348  
AUUS46 KPDT 291131  
DDOPDT  
 
DAILY DISPERSION OUTLOOK  
NATIONAL WEATHER SERVICE PENDLETON OR  
431 AM PDT THU MAY 29 2025  
 
*** AIR DISPERSION CATEGORIES: GOOD, FAIR, POOR ***  
 
FOR THE COLUMBIA BASIN FROM PENDLETON TO WALLA WALLA AND PASCO  
 
7:00 AM AFTERNOON  
SURFACE WINDS SW 12-25 MPH. W 15-25 MPH.  
TRANSPORT WINDS SW 15-25 MPH. W 17-26 MPH.  
MIXING HEIGHT NEAR SURFACE. 8000 FT MSL.  
DISPERSION CATEGORY GOOD. GOOD.  
OUTLOOK FOR FRI MAY 30 POOR.  
OUTLOOK FOR SAT MAY 31 GOOD.  
 
VENTILATION INDEX (CATEGORY) 216 (POOR). 908 (GOOD).  
OUTLOOK FOR FRI MAY 30 157 (POOR).  
OUTLOOK FOR SAT MAY 31 538 (FAIR).  
 
FOR THE UPPER YAKIMA VALLEY INCLUDING YAKIMA...UNION GAP...  
SELAH...AND NACHES AREA  
 
7:00 AM AFTERNOON  
SURFACE WINDS NW 6-12 MPH. NW 12-20 MPH.  
TRANSPORT WINDS NW 7-13 MPH. NW 16-22 MPH.  
MIXING HEIGHT NEAR SURFACE. 8000 FT MSL.  
DISPERSION CATEGORY POOR. GOOD.  
OUTLOOK FOR FRI MAY 30 POOR.  
OUTLOOK FOR SAT MAY 31 GOOD.  
 
VENTILATION INDEX (CATEGORY) 113 (POOR). 890 (GOOD).  
OUTLOOK FOR FRI MAY 30 122 (POOR).  
OUTLOOK FOR SAT MAY 31 607 (GOOD).  
 
FOR THE GRANDE RONDE RIVER VALLEY  
 
7:00 AM AFTERNOON  
SURFACE WINDS NW 5-10 MPH. NW 12-20 MPH.  
TRANSPORT WINDS NW 6-12 MPH. NW 15-25 MPH.  
MIXING HEIGHT NEAR SURFACE. 8000 FT MSL.  
DISPERSION CATEGORY POOR. GOOD.  
OUTLOOK FOR FRI MAY 30 POOR.  
OUTLOOK FOR SAT MAY 31 GOOD.  
 
VENTILATION INDEX (CATEGORY) 106 (POOR). 631 (GOOD).  
OUTLOOK FOR FRI MAY 30 106 (POOR).  
OUTLOOK FOR SAT MAY 31 511 (FAIR).  
 
FOR THE BASE OF THE NORTHERN BLUE MOUNTAINS  
 
7:00 AM AFTERNOON  
SURFACE WINDS SW 12-22 MPH. W 15-25 MPH.  
TRANSPORT WINDS SW 14-22 MPH. W 18-26 MPH.  
MIXING HEIGHT NEAR SURFACE. 6000 FT MSL.  
DISPERSION CATEGORY FAIR. GOOD.  
OUTLOOK FOR FRI MAY 30 FAIR.  
OUTLOOK FOR SAT MAY 31 FAIR.  
 
VENTILATION INDEX (CATEGORY) 201 (POOR). 808 (GOOD).  
OUTLOOK FOR FRI MAY 30 162 (POOR).  
OUTLOOK FOR SAT MAY 31 382 (FAIR).  
 
SELECT AFTERNOON FORECAST VENTILATION INDICES FOR SOME CITIES  
CLE ELUM 831 (GOOD)  
ELLENSBURG 969 (GOOD)  
GOLDENDALE 893 (GOOD)  
TRI-CITIES 868 (GOOD)  
WALLA WALLA 753 (GOOD)  
YAKIMA 884 (GOOD)  
BEND 397 (FAIR)  
PRINEVILLE 644 (GOOD)  
ENTERPRISE 506 (FAIR)  
HERMISTON 1021 (GOOD)  
JOHN DAY 682 (GOOD)  
LA GRANDE 711 (GOOD)  
MADRAS 533 (FAIR)  
MEACHAM 654 (GOOD)  
PENDLETON 942 (GOOD)  
REDMOND 638 (GOOD)  
SENECA 774 (GOOD)  
THE DALLES 826 (GOOD)  
 
METEOROLOGICAL INFORMATION PROVIDED IN THIS PRODUCT REPRESENTS ONLY  
SOME OF THE FACTORS USED IN BURN DECISIONS. BURN DECISIONS ARE  
OUTSIDE THE PURVIEW OF THE NATIONAL WEATHER SERVICE.  
 
THE VENTILATION INDEX IS A TOOL TO ASSIST SMOKE MANAGEMENT  
AGENCIES IN DETERMINING BURN OR NO BURN DECISIONS. A VENTILATION  
INDEX GRAPHIC IS ON THE PENDLETON WEBSITE AT THE FOLLOWING ADDRESS:  
HTTPS://WWW.WEATHER.GOV/PDT/DSSBRIEFING  
 
IF YOU WOULD LIKE TO KNOW MORE ABOUT THIS PRODUCT...CONTACT THE  
NATIONAL WEATHER SERVICE IN PENDLETON.  
 
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