[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 12:00pm.

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, from this storm, have
     exceeded 1.5 inches along the coast, with Astoria setting a daily record 
     with 1.41 inches of rain on Thursday. About one-half of an inch of rain
     fell across the Willamette Valley Thursday evening, with another quarter
     of an inch falling this morning.

     Strong 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 the north coastal range,
     Mt. Hebo recorded a gust of 82 mph at about 4:30 a.m. In the Willamette
     Valley, southerly winds gusted to 39 mph at Salem and to 38 mph at
     McMinnville early this morning.

     The warm front moved through the north valley earlier this morning, with
     temperatures climbing into the low 50s across much of the valley.  Doppler
     radar showed the steady rainfall had shifted east of the north valley by
     mid-morning.  However, a wave forming along the cold front, just off the
     southern Oregon coast, was delaying the eastward progress of the southern
     flank of the storm.  Rain was continuing to fall late this morning from the
     southern Willamette Valley southward across most of southwestern Oregon.

     The late-morning ODA surface analysis showed that southerly pressure-gradients
     had strengthened considerably across central and eastern Oregon, where wind
     gusts between 35 and 45 mph were common.  Meanwhile, the southerly gradients
     were slowly relaxing west of the Cascades, but it was still a bit blustery in
     some locations.  Salem was still getting gusts to about 25 mph, with gusts over
     30 mph along the coastline.  Late-morning temperatures ranged from the low 40s,
     with rain, in Eugene, to the low 50s, with some sunbreaks, in Astoria.

     The snow level was near 5000 feet earlier this morning, but ODOT road cameras
     showed the rain had changed to snow over the Cascade Passes by midday, with snow
     beginning to accumulate on road surfaces.  There will be a break in the steady
     precipitation, from north to south, across western Oreogn this afternoon.  The
     north valley has already seen the rainfall let up.  A cold upper-level trough will
     bring showers to western Oregon later this afternoon and evening, with
     snow levels continuing to drop.  Expect wintry driving conditions over the
     Cascade passes from now through early Saturday.

Surface Winds:
     SW 10-20 G25 this afternoon.
Transport Winds:
     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 was 53. The afternoon high will be near 49.
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 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...Chance of Light Rain.  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