<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 07 2010</div>
<div> </div>
<div>BURN ADVISORY:</div>
<div> </div>
<div> Recommended burn times for agricultural burning are from 9:00am to 5:30pm.</div>
<div> Prep burning is allowed from 2:00pm to 5:00pm with a 50 acre limit. </div>
<div> Propane flaming is allowed from 2:00pm to 5:00pm. </div>
<div> </div>
<div>WEATHER DISCUSSION:</div>
<div> </div>
<div> Upper air charts show a northwesterly flow over the Pacific Northwest this</div>
<div> morning. Embedded in that flow is an upper disturbance located off the coast of</div>
<div> central British Columbia. This will drop into the region tomorrow and carve out</div>
<div> an upper level trough that will linger until about Thursday.</div>
<div> </div>
<div> Satellite pictures show a band of clouds centered on a line from south-central</div>
<div> Washington to SW Oregon. To the northwest of that cloud band is an area of</div>
<div> showers. </div>
<div> </div>
<div> Rainfall totals so far this morning have ammounted to just a couple of</div>
<div> hundredths to a little less than a tenth of an inch so far. </div>
<div> </div>
<div> The morning sounding showed some cooling aloft and a fairly unstable atmosphere.</div>
<div> Cloud cover will hold temperatures about 10 degrees below average for this time</div>
<div> of year however, and the cool surface temperatures will limit mixing heights</div>
<div> somewhat. Maximum Mixing heights will be around 3900 feet this afternoon. </div>
<div> </div>
<div> Pressure gradients, and consequently transport winds, will be quite light today.</div>
<div> While the Newport to Salem gradient was 0.7mb onshore and the Salem to Redmond</div>
<div> gradient was 0.4 onshore at 8:00am this morning, models indicate gradient</div>
<div> stacking to the east will increase this afternoon. </div>
<div> </div>
<div> For the mid Willamette Valley expect mostly cloudy skies today with scattered</div>
<div> light showers this afternoon. Salem's high temperature today will be near 69</div>
<div> and the minimum relative humidity will drop to about 53%</div>
<div> </div>
<div> Sunset tonight: 7:32 pm </div>
<div> </div>
<div>THREE-HOURLY DATA: </div>
<div> </div>
<div> 11am 2pm 5pm 8pm </div>
<div> Temperature: 64 68 69 62 </div>
<div> Relative Humidity: 70% 57% 53% 67% </div>
<div> Surface Wind Direction: 170 200 240 290 </div>
<div> Surface Wind Speed: 4 4 5 4 </div>
<div> Transport Wind Direction: 300 250 280 290 </div>
<div> Transport Wind Speed: 5 5 5 3 </div>
<div> Estimated Mixing Height: 2800 3500 3900 500</div>
<div> Ventilation Index: 14 18 20 2</div>
<div> </div>
<div>EXTENDED DISCUSSION:</div>
<div> </div>
<div> Models indicate onshore flow continuing but gradient stacking to the east for at</div>
<div> least the next two days. The upper level trough will move to the east Friday and</div>
<div> temporary ridging will set up over the region for more sunshine. Another trough</div>
<div> moves in over the weekend for cooler temperatures. The details of the trough are</div>
<div> not clear at this point but there is a potential for at least some rain at some</div>
<div> point over the weekend.</div>
<div> </div>
<div>EXTENDED FORECAST: </div>
<div> </div>
<div> Wednesday: Mostly cloudy, a few showers. Wind SW 6 mph. Chance of precip 30%.</div>
<div> Thursday: Partly sunny, with a high near 69. Calm wind becoming west southwest</div>
<div> around 6 mph. </div>
<div> Friday: Mostly sunny, with a high near 71. </div>
<div> Saturday: Partly sunny, with a high near 71. </div>
<div> Sunday: Mostly cloudy, with a high near 70. </div>
<div> Monday: Partly sunny, with a high near 72. </div>
<div> </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> </div>
<div> </div>
<div> </div>
<div> </div>
<div> </div>
<div><font face="Calibri, sans-serif" size="2"> </font></div>
<div><font face="Calibri, sans-serif" size="2"> </font></div>
</font>
</body>
</html>