smoke from the region, but it will also bring a
     chance of showers and cooler weather to the entire state. 
     The thundershower threat, however, will shift east of the
     Cascades, as the westerly flow aloft stabilizes the air mass
     over Western Oregon.

     Another weak frontal system is forecast to brush across
     Washington and Oregon, in the westerly flow aloft, on
     Saturday...continuing the chance of showers in the
     Willamette Valley.  The jet stream begins to lift north
     Sunday with a more typical summer-time pattern developing
     for early next week.  That means onshore flow across Western
     Oregon with morning clouds and afternoon sunshine.  The storm
     track is forecast to remain close enough to the region to keep
     temperatures near normal.

Thu (03 Jul):  Mostly Cloudy, Hazy, & Muggy.  Chance of Showers or Thundershowers.  59/82

Fri (04 Jul):  Mostly Cloudy and Cooler.  Chance of a Showers.  59/73

Sat (05 Jul):  Mostly Cloudy.   Chance of Showers.  55/75

Sun (06 Jul):  Morning Clouds...Mostly Sunny.  53/75

Mon (07 Jul):  Morning Clouds...Mostly Sunny.  53/80

Tue (08 Jul):  Mostly Sunny.  53/82

Wed (09 Jul):  Mostly Sunny.  54/84

ODA Meteorologist
weather at oda.state.or.us