828  
FXUS65 KBOI 210842  
AFDBOI  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BOISE ID  
242 AM MDT SAT APR 21 2018  
   
SHORT TERM...TODAY THROUGH SUNDAY
 
A THROUGH OF LOW PRESSURE  
WILL SWING ITS WAY EASTWARD THROUGH THE PACIFIC NORTHWEST TODAY.  
THE MID-LEVEL PORTION OF THE TROUGH WILL PASS THROUGH EASTERN  
OREGON AND SOUTHWEST IDAHO THIS MORNING AND BE EAST OF THE AREA BY  
EARLY AFTERNOON. AT THE SURFACE A COLD FRONT WILL WORK ITS WAY  
THROUGH THE AREA LATE MORNING THROUGH MID AFTERNOON. THE FRONT  
WILL BE ACCOMPANIED BY A SURGE OF NORTHWESTERLY WINDS. THIS WILL  
MAKE FOR ANOTHER BREEZY AFTERNOON FOR NEARLY ALL VALLEY LOCATIONS.  
OTHER THAN THE WIND, THERE WILL BE A SLIGHT INCREASE IN CLOUD  
COVER. ANOTHER TROUGH OF LOW PRESSURE IS ANTICIPATED FOR SUNDAY  
AFTERNOON. THE MODELS ARE IN GENERAL AGREEMENT THAT THIS TROUGH  
WILL PROVIDE ENOUGH INSTABILITY TO GENERATE ISOLATED SHOWERS AND A  
FEW THUNDERSTORMS LATE SUNDAY. LIMITED MOISTURE WILL MEAN THAT  
CONVECTION WILL BE FAVORED OVER HIGHER TERRAIN. IN THIS CASE THE  
BOISE MOUNTAINS WILL HAVE THE BEST CHANCE OF FIRING UP A SHOWER OR  
TWO. TEMPERATURES WILL HOVER SLIGHTLY ABOVE NORMAL FOR MOST  
AREAS.  
   
LONG TERM...SUNDAY NIGHT THROUGH FRIDAY
 
SUNDAY NIGHT AND  
MONDAY THE UPPER LEVEL TROUGH WILL CONTINUE TO GENERATE SHOWERS,  
MAINLY OVER THE HIGHER TERRAIN. WITH THE COLDEST AIR ALOFT OVER OUR  
AREA SUNDAY EVENING, MARGINAL INSTABILITY WILL SUPPORT A SLIGHT  
CHANCE OF THUNDERSTORMS. SHOWERS WILL END MONDAY EVENING AS THE  
TROUGH EXITS TO THE EAST AND A WARM UPPER LEVEL HIGH PRESSURE RIDGE  
BUILDS OVER THE INTERMOUNTAIN REGION. THE RIDGE WILL MAINTAIN DRY  
WEATHER AT LEAST THROUGH FRIDAY, AND TEMPERATURES WILL AVERAGE 5 TO  
10 DEGREES ABOVE NORMAL THROUGH SATURDAY. FRIDAY NIGHT AND SATURDAY  
MODELS SHOW AN UPPER LEVEL TROUGH APPROACHING THE RIDGE FROM THE  
WEST, BUT SOLUTIONS DIFFER, AND IT IS STILL UNCERTAIN HOW MUCH AND  
WHEN THIS FEATURE WILL EFFECT OUR WEATHER.  
 

 
   
AVIATION
 
VFR UNDER MOSTLY CLEAR SKIES. SURFACE WINDS VARIABLE 5-  
10 KTS BECOMING NORTHWEST 10-20 KTS AFTER 18Z. WINDS ALOFT NEAR 10K  
FT MSL WEST 15-25 KTS.  
 
SUNDAY OUTLOOK...VFR. ISOLATED AFTERNOON AND EVENING THUNDERSTORMS  
OVER THE HIGHER TERRAIN.  
 

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

 
 

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