<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>9:00 AM PDT THU AUG 5 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> Recommended burn times for agricultural burning are
from<o:p></o:p></p>
<p class=MsoNormal> 1:00pm to 6:30pm.<o:p></o:p></p>
<p class=MsoNormal> Prep burning is allowed from 1:00pm to 2:00pm with a 50
acre limit. <o:p></o:p></p>
<p class=MsoNormal> Propane flaming is allowed from 1:00pm to 5:00pm. <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>An upper-level trough remains over the Pacific Northwest.
The main circulation center is over western Washington, with a few showers falling
over the northern Washington Cascades this morning. A weaker mid-level
circulation center is over southwestern Oregon, and that is having a
significant impact on air quality across western Oregon. The Salem sounding
this morning showed easterly winds from 5000 feet up to about 8000 feet, which
circulated some wildfire smoke, from the Rooster Rock Fire in central Oregon,
over the Cascades and across the Willamette Valley during the night.
Nephelometer readings in the northern Cascades and in the Willamette Valley are
slightly elevated this morning, and skies appear hazy.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Onshore flow is weak this morning. Visible satellite
imagery shows low clouds along the coast with only minor penetration into the
western valleys. Increased sunshine will result in valley temperatures
climbing into the mid 80s this afternoon.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Air quality should begin improving this afternoon, as both
upper-level disturbances slowly drift eastward. Winds will shift to
northwesterly, below about 5000 feet, as onshore flow increases across westerly
Oregon. However, the winds above 5000 feet may continue to circulate some
elevated wildfire smoke over the region through this evening, before turning
onshore tonight and Friday. Transport winds will need to be monitored for the
possibility of open burning this afternoon.<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, hazy, and warmer. After reaching 81 degrees
on Wednesday, Salem's high temperature today will be near 86 degrees. The
mixing height will climb to 3000 feet about 1 p.m. and will likely top out near
4500 feet around 5 p.m. A stronger evening sea breeze is expected today with
the mixing height dropping to near 2000 feet by sunset. Surface and transport
winds will be NW 3-6 mph this morning, then increase to NW 5-10 this afternoon
and NW 7-12 this evening. Relative humidity is forecast to drop to 50% by 2
p.m. and to near 36% by 5 p.m. The ventilation index will climb to about 45
late this afternoon.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Silverton area sunset tonight: 8:28 pm <o:p></o:p></p>
<p class=MsoNormal> <o:p></o:p></p>
<p class=MsoNormal>THREE-HOURLY DATA: <o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal> 11am 2pm 5pm
8pm <o:p></o:p></p>
<p class=MsoNormal> Temperature: 74 82 86
77 <o:p></o:p></p>
<p class=MsoNormal> Relative Humidity: 57% 43% 36%
47% <o:p></o:p></p>
<p class=MsoNormal> Surface Wind Direction: 340 310 310
270 <o:p></o:p></p>
<p class=MsoNormal> Surface Wind Speed: 3 5 7
7 <o:p></o:p></p>
<p class=MsoNormal> Transport Wind Direction: 320 330 320
310 <o:p></o:p></p>
<p class=MsoNormal> Transport Wind Speed: 4 6 10 12
<o:p></o:p></p>
<p class=MsoNormal> Estimated Mixing Height: 2000 3700 4500
2000<o:p></o:p></p>
<p class=MsoNormal> Ventilation Index: 8 22 45
24<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 troughs are both forecast to finally shift
east of the Cascades Friday with the winds at transport level and aloft turning
onshore. That should clear the skies of wildfire smoke and may provide an open
burning opportunity Friday afternoon. Morning clouds will likely penetrate
inland to the Cascade crest with high temperatures cooling back into the low
80s across the Willamette valley. <o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Stronger onshore flow will bring further cooling over the
weekend, with a weak cold front forecast to come onshore Saturday evening.
Marine clouds will be extensive by Sunday morning with local drizzle possible.
High temperatures should fall to about 10 degrees below normal by Sunday.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Another upper-level trough is forecast to drop into the
region early next week for continued cooler than normal conditions and strong
onshore flow. Open burning opportunities may be possible, if the deep marine
layer does not create too much gradient-stacking. <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>Friday: Morning clouds, then partly cloudy. Wind: NW 5-15
mph. 55/82<o:p></o:p></p>
<p class=MsoNormal>Saturday: Morning clouds, then partly cloudy. 55/77<o:p></o:p></p>
<p class=MsoNormal>Sunday: Chance of morning drizzle. Partly sunny in the
afternoon. 54/75<o:p></o:p></p>
<p class=MsoNormal>Monday: Morning clouds. Afternoon clearing. 54/78 <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>