[willamette-fcst] Forecast - Friday, March 12th, 2010

[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: 
     Friday, March 12th, 2010 at 9:00am.

Burn Advisory:
     Recommended burn times for agricultural burning are from now until 4:00pm.
     Stack burning is not allowed.

Weather Discussion:
     A strong cold front stalled just off the Oregon coast overnight,
     with an active warm front moving northward, down the Willamette
     Valley, early this morning.  Rainfall totals along the coast have
     exceeded 1.5 inches, over the past 24 hours, with a daily record 
     of 1.41 inches set  yesterday at Astoria. About one-half of an
     inch of rain fell across the Willamette Valley Thursday, with
     another one-quarter to one-half of an inch falling this morning.

     South south winds pounded the coastline overnight, with
     gusts of 75 mph at Cape Mears and 72 mph at Cape Foul Weather. 
     Garibaldi recorded a gust of 71 mph.  Cannon Beach had gusts
     to 60 mph.  In southerly winds gusted to 39 mph at Salem and to
     38 mph at McMinnville.  The warm front moved into the north valley
     earlier this morning, with temperatures climbing into the low 50s
     across much of the valley.  Doppler radar showed the heavy rain,
     associated with the warm front, had pushed north and east of the valley
     at mid-morning.  Valley temperatures and winds had also both backed
     off a bit.  Mid-morning temperatures were in the mid to upper 40s.
     The snow level is near 5000 feet this morning, with ODOT road cameras
     showing rain over the Cascade Passes.

     A low-pressure area is forming another weak wave along the frontal zone,
     off the southern Oregon coast.  That will slow the eastward progression
     of the cold front, which will eventually move onshore later this morning.
     The cold front will be accompanied by another burst of steady rain and
     blustery conditions across western Oregon. A cold upper-level trough will
     bring showers to western Oregon later this afternoon and evening, with
     snow levels dropping below the Cascade passes.

Surface Winds:
     SSW 10-20 G30 this morning, SW 10-20 G25 this afternoon.
Transport Winds:
     SSW 25 this morning, SW 22 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 3500 feet.  Ventilation index 88.
High Temperature:
     Salem\'s high temperature today will be near 53.
Humidities:
     Minimum relative humidity will be near 67%.
Sunrise/Sunset:
     Salem sunset tonight: 6:14pm; sunrise tomorrow: 6:28am.

Extended Outlook:
     A cold upper-level trough, with much lower snow levels, is
     forecast to swing over the region tonight and Saturday.  A
     weak upper-level ridge will move onshore Saturday evening
     and clear skies across western Oregon.  That will lead to
     cool overnight temperatures Saturday night.  However, a warm
     front may bring enough middle and high clouds into the
     region to hold minimums above the freezing mark.  The
     upper-level ridge may be just strong enough to deflect
     precipitation from the warm front north of Oregon, but there
     is a slight chance of light rain across the northwest corner
     of the state Sunday.

     The warm front will push north, into western Washington, on
     Monday, with a mild southwesterly flow aloft returning
     spring-like conditions to western Oregon.  The warm-up will
     be short-lived, with a cold front sweeping onshore, with
     more rain and cooler temperatures, Tuesday.  A weak
     upper-level trough will keep a chance of showers over mainly
     the northern half of western Oregon on Wednesday, as the
     flow aloft turns more westerly.

     The long-range computer models have been all over the board
     with their projections, beginning the middle of next week,
     with the latest guidance building a ridge of high pressure
     over the west coast for a return to warmer weather.  Some of
     the long-range guidance, however, drop a quick cold trough
     over the region, so the forecast beyond next Wednesday is
     still very much in question.  I will broad-brush it for now
     and and lean temperatures towards climatological normals.

Sat (13 Mar):  Showers Decreasing Late.  Snow Level 1500 Feet...Rising to 2500 Feet.  37/51

Sun (14 Mar):  Mostly Cloudy North...Slight Chance Sprinkles.  Partly Cloudy South.  33/58

Mon (15 Mar):  Considerable High Clouds and Mild.  38/63

Tue (16 Mar):  Rain Likely and Cooler.  Snow Level Above 5000 Feet..Dropping Late.  42/57

Wed (17 Mar):  Decreasing Chance of Showers.  Snow Level 3-4000 Feet.  38/55

Thu (18 Mar):  Partly Cloudy.  37/57

Fri (19 Mar):  Partly Cloudy.  37/58

ODA Meteorologist
weather at oda.state.or.us