[willamette-fcst] Forecast - Wednesday, August 13th, 2008

Willamette Valley Ag/Burning Forecast willamette-fcst at listsmart.osl.state.or.us
Wed Aug 13 08:03:23 PDT 2008




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, August 13th, 2008 at 9:00am.

Burn Advisory:
     Agricultural burning is not recommended.
     Preparatory burning is not allowed.
     Propane flaming is not allowed.
     Stack burning is not allowed.

Weather Discussion:
     A strong ridge is forecast to build over the Pacific
     Northwest, beginning today, with the surface flow turning
     northerly and valley highs climbing into the mid to upper
     80s.  The Salem sounding this morning showed
     north-northeasterly winds from just above the surface to
     about 3000 feet.  The air mass aloft had not started warming
     much yet, so mixing hights should climb above 3000 feet this
     afernoon.  North-northeasterly transport winds are expected
     to continue today.  That is not conducive to good
     ventialtion for most of the valley but could create a
     burning opportunity for fields on the west side of the
     valley later this morning.

     The ODA surface analysis showed high pressure building into
     Western Washington with northerly gradients developing
     across Western Oregon.  Valley winds were generally from the
     north at less than 10 mph with temperatures in the low to
     mid 60s.  Satellite imgery showed mostly clear skies across
     Oregon, except for patchy low clouds along the coast and in
     the extreme north valley. The air mass will warm today in
     response to the building ridge over the region.  Valley
     temperatures will climb into the upper 80s this afternoon
     with increasing north winds.  Coastal locations will also
     see sunshine and northerly winds this afternoon with highs
     in the 65-75 degree range.

Surface Winds:
     N 5-10 this morning, N 10-20 this afternoon.
Transport Winds:
     NNE 13 this morning, NNE 13 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 3700 feet.  Ventilation index 48.
High Temperature:
     Salem\'s high temperature today will be near 87.
Humidities:
     Relative humidity drops to 50% by 11am.
     Minimum relative humidity will be near 34%.
Sunrise/Sunset:
     Salem sunset tonight: 8:21pm; sunrise tomorrow: 6:13am.

Extended Outlook:
     We are in for a heat-wave.  The upper-level ridge will
     amplify Thursday with warmer air aloft and offshore surface
     gradients lifting temperatures into the mid 90s across the
     Willamette Valley and the 70s to low 80s along the coast. 
     Even with high afternoon surface temperatures, mixing
     heights will struggle to reach 3000 feet due to very warm
     air aloft.

     The upper-level ridge axis is forecast to shift east of the
     Cascades Friday afternoon with southerly flow aloft
     developing over Western Oregon.  That will likely begin
     transporting smoke, from California wildfires, back over
     Western Oregon and make for hazy conditions.  The air aloft
     will continue to warm with valley temperatures approaching
     daily record highs under a broad surface themal trough.

     An upper-level disturbance is forecast to approach the
     Oregon Coast Friday and begin to increase the moisture and
     instability over the western half of the state.  The thermal
     trough may begin to shift east of the Cascades late
     Saturday, but not before temperatures climb to near the
     century mark in the valley for the second straight day.

     The upper-level ridge is forecast to shift over Western
     Montana Sunday with increasing southwesterly flow aloft over
     Oregon.  That will bring more stable air into the region and
     increase the onshore flow for cooler temperatures across the
     interior of Western Oregon.  The onshore flow will continue
     Monday with a stronger trough forecast to approach the
     coastline Tuesday.  That system may create a burning
     opportunity Tuesday afternoon, before bringing a chance of
     light rain to Western Oregon Wednesday.

Tomorrow (14 Aug):  Sunny and Hot.  58/95

Fri (15 Aug):  Sunny, Hot and Hazy.  Slight Chance of T-Storms Late.  62/100

Sat (16 Aug):  Mostly Sunny, Hot, and Hazy.  Slight Chance of T-Storms.  62/98

Sun (17 Aug):  Partly Cloudy and Much Cooler.  60/87

Mon (18 Aug):  Mostly Sunny.  55/85

Tue (19 Aug):  Mostly Sunny.  53/83

Wed (20 Aug):  Mostly Cloudy and Cooler.  Chance of Light Rain.  55/72

ODA Meteorologist
weather at oda.state.or.us












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