<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<meta name="Generator" content="Microsoft Exchange Server">
<!-- converted from rtf -->
<style><!-- .EmailQuote { margin-left: 1pt; padding-left: 4pt; border-left: #800000 2px solid; } --></style>
</head>
<body>
<font face="Courier New, monospace" size="2">
<div>SILVERTON HILLS FIELD BURNING FORECAST</div>
<div>OREGON DEPARTMENT OF FORESTRY WEATHER OFFICE</div>
<div>9:00 AM PDT TUE SEP 21 2010</div>
<div> </div>
<div>BURN ADVISORY:</div>
<div> </div>
<div> Recommended burn times for agricultural burning are from noon to 5:00pm.</div>
<div> Prep burning is allowed from noon to 5:00pm with a 50 acre limit. </div>
<div> Propane flaming is allowed from noon to 5:00pm. </div>
<div> </div>
<div> </div>
<div>WEATHER DISCUSSION:</div>
<div> </div>
<div> Morning upper air charts show a trough to the north, over southern British </div>
<div> Columbia and northern Washington, and another trough to the southwest, about </div>
<div> 500 miles west of Brookings. The northern trough will pull out to the east </div>
<div> today and the one to the southwest should push into northern California. </div>
<div> This will leave the Willamette Valley in the middle for dry weather today </div>
<div> and tomorrow. </div>
<div> </div>
<div> The morning Salem sounding showed a fairly unstable atmosphere up to above </div>
<div> 7000 feet. There is an inversion from 7400 to 8000 feet with stable </div>
<div> conditions above. However, daytime heating should easily push the mixing </div>
<div> height to the inversion level and maximum mixing heights this afternoon </div>
<div> should be about 7200 feet. </div>
<div> </div>
<div> Winds on the morning Salem sounding were light and variable with a tendency </div>
<div> to northerly up to about 5000 feet. Computer models today are consistent in </div>
<div> showing a northerly wind throughout the day today. Trajectory forecasts bring </div>
<div> any smoke from mid Marion County into central Lane County near Eugene and </div>
<div> Springfield. </div>
<div> </div>
<div> For the mid Willamette Valley today expect mostly cloudy skies this </div>
<div> morning with some sunshine this afternoon. Winds will be light northerly </div>
<div> becoming light northwesterly later this afternoon. Salem's high </div>
<div> temperature today will be near 70. Relative humidity drops to 50% </div>
<div> by 1pm. Minimum relative humidity 41%.</div>
<div> </div>
<div> Sunset tonight: 7:06 pm </div>
<div> </div>
<div> </div>
<div>THREE-HOURLY DATA: </div>
<div> </div>
<div> 11am 2pm 5pm 8pm </div>
<div> Temperature: 62 69 70 64 </div>
<div> Relative Humidity: 65% 45% 41% 52% </div>
<div> Surface Wind Direction: 360 340 340 300 </div>
<div> Surface Wind Speed: 3 4 6 5 </div>
<div> Transport Wind Direction: 010 360 360 330 </div>
<div> Transport Wind Speed: 10 10 10 10 </div>
<div> Estimated Mixing Height: 2800 7100 7200 500</div>
<div> Ventilation Index: 28 71 72 5</div>
<div> </div>
<div> </div>
<div> </div>
<div>EXTENDED DISCUSSION:</div>
<div> </div>
<div> Tomorrow will be another drying day, however there likely will be </div>
<div> areas of morning fog which may deposit some dew. Both the NAM and </div>
<div> the GFS models are showing measurable precipitation for Thursday </div>
<div> afternoon. Friday will see minor ridging for dry weather. Longer </div>
<div> range, models are less pessimistic than they were earlier regarding </div>
<div> the weekend. A deep upper low in the Pacific may remain far </div>
<div> enough off the coast that moisture will rotate northward offshore </div>
<div> through much of the weekend. At this point Saturday looks dry, </div>
<div> but we will mention a possibility of rain for Sunday and Monday,</div>
<div> but low confidence beyond Saturday. </div>
<div> </div>
<div>EXTENDED FORECAST: </div>
<div> </div>
<div> Wednesday: Areas of fog before 11am. Otherwise, partly sunny, with a high near</div>
<div> 72. Calm wind becoming west northwest between 5 and 8 mph. </div>
<div> Thursday: A 40 percent chance of rain after 11am. Mostly cloudy, with a high</div>
<div> near 67. South southwest wind between 6 and 8 mph. </div>
<div> Friday: Partly sunny, with a high near 74. </div>
<div> Saturday: Mostly sunny, with a high near 76. </div>
<div> Sunday: A chance of showers. Mostly cloudy, with a high near 72. </div>
<div> Monday: A chance of rain. Mostly cloudy, with a high near 74. </div>
<div> </div>
<div>Notes: </div>
<div> 1. Mixing height, as used here, is the lowest height at which the</div>
<div> potential temperature exceeds the potential temperature at the surface. </div>
<div> As a practical matter it is the approximate height to which a </div>
<div> smoke plume will rise assuming good ignition, dry fuels, and </div>
<div> winds less than about 15mph. </div>
<div> 2. Transport winds are a layer average through the mixing height, </div>
<div> weighted slightly toward the winds at the top of the layer. </div>
<div> 3. Ventilation Index is the height of the mixing layer times </div>
<div> the transport wind speed divided by 1000. </div>
<div> 4. Surface wind direction is the general expected wind direction. </div>
<div> At a specific point surface winds are highly dependent on </div>
<div> local terrain conditions.</div>
<div> </div>
<div>This forecast is provided under an agreement between the Oregon Department of</div>
<div>Agriculture and the Oregon Department of Forestry. For information contact ODA</div>
<div>at 503-986-4701.</div>
<div><font face="Calibri, sans-serif"> </font></div>
</font>
</body>
</html>