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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link="#0563C1" vlink="#954F72"><div class=WordSection1><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>8:45 AM PDT WED SEP 10, 2014<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 not allowed.<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>Oregon lies between a building upper-level ridge, in the eastern Gulf of Alaska, and a cool “autumn-like” weather system diving southward into Montana. That is producing a dry northwesterly flow aloft today with weakening onshore low-level winds. Some marine low clouds have penetrated into the northern Willamette Valley this morning but should quickly give way to sunshine today.<o:p></o:p></p><p class=MsoNoSpacing><o:p> </o:p></p><p class=MsoNoSpacing>The sounding over Salem this morning showed considerable warming of the layer between 2000 feet and 8000 feet, so mixing heights will struggle to reach 3000 feet this afternoon. As a thermal trough builds northward along the coast, dry north to NE low-level winds will increase this afternoon, possibly putting sections of the valley into State Fire Marshal Burn-Ban Conditions by late this afternoon.<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>Patchy morning clouds…otherwise sunny with near-average temperatures.<o:p></o:p></p><p class=MsoNoSpacing><o:p> </o:p></p><p class=MsoNoSpacing>Salem's high temperature today will be near 81°F (average is 79°F).<o:p></o:p></p><p class=MsoNoSpacing>Relative humidity: Dropping to 50% around 11 a.m. and to near 30% by 5 p.m.<o:p></o:p></p><p class=MsoNoSpacing>Surface winds: N 5-10 mph this morning; N 10-15 mph this afternoon.<o:p></o:p></p><p class=MsoNoSpacing>Transport winds: NNE 10 mph this morning; NNE 10-15 mph this afternoon.<o:p></o:p></p><p class=MsoNoSpacing>Mixing height: Rising to 3500 feet by 5 p.m.<o:p></o:p></p><p class=MsoNoSpacing>Salem’s sunset tonight: 7:32 p.m.<o:p></o:p></p><p class=MsoNoSpacing><o:p> </o:p></p><p class=MsoNoSpacing>(Salem Airport data for Tuesday, September 9th: High 76°F; Rainfall: .00”)<o:p></o:p></p><p class=MsoNoSpacing>(Maximum Ventilation Index expected today: 55)<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>The building upper-level ridge in the eastern Gulf of Alaska is forecast to push closer to the coast Thursday and Friday. A dry northwesterly flow aloft will continue with a general warming of the air mass over Oregon. A coastal thermal trough will turn low-level winds northeasterly; warming valley temperatures into the mid-80s Thursday and upper-80s on Friday.<o:p></o:p></p><p class=MsoNoSpacing><o:p> </o:p></p><p class=MsoNoSpacing>The combination of NE winds and low humidity will raise wildfire concerns and may put much of the valley into State Fire Marshal Burn-Ban Conditions both Thursday and Friday afternoon. The thermal trough is forecast to move inland over western Oregon this weekend, which will decrease winds but spike temperatures in the low-90s.<o:p></o:p></p><p class=MsoNoSpacing><o:p> </o:p></p><p class=MsoNoSpacing>Southwesterly flow aloft will turn low-level winds back onshore and initiate a cool-down early next week, with the potential for burning opportunities. No significant precipitation is predicted 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=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><o:p> </o:p></p></div></body></html>