798  
FXUS65 KBOI 080433  
AFDBOI  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BOISE ID  
933 PM MST WED DEC 7 2022  
   
DISCUSSION
 
FOG AND LOW STRATUS ARE EXPANDING ACROSS THE SNAKE  
BASIN THIS EVENING AND WILL CONTINUE TO FILL UP THE VALLEYS BELOW  
ABOVE 4500 FEET MSL TONIGHT. NEXT SYSTEM WILL ARRIVE LATE  
THURSDAY, BRINGING LIGHT SNOW TO ALL AREAS. THE SYSTEM WILL WEAKEN  
CONSIDERABLY AS IT MOVES ACROSS OUR REGION, SO LIGHT SNOW  
ACCUMULATIONS EXPECTED. FOLLOWING SYSTEM ON FRIDAY NIGHT LOOKS  
STRONGER AND WARMER. FORECAST UPDATE OUT SHORTLY.  
 

 
   
AVIATION
 
AREAS OF IFR/LIFR CONDITIONS DUE TO LOW CLOUDS AND DENSE  
FOG WILL RETURN THIS EVENING. FOG/STRATUS WILL PERSIST THROUGH MUCH  
OF THURSDAY MORNING BEFORE DISSIPATING BY EARLY AFTERNOON. NEXT  
SYSTEM WILL BRING SNOW TO SE OREGON THURSDAY NIGHT AND INTO SW IDAHO  
FRIDAY MORNING. MTNS OBSCURED. SURFACE WINDS: VARIABLE LESS THAN 10  
KT EXCEPT EAST 5-15 KTS FROM KJER/KTWF WEST THROUGH KMUO. WIND ALOFT  
AT 10KFT MSL: W-SW 10-20 KT.  
 

 
   
PREV DISCUSSION
 
 
SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT...THE EAST-SOUTHEAST  
WINDS MOVING DOWN THE SNAKE PLAIN THIS AFTERNOON HAVE ERODED THE  
STRATUS SOUTHEAST OF BOISE. THE STRATUS MAY CONTINUE TO ERODE  
FURTHER WESTWARD INTO THE LOWER TREASURE VALLEY, BUT IT IS NOT  
EXPECTED TO COMPLETELY CLEAR OUT OF THE LOWER VALLEYS THROUGH  
THURSDAY MORNING. THE PATCHY FOG WILL CONTINUE IN THESE AREAS  
THROUGH THURSDAY MORNING. THE FOG MAY BE LOCALLY DENSE. A WEAK  
UPPER RIDGE WILL MOVE ACROSS THE AREA FOR DRY CONDITIONS THROUGH  
THURSDAY MORNING. THE FIRST OF TWO PACIFIC TROUGHS WILL SPREAD  
SNOW INTO SOUTHEAST OREGON LATE THURSDAY AFTERNOON AND EVENING,  
AND ACROSS SOUTHWEST IDAHO THURSDAY NIGHT INTO FRIDAY MORNING.  
SNOWFALL ACCUMULATIONS WILL GENERALLY RANGE FROM 1 TO 3 INCHES IN  
THE VALLEYS AND 3 TO 6 INCHES IN THE MOUNTAINS. THERE WILL BE A 6  
TO 12 HOUR DRY PERIOD ON FRIDAY BEFORE THE SECOND SYSTEM STARTS TO  
MOVE INTO THE AREA FRIDAY NIGHT. ADDITIONAL SNOW ACCUMULATIONS  
ARE LIKELY BY EARLY FRIDAY MORNING WITH MORE SNOW THROUGH THE  
WEEKEND (SEE DISCUSSION BELOW FOR DETAILS). TEMPERATURES WILL  
REMAIN SEVERAL DEGREES BELOW NORMAL. WINDS WILL BE GUSTY AT TIMES,  
ESPECIALLY THURSDAY AFTERNOON-EVENING AND AGAIN LATE FRIDAY  
NIGHT.  
 
LONG TERM...SATURDAY THROUGH WEDNESDAY...A DEEP AND STRONG UPPER  
LEVEL LOW WILL SLIDE DOWN THE PACIFIC COAST FROM CANADA TO OFF OF  
OREGON SATURDAY INTO SUNDAY, PUTTING US IN SOUTHWEST FLOW ALOFT.  
THIS WILL BRING MOISTURE AND WARMER AIR INTO THE REGION. WITH COLD  
AIR ALREADY IN PLACE, ALL ELEVATIONS WILL SEE SNOW SATURDAY  
MORNING, BUT AROUND NOON SNOW IS EXPECTED TO MIX WITH OR CHANGE TO  
RAIN BELOW ROUGHLY 2900 FT. THERE IS A SIGNIFICANT AMOUNT OF  
DISAGREEMENT ON THIS, HOWEVER, WITH SOME MODELS KEEPING THE SNOW  
LEVEL LOW ENOUGH TO RESULT IN SNOW THROUGH THE DAY. HOPEFULLY,  
FUTURE RUNS WILL START TO CONVERGE ON THIS AND WE CAN HAVE A BIT  
MORE CONFIDENCE IN THE SNOW LEVEL FORECAST. IT IS IMPORTANT  
BECAUSE IF IT'S ALL SNOW, THE LOWER TREASURE EXTENDING EAST INTO  
ELMORE COUNTY COULD SEE 3 TO 7 INCHES OF SNOW, WHEREAS THE CURRENT  
FORECAST HAS 1 TO 4 INCHES BEFORE SNOW MIXES WITH OR CHANGES TO  
RAIN (SEVERELY LIMITING FURTHER ACCUMULATION). MODELS ARE IN  
BETTER AGREEMENT ON HIGH TEMPERATURES SATURDAY, WITH MOST OF THE  
SNAKE PLAIN FROM TWIN FALLS TO ONTARIO RISING INTO THE UPPER 30S.  
HEAVY SNOW IS FORECAST FOR THE MOUNTAINS, AND IT IS LIKELY THAT  
HEADLINES (ANOTHER WATCH OR WARNING) WILL BE NEEDED AFTER THE ONE  
CURRENTLY OUT FOR THU/FRI EXPIRES. SNOW TOTALS IN THE MOUNTAINS  
WITH THIS SYSTEM WILL GENERALLY RANGE FROM 9 TO 18 INCHES, BUT  
AMOUNTS OVER 2 FT ARE POSSIBLE ON THE HIGHEST PEAKS (AMOUNTS FROM  
FRIDAY NIGHT THROUGH SUNDAY).  
 
PRECIPITATION WILL LAST THROUGH SATURDAY NIGHT AND MOST OF SUNDAY  
BEFORE TAPERING OFF SUNDAY NIGHT FROM WEST TO EAST AS THE UPPER  
LOW MOVES BY JUST TO THE SOUTH OF NV BORDER. THIS WILL BRING A  
COLD FRONT AND SWITCH ANY RAIN BACK TO SNOW SUNDAY NIGHT. BY THAT  
TIME, HOWEVER, MOST OF THE EVENT WILL BE OVER, SO ONLY MINOR SNOW  
AMOUNTS ARE FORECAST BELOW 3000 FT. MONDAY THROUGH WEDNESDAY  
SHOULD BE DRY, WITH ONLY A SLIGHT CHANCE OF SNOW SHOWERS MAINLY IN  
THE MOUNTAINS.  
 

 
   
BOI WATCHES/WARNINGS/ADVISORIES
 
 
ID...WINTER WEATHER ADVISORY FROM 5 PM THURSDAY TO 11 AM MST FRIDAY  
IDZ011>014-028-029-033.  
OR...WINTER WEATHER ADVISORY FROM 5 PM THURSDAY TO 11 AM MST FRIDAY  
ORZ061>064.  
 

 
 

 
 
WWW.WEATHER.GOV/BOISE  
WWW.FACEBOOK.COM/NWSBOISE  
WWW.TWITTER.COM/NWSBOISE  
 
DISCUSSION...KA  
AVIATION.....JDS  
PREV SHORT TERM...BW  
PREV LONG TERM....SP  
 
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