SMI South Central (Smoke Management Instructions) South Central Smoke Management Instructions

[ODF Smoke Management Instructions]

SMOKE MANAGEMENT FORECAST AND INSTRUCTIONS

SALEM FORESTRY WEATHER CENTER

OREGON DEPARTMENT OF FORESTRY



ISSUED: Wednesday, April 20, 2011       2:40 PM      Pete Parsons



1.  DISCUSSION AND FORECAST FOR SOUTH CENTRAL OREGON ZONES 624 AND 625


THURSDAY

A very cool upper-level trough will remain over the Pacific Northwest, with two embedded disturbances affecting the region.  One system is forecast to cut across Washington and northern Oregon, while another starts out over south-central Oregon and progresses eastward during the day.  The southern system will bring some rain and snow to south-central Oregon Wednesday night, with locally up to .25 inches possible.

The northern system will help to kick the southern system east of the region during the day, with a drier and cool northwesterly flow prevailing by the afternoon. Mixing will be good with northwesterly surface and transport winds.  The chance of showers will end by Thursday evening with clearing skies.
OUTLOOK (FRIDAY-SUNDAY)
A weak upper-level ridge of high pressure is forecast to bring generally dry and warmer conditions on Friday. After a cold start, with morning minimums well down into the 20s, mostly sunny skies should warm afternoon surface temperatures close to normal.  A weak disturbance, in an undercutting westerly jet stream, will bring some increasing clouds in the afternoon, with a risk of a shower near the California border. The freezing level will only rise to about 7000 feet, so afternoon heating will provide good mixing.  Transport winds will turn mostly light southerly.

The weak ridge 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 bring mostly cloudy skies along with a chance of light rain by the afternoon.  The snow level is forecast to drop to 5500 feet.  Light southerly morning transport winds will increase, from the south to southwest, with good afternoon mixing.

A strengthening westerly jet stream will drive a strong cold front across the region late Saturday night and early Easter Sunday, followed by a cold and unstable upper-level trough Sunday afternoon and night.  Rain and snow are likely, with the snow level dropping to near the valley floors.  Precipitation totals could locally exceed .25 inches.  Mixing should be good with Southwest to west transport winds.


2.  DISPERSION



THURSDAY

Mixing height above 5000 ft throughout the day.  Mixing height lowers to 2300 - 3300 ft during the evening.



Transport wind WNW to NNW at 10 - 20 mph.



Surface wind W to NW at 6 - 10 mph during the morning.  Surface wind increases to WNW to NNW at 9 - 15 mph during the afternoon and evening.



OUTLOOK:



FRIDAY

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



SATURDAY

Mixing height below 1000 ft early rising to 2300 - 3300 ft by late morning rising above 5000 ft during the afternoon.  Transport wind SSE to SSW at 9 - 15 mph during the morning becoming SSW to SW at 12 - 24 mph during the afternoon.  Surface wind SSE to SSW at 4 - 8 mph.



SUNDAY

Mixing height 3500 - 4500 ft during the morning rising above 5000 ft during the afternoon.  Transport wind WSW to W at 12 - 24 mph during the morning becoming WSW to WNW at 22 - 38 mph during the afternoon.  Surface wind SW to W at 9 - 15 mph.



3.  BURNING INSTRUCTIONS FOR ZONES 624 AND 625 INCLUDING THE WALKER

    RANGE PORTION OF ZONE 624

This instruction is valid for burning conducted on Thursday, April 21, 2011.

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Avoid ignitions within 10 miles to the WNW through N of SSRAs.  For units that will smolder significantly through the night avoid burning within at least 15 miles in all directions of SSRAs.



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4.  SPECIAL NOTE:



    The smoke management forecaster is available at (503)

    945-7401.  The smoke management forecaster is available

    to discuss specific burns.  The duty forecaster phone

    number is (503) 945-7401. Please call this number and

    not individual's numbers to discuss daily burning. Please

    avoid calling before 8 a.m. and between 2 to 3 p.m.



    This 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

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