[willamette-fcst] Forecast - Tuesday, June 23rd, 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: 
     Tuesday, June 23rd, 2009 at 9:00am.

Burn Advisory:
     Agricultural burning is allowed.  Suggested burn times are from 2:00pm until 7:00pm.
     Preparatory burning is not allowed.
     Propane flaming is not allowed.
     Stack burning is not allowed.

Weather Discussion:
     The upper-level low pressure system, that was centered over
     eastern Washington Monday, shifted northeastward into
     Montana and southern Canada overnight.  Weak westerly flow
     aloft prevailed this morning over Washington and Oregon,
     with the region getting a break from Pacific storm activity
     today.  Satellite imagery showed mostly clear skies over
     both states, for a change.  That allowed overnight
     temperatures to drop into the 40s again across most of the
     Willamette Valley.  After tying a record low Monday morning
     with 39 degrees, Eugene dipped to 41 degrees this morning. 
     Meacham, in northeastern Oregon, was the cold spot in the
     state this morning with a minumum of 30 degrees. Mid-morning
     temperatures were mostly in the 50s across the state.

     The Salem sounding this morning showed considerable warming
     aloft (between 3000 and 9000 feet) since Monday afternoon,
     in response to a very weak upper-level ridge moving over the
     region.  The mid-morning ODA surface analysis high pressure
     had moved inland over northern Washington with a thermal
     low-pressure center over northern California.  That was
     producing much drier north to northeasterly gradients across
     Washington and Oregon, with no marine morning clouds forming
     in the western valleys nor along the coast.  After a rather
     chilly start to the day, warmer air aloft and a full day of
     sunshine will help temperatures climb above normal this
     afternoon.  Willamette Valley highs should reach near 80
     degrees.  Northerly winds may become a bit brisk along the
     central and southern coast as well as the southern
     Willamette Valley this afternoon.

Surface Winds:
     N 5-12 this morning, N 8-15 G20 South this afternoon.
Transport Winds:
     NE 12 this morning, NNE 12 this afternoon.
Atmospheric Ventilation Conditions:
     Maximum mixing height today will be near 3300 feet.  Ventilation index 40.
High Temperature:
     Salem\'s high temperature today will be near 79.
Humidities:
     Relative humidity drops to 50% by 11.
     Minimum relative humidity will be near 30%.
Sunrise/Sunset:
     Salem sunset tonight: 9:03pm; sunrise tomorrow: 5:27am.

Extended Outlook:
     The next weather system is forecast to be directed mainly at
     southern British Columbia and western Washington but may be
     strong enough to bring some light showers as far south as
     northwestern Oregon late Wednesday through early Thursday.
     The main effect from this system will be an increase in the
     onshore flow Wednesday afternoon and night, along with more
     clouds. Temperatures will most likely cool back below normal
     on Thursday, with considerable clouds and a chance of
     morning drizzle or light showers.

     A weak ridge will shift the jet stream northward, to over
     southern British Columbia, on Friday.  Continued onshore
     flow will keep some morning clouds over western Oregon with
     afternoon sunshine lifting temperatures close to normal. The
     jet stream is forecast to sag southward on Saturday, with
     another weak cold front possibly spreading light showers as
     far south as northwestern Oregon by late in the day.  The
     chance of showers will continue into Sunday with another
     weak ridge drying out the atmosphere a bit on Monday.  No
     major changes are forecast in the weather pattern through
     next week, with onshore flow keeping temperatures moderate.

Tomorrow (24 Jun):  Increasing Clouds in the Afternoon. Chance of Showers North Late.  51/79

Thu (25 Jun):  Chance of AM Showers...Afternoon Clearing and Cooler.  56/73

Fri (26 Jun):  AM Clouds...Becoming Mostly Sunny.  53/76

Sat (27 Jun):  Increasing Clouds.  Slight Chance of Showers North late.  52/76

Sun (28 Jun):  Mostly Cloudy.  Slight Chance of Showers North.  51/75

Mon (29 Jun):  Morning Clouds.  Partly Sunny in the Afternoon.  50/77

Tue (30 Jun):  Morning Clouds.  Partly Sunny in the Afternoon.  50/77

ODA Meteorologist
weather at oda.state.or.us