[willamette-fcst] Forecast - Friday, April 24th, 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.

...Next Update Not Until Tuesday, April 28th, at 9:00am...

NOON UPDATE

Issued: 
     Friday, April 24th, 2009 at 12:00pm.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from now until 6:00pm.
     Straw stack burning is allowed from now until 6:00pm.

Weather Discussion:
     In the wake of the cold upper-level trough, that brought a
     few showers to northwestern Oregon and much cooler weather
     to the entire state Thursday, clearing skies overnight
     allowed temperatures to locally drop below freezing this
     morning across western Oregon and into the teens and 20s
     across central and eastern Oregon.  McMinnville dropped to
     29 degrees this morning and Hillsboro hit 30.  Eugene and
     Corvallis also hit the freezing mark.  Baker City was the
     cold spot in the state with a minumum of 17 degrees. 
     Meacham and Burns were not much warmer, both recording lows
     of 20 degrees.

     Areas of low clouds, early this morning across western
     Oregon, had given way to mostly sunny skies by midday.  A
     weak upper-level ridge was warming the air mass aloft enough
     to cap convective clouds and prevent them from building into
     showers.  The late-morning ODA surface analysis showed high
     pressure over western Washington and western Oregon with
     weak northerly pressure gradients over western Oregon and
     stronger northwesterly gradients across eastern Oregon.  

     Visible satellite imagery showed mostly clear skies across
     all but the extreme southeast corner of Oregon at midday. 
     Winds were generally northerly at 10 mph or less across
     western Oregon but increased to nearly 20 mph from
     south-central to eastern Oregon.  Temperatures were mostly
     in the upper 40s and low 50s on both sides of the Cascades.

     A dry and stable north-northeasterly flow aloft will keep
     skies mostly clear throug this evening, although continued
     cool air aloft will ony allow valley temperatures to climb
     to about 60 degrees this afternoon.  Northerly winds will
     become more northwesterly by this evening.  High mixing heights
     and north-northwesterly transport winds will make for good
     ventilation conditions across western Oregon this afternoon.

Surface Winds:
     NNW 5-15 this afternoon.
Transport Winds:
     NNW 10 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 5500 feet.  Ventilation index 55.
High Temperature:
     Salem\'s high temperature today will be near 60.
Humidities:
     Minimum relative humidity will be near 36%.
Sunrise/Sunset:
     Salem sunset tonight: 8:09pm; sunrise tomorrow: 6:10am.

Extended Outlook:
     It will be another locally frosty morning Saturday, with
     mostly clear skies and light winds.  An upper-level
     disturbance is forecast to turn the flow aloft more
     northwestly by Saturday afternoon.  The bulk of the energy
     from this system will pass well east of the region, but some
     cooling and destabilizing of the air mass will bring a few
     more clouds back to northern Oregon along with a slight
     chance of an afternoon shower.  The snow level will be
     around 4000 feet, so a few snow showers are possible in the
     northern mountains.

     Another upper-level impulse is forecast to slide mainly
     across eastern Washington and northeastern Oregon late
     Sunday, but it will help a stronger upper-level trough to
     start carving out over the Pacific Northwest.  That should
     keep temperatures below normal.  A much stronger system is
     forecast to drop over the region late Monday and Tuesday for
     an increased chance of showers and continued low snow
     levels.  The showers should taper off, from west to east,
     across the state on Wednesday.

     A drier but continued cool north-northeasterly flow aloft is
     forecast for next Thursday and Friday.  That will likely
     bring back mostly sunny and cool weather, much like we are
     seeing today across the state.

Tomorrow (25 Apr):  Partly Cloudy. Slight Chance of Showers. Snow Level 4000 Feet. 34/57

Sun (26 Apr):  Partly Cloudy.  Slight Chance of Showers.  Snow Level 4000 Feet.  35/59

Mon (27 Apr):  Mostly Cloudy.  Slight Chance of Showers.  Snow Level 4500 Feet   35/59

Tue (28 Apr):  Mostly Cloudy.  Chance of Showers.  Snow Level 3500 Feet.  36/58

Wed (29 Apr):  Mostly Cloudy.  Decreasing Chance of Showers.  Snow Level 4000 Feet.  36/60

Thu (30 Apr):  Partly Cloudy.  36/63

Fri (01 May):  Mostly Sunny.  Seasonably Cool.  38/65

ODA Meteorologist
weather at oda.state.or.us