OPEN BURNING ANNOUNCEMENT MODEL GUIDANCE
100 PM PDT MON AUG 24 2026
NBM model output for: Portland KPDX  45.59N, -122.59W 
Model Run Time:  2026-08-24 19Z

                             Mixing      Sfc     Transport                                 
                   Time      Height     Winds      Winds   Ventilation                    
  Day   Date      (PDT)     (ft MSL)    (mph)      (mph)      Index       Remarks         
  === ========   ========   =======    =======    =======    =======      =======         
  Mon Aug 24th    1:00 pm     3200     070/08     090/13       41        Criteria Met
  Mon Aug 24th    2:00 pm     3800     070/08     090/12       44        Criteria Met
  Mon Aug 24th    3:00 pm     4500     070/07     090/10       47        Criteria Met
  Mon Aug 24th    4:00 pm     4800     060/07     090/09       44        Criteria Met
  Mon Aug 24th    5:00 pm     4000     050/07     080/08       32        Criteria Met
  Mon Aug 24th    6:00 pm     2800     050/06     070/08       23        
  Mon Aug 24th    7:00 pm     1600     030/06     060/08       13        
  Mon Aug 24th    8:00 pm      500     330/06     020/08        4        
  Mon Aug 24th    9:00 pm      400     330/05     020/08        3        
  Mon Aug 24th   10:00 pm      400     330/03     040/07        3        
  Mon Aug 24th   11:00 pm      400     320/00     030/05        2        

  Tue Aug 25th   12:00 am      400     150/00     110/05        2        
  Tue Aug 25th    1:00 am      400     160/00     140/05        2        
  Tue Aug 25th    2:00 am      400     160/00     170/05        2        
  Tue Aug 25th    3:00 am      500     130/03     170/06        3        
  Tue Aug 25th    4:00 am      500     130/05     180/06        3        
  Tue Aug 25th    5:00 am      500     130/06     170/06        3        
  Tue Aug 25th    6:00 am      500     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     180/08       10        
  Tue Aug 25th   10:00 am     1800     180/07     190/08       14        
  Tue Aug 25th   11:00 am     2200     190/08     200/08       18        
  Tue Aug 25th   12:00 pm     2800     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     210/08       31        Criteria Met
  Tue Aug 25th    5:00 pm     5200     220/07     220/10       54        Criteria Met
  Tue Aug 25th    8:00 pm      800     320/08     330/10        8        
  Tue Aug 25th   11:00 pm      600     300/03     340/06        3        

  Wed Aug 26th    2:00 am      600     320/02     340/03        2        
  Wed Aug 26th    5:00 am      600     270/00     340/02        1        
  Wed Aug 26th    8:00 am     1300     270/00     220/03        4        
  Wed Aug 26th   11:00 am     2800     210/03     210/05       13        
  Wed Aug 26th    2:00 pm     3900     230/05     220/06       22        
  Wed Aug 26th    5:00 pm     5600     250/05     230/06       32        
  Wed Aug 26th    8:00 pm     1600     300/07     310/08       13        
  Wed Aug 26th   11:00 pm      700     320/05     340/07        5        

  Thu Aug 27th    2:00 am      700     300/02     050/03        2        
  Thu Aug 27th    5:00 am      800     180/02     170/03        3        
  Thu Aug 27th    8:00 am     1700     190/05     190/05        8        
  Thu Aug 27th   11:00 am     3800     210/07     210/07       26        

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.