[willamette-fcst] Forecast - Wednesday, September 16th, 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.

Issued: 
     Wednesday, September 16th, 2009 at 8:50am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from 11:00am until 5:00pm.
     Preparatory burning is not allowed.
     Propane flaming is allowed from 11:00am until 2:00pm.
     Straw stack burning is allowed from 11:00am until 5:00pm.

Weather Discussion:
     A narrow cold front was spreading clouds onto the Washington
     and Oregon coastlines, at mid-morning, with Doppler radar
     showing a band of light to moderate rain just offshore.
     Skies were mostly sunny over the interior of both states.
     The cold front will continue to weaken, as it slowly moves
     onshore this morning.

     After seeing morning minimums mostly in the low to mid 50s,
     Willamette Valley temperatures had recovered into the upper
     50s and low 60s, by mid-morning, under mostly sunny skies. 
     Clouds will increase, from west to east, across the
     Willamette Valley late this morning. Some light rain will
     likely spread across the valley during the afternoon, but
     rainfall amounts should only range from a trace to a few
     hundredths of an inch. Temperatures will likely climb into
     the mid 70s, early this afternoon, before cooling in
     response to the cold front during the late afternoon. 
     Increasing southerly winds this morning will veer to
     west-southwesterly by late this afternoon.

     If the cold front comes onshore slowly enough, and transport
     winds are not too southerly, ahead of it, ventilation
     conditions could possibly allow for open burning early this
     afternoon. However, there are no reports of any fields
     available and ready for burning at this time.  There does
     not appear to be much instability in the wake of this
     system, so skies should begin clearing overnight.

Surface Winds:
     S 5-12 this morning, WSW 5-15 this afternoon.
Transport Winds:
     SSW 15 this morning, SW 15 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 3500 feet.  Ventilation index 53.
High Temperature:
     Salem\'s high temperature today will be near 76.
Humidities:
     Minimum relative humidity will be near 50%.
Sunrise/Sunset:
     Salem sunset tonight: 7:20pm; sunrise tomorrow: 6:54am.

Extended Outlook:
     Skies should become at least partly sunny Thursday, after a
     chance of a morning sprinkle.  Weak onshore flow will keep
     temperatures near-normal (mid 70s). Further warming and
     drying is likely on Friday.  A little stronger cold front is
     forecast to bring some light rain to the northern Willamette
     Valley, and a chance of light rain to the south valley,
     Saturday morning.  Showers will quickly taper off, in the
     wake of the cold front, Saturday evening.

     All of the long-range computer models are still showing a
     strong upper-level ridge building over the west coast,
     beginning Sunday.  Increasing offshore flow will likely
     combine with sunny skies and warming aloft to send surface
     temperatures well above normal by early next week.  Summer
     officially ends next Tuesday afternoon, but the warm and dry
     weather is forecast to continue through most, if not all, of
     next week.

Tomorrow (17 Sep):  Chance of an AM Sprinkle...Partly Sunny in the Afternoon.  53/76

Fri (18 Sep):  Mostly Sunny and Warmer.  50/83

Sat (19 Sep):  AM Rain Likely North...Chance of Rain South.  Clearing by Evening.  55/73

Sun (20 Sep):  Sunny and Warmer.  Offshore Flow Developing.  50/80

Mon (21 Sep):  Sunny and Very Warm.  Strong Offshore Flow.  54/90

Tue (22 Sep):  Sunny and Very Warm.  Strong Offshore Flow.  54/90

Wed (23 Sep):  Sunny and Very Warm.  Light Winds.  53/87

ODA Meteorologist
weather at oda.state.or.us