OPEN BURNING ANNOUNCEMENT MODEL GUIDANCE
1000 AM PDT MON AUG 24 2026
NBM model output for: Portland KPDX  45.59N, -122.59W 
Model Run Time:  2026-08-24 16Z

                             Mixing      Sfc     Transport                                 
                   Time      Height     Winds      Winds   Ventilation                    
  Day   Date      (PDT)     (ft MSL)    (mph)      (mph)      Index       Remarks         
  === ========   ========   =======    =======    =======    =======      =======         
  Mon Aug 24th   10:00 am     1400     350/07     070/09       13        
  Mon Aug 24th   11:00 am     2100     040/08     080/12       24        
  Mon Aug 24th   12:00 pm     2800     060/08     090/13       35        
  Mon Aug 24th    1:00 pm     3300     070/08     090/12       38        Criteria Met
  Mon Aug 24th    2:00 pm     3900     070/08     090/12       45        Criteria Met
  Mon Aug 24th    3:00 pm     4500     060/07     090/10       47        Criteria Met
  Mon Aug 24th    4:00 pm     4600     060/07     090/09       42        Criteria Met
  Mon Aug 24th    5:00 pm     4000     050/07     080/09       37        Criteria Met
  Mon Aug 24th    6:00 pm     2700     050/07     060/08       22        
  Mon Aug 24th    7:00 pm     1600     030/06     050/08       13        
  Mon Aug 24th    8:00 pm      700     330/06     020/09        6        
  Mon Aug 24th    9:00 pm      400     330/05     020/08        3        
  Mon Aug 24th   10:00 pm      400     330/03     030/07        3        
  Mon Aug 24th   11:00 pm      400     330/00     010/05        2        

  Tue Aug 25th   12:00 am      400     150/00     090/03        1        
  Tue Aug 25th    1:00 am      400     150/00     130/05        2        
  Tue Aug 25th    2:00 am      400     170/00     170/06        2        
  Tue Aug 25th    3:00 am      400     140/02     180/06        2        
  Tue Aug 25th    4:00 am      500     130/05     180/07        3        
  Tue Aug 25th    5:00 am      500     130/06     160/06        3        
  Tue Aug 25th    6:00 am      500     130/06     150/06        3        
  Tue Aug 25th    7:00 am      600     140/05     160/06        3        
  Tue Aug 25th    8:00 am     1100     150/06     180/08        9        
  Tue Aug 25th    9:00 am     1300     170/06     180/08       10        
  Tue Aug 25th   10:00 am     1900     180/07     190/08       15        
  Tue Aug 25th   11:00 am     2200     190/07     200/07       15        
  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     1100     320/08     330/10       11        
  Tue Aug 25th   11:00 pm      700     320/03     340/07        5        

  Wed Aug 26th    2:00 am      600     320/00     330/03        2        
  Wed Aug 26th    5:00 am      500     360/00     320/02        1        
  Wed Aug 26th    8:00 am     1300     270/00     220/03        4        
  Wed Aug 26th   11:00 am     2800     220/03     210/05       13        
  Wed Aug 26th    2:00 pm     3900     230/05     220/06       22        
  Wed Aug 26th    5:00 pm     5600     260/05     230/07       39        
  Wed Aug 26th    8:00 pm     1600     300/07     320/08       13        
  Wed Aug 26th   11:00 pm      700     320/05     340/07        5        

  Thu Aug 27th    2:00 am      700     270/03     360/03        2        
  Thu Aug 27th    5:00 am      800     180/03     150/03        3        
  Thu Aug 27th    8:00 am     1700     190/06     190/06       10        

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.