[willamette-fcst] Silverton Hills AM Forecast_Tom
Willamette Valley Field Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Tue Sep 8 08:37:33 PDT 2015
SILVERTON HILLS FIELD BURNING FORECAST
OREGON DEPARTMENT OF FORESTRY WEATHER OFFICE
8:45 AM PDT TUE SEP 08, 2015
BURN ADVISORY:
Agricultural burning is not recommended.
Prep burning is not allowed.
WEATHER DISCUSSION:
An upper-level ridge is currently off the coast of Oregon, suppressing mixing as it warms the air aloft. Down at the surface, an area of higher pressure near the Oregon coast is creating northerly winds, which will increase as the Silverton Hills heat up today above seasonal averages. Wind direction and speeds may not produce favorable open burning opportunities today.
TODAY'S FORECAST:
Mostly Sunny becoming Windy and warm this afternoon.
Salem's high temperature today will be near 81°F (average is 79°F).
Relative humidity: Dropping near 40% by 5 p.m.
Surface winds: N 5-10 mph this morning; N-NE 15-20 mph this afternoon.
Transport winds: NE 10-15 mph this morning; N-NE 15-20 mph this afternoon.
Mixing height: Above 3000 feet after 2 p.m. and 3500 feet by 5 p.m.
Salem's sunset tonight: 7:36 p.m.
(Salem Airport data for Monday, September 7th: High 77°F; Rainfall: .00")
(Maximum Ventilation Index expected today: 70)
EXTENDED DISCUSSION:
The upper-level ridge will continue to strengthen as the week progresses, remaining stationary off the coast of Oregon through Friday afternoon. Higher pressure will maintain northerly winds over the Silverton Hills, warming air further above seasonal averages and producing summer-like conditions. Skies will remain mostly clear during the day, with no rainfall expected at this time. Onshore gradients will be weak, and are likely to be the key factor to determine whether favorable open burning conditions develop later this week. The current outlook does not indicate a return to westerly flow over Oregon until early next week.
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
Tom Jenkins, AEM
ODF Meteorologist
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