OPEN BURNING ANNOUNCEMENT MODEL GUIDANCE
300 PM PDT MON AUG 24 2026
NBM model output for: Portland KPDX  45.59N, -122.59W 
Model Run Time:  2026-08-24 22Z

                             Mixing      Sfc     Transport                                 
                   Time      Height     Winds      Winds   Ventilation                    
  Day   Date      (PDT)     (ft MSL)    (mph)      (mph)      Index       Remarks         
  === ========   ========   =======    =======    =======    =======      =======         
  Mon Aug 24th    4:00 pm     4700     050/07     090/09       43        Criteria Met
  Mon Aug 24th    5:00 pm     4200     060/07     080/08       34        Criteria Met
  Mon Aug 24th    6:00 pm     2900     050/06     070/07       20        
  Mon Aug 24th    7:00 pm     1600     020/06     060/08       13        
  Mon Aug 24th    8:00 pm      500     330/06     020/08        4        
  Mon Aug 24th    9:00 pm      400     340/05     030/07        3        
  Mon Aug 24th   10:00 pm      400     330/03     050/05        2        
  Mon Aug 24th   11:00 pm      400     360/00     040/03        1        

  Tue Aug 25th   12:00 am      400     140/00     130/03        1        
  Tue Aug 25th    1:00 am      400     150/00     160/05        2        
  Tue Aug 25th    2:00 am      400     160/00     170/06        2        
  Tue Aug 25th    3:00 am      500     130/03     180/07        3        
  Tue Aug 25th    4:00 am      500     130/05     180/07        3        
  Tue Aug 25th    5:00 am      600     130/06     160/07        4        
  Tue Aug 25th    6:00 am      600     130/06     160/06        3        
  Tue Aug 25th    7:00 am      600     140/05     160/06        3        
  Tue Aug 25th    8:00 am     1100     160/06     180/08        9        
  Tue Aug 25th    9:00 am     1300     170/06     190/09       12        
  Tue Aug 25th   10:00 am     1900     180/07     190/08       15        
  Tue Aug 25th   11:00 am     2200     190/08     200/08       18        
  Tue Aug 25th   12:00 pm     2900     200/08     200/08       23        
  Tue Aug 25th    1:00 pm     3400     200/08     200/08       27        Criteria Met
  Tue Aug 25th    2:00 pm     3900     210/08     210/09       36        Criteria Met
  Tue Aug 25th    3:00 pm     4400     210/07     210/09       41        Criteria Met
  Tue Aug 25th    4:00 pm     4700     210/07     210/10       49        Criteria Met
  Tue Aug 25th    5:00 pm     5100     220/07     220/10       53        Criteria Met
  Tue Aug 25th    8:00 pm      800     310/08     330/10        8        
  Tue Aug 25th   11:00 pm      600     300/03     340/06        3        

  Wed Aug 26th    2:00 am      600     280/02     340/03        2        
  Wed Aug 26th    5:00 am      500     270/00     320/02        1        
  Wed Aug 26th    8:00 am     1500     270/00     260/03        5        
  Wed Aug 26th   11:00 am     3000     210/03     220/05       14        
  Wed Aug 26th    2:00 pm     3900     220/05     220/05       18        
  Wed Aug 26th    5:00 pm     5600     250/05     250/07       39        
  Wed Aug 26th    8:00 pm     1500     300/07     320/09       14        
  Wed Aug 26th   11:00 pm      800     310/05     330/07        6        

  Thu Aug 27th    2:00 am      700     270/02     070/02        2        
  Thu Aug 27th    5:00 am     1000     190/02     180/03        3        
  Thu Aug 27th    8:00 am     1800     200/05     200/06       10        
  Thu Aug 27th   11:00 am     4200     210/07     220/07       29        
  Thu Aug 27th    2:00 pm     6900     230/08     250/08       56        Criteria Met

Notes:
  Mixing Height = NBM mixing height (MHT)                               
  SFC Winds = NBM 10 meter winds                                        
  Transport Winds = NBM transport wind through the mixed layer          

Criteria:
  Field-burning season (July 5 - September 30):
    Mixing Height >= 3000 feet, with Surface Winds >= 5 mph and
	Transport Winds >= 7 mph.
  Rest of year:
    Mixing Height >= 2000 feet or Ventilation Index >= 20, with
	Surface Winds >= 5 mph and Transport Winds >= 7 mph.

  In addition (both seasons):
    Transport wind direction greater than 10 and less than 350 degrees.
  Ventilation Index = Mixing Height (ft) x
    Transport Wind (mph) / 1000.