[willamette-fcst] Willamette Valley Field Burning Forecast

[Willamette Valley Field Burning Forecast]

SILVERTON HILLS FIELD BURNING FORECAST

OREGON DEPARTMENT OF FORESTRY WEATHER OFFICE

8:45 AM PDT MON JUL 21, 2014



BURN ADVISORY:



Agricultural burning is not recommended.

Prep burning is not allowed.



WEATHER DISCUSSION:



Upper level low is off northern Vancouver Island this morning. It is currently swinging another frontal band into the state, mainly to the south. Morning radar is showing scattered light moisture to the south of Eugene. A combination of higher and lower clouds are moving into the area from the southwest. Current pressure gradients are +1.3 mb from Newport to Salem and +2.1 mb from Salem to Redmond.



Upper low will slowly move toward the state today keeping skies mostly cloudy. Sprinkles or a light shower are also possible today. The amount of cloud cover that stays through the day will determine the high temperatures but models are forecasting near 80F. With more afternoon heating to the east, expect the gradient stacking to shift to west of the Willamette Valley and gradually turn wind flow more northwesterly from northerly this morning. Cloud cover will keep mixing levels fairly low until the afternoon hours.



TODAY'S FORECAST:



Mostly Cloudy.



Salem's high temperature today will be near 78 degrees (average is 83).

Relative humidity: Dropping to 60% by noon and dropping to 40 - 45 percent around 5 p.m.

Surface winds: Northerly at 4 - 7 mph this morning becoming NW to N 5 - 10 mph this afternoon.

Transport winds: N to NNE at 5 - 10 mph during the morning becoming to WNW to NNW at 5 - 10 mph this afternoon.

Mixing height: Morning below 2500 ft, rising to near 3000 ft by 1 p.m. and to 4500 - 5000 ft by 5 p.m.

Salem's sunset tonight: 8:50 p.m.



(Salem Airport data for Wednesday, July 14th: High 75°F; Rainfall: .00")

(Maximum Ventilation Index expected today: 50)



EXTENDED DISCUSSION:



Upper level low moves closer to the state tomorrow with shower activity potentially increasing during the afternoon hours. Wind flow looks like it will turn westerly sooner than today opening up a burn opportunity if moisture doesn't arrive too soon. Low eventually moves into the state Wednesday bringing more showers and probably wetting fields. Flat ridge will follow on Thursday and Friday bringing drying and warming. Wind flow will likely turn northerly.



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/20140721/15a29712/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Silverton Hills AM Forecast_Nick.doc
Type: application/msword
Size: 34304 bytes
Desc: Silverton Hills AM Forecast_Nick.doc
URL: <https://omls.oregon.gov/pipermail/willamette-fcst/attachments/20140721/15a29712/attachment.doc>