[willamette-fcst] Silverton Hills AM Forecast_doug.doc
Willamette Valley Field Burning Forecast
willamette-fcst at listsmart.osl.state.or.us
Fri Jul 12 08:39:53 PDT 2013
SILVERTON HILLS FIELD BURNING FORECAST
OREGON DEPARTMENT OF FORESTRY WEATHER OFFICE
9:00 AM PDT FRI. JUL 12, 2013
BURN ADVISORY:
Recommended burn times for agricultural burning from 10:00 a.m. to 7:00 p.m.
Prep burning is allowed 10:00 a.m. until 3:00 p.m. with a 50-acre limit.
WEATHER DISCUSSION:
A moderately strong upper trough continues to be entrenched along the Pacific coastline this morning, with generally dry southwesterly flow aloft over western Oregon. Some energy within the trough will push eastward later today and increase our cloud cover as well as assist an onshore eastward surge late this afternoon and evening. Some coastal low-cloud intrusions are currently over the lower elevations over the extreme northwestern corner of Oregon, with deeper clouds getting close to the coastline and moving eastward.
The upper trough remains in place for the next several days, with more weak waves of energy skirting western Oregon as they periodically progress eastward.
Cloud cover over western Oregon and the surge will limit valley maximum temperatures to the middle to upper 70s this afternoon. Transport winds should remain mostly northerly with some increase in NW flow late this afternoon and evening.
TODAY'S FORECAST:
Becoming partly cloudy with seasonably cool temperatures.
Salem's high temperature today will be in the upper 70s.
Relative humidity: Will drop below 60% by 11:00 a.m. and to 40-45% by 5 p.m.
Surface winds: N 5-10 mph this morning through the afternoon; NNW 7-15 mph this evening.
Transport winds: NNE 10-15 mph transitioning into NW flow late afternoon
Mixing height: Rising to near 5000 feet this afternoon.
Salem's sunset tonight: 8:58 p.m.
(Salem Airport data for Thursday, July 11th: High 79°F; Rainfall .00")
(Maximum Ventilation index expected today: 60)
EXTENDED DISCUSSION:
The upper-level trough just to our west should persist through the weekend, with a portion of the trough progressing eastward into eastern OR and WA on Saturday. Expect partly cloudy conditions and continued cool temperatures with maximums in the upper 70s.
Upper-level troughing will persist just west of Oregon Sunday. No showers are expected, but the threat of some morning low clouds over the Willamette Valley persists. Mostly sunny conditions are likely in the afternoon. Maximum temperatures will likely warm to the low 80s. On Monday and Tuesday the slow warming is likely to continue with dry conditions persisting.
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 15mph.
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 and the Oregon Department of Forestry. For information contact ODA at 503-986-4701.
Doug Wesley
ODF Meteorologist
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://omls.oregon.gov/pipermail/willamette-fcst/attachments/20130712/fcd12668/attachment.html>
More information about the willamette-fcst
mailing list