[willamette-fcst] Silverton Hills AM Forecast_Gary.doc

[Willamette Valley Field Burning Forecast]

SILVERTON HILLS FIELD BURNING FORECAST

OREGON DEPARTMENT OF FORESTRY WEATHER OFFICE

8:55 AM PDT THU AUG 11, 2016


BURN ADVISORY:



Agricultural burning is not recommended.



Prep burning is not allowed.



WEATHER DISCUSSION:



An upper level ridge building offshore will increasingly dominate Oregon weather today as a low level thermal ridge moves over the valley. Gradient stacking is expected to balance this afternoon but winds will remain northerly, or even slightly northeast. With the warm aloft the mixing heights will also be rather slow to rise. The primary limiting factor today is the north winds.



Sunny and warmer.



Salem's high temperature today will be near 88°F (average is 83°F).

Relative humidity:  Falling to 45% by 2:00 p.m. and 33% by 5:00 p.m.

Surface winds: N 5-10 mph.

Transport winds: N 12-16 mph.

Mixing height: Rising to 3000 feet about 2:00 p.m. and 3500 feet at 5:00 p.m.

Salem's sunset tonight: 8:23 p.m.



(Salem Airport data for Wednesday, August 10th: High 81°F; Rainfall: .00")

(Maximum Ventilation Index expected today: 56)



EXTENDED DISCUSSION:



The thermal ridge will persist on Friday and most of Saturday with north or northeast winds and limited mixing heights, and burning chances on Friday look slim. A marine push will cool the valley by Sunday but the ridge will gradually build again during the coming week. No rain is expected in the next week and the burning opportunities will probably be slightly better early in the week before the ridge builds again.



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



Gary Votaw

ODF Meteorologist

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://omls.oregon.gov/pipermail/willamette-fcst/attachments/20160811/5c55eb27/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Silverton Hills AM Forecast_Gary.doc
Type: application/msword
Size: 29696 bytes
Desc: Silverton Hills AM Forecast_Gary.doc
URL: <https://omls.oregon.gov/pipermail/willamette-fcst/attachments/20160811/5c55eb27/attachment.doc>