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<p class="MsoNoSpacing">SILVERTON HILLS FIELD BURNING FORECAST<o:p></o:p></p>
<p class="MsoNoSpacing">OREGON DEPARTMENT OF FORESTRY WEATHER OFFICE<o:p></o:p></p>
<p class="MsoNoSpacing">8:55 AM PDT THU SEP 14, 2017<o:p></o:p></p>
<p class="MsoNoSpacing"><o:p> </o:p></p>
<p class="MsoNoSpacing"><b>BURN ADVISORY:<o:p></o:p></b></p>
<p class="MsoNoSpacing"><b><o:p> </o:p></b></p>
<p class="MsoNoSpacing">Agricultural burning is not recommended.<o:p></o:p></p>
<p class="MsoNoSpacing"><o:p> </o:p></p>
<p class="MsoNoSpacing">Prep burning is allowed from 11 a.m. until 2 p.m. with a 50-acre limit.<o:p></o:p></p>
<p class="MsoNoSpacing"><o:p> </o:p></p>
<p class="MsoNoSpacing"><b>WEATHER DISCUSSION:<o:p></o:p></b></p>
<p class="MsoNoSpacing"><o:p> </o:p></p>
<p class="MsoNoSpacing">A dry upper-level trough will bring seasonal temperatures today under partly cloudy skies. Cool air aloft will provide excellent mixing. Weak onshore gradients have some negative-stacking this morning but should become balanced this
afternoon. However, transport winds are predicted to remain mostly northerly and will be the limiting factor for burning.<o:p></o:p></p>
<p class="MsoNoSpacing"><o:p> </o:p></p>
<p class="MsoNoSpacing"><b>TODAY’S FORECAST:<o:p></o:p></b></p>
<p class="MsoNoSpacing"><o:p> </o:p></p>
<p class="MsoNoSpacing">Partly cloudy and mild.<o:p></o:p></p>
<p class="MsoNoSpacing"><o:p> </o:p></p>
<p class="MsoNoSpacing">Salem's high temperature today will be near 76°F (average is 78°F).<o:p></o:p></p>
<p class="MsoNoSpacing">Relative humidity: Dropping to 50% by 11 a.m. and to 30% by 5 p.m.<o:p></o:p></p>
<p class="MsoNoSpacing">Surface winds: N 5 mph this morning; NNW 5-10 mph this afternoon.<o:p></o:p></p>
<p class="MsoNoSpacing">Transport winds: N 5-10 mph this morning; NNW 8-13 mph this afternoon.<o:p></o:p></p>
<p class="MsoNoSpacing">Mixing height: Rising to 3000 feet by 11 a.m. and to 6000 feet by 5 p.m.<o:p></o:p></p>
<p class="MsoNoSpacing">Salem’s sunset tonight: 7:24 p.m.<o:p></o:p></p>
<p class="MsoNoSpacing"><o:p> </o:p></p>
<p class="MsoNoSpacing">(Salem Airport data for Wednesday, September 13th: High 77°F; Rainfall: .00”)<o:p></o:p></p>
<p class="MsoNoSpacing">(Maximum Ventilation Index expected today: 40)<o:p></o:p></p>
<p class="MsoNoSpacing">
<o:p></o:p></p>
<p class="MsoNoSpacing"><b>EXTENDED DISCUSSION:<o:p></o:p></b></p>
<p class="MsoNoSpacing"><o:p> </o:p></p>
<p class="MsoNoSpacing">A weak and transitory upper-level ridge will clear skies on Friday with afternoon temperatures warming to near 80°F. The air aloft will remain cool enough for good daytime mixing with northerly transport winds turning northeasterly
Friday night.<o:p></o:p></p>
<p class="MsoNoSpacing"><o:p> </o:p></p>
<p class="MsoNoSpacing">Low-level winds are expected to veer from NE to SE on Saturday, as the weak upper-level ridge breaks down. Increasing westerly flow aloft should push some clouds into the area by Saturday afternoon.<o:p></o:p></p>
<p class="MsoNoSpacing"><o:p> </o:p></p>
<p class="MsoNoSpacing">A major change in the weather pattern is expected on Sunday, as the first fall-like storm of the season gets pushed onshore. Ahead of the cold front, low-level winds will increase and veer to the S-SW Sunday morning. Light rain is
predicted to spread across the Willamette Valley Sunday afternoon. The timing of this system does not appear optimal for field-burning, as it may come in too early in the day.<o:p></o:p></p>
<p class="MsoNoSpacing"><o:p> </o:p></p>
<p class="MsoNoSpacing">An even stronger weather system is expected to bring more significant rain on Monday with temperatures cooling into the low-60s. Rainfall totals may exceed one-half inch. Cool and showery weather is expected to extend at least through
the middle of next week.<o:p></o:p></p>
<p class="MsoNoSpacing"><o:p> </o:p></p>
<p class="MsoNoSpacing">The National Weather Service’s digital forecast is available at:<o:p></o:p></p>
<p class="MsoNoSpacing"><a href="http://forecast.weather.gov/MapClick.php?lat=44.90549606158295&lon=-122.8106689453125&site=pqr&unit=0&lg=en&FcstType=text">http://forecast.weather.gov/MapClick.php?lat=44.90549606158295&lon=-122.8106689453125&site=pqr&unit=0&lg=en&FcstType=text</a><o:p></o:p></p>
<p class="MsoNoSpacing"><o:p> </o:p></p>
<p class="MsoNoSpacing">Notes:<o:p></o:p></p>
<p class="MsoNoSpacing">
<o:p></o:p></p>
<p class="MsoNoSpacing"> 1. Mixing height, as used here, is the lowest height at which the<o:p></o:p></p>
<p class="MsoNoSpacing"> potential temperature exceeds the potential temperature at the<o:p></o:p></p>
<p class="MsoNoSpacing"> surface. As a practical matter it is the approximate height to<o:p></o:p></p>
<p class="MsoNoSpacing"> which a smoke plume will rise assuming good ignition, dry fuels,<o:p></o:p></p>
<p class="MsoNoSpacing"> and winds less than about 15 mph.<o:p></o:p></p>
<p class="MsoNoSpacing">
<o:p></o:p></p>
<p class="MsoNoSpacing"> 2. Transport winds are a layer average through the mixing height,
<o:p></o:p></p>
<p class="MsoNoSpacing"> weighted slightly toward the winds at the top of the layer.<o:p></o:p></p>
<p class="MsoNoSpacing">
<o:p></o:p></p>
<p class="MsoNoSpacing"> 3. Ventilation Index is the height of the mixing layer (ft) times
<o:p></o:p></p>
<p class="MsoNoSpacing"> the transport wind speed (mph) divided by 1000.<o:p></o:p></p>
<p class="MsoNoSpacing">
<o:p></o:p></p>
<p class="MsoNoSpacing"> 4. Surface wind direction is the general expected wind direction.
<o:p></o:p></p>
<p class="MsoNoSpacing"> At a specific point surface winds are highly dependent on local<o:p></o:p></p>
<p class="MsoNoSpacing"> terrain conditions. <o:p></o:p></p>
<p class="MsoNoSpacing"><o:p> </o:p></p>
<p class="MsoNormal"> 5. In accordance with OAR 837-110-0090, all field burning shall be
<span style="font-family:"Calibri",sans-serif"><o:p></o:p></span></p>
<p class="MsoNormal"> banned when any two of the following criteria are present:<o:p></o:p></p>
<p class="MsoNormal"> A. Temperature of 95 degrees Fahrenheit or above<o:p></o:p></p>
<p class="MsoNormal"> B. Relative humidity of 30 percent or below
<o:p></o:p></p>
<p class="MsoNormal"> C. Wind speed of 15 miles per hour or higher<o:p></o:p></p>
<p class="MsoNoSpacing"><o:p> </o:p></p>
<p class="MsoNoSpacing">This forecast is provided under an agreement between the Oregon Department<o:p></o:p></p>
<p class="MsoNoSpacing">of Agriculture (ODA) and the Oregon Department of Forestry (ODF). For<o:p></o:p></p>
<p class="MsoNoSpacing">information contact ODA at 503-986-4701.<o:p></o:p></p>
<p class="MsoNoSpacing"><o:p> </o:p></p>
<p class="MsoNoSpacing"><b>To add/remove your email address from this list, please go to:<o:p></o:p></b></p>
<p class="MsoNoSpacing"><o:p> </o:p></p>
<p class="MsoNoSpacing"><a href="http://listsmart.osl.state.or.us/mailman/listinfo/willamette-fcst">http://listsmart.osl.state.or.us/mailman/listinfo/willamette-fcst</a><o:p></o:p></p>
<p class="MsoNoSpacing"><o:p> </o:p></p>
<p class="MsoNoSpacing">Pete Parsons<o:p></o:p></p>
<p class="MsoNoSpacing">ODF Meteorologist<o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
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