[willamette-fcst] Forecast - Wednesday, May 14th, 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.

NOON UPDATE

...Next Update Not Until 9 am Thursday, May 15th, 2008...

Issued: 
     Wednesday, May 14th, 2008 at 12:00pm.

Burn Advisory:
     Agricultural burning is not recommended.
     Stack burning is not allowed.

Weather Discussion:
     A strong warm front was able to tap some tropical moisture
     and drop impressive amounts of rain across Washington and
     Northern Oregon Tuesday and Tuesday night.  Rainfall totals
     since Tuesday morning were close to one inch along the
     Washington and Extreme Northern Oregon Coastlines, and in
     the Washington and Extreme Northern Oregon Cascades. 
     Timberline Lodge has picked up 1.02 inches of rain since
     Tuesday morning.

     About one-tenth to one-third of an inch fell across the
     interior of Western Washington with a little over a tenth of
     an inch falling in the extreme Northern Willamette Valley. 
     The westerly flow aloft created a rain-shadow region over
     Central Washington and North-Central Oregon with only trace
     amounts of rain there.  However, about one-quarter of an
     inch of rain fell from Eastern Washington southward through
     NE Oregon.  Temperatures were very mild overnight with
     minimums in the low to mid 50s across Western Oregon and the
     mid 40s to mid 50s east of the Cascades.

     Infrared satellite imagery showed cloudy skies still
     covering all of Washington and Oregon at midday.  Doppler
     radar showed areas of light rain decreasing across
     Washington and all but over across Northern Oregon.  The
     northwesterly flow aloft is drying out and rapidly becoming
     northerly, in response to a building upper-level ridge of
     high pressure just offshore.  The ODA surface analysis
     showed the warm front weakening near the NW tip of
     Washington.  High pressure was strengthening over Western
     Oregon with weak southerly gradients across the Willamette
     Valley.

     As the upper-level ridge continues the build northward,
     along the coastline, this afternoon, the air mass will
     further dry out, from west to east, and allow for some
     sunshine to begin making an appearance over Western Oregon. 
     The clouds will begin to clear from Eastern Oregon by
     tonight.  Surface gradients will become northerly this
     afternoon across Western Oregon, as high pressure builds
     northward into Washington.  Clearing skies will combine with
     very warm air aloft (freezing levels above 10,000 feet) to
     lift temperatures above normal across Western Oregon this
     afternoon.

     Willamette Valley highs should push into the low 70s, after
     being below normal for more than a week.  Temperatures east
     of the Cascades will range from the mid 60s to the mid 70s. 
     The warm spot today will be SW Oregon, where highs should
     climb locally into the low 80s.  Clearing skies will allow
     temperatures to be slightly cooler tonight than they were
     this morning across the state.  However, it will still be a
     mild night with Willamette Valley lows near 50 degrees.

Surface Winds:
     Becoming N 5-10 (G 15 south valley) later this afternoon.
Transport Winds:
     NNE 10 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 3000 feet.  Ventilation index 30.
High Temperature:
     Salem\'s high temperature today will be near 72.
Humidities:
     Minimum relative humidity will be near 57%.
Sunrise/Sunset:
     Salem sunset tonight: 8:34pm; sunrise tomorrow: 5:43am.

Extended Outlook:
     The upper-level ridge is forecast to continue to build over
     the Pacific Northwest with sunny and much warmer weather
     across all of Oregon for the end of the week.  Temperatures
     will become progressively warmer Thursday and Friday, as the
     surface winds turn offshore.  Willamette Valley highs will
     shoot well into the 80s Thursday and likely into the low 90s
     Friday, which would break some daily records.  It appears
     that the warmest day west of the Cascades will be Friday,
     and Saturday will be the warmest day for Eastern Oregon.

     The upper-level ridge is forecast to shift east of the
     Cascades Saturday, along with the associated surface thermal
     trough.  that should bring cooler onshore winds into the
     Willamette Valley in time to cap the afternoon heating in
     the mid 80s.  The cooling trend is forecast to progress
     eastward, across Central and Eastern Oregon, Sunday, with
     increasing onshore flow west of the Cascades cooling
     temperatures back to near normal.  A strong westerly jet
     stream is forcast to bring back a chance of rain to Western
     Oregon by Monday evening with temperatures likely falling
     back below normal.

Tomorrow (15 May):  Sunny and Unseasonably Warm.  50/84

Fri (16 May):  Sunny with Possible Record High Temperatures.  54/92

Sat (17 May):  Sunny and Very Warm.  55/85

Sun (18 May):  Partly Cloudy and Cooler.  50/73

Mon (19 May):  Mostly Cloudy.  Chance of Rain Late.  47/68

Tue (20 May):  Chance of Rain.  46/65

Wed (21 May):  Partly Sunny.  41/69

ODA Meteorologist
weather at oda.state.or.us