SMI West (Smoke Management Instructions) Western Oregon Smoke Management Instructions

Wed Apr 20 14:30:40 PDT 2011

SMOKE MANAGEMENT FORECAST AND INSTRUCTIONS

SALEM FORESTRY WEATHER CENTER

OREGON DEPARTMENT OF FORESTRY

ISSUED: Wednesday, April 20, 2011       2:30 PM      Pete Parsons

1.  DISCUSSION AND FORECAST FOR THE WESTERN OREGON AREA FORECAST ZONES 601-623

THURSDAY

A very cool upper-level trough will remain over the Pacific Northwest, with a couple of embedded disturbances affecting the region.  One system is forecast to cut across Washington and northern Oregon, while another exits southern Oregon.  The northern system will not have a lot of moisture to work with but should bring scattered showers to the northern third of Oregon.  The air aloft will be cold enough for these showers to fall as snow, down to about 1000 feet, in the early morning, before rising to around 2500 feet in the afternoon.  The southern system could locally bring as much as .25 inches of precipitation to southwestern Oregon Wednesday night, before pushing eastward across south-central and southeastern Oregon on Thursday.  Snow levels across southern Oregon will be around 3000 feet.

A cool but drier northwesterly flow aloft will develop across all of western Oregon Thursday afternoon and begin to stabilize the air mass.  The air aloft will remain unseasonably cool, so daytime heating should provide good mixing and enough instability for at least widely scattered afternoon showers, especially over higher terrain.  Surface temperatures will remain about 10 degrees below normal with mostly northwesterly transport winds.
OUTLOOK (FRIDAY-SUNDAY)
A weak upper-level ridge of high pressure is forecast to bring generally dry and warmer conditions on Friday, with an undercutting westerly jet stream continuing to bring a slight chance of showers to northern California and higher terrain of extreme southern Oregon.  After a cold start, partly to mostly sunny skies should warm afternoon surface temperatures close to normal.  The freezing level will only rise to about 6000 feet north and 7000 feet south, so afternoon heating will provide good mixing.  Transport winds will turn offshore.

The ridge of high pressure is forecast to move over Idaho on Saturday with increasing westerly flow aloft over Oregon.  The first in a series of potent weather systems will likely spread rain back into southwestern Oregon by afternoon and across all of western Oregon by evening.  The snow level is forecast to drop to 5000 feet.  Light morning transport winds will increase, from the southeast to south, with good afternoon mixing.

A strengthening westerly jet stream will drive a strong cold front across western Oregon early Easter Sunday morning, followed by a cold and unstable upper-level trough.  Morning rain and mountain snow will turn showery, in the afternoon, with the snow level dropping to 3000 feet north and 4000 feet south.  Precipitation totals could locally exceed .50 inches.  Mixing should be good with brisk southwesterly transport winds.

2.  DISPERSION

Zone 601-612 (North Coast Range and Cascades):

MORNING

Mixing height 3500 - 4500 ft.

Transport wind WSW to WNW at 10 - 18 mph.

Surface wind WSW to WNW at 8 - 12 mph.

AFTERNOON

Mixing height rising above 5000 ft.

Transport wind WNW to NW at 10 - 20 mph.

Surface wind W to NW at 6 - 10 mph.

EVENING

Mixing height 2000 - 3000 ft.

Transport wind WNW to NNW at 9 - 15 mph.

Surface wind similar to afternoon.

Zone 615-623 (South Coast Range and Cascades):

MORNING

Mixing height 3000 - 4000 ft.

Transport wind NW to N at 4 - 8 mph.

Surface wind NW to N at 4 - 8 mph.

AFTERNOON

Mixing height rising above 5000 ft.

Transport wind similar to morning.

Surface wind similar to morning.

EVENING

Mixing height 2000 - 3000 ft.

Transport wind NNW to NNE at 6 - 10 mph.

Surface wind similar to afternoon.

OUTLOOK:

FRIDAY

Mixing height below 1000 ft early rising to 3000 to 4000 ft by late morning rising above 5000 ft during the afternoon.  Transport wind ENE to ESE at 4 - 8 mph.  Surface wind light and variable.

SATURDAY

Mixing height below 1000 ft early rising to 2200 to 3200 ft by late morning rising above 5000 ft during the afternoon.  Transport wind SE to S at 8 - 12 mph during the morning becoming S to SSW at 12 - 24 mph during the afternoon.  Surface wind ESE to S at 4 - 8 mph during the morning becoming SSE to SSW at 6 - 10 mph during the afternoon.

SUNDAY

Mixing height 3800 to 4800 ft during the morning rising above 5000 ft during the afternoon.  Transport wind SSW to SW at 19 - 33 mph.  Surface wind S to SW at 10 - 18 mph during the morning becoming SW to W at 9 - 15 mph during the afternoon.

3.  BURNING INSTRUCTIONS FOR ALL ZONES IN THE WESTERN OREGON AREA

These instructions are valid for burning conducted on Thursday, April 21, 2011.

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Coast Range

Zone 601 and 612

Units should be 1000 tons or less, spaced 5 miles apart, and 10 miles from downwind SSRAs.  Restrict units in or near corridors to 500 tons or less.

Zone 602, 603, and 620

Units should be 500 tons or less, spaced 5 miles apart, and 10 miles from downwind SSRAs.  Avoid burning in or near corridors.  Higher tonnage is possible south of the Siuslaw River in Zone 603.  Call the forecaster.  Higher tonnage is possible south of the Rogue River in Zone 620.  Call the forecaster.

Zone 615, 618, and 619

Use standard guidance matrix. (See section 5 below.)  Avoid burning directly upwind of the North Bend/Coos Bay SSRA.

Zone 616 west of R8W

Units should be 1500 tons or less, spaced 5 miles apart, and 10 miles from downwind SSRAs.

Zone 616 east of R9W

Units should be 750 tons or less, spaced 5 miles apart, and 10 miles from downwind SSRAs.  Restrict units to 500 tons or less south of T30S.

Cascades

Zone 605, 606, 607, 608, 609, 611, 616, 617, and 623

Use standard guidance matrix. (See section 5 below.)  Ensure adequate distance from downwind SSRAs for smoke to dissipate.  From T12S through T17S in Zone 608 units should be 1000 tons or less, spaced 5 miles apart.  South of T30S in Zone 616 units should be 500 tons or less, spaced 5 miles apart.  South of T30S in Zone 617 units should be 750 tons or less, spaced 5 miles apart.

Zone 610

Units should be 1000 tons or less, spaced 5 miles apart, and 10 miles from downwind SSRAs.

Zone 620 and 622

Units should be 500 tons or less, spaced 5 miles apart, and 10 miles from downwind SSRAs.

Siskiyous

Use standard guidance matrix. (See section 5 below.)

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4.  SPECIAL NOTE:

    Call the smoke management duty forecaster at (503) 945-7401 to

    discuss burning.  Please do not call individual's numbers to

    discuss daily burning.  If the forecaster is not available,

    leave a message and he will return your call as soon as possible.

    Avoid calling between 2 to 2:30 p.m.

    The forecast is available on the Internet at:

      http://oregon.gov/ODF/FIRE/fire.shtml/#Smoke_Management

    Please ensure your units have been planned and accomplished by checking:

      http://oregon.gov/ODF/FIRE/SMP/dailysmoke.shtml

5.  STANDARD GUIDANCE MATRIX:

  * Greater than 5000 ft mixing height:  No burning within 5 miles of

    downwind SSRA.  Maximum 100 tons per mile from downwind SSRA.

    Example:  500 ton maximum allowed if burned 5 miles from downwind SSRA.

  * 3000 - 5000 ft mixing height:  No burning within 10 miles of

    downwind SSRA.  Maximum 75 tons per mile from downwind SSRA.

    Example:  750 ton maximum allowed if burned 10 miles from downwind SSRA.

  * Less than 3000 ft mixing height:  No burning within 15 miles of

    downwind SSRA.  Maximum 50 tons per mile from downwind SSRA.

    Example:  750 ton maximum allowed if burned 15 miles from downwind SSRA.

  * All exceptions must be coordinated with the duty forecaster

    prior to ignition.

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