179  
FNUS21 KWNS 061630  
FWDDY1  
 
DAY 1 FIRE WEATHER OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
1129 AM CDT SAT SEP 06 2025  
 
VALID 061700Z - 071200Z  
 
THE ONLY CHANGE TO THE ONGOING FORECAST WAS TO EXPAND THE ISOLATED  
DRY THUNDERSTORM AREA INTO NORTHERN CALIFORNIA. HERE, PRECIPITABLE  
WATER VALUES ARE RUNNING BETWEEN 0.5"-0.75". LOW-TO-MID-LEVEL FLOW  
IS SUFFICIENTLY STRONG (ON THE ORDER OF 20-25 KNOTS) THAT, WHEN  
COUPLED WITH THE LOW PRECIPITABLE WATER VALUES, ANY THUNDERSTORM  
THAT CAN DEVELOP WOULD POSE AT LEAST SOME POTENTIAL FOR BEING ON THE  
DRY SIDE.  
 
..MARSH.. 09/06/2025  
   
PREV DISCUSSION  
/ISSUED 0142 AM CDT SAT SEP 06 2025/  
   
..SYNOPSIS  
 
A MID-LEVEL TROUGH WILL PROGRESS ACROSS THE NORTHEAST WHILE UPPER  
RIDGING PERSISTS OVER THE ROCKIES, AND ANOTHER UPPER TROUGH IMPINGES  
ON THE WEST COAST TODAY. THE WEST COAST UPPER TROUGH WILL PROVIDE  
ENOUGH UPPER SUPPORT ATOP A DRY BOUNDARY LAYER TO ENCOURAGE LOCALLY  
DRY AND WINDY CONDITIONS TO THE LEE OF THE NORTHERN SIERRA THIS  
AFTERNOON. WHILE OCCASIONAL BOUTS OF 15 MPH SUSTAINED SOUTHWESTERLY  
SURFACE WINDS MAY OVERLAP WITH 15-20 PERCENT RH, THE BRIEF AND  
LOCALIZED NATURE OF THESE CONDITIONS PRECLUDE ELEVATED HIGHLIGHTS.  
 
FARTHER TO THE NORTHEAST, UPPER SUPPORT FROM THE AFOREMENTIONED  
UPPER TROUGH WILL ENCOUNTER GREATER BUOYANCY, WHICH WILL SUPPORT  
SCATTERED THUNDERSTORM DEVELOPMENT DURING THE AFTERNOON INTO THE  
EVENING HOURS. STORMS WILL BE MOST LIKELY OVER PORTIONS OF THE  
PACIFIC NORTHWEST INTO THE NORTHERN ROCKIES. HERE, FORECAST  
SOUNDINGS SHOW A DRY BOUNDARY LAYER EXTENDING TO AT LEAST 700 MB,  
SUGGESTING THAT A MIX OF WET AND DRY THUNDERSTORMS MAY OCCUR.  
REGARDLESS OF PRECIPITATION PRODUCTION, SOME OF THESE STORMS MAY  
OVERSPREAD PATCHES OF VERY DRY FUELS THAT MAY BE EASILY IGNITED BY  
LIGHTNING, WARRANTING THE CONTINUANCE OF DRY THUNDERSTORM HIGHLIGHTS  
OVER THE PACIFIC NORTHWEST TO NORTHERN ROCKIES.  
   
..PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT  
 
 
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