[willamette-fcst] Forecast - Tuesday, April 21st, 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.

Issued: 
     Tuesday, April 21st, 2009 at 9:00am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from 2:00pm until 6:00pm.
     Straw stack burning is allowed from 2:00pm until 6:00pm.

Weather Discussion:
     Most of Oregon basked in sunny skies Monday with unseasnably
     warm temperatures.  Highs climbed into the low 80s in the
     northern Willamette Valley and into the upper 70s in the
     south valley.  There was a wide range of temperatures along
     the coast, due to band of low clouds and fog that hugged the
     central coastline but stayed offshore along the north and
     extreme south coast.  Newport was only 55 degrees with low
     clouds all day.  Cold northwesterly winds also kept North
     Bend in the mid 50s.  However, Astoria warmed to 67 degrees,
     and Tillamook hit 64.  Brookings, on the extreme southern
     coast, had sunny skies and downsloping winds, which warmed
     them to 80 degrees.

     Several daily high temperatures were either tied or broken
     Monday from southwestern Oregon, across central Oregon, and
     into eastern Oregon.  Medford was the hot spot in the state
     with a record-breaking 90 degrees.  Redmond and Burns tied
     their daily record highs of 83 and 79 respectively.  The
     Dalles set a new record high with 87 degrees.

     Clear skies and light winds overnight allowed overnight
     temperatures to drop back into the 40s across the Willamette
     Valley. Eugene, McMinnville, and Hillsboro all dipped to at
     least 41 degrees early this morning.  Aurora and Portland
     stayed in the upper 40s.

     The mid-morning ODA surface analysis showed a thermal trough
     along the southern Oregon Coast, with a weak branch of it
     over the southern Willamette Valley. Surface gradients were
     light northern across western Oregon.  The Salem sounding
     this morning showed northeasterly winds from just above the
     surface to about 3000 feet...backing to northwesterly above
     5000 feet and southwesterly above 8000 feet.  Temperatures
     remained very warm aloft, so one more unseasonably warm day
     it on tap.

     Visible satellite imagery showed low clouds and fog along
     the Washington and Oregon coastlines...about as far south as
     North Bend. There was some penettation of low clouds into
     the coastal mountain gaps this morning..indicating increased
     onshore flow, compared with yesterday.  Skies were sunny
     across the remainder of the state.  Mid-morning temperatures
     were a degrees or two warmer over most of the interior of
     Oregon, compared to the same time yesterday.  Readings were
     in the mid 40s along the coast and generally in the 50s
     across the interior of both western and eastern Oregon.

     Sunshine should prevail statewide this afternoon, with the
     exception of local areas of low clouds and fog along the
     coastal strip.  Increasing onshore flow late this afternoon
     will make for cooler high temperatures along the coast today
     and similar highs compared to yesterday in the western
     valleys.  Highs will likely be a couple of degrees warmer
     than yesterday east of the Cascades, whre the onshore flow
     will not really kick in until tonight.  Since some of the
     daily record high temperatures in the western valleys are
     not as warm today as they were for yesterday, some records
     could be reached today.  The record high for Salem today is
     only 80 degrees, so that could be met this afternoon.  The
     thermal trough will be forced east of the Cascades this
     evening, with increasing onshore flow bringing low clouds
     into the western valleys overnight.

Surface Winds:
     N 5-12 this morning, N 5-15 this afternoon.
Transport Winds:
     NE 12 this morning, NNW 15 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 5000 feet.  Ventilation index 75.
High Temperature:
     Salem\'s high temperature today will be near 80.
Humidities:
     Minimum relative humidity will be near 31%.
Sunrise/Sunset:
     Salem sunset tonight: 8:05pm; sunrise tomorrow: 6:15am.

Extended Outlook:
     Significant cooling will begin Wednesday, as a cold
     upper-level trough, from the Gulf of Alaska, dives
     southeastward towards the Pacific Northwest.  Increasing
     westerly flow aloft will advance the surface thermal trough
     into Idaho with strong onshore flow developing across all of
     Oregon.  A surface cold front will also increase the chance
     of showers along the coast and into the Willamette Valley by
     Wednesday afternoon.

     A potent surface cold front is forecast to sweep across the
     state late Wednesday and Thursday, followed by a cool
     upper-level trough Friday.  The long-range computer guidance
     is farily consistent in forecasting another cool trough to
     drop southward over the region next weekend, maintaining a
     chance of showers and seasonably cool temperatures.  The
     flow aloft is forecast to turn northeasterly and dry out
     early next week, with a building ridge of high pressure
     bringing back above normal temperatures by Tuesday.

Tomorrow (22 Apr):  Mostly Cloudy and Much Cooler.  Chance of Showers by Afternoon.  45/63

Thu (23 Apr):  Mostly Cloudy and Cool.  Chance of Showers.  Snow Level 3000 Feet.  42/57

Fri (24 Apr):  Mostly Cloudy and Cool.  Chance of Showers.  Snow Level 3500 Feet.  38/59

Sat (25 Apr):  Seasonably Cool with a Chance of Showers.  Snow Level 4000 feet.  39/60

Sun (26 Apr):  Seasonably Cool with a Chance of Showers.  Snow Level 4000 feet.  39/60

Mon (27 Apr):  Mostly Sunny.  37/64

Tue (28 Apr):  Sunny and Warm.  40/70

ODA Meteorologist
weather at oda.state.or.us