<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=us-ascii">
<meta name=Generator content="Microsoft Word 12 (filtered medium)">
<style>
<!--
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:10.0pt;
font-family:"Courier New";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
span.EmailStyle17
{mso-style-type:personal-compose;
font-family:"Calibri","sans-serif";
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
-->
</style>
<!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang=EN-US link=blue vlink=purple>
<div class=WordSection1>
<p class=MsoNormal>SILVERTON HILLS FIELD BURNING FORECAST<o:p></o:p></p>
<p class=MsoNormal>OREGON DEPARTMENT OF FORESTRY WEATHER OFFICE<o:p></o:p></p>
<p class=MsoNormal>12:00 PM PDT FRI JUL 30 2010<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>BURN ADVISORY:<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal> Agricultural burning is not recommended.<o:p></o:p></p>
<p class=MsoNormal> Prep burning is not allowed. <o:p></o:p></p>
<p class=MsoNormal> Propane flaming is allowed from 2:00 p.m. until 5:00
p.m. <o:p></o:p></p>
<p class=MsoNormal> <o:p></o:p></p>
<p class=MsoNormal>WEATHER DISCUSSION:<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Midday satellite imagery shows low clouds continuing to
blanket the northern and central coast but beginning to break up in the extreme
northern Willamette Valley. The central and southern valley avoided marine
clouds this morning. Temperatures are running within a degree or two of 24
hours ago, so the high temperature forecast of 84 degrees looks on track.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>The late-morning surface analysis showed the thermal trough
had shifted just east of Redmond with weak onshore flow across western Oregon.
There was some mild gradient-stacking, with 2.7 mb from Newport to Salem and
4.2 mb from Salem to Redmond, but daytime heating should reverse that by 3 p.m.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>The significant weather feature today is an upper-level trough
that is sluggishly advancing closer to the coastline. The air aloft is slowly
cooling, which should provide higher mixing heights today compared with the
past couple of afternoons. It is still uncertain if this system will progress
far enough eastward to create an open burning opportunity this afternoon, but
at least marginal burning conditions appear likely to develop.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Transport winds will need to be closely monitored, for a
forecast shift to northwesterly, this afternoon. Possible thunderstorm development,
over the Cascades, will also need to be closely watched, because that could
adversely affect the pressure gradient-stacking and inhibit smoke evacuation.<o:p></o:p></p>
<p class=MsoNormal> <o:p></o:p></p>
<p class=MsoNormal>TODAY’S FORECAST:<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Mostly sunny and warm. Salem's high temperature today will
be near 84 degrees. The mixing height will not climb to 3000 feet until around
2 p.m. but may rapidly lift to near 4500 feet. Look for a cooling sea breeze
to quickly drop to mixing height to around 1000 feet just before sunset. Light
surface and transport winds should increase and turn northwesterly this
afternoon. Relative humidity will drop to near 32% by late this afternoon. The
ventilation index should climb to about 36 late this afternoon.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Silverton area sunset tonight: 8:35 pm <o:p></o:p></p>
<p class=MsoNormal> <o:p></o:p></p>
<p class=MsoNormal>EXTENDED DISCUSSION:<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>The upper-level trough is forecast to move across Oregon
over the weekend with the flow aloft turning northwesterly by Sunday. That
will bring a significant surge of marine air into the Willamette Valley with
high temperatures cooling to below normal. Another weak upper-level trough may
move into the region early next week, with continued onshore flow only allowing
temperatures to warm to near normal. This weather pattern may provide multiple
burning opportunities during the upcoming week. <o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>EXTENDED FORECAST: <o:p></o:p></p>
<p class=MsoNormal> <o:p></o:p></p>
<p class=MsoNormal>Saturday: Morning clouds, then mostly sunny but cooler.
52/75 <o:p></o:p></p>
<p class=MsoNormal>Sunday: Morning clouds, then mostly sunny. 51/79<o:p></o:p></p>
<p class=MsoNormal>Monday: Morning clouds, then mostly sunny. 51/80 <o:p></o:p></p>
<p class=MsoNormal>Tuesday: Mostly sunny. 52/84 <o:p></o:p></p>
<p class=MsoNormal>Wednesday: Mostly sunny. 52/83 <o:p></o:p></p>
<p class=MsoNormal>Thursday: Morning clouds, then mostly sunny. 52/82<o:p></o:p></p>
<p class=MsoNormal>Friday: Morning clouds, then mostly sunny. 52/81<o:p></o:p></p>
<p class=MsoNormal> <o:p></o:p></p>
<p class=MsoNormal>Notes:<o:p></o:p></p>
<p class=MsoNormal> <o:p></o:p></p>
<p class=MsoNormal> 1. Mixing height, as used here, is the lowest height
at which the<o:p></o:p></p>
<p class=MsoNormal> potential temperature exceeds the potential
temperature at the<o:p></o:p></p>
<p class=MsoNormal> surface. <o:p></o:p></p>
<p class=MsoNormal> As a practical matter it is the approximate height
to which a <o:p></o:p></p>
<p class=MsoNormal> smoke plume will rise assuming good ignition, dry
fuels, and <o:p></o:p></p>
<p class=MsoNormal> winds less than about 15mph. <o:p></o:p></p>
<p class=MsoNormal> 2. Transport winds are a layer average through the
mixing height, <o:p></o:p></p>
<p class=MsoNormal> weighted slightly toward the winds at the top of
the layer. <o:p></o:p></p>
<p class=MsoNormal> 3. Ventilation Index is the height of the mixing layer
times <o:p></o:p></p>
<p class=MsoNormal> the transport wind speed divided by 1000. <o:p></o:p></p>
<p class=MsoNormal> 4. Surface wind direction is the general expected wind
direction. <o:p></o:p></p>
<p class=MsoNormal> At a specific point surface winds are highly
dependent on local<o:p></o:p></p>
<p class=MsoNormal> terrain conditions.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>This forecast is provided under an agreement between the
Oregon Department of<o:p></o:p></p>
<p class=MsoNormal>Agriculture and the Oregon Department of Forestry. For
information contact ODA at 503-986-4701.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Pete Parsons<o:p></o:p></p>
<p class=MsoNormal>ODF Meteorologist<o:p></o:p></p>
</div>
</body>
</html>