903  
FXUS65 KBOI 230955 CCA  
AFDBOI  
 
AREA FORECAST DISCUSSION...CORRECTED  
NATIONAL WEATHER SERVICE BOISE ID  
326 AM MDT SAT OCT 23 2021  
   
SHORT TERM...TODAY THROUGH MONDAY NIGHT
 
PRECIPITATION HAS  
GENERALLY ENDED IN OUR CWA FOR THE TIME BEING. THE NEXT PACIFIC  
TROUGH WAS NEARING THE COAST THIS MORNING BUT WILL WEAKEN AS IT  
COMES INLAND TO OUR CWA WITH ONLY LIGHT RAIN SHOWERS TODAY AND  
TONIGHT. THESE SHOWERS SHOULD BE MAINLY IN THE MOUNTAINS WITH  
RAIN AMOUNTS LESS THAN A TENTH OF AN INCH. AN INTENSE STORM WILL  
DEVELOP IN THE NORTH PACIFIC LATER TODAY AND TONIGHT AND MOVE TO  
NEAR 45/130 OFF WASHINGTON SUNDAY. FROM THAT POSITION THE STORM  
WILL SEND A MAJOR SURGE OF PRECIPITATION INLAND INTO OUR CWA  
SUNDAY THROUGH MIDDAY MONDAY. IN ADDITION, SOUTHEAST WINDS WILL  
INCREASE IN EASTERN OREGON AND IN SOUTHERNMOST IDAHO. SUSTAINED  
WINDS 25 TO 35 MPH WITH GUSTS TO 55 MPH ARE EXPECTED. GUSTS TO 65  
MPH WILL BLOW OVER THE HIGHER MOUNTAINS. A WIND ADVISORY HAS BEEN  
ISSUED FOR NEARLY ALL OF EASTERN OREGON, AND IDAHO SOUTH OF OF THE  
SNAKE RIVER. HEAVY RAIN WILL BEGIN IN HARNEY COUNTY/OR EARLY  
SUNDAY MORNING AND SPREAD RAPIDLY EAST-NORTHEAST ACROSS WESTERN  
IDAHO BY NOON AND CONTINUE THROUGH SUNDAY NIGHT. RAIN WILL CONTINUE  
INTO MONDAY ON THE IDAHO SIDE, BUT WILL DECREASE IN EASTERN OREGON.  
TOTAL RAINFALL BETWEEN 6 AM MDT SUNDAY AND 6 PM MDT MONDAY WILL BE  
1 TO 2 INCHES IN THE MOUNTAINS OF EASTERN OREGON AND THROUGHOUT  
WESTERN IDAHO NORTH OF THE SNAKE BASIN. AMOUNTS IN THE SNAKE BASIN  
DURING THAT TIME PERIOD SHOULD BE .50 TO .75 INCH, AND IN SOUTHERN  
HARNEY AND MALHEUR COUNTIES ABOUT A HALF INCH. FOR THE ENTIRE STORM  
ANOTHER HALF INCH MAY FALL. HEAVY RAIN FALLING ON STEEP TERRAIN  
MAY BRING DOWN MUD AND ROCKS, AND TRAVELERS WOULD BE WISE TO AVOID  
THOSE AREAS. PRECIPITATION WILL BE ALMOST ENTIRELY RAIN, WITH  
ACCUMULATING SNOW ONLY ABOVE 6500-7000 FEET.  
   
LONG TERM...TUESDAY THROUGH SATURDAY
 
A SHORTWAVE TROUGH WILL  
ARRIVE ON TUESDAY AFTERNOON WITH SHOWERS EXPECTED THROUGH  
WEDNESDAY. SNOW LEVELS WILL BE AROUND 5500-6500FT WITH THIS  
SYSTEM. ZONAL FLOW WILL GENERALLY CONTINUE WEDNESDAY THROUGH  
FRIDAY BUT THE STORM TRACK WILL MOVE NORTHWARD AS A WEAK RIDGE  
SETS UP OVER THE GREAT BASIN. THIS WILL BRING GENERALLY DRY  
CONDITIONS, WITH A SLIGHT CHANCE OF SHOWERS ACROSS THE MOUNTAINS  
NORTH OF A LINE FROM BURNS/OR TO BOISE. TEMPERATURES WILL WARM  
TO AROUND 5-10 DEGREES ABOVE NORMAL BY THURSDAY LASTING THROUGH  
FRIDAY. A FRONTAL SYSTEM MAY ARRIVE FROM THE NORTHWEST ON  
SATURDAY, BUT FORECAST CONFIDENCE REMAINS LOW.  
 

 
   
AVIATION
 
MOSTLY VFR. PATCHY FOG IN MOUNTAIN VALLEYS THROUGH THIS  
MORNING, INCLUDING KBKE. ISOLATED TO SCATTERED SHOWERS TODAY ACROSS  
THE REGION. LOCAL MVFR/IFR CONDITIONS IN SHOWERS WITH MOUNTAIN  
OBSCURATION CONTINUING. SNOW LEVEL 6000 FT MSL. SURFACE WINDS: SW-SE  
5-15KT. WINDS ALOFT AT 10K FT MSL: SW-W 15-25KT.  
 
SUNDAY OUTLOOK...WIDESPREAD RAIN WILL ARRIVE WEST TO EAST SUNDAY  
MORNING, WITH PERIODS OF MODERATE TO HEAVY RAIN EXPECTED. SNOW  
LEVELS 6000-7000FT MSL SUNDAY MORNING RISING TO 8000-9000 FT MSL  
BY SUNDAY EVENING. MOUNTAINS OBSCURED. MVFR TO LIFR IN RAIN/SNOW.  
SURFACE WINDS SW-SE 20-30KT WITH GUSTS 35-45KT. WINDS ALOFT AT  
10KFT MSL INCREASING TO SW 50-70KT IN EASTERN OR BY 15Z/SUN AND  
SOUTHWEST ID BY 21Z/SUN.  
 

 
   
BOI WATCHES/WARNINGS/ADVISORIES
 
 
ID...WIND ADVISORY FROM NOON TO 9 PM MDT SUNDAY IDZ015-029-030.  
OR...WIND ADVISORY FROM NOON MDT /11 AM PDT/ TO 9 PM MDT /8 PM PDT/  
SUNDAY ORZ061>063.  
 

 
 

 
 
WWW.WEATHER.GOV/BOISE  
WWW.FACEBOOK.COM/NWSBOISE  
WWW.TWITTER.COM/NWSBOISE  
 
SHORT TERM...LC  
LONG TERM....KA  
AVIATION.....KA  
 
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