[willamette-fcst] Silverton Hills Forecast - Thu, Jul 01 2010

[Willamette Valley Ag/Burning Forecast]

SILVERTON HILLS FIELD BURNING FORECAST
OREGON DEPARTMENT OF FORESTRY WEATHER OFFICE
9:00 AM PDT THU JUL 01 2010

...Corrected Burning Instructions...						
										
WEATHER DISCUSSION:

A weak cold front will bring increasing clouds today with a chance of showers by late in the afternoon.  Ventilation conditions will be good, ahead of the cold, early this afternoon.  Mixing heights will rapidly lower late in the afternoon and evening, due to increasing onshore flow.  The high temperature, of near 70 degrees, will likely be met in the mid-afternoon with a cooling sea breeze in the late afternoon and evening.	


     Prep burning is not allowed. 
     Propane flaming is not allowed.								
										
TODAY:		

                                 11am     2pm     5pm     8pm			
     Temperature:                 63       70      69      63  			
     Relative Humidity:           54%      39%     42%     60%     			
     Surface Wind Direction:     200      200     230     250 		
     Surface Wind Speed:           6        7       8       7    			
     Transport Wind Direction:   230      230     270     260 
     Transport Wind Speed:         6       10      12      15  
     Estimated Mixing Height:   3500     6000    3000    1500
     Ventilation Index:           21       60      36      22

                               Sunset: 8:57 pm				
										
EXTENDED OUTLOOK:

An upper-level trough will maintain cool and showery conditions on Friday.  The flow aloft will turn northwesterly over the holiday weekend with dry weather and progressively warmer temperatures.  The long-range computer models are indicating that an upper-level ridge will build over the region during the middle of next week, which will likely bring the Willamette Valley a couple of days of 90-degree temperatures for the first time this year.	
     
     Friday: Mostly cloudy and cooler with a chance of showers.  high near 67.
     Wind: W 5-15 mph with possile gusts to near 20 mph in the afternoon.
     Friday Night: Mostly cloudy with a chance of showers.  Low near 50. West to
     northwest wind decreasing to 5-10 mph late.
     Saturday: Morning clouds...becoming partly sunny.  High near 73. North NW 5-15 mph
     in the north valley and northerly 10-20 mph in the south valley.
     Saturday Night: Mostly cloudy.  Low near 50.  
     Independence Day: Partly sunny.  High near 77.  North to northwest winds.  
     Monday: Mostly sunny.  High near 80. Brisk north winds in the south valley. 
     Tuesday: Sunny and warm.  High near 88.  North winds.
     Wednesday: Sunny.  High near 92.

										
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.									
										
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 times 
         the transport wind speed 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.