[willamette-fcst] Forecast - Tuesday, May 13th, 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: 
     Tuesday, May 13th, 2008 at 9:00am.

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

Weather Discussion:
     Infrared satellite pictures showed mid and high clouds
     pushing onshore Monday afternoon, in response to an
     apporaching warm front.  Clouds spread across all of
     Washington and much of Oregon overnight with sprinkles and
     areas of very light rain extending from Western Washington
     southward along the Northern Oregon Coast and the Willamette
     Valley.  Rainfall totals in Western Oregon ranged from a
     trace to a couple hundredths of an inch overnight.

     Clouds held temperatures up overnight, west of the Cascades,
     with valley minimums in the upper 40s and low 50s.  Clouds
     also made for a mild morning in Central Oregon with Redmond
     staying in the mid 40s.   It was not as cloudy along the
     eastern border, so Baker City and Rome were able to cool to
     27 degrees.  Burns was the cold spot in the state with a
     morning low of 25 degrees.

     The approaching warm front was still about 180 miles off the
     coastline at mid-morning.  The ODA surface analysis showed
     weak southerly gradients over Western Oregon and almost flat
     gradients east of the Cascades.  Satellite imagery showed
     cloudy skies over all of Washington and most of Oregon. 
     Areas of filtered sunshine were visible east of the Cascade.
     
     As the warm front approaches the coastline today, light
     rain should increase in coverage across Western Washington
     and NW Oregon with some sprinkles also possible over
     northern sections of Eastern Oregon.

     The air aloft has warmed considerably since Monday morning. 
     The freezing level over Salem jumped from 3800 feet Monday
     morning to 11,200 feet this morning. Even with warming
     aloft, cloudy skies will keep surface temperatues slightly
     below normal across Western Oregon for one more day. 
     However, the warming aloft is a sign that big changes are
     on the way beginning Wednesday...

Surface Winds:
     S 5 this morning, SSW 5-10 this afternoon.
Transport Winds:
     SSW 8 this morning, SW 15-20 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 2500 feet.  Ventilation index 20.
High Temperature:
     Salem\'s high temperature today will be near 62.
Humidities:
     Minimum relative humidity will be near 60%.
Sunrise/Sunset:
     Salem sunset tonight: 8:33pm; sunrise tomorrow: 5:44am.

Extended Outlook:
     An unseasonably strong upper-level ridge is forecast to
     bring sunny and much warmer weather to all of Oregon later
     this week.  Some light showers are still possible over NE
     Oregon through Wednesday afternoon, with the upper-level
     ridge slowly clearing skies, from west to east, across the
     state during the day.  Surface winds will turn northerly
     Wednesday afternoon across Western Oregon with afternoon sunshine
     and warm air aloft helping temperatures climb above normal.

     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
     possibly 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, and associated surface thermal
     trough, are forecast to push east of the Cascades Saturday. 
     Cooling onshore winds should cap Saturday afternoon
     temperatures in the 80s across the Willamette Valley.

     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.

Tomorrow (14 May):  Becoming Mostly Sunny and Warmer.  51/71

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

Fri (16 May):  Sunny with Possible Record High Temperatures.  54/91

Sat (17 May):  Sunny and Very Warm.  55/86

Sun (18 May):  Partly Cloudy and Cooler.  48/73

Mon (19 May):  Mostly Cloudy.  Chance of Rain Late.  46/68

Tue (20 May):  Chance of Showers.  47/68

ODA Meteorologist
weather at oda.state.or.us