SMI Northeast (Smoke Management Instructions) Northeast Oregon 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       2:35 PM      Pete Parsons



1.  DISCUSSION AND FORECAST FOR NORTHEAST FORECAST AREA ZONES 630-638


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 exits southern Oregon.  The northern system will not have a lot of moisture to work with. However, it will tap into some moisture, from the southern system, and draw it into northeastern Oregon Wednesday night and early Thursday, for widespread light rain and snow.

Mixing will be good Thursday, but burning opportunities may be limited by snowfall.  Ahead of the northern cold front, 1-4 inches of new snow are likely, above about 3000 feet, Wednesday night and early Thursday.  In the wake of the cold front, west to northwesterly surface and transport winds will become brisk Thursday afternoon, with the snow level dropping further to near 2500 feet.  Precipitation will turn showery, with the rain and snow showers tapering off Thursday night.
OUTLOOK (FRIDAY-SUNDAY)
A weak upper-level ridge of high pressure is forecast to bring clearing skies and dry but cool conditions on Friday.  After an unseasonably cold morning, with minimums well down into the 20s, mostly sunny skies will help afternoon temperatures recover to within 10 degree of normal.  The freezing level will only rise to about 4500 feet, so afternoon heating will provide good mixing.  Transport winds will slacken and turn offshore.

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 increase clouds across northeastern Oregon with a chance of showers returning, from west to east, during the afternoon and evening.  The snow level is forecast to drop to 5500 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 northeastern Oregon Easter Sunday morning, followed by a cold and unstable upper-level trough Sunday afternoon and night.  Rain and mountain snow is likely, with the snow level dropping to 4000 feet.  Precipitation totals could locally exceed .25 inches.  Mixing should be good with brisk westerly transport winds.


2.  DISPERSION



THURSDAY

Mixing height above 5000 ft throughout the day.  Mixing height lowers to 3000 - 4000 ft during the evening.



Transport wind W to NW at 15 - 27 mph during the morning and afternoon.  Transport wind decreases to WNW to NW at 12 - 24 mph during the evening.



Surface wind W to NW at 10 - 21 mph during the morning and afternoon.  Surface wind decreases to W to NW at 8 - 12 mph during the evening.



OUTLOOK:



FRIDAY

In the west mixing height below 1000 ft early rising to 3000 to 4000 ft by late morning rising above 5000 ft during the afternoon.  In the east mixing height 2000 to 3000 ft during the morning rising above 5000 ft during the afternoon.  Transport wind light and variable.  Surface wind light and variable.



SATURDAY

Mixing height below 1000 ft early rising to 3000 to 4000 ft by late morning rising above 5000 ft during the afternoon.  Transport wind SE to SSW at 6 - 10 mph during the morning becoming SSE to SSW at 10 - 18 mph during the afternoon.  Surface wind SE to S at 4 - 8 mph.



SUNDAY

Mixing height 3500 to 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 20 - 36 mph during the afternoon.  Surface wind SW to W at 9 - 15 mph.



3.  BURNING INSTRUCTIONS FOR NORTHEAST OREGON ZONES 630-638

    The following considerations should be adhered to in addition to

    the requirements of the Oregon Smoke Management Plan. These

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

    ==================================================================



Avoid ignitions within 10 miles to the W through NW of SSRAs.  For units that will smolder significantly through the night avoid burning within at least 15 miles to the SSW through NW in or near drainages leading to SSRAs.  Care needed in selecting units as smoke will likely fumigate along the ground in wind prone areas.



    =========================================================

4.  SPECIAL NOTE:



    The smoke management forecaster is available at (503)-

    945-7401. Please call this number and not individual's

    numbers to discuss daily burning.  For large burns (over

    2000 tons) or burns extending over a considerable period,

    please request a special forecast.  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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