[willamette-fcst] Willamette Valley Field Burning Forecast

Fri Aug 14 11:45:51 PDT 2015

SILVERTON HILLS FIELD BURNING FORECAST

OREGON DEPARTMENT OF FORESTRY WEATHER OFFICE

11:45 AM PDT FRI AUG 14, 2015

BURN ADVISORY:

Agricultural burning is not recommended.

Prep burning not allowed.

WEATHER DISCUSSION:

Upper level low is opening up into a trough as it moves into the state. Marine clouds from the eastern Pacific remain banked up to the Cascade crest. A few light showers are moving northward in the Coast Range, otherwise no new shower development has showed up on radar. Atmosphere is unstable with transport and surface winds S to SW at 10 - 16 mph. Pressure gradients are negatively stacked at +1.3 mb from Newport to Salem and +2.8 mb from Salem to Redmond.

Upper level trough will lift through the state today and tonight from SW to NE. The trough moving through will create dynamic lift and bring the possibility of some light showers later this afternoon. Will monitor carefully to see whether any showers develop or move into the Silverton hills area. SW to WSW wind flow and good mixing should make for burn opportunities.

TODAY'S FORECAST:

Mostly cloudy with a chance of showers.

Salem's high temperature today will be near 74 degrees (average is 83).

Relative humidity: Will drop below 60 percent around noon and reach a low of 52 percent around 4 p.m.

Surface winds: S to SW at 8 - 18 mph

Transport winds: SSW to WSW at 15 - 25 mph this afternoon.

Mixing height: Above 5000 ft.

Salem's sunset tonight: 8:20 p.m.

(Salem Airport data for Thursday, Aug 13: High 87°F; Rainfall: .00")

(Maximum Ventilation Index expected today: 100)

EXTENDED DISCUSSION:

Upper level trough will quickly weaken as it moves east of the state on Saturday. This will be replaced by a weak trough that will remain over the state through the weekend. Skies clear and temperatures warm back into the 80s. Wind flow N to NW on Saturday and northerly on Sunday. Another trough drops southward out of British Columbia on Monday and turns wind flow NW'erly during the afternoon, providing another chance for a burn opportunity. A ridge will follow on Tuesday and Wednesday with winds turning back to N to NE.

The National Weather Service's digital forecast is available at:

http://forecast.weather.gov/MapClick.php?lat=44.90549606158295&lon=-122.8106689453125&site=pqr&unit=0&lg=en&FcstType=text

Notes:

     1.  Mixing height, as used here, is the lowest height at which the

         potential temperature exceeds the potential temperature at the

         surface.  As a practical matter it is the approximate height to

         which a smoke plume will rise assuming good ignition, dry fuels,

         and winds less than about 15 mph.

     2.  Transport winds are a layer average through the mixing height,

         weighted slightly toward the winds at the top of the layer.

     3.  Ventilation Index is the height of the mixing layer (ft) times

         the transport wind speed (mph) divided by 1000.

     4.  Surface wind direction is the general expected wind direction.

         At a specific point surface winds are highly dependent on local

         terrain conditions.

This forecast is provided under an agreement between the Oregon Department

of Agriculture (ODA) and the Oregon Department of Forestry (ODF).  For

information contact ODA at 503-986-4701.

To add/remove your email address from this list, please go to:

http://listsmart.osl.state.or.us/mailman/listinfo/willamette-fcst

Nick Yonker

ODF Meteorologist

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://omls.oregon.gov/pipermail/willamette-fcst/attachments/20150814/8638dcd8/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Silverton Hills Midday Forecast_Nick.doc
Type: application/msword
Size: 32768 bytes
Desc: Silverton Hills Midday Forecast_Nick.doc
URL: <https://omls.oregon.gov/pipermail/willamette-fcst/attachments/20150814/8638dcd8/attachment.doc>