920  
FXUS65 KBOI 202157  
AFDBOI  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BOISE ID  
257 PM MST TUE FEB 20 2018  
   
SHORT TERM...TONIGHT THROUGH THURSDAY
 
THE COLD AIR MASS  
WILL BE PUNCTUATED BY A COUPLE OF STORM SYSTEMS THAT MOVE THROUGH  
THE REGION. THE FIRST WAVE WILL BE THE WEAKER OF THE TWO, MOVING  
INTO SOUTHEAST OREGON WITH LIGHT SNOW LATE TONIGHT. LOWER VALLEYS  
OF SOUTHWEST IDAHO COULD SEE A SNOW SHOWER, ESPECIALLY IN THE  
LOWER TREASURE VALLEY, BUT GENERALLY PRECIPITATION WILL FOCUS OVER  
SOUTHEAST OREGON AND MOUNTAINS OF SOUTHWEST IDAHO. THE NEXT WAVE  
DROPS NORTH TO SOUTH ALONG THE COAST LATE WED/THUR. THIS TRACK  
WILL AGAIN FOCUS SNOWFALL ACROSS SOUTHEAST OREGON. DO SEE A BETTER  
CHANCE OF LIGHT SNOW ACROSS THE TREASURE VALLEY AND SOUTHWEST  
IDAHO MOUNTAINS THURSDAY MORNING AS A SURFACE LOW WRAPS UP OVER  
NORTHERN NV. TEMPERATURES WILL HOLD BETWEEN 10 AND 15 DEGREES  
BELOW NORMAL THROUGH THURSDAY.  
 
   
LONG TERM...THURSDAY NIGHT THROUGH TUESDAY
 
THE COLD UPPER LEVEL  
TROUGH OVER THE WESTERN U.S. THURSDAY NIGHT WILL MIGRATE SLOWLY  
EAST ON FRIDAY AS A WEAK TROUGH APPROACHES FROM THE GULF OF  
ALASKA. PRECIPITATION WILL END BY FRIDAY AFTERNOON, BUT THE  
ONCOMING TROUGH WILL BRING ANOTHER ROUND OF SNOW SHOWERS WILL  
ARRIVE OVER OUR NORTHERN ZONES FRIDAY NIGHT AND SPREAD SOUTH TO  
THE NEVADA BORDER ON SATURDAY. SNOW WILL CONTINUE THROUGH SUNDAY  
IN THE MOUNTAINS BUT DECREASE TO ISOLATED IN THE VALLEYS.  
TEMPERATURES WILL AVERAGE 10 TO 15 DEGREES BELOW NORMAL ON FRIDAY,  
5 TO 10 DEGREES BELOW NORMAL ON SATURDAY, AND AROUND 5 DEGREES  
BELOW NORMAL ON SUNDAY.  
 
SUNDAY EVENING THROUGH WEDNESDAY MORNING...TROUGHING EXPECTED TO  
BE THE DOMINANT, INFLUENTIAL FEATURE AFFECTING THE AREA WITH  
EMBEDDED TROUGH-RIDGE COUPLETS PERIODICALLY PROPAGATING ACROSS THE  
CWA. MODELS IN AGREEMENT WITH THE HANDLING OF THESE FEATURES AND  
WEATHER RAMIFICATIONS THEREOF. EXPECT PERIODS OF MOSTLY CLOUDY  
CONDITIONS, WIDE-SPREAD SNOWFALL, AND GUSTIER NORTHWESTERLY WINDS.  
GENERAL WIND FLOW WILL BE BREEZY NORTHWEST WIND...STRONGER IN  
HIGHER MOUNTAINOUS AREAS. HEAVIEST ACTIVITY EXPECTED TO BE FROM  
SUNDAY EVENING THROUGH MONDAY WITH GRADUAL LESSONING OF ACTIVITY  
BEYOND THAT. TEMPERATURES AROUND 3-5 DEGREES BELOW NORMAL.  
 

 
   
AVIATION
 
MAINLY VFR. SNOW SHOWERS SPREADING INTO EASTERN OREGON  
AND THE WEST CENTRAL IDAHO MOUNTAINS LATE TONIGHT, BECOMING MORE  
WIDESPREAD WEDNESDAY MORNING NORTH OF A KREO-KONO-KSNT LINE.  
ISOLATED SNOW SHOWERS ELSEWHERE. IMPROVING CONDITIONS WEDNESDAY  
AFTERNOON. SURFACE WINDS MAINLY SOUTHEAST 10 KTS OR LESS TONIGHT  
INCREASING TO 10-15 KTS WEDNESDAY AFTERNOON. WINDS ALOFT AT 10K FT  
MSL VARIABLE LESS THAN 10 KTS EXCEPT WEST 10-20 KTS SOUTHEAST OF  
KMUO. WINDS ALOFT AT 10K FT MSL WEST 10-20 KTS.  
 

 
 
   
BOI WATCHES/WARNINGS/ADVISORIES
 
 
ID...NONE.  
OR...NONE.  
 

 
 

 
 
WWW.WEATHER.GOV/BOISE  
WWW.FACEBOOK.COM/NWSBOISE  
WWW.TWITTER.COM/NWSBOISE  
 
SHORT TERM...DG  
LONG TERM....JT/WH  
AVIATION.....JT  
 
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