465  
FXUS65 KBOI 282119  
AFDBOI  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BOISE ID  
219 PM MST MON NOV 28 2022  
   
SHORT TERM...TONIGHT THROUGH WEDNESDAY NIGHT
 
TODAY'S WINTER  
WEATHER ADVISORY WAS CANCELLED AROUND 130 PM MST AS KCBX RADAR  
INDICATED ONLY SCATTERED LIGHT SNOW SHOWERS STILL FALLING AND  
MAINLY IN REMOTE AREAS OF OWYHEE COUNTY. SNOW SHOWERS WILL END  
IN ALL AREAS THIS EVENING AND SKIES WILL PARTIALLY CLEAR ABOVE  
NEW SNOW COVER RESULTING IN MUCH COLDER TEMPERATURES BY MORNING.  
RESIDUAL MOISTURE NEAR THE GROUND WILL DEVELOP PATCHY DENSE FOG  
IN THE VALLEYS. AFTER A PARTLY CLOUDY AND COLD DAY TUESDAY CLOUDS  
WILL SPREAD IN FROM THE NORTHWEST TUESDAY EVENING AHEAD OF AN  
APPROACHING PACIFIC WARM FRONT. THE WARM FRONT WILL SPREAD LIGHT  
SNOW ACROSS THE NORTHERN HALF OF OUR CWA TUESDAY NIGHT AND BRING  
MILDER TEMPERATURES. ON WEDNESDAY WINDS ALOFT WILL BACK FROM  
NORTHWESTERLY TO WESTERLY AND TAP INTO MOIST AIR IN THE PACIFIC  
SOUTH OF 40N AND WEST OF 135W. THIS MOISTURE WILL COME INTO OUR  
CWA BEGINNING LATE WEDNESDAY AS AN UPPER TROUGH DEEPENS ALONG THE  
NORTHWEST COAST. AN ATMOSPHERIC RIVER WILL TAKE SHAPE FROM THE  
SUBTROPICAL PACIFIC INTO OREGON AND CENTRAL IDAHO WEDNESDAY NIGHT  
AND PERSIST THROUGH THURSDAY AND THURSDAY NIGHT, LIKELY RESULTING  
IN HEAVY SNOW OVER THE HIGHER TERRAIN (ABOVE 4000 FEET MSL) OF  
OUR CWA NORTH OF THE SNAKE BASIN. LOWER ELEVATIONS WILL HAVE ONLY  
RAIN OR MIXED RAIN AND SNOW UNTIL THE UPPER TROUGH COMES INLAND  
WITH COLDER AIR THURSDAY. A WINTER STORM WATCH HAS BEEN ISSUED FOR  
THIS EVENT IN BAKER COUNTY (EXCEPT THE I-84 CORRIDOR) AND IN THE  
IDAHO MOUNTAINS NORTH OF THE SNAKE BASIN BEGINNING LATE WEDNESDAY  
OR WEDNESDAY EVENING.  
   
LONG TERM...THURSDAY THROUGH MONDAY
 
A LONG LASTING PRECIPITATION  
EVENT WILL DOMINATE THE EARLY PART OF THE EXTENDED PERIOD, WITH COLD  
AND WET CONDITIONS LIKELY AGAIN SUNDAY INTO MONDAY. A TROUGH WILL  
MOVE INTO THE REGION EARLY THURSDAY, BRINGING COLDER AIR AND  
WIDESPREAD PRECIPITATION THROUGH EARLY SATURDAY. THERE IS HIGH  
FORECAST CONFIDENCE IN ELEVATIONS ABOVE 3500 FEET MSL RECEIVING  
12-18 INCHES OF SNOW, WITH SOME ESPECIALLY HIGH-ELEVATION PASSES  
AND RIDGETOPS RECEIVING UP TO TWO FEET OF SNOW WITH THIS SYSTEM.  
THE LONG DURATION NATURE OF THIS EVENT AND ACCUMULATION POTENTIAL  
NECESSITATED A WINTER STORM WATCH FOR MOST ZONES IN THE CENTRAL  
MOUNTAINS THROUGH FRIDAY. THERE IS LOW FORECAST CONFIDENCE IN  
LOW-ELEVATION VALLEY PRECIPITATION TYPE AND TEMPERATURES, AND  
THEREFORE SNOW ACCUMULATION IN MOST LOW-ELEVATION VALLEYS ON  
THURSDAY INTO FRIDAY. MOST VALLEYS WILL SEE AT LEAST A QUARTER TO  
A HALF INCH OF WATER EQUIVALENT PRECIPITATION THURSDAY THROUGH  
EARLY SATURDAY, WITH VARIATION IN THE BAKER VALLEY, OR AND THE  
TREASURE VALLEY IN ID DEPENDING ON HOW MUCH SHADOWING OCCURS FROM  
THE MOUNTAINS TO THE SOUTHWEST. VALLEY TEMPERATURES ARE FORECAST  
TO BE IN UPPER 30S AND LOWER 40S DURING THE DAY ON THURSDAY. SOME  
ENSEMBLE MEMBERS SHOW UPWARD OF 2-4 INCHES FOR LOCATIONS IN THE  
TREASURE VALLEY BY LATE FRIDAY, WHILE THE AVERAGE OF ALL ENSEMBLE  
MEMBERS SHOWS MORE LIKE 1-2 INCHES BY LATE FRIDAY. CONDITIONS WILL  
ALSO BE FAIRLY WINDY THROUGH FRIDAY, WITH BREEZY EAST-SOUTHEAST  
WINDS ON THURSDAY, SHIFTING TO THE WEST-SOUTHWEST ON FRIDAY.  
EXPECT COLD CONDITIONS WITH A SLIGHT CHANCE OF LIGHT SNOW SHOWERS  
SATURDAY INTO SUNDAY. SIGNIFICANT MODEL UNCERTAINTY REMAINS WITH A  
CUTOFF LOW AND DEEP TROUGH MOVING INTO THE REGION FROM THE PACIFIC  
NORTHWEST ON SUNDAY INTO MONDAY, WITH MODELS DIVERGING ON  
PRECIPITATION TIMING, ACCUMULATION, AND LOCATION FOR SUNDAY INTO  
MONDAY.  
 

 
   
AVIATION
 
AREAS OF LOW CLOUDS AND PATCHY VALLEY FOG TUESDAY  
MORNING. ISOLATED IFR-LIFR SNOW SHOWERS, ENDING BY 29/06Z.  
MOUNTAINS OBSCURED. SURFACE WINDS: VARIABLE 5-10 KT BECOMING W-NW  
10-20 KT BY 28/18Z, STRONGEST ACROSS SE OR AND THE MAGIC VALLEY.  
WINDS ALOFT AT 10KFT MSL: W-NW 25-35 KT.  
 

 
   
BOI WATCHES/WARNINGS/ADVISORIES
 
 
ID...WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH LATE THURSDAY  
NIGHT IDZ011-033.  
WINTER STORM WATCH FROM WEDNESDAY AFTERNOON THROUGH LATE  
THURSDAY NIGHT IDZ013.  
WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH LATE THURSDAY  
NIGHT IDZ028.  
OR...WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH LATE THURSDAY  
NIGHT ORZ062.  
 

 
 

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