[willamette-fcst] Silverton Hills AM Forecast_Pete.doc

[Willamette Valley Field Burning Forecast]

SILVERTON HILLS FIELD BURNING FORECAST

OREGON DEPARTMENT OF FORESTRY WEATHER OFFICE

8:50 AM PDT MON JUL 11, 2016



BURN ADVISORY:



Recommended times for agricultural burning are from 11 a.m. until 7 p.m.



Prep burning is not allowed.



WEATHER DISCUSSION:



An unseasonably strong upper-level trough produced approximately one-half inch of rain, since last Thursday, across the northern Willamette Valley.  Damp fields will likely need some drying days, before they can be burned.



A minor upper-level ridge will bring drying today with morning clouds giving way to some sunshine this afternoon.  Temperatures will remain below average.



TODAY'S FORECAST:



Cloudy this morning with possible sprinkles.  Clearing this afternoon.



Salem's high temperature today will be near 76°F (average is 81°F).

Relative humidity:  Dropping to 60% by noon and to near 40% by 5 p.m.

Surface winds: Light this morning; NW 5-10 mph later this afternoon.

Transport winds: SW 2-5 mph this morning; W 5-10 mph later this afternoon.

Mixing height: Rising to 4000 feet at 11 a.m. to 6000 feet by 5 p.m.

Salem's sunset tonight: 8:58 p.m.



(Salem Airport data for Sunday, July 10th: High 70°F; Rainfall: .18")

(Salem Airport rainfall since last Thursday: .45")

(Maximum Ventilation Index expected today: 60)



EXTENDED DISCUSSION:



A weak cold front will likely bring more showers on Tuesday with rainfall totals expected to be near one-tenth of an inch.  The rest of the week looks dry with just a threat of light showers returning Friday afternoon.  Onshore flow will continue, but mostly sunny afternoons will help temperatures recover to near average.  Good afternoon mixing and NW transport winds may provide burning opportunities for dry fields.



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



Pete Parsons

ODF Meteorologist
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