[willamette-fcst] Forecast - Thursday, November 19th, 2009

[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.

...Corrected Wording at end of Weather Discussion...

Issued: 
     Thursday, November 19th, 2009 at 9:00am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from now until 2:30pm.
     Straw stack burning is allowed from now until 2:30pm.

Weather Discussion:
     An active frontal boundary stalled over western Washington
     and northwestern Oregon Wednesday night.  Over one inch of
     rain fell overnight along sections of the northern Oregon
     Coast, the northern coastal range, and the over western
     slopes of the extreme northern Oregon Cascades.  The
     heaviest rains, though, fell further north, across western
     Washington.  The central Washington Coast picked up around
     two inches of rain, with more than three inches falling
     along the northern Washington Coast.  Less than one-quarter
     of an inch of rain fell over the Willamette Valley, with the
     south valley only picking up a few hundredths of an inch.

     A fairly strong low-pressure center tracked well to the
     northwest of the region, moving inland this morning north of
     Vancouver Island, British Columbia.  It was still close
     enough to bring strong southerly winds to the coast and
     blustery conditions to the Willamette Valley overnight. 
     Winds gutsed between 50 and 60 mph along most of the central
     and northern Oregon Coast overnight, with gusts to 35 mph in
     the Willamette Valley.  The southerly winds held minimum
     temperatures mostly in the mid to upper 40s in the
     Willamette Valley and low to mid 50s along the coast.

     The frontal system is forecast to reactivate and push
     slightly north today, as another wave of low-pressure
     develops along the front, well offshore.  This low-pressure
     center is also forecast to track northeastward, moving inland
     just north of Vancouver Island, British Columbia late
     tonight.  That will increase the rainfall along the front,
     with the bulk of the moisture staying north and west of
     Oregon, until late tonight, when the cold front finally
     comes onshore.

     Southerly pressure gradients will be increasing across
     western Oregon today, so the National Weather Service has
     issued a High Wind Warning, valid until midnight, for the
     Oregon Coast.  South winds were gusting from 50-60 mph along
     the northern and central coast this morning and will likely
     increase to as high as 75 mph, over exposed headlands and
     beaches, this afternoon and evening.  Southerly winds in the
     Willamette Valley will likely continue to gust as high as 35
     mph throughout the day and into this evening

     Oregon will be in the warm-sector of the storm, with
     blustery south winds lifting Willamette Valley temperatures
     into the mid to upper 50s this afternoon.  The freezing
     level over Salem was measured at 7000 feet this morning and
     may rise slightly more this afternoon.  Rainfall may be
     locally heavy over the extreme northwestern corner of the
     state today but should be light elsewhere over western
     Oregon. The southern Willamette Valley may not see any rain
     until later this evening.

Surface Winds:
     S 15-25 G35 this morning, S 15-25 G35 this afternoon.
Transport Winds:
     S 35 this morning, S 35 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 3000 feet.  Ventilation index 105.
High Temperature:
     Salem\'s high temperature today will be near 58.
Humidities:
     Minimum relative humidity will be near 45%.
Sunrise/Sunset:
     Salem sunset tonight: 4:39pm; sunrise tomorrow: 7:17am.

Extended Outlook:
     The cold front is forecast to finally come onshore tonight
     and progress across western Oregon Friday morning.  Rainfall could
     be locally heavy, especially along the coast and in the
     coastal range, through Friday morning.  Strong southerly
     winds will turn more southwesterly and begin decreasing,
     after the front passes through Friday morning.  The steady
     rain will turn to showers Friday afternoon, with the snow
     level dropping back to around 2500 feet by Friday night. 
     Accumulating snow is expected over the mountain passes by
     Friday evening.

     Showers will taper off Saturday, with yet another weather
     system forecast to come onshore Saturday evening.  That will
     be a colder system, with possibly heavy snow in the
     Cascades.  Showers will taper off Sunday afternoon.  A
     weaker system is slated to spread more rain across western
     Oregon Monday...along with rising snow levels.  We may get a
     break from the rain next Tuesday and Wednesday.  A wet pattern
     is forecast to return about next Thursday.

Fri (20 Nov):  Rain and Windy...Turning to Showers.  Snow Level Dropping to 2500 Feet.  45/50

Sat (21 Nov):  Showers Early...Rain and Wind Late.  Snow Level 3-4000 Feet.  39/48

Sun (22 Nov):  Showers.  Snow Level near 3000 Feet. 40/49

Mon (23 Nov):  Light Rain Likely.  Snow Level Rising to 5-6000 Feet.  42/54

Tue (24 Nov):  Areas of AM Fog...Partly Sunny and Mild.  40/53

Wed (25 Nov):  Areas of AM Fog...Partly Sunny and Mild.  38/53

Thu (26 Nov):  Rain Likely.  Snow Level 6000 Feet.  43/51

ODA Meteorologist
weather at oda.state.or.us