539  
FXUS65 KBOI 261454  
AFDBOI  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BOISE ID  
854 AM MDT SUN MAR 26 2017  
   
DISCUSSION
 
PACIFIC FRONTAL SYSTEM NOW ONSHORE AND MAKING STEADY  
EASTWARD PROGRESS ACROSS WESTERN WA AND OR. SYSTEM WILL BRING RAIN  
AND MOUNTAIN SNOW NEARLY EVERYWHERE THIS AFTERNOON AND TONIGHT. POST-  
FRONTAL NORTHWEST WINDS WILL INCREASE TO 20-35 MPH MONDAY AFTERNOON  
IN THE UPPER TREAASURE VALLEY AND WESTERN MAGIC VALLEY. THE SNAKE  
RIVER AT WEISER, AND THE BOISE RIVER AT GLENWOOD IN BOISE, WILL  
CONINUE IN MINOR FLOOD THROUGH AT LEAST TUESDAY. NO UPDATES.  
 

 
   
AVIATION...VFR CONDITIONS CONTINUE THIS MORNING
 
BUT TRENDING TO  
MVFR ACROSS KBNO 16-18Z. KBKE AND KMYL SHOULD SEE CONDITIONS  
LOWERING TO MVFR/IFR AROUND 21Z AND KBOI AND SITES EAST AROUND 00Z.  
PRECIP STARTS AS RAIN ACROSS MOST LOCATIONS BECOMING SNOW ABOVE 5000  
FEET THIS EVENING. SURFACE WINDS EAST TO SOUTHEAST 5 TO 15 KTS ACROSS  
SOUTHWEST IDAHO AND GENERALLY SOUTH TO SOUTHWEST IN EASTERN OREGON.  
WINDS SHIFTING WEST TO NORTHWEST BY 27/1200Z. 10KFT WINDS GENERALLY  
15 TO 20 KTS FROM THE SOUTHWEST.  
 

 
   
PREV DISCUSSION
 
 
SHORT TERM...TODAY THROUGH MONDAY...A BROAD TROUGH OF LOW PRESSURE  
IS POISED TO MOVE ASHORE IN THE PACIFIC NORTHWEST TODAY.  
THE LEADING EDGE OF THE TROUGH AND ASSOCIATED MOISTURE AND CLOUD  
COVER IS CURRENTLY MOVING OVERHEAD IN WESTERN WASHINGTON. NO  
SHOWER ACTIVITY IS PRESENT ACROSS MUCH OF THE INTERIOR PACIFIC  
NORTHWEST, HOWEVER, COASTAL RADARS ARE INDICATING PRECIPITATION IS  
NOT FAR OFF-SHORE.  
 
THE TROUGH IS EXPECTED TO MOVE INTO WASHINGTON AND OREGON TODAY,  
AND ACROSS IDAHO OVERNIGHT AND INTO SUNDAY. A WARM FRONT  
ASSOCIATED WITH THE TROUGH WILL PUSH SOUTH TO NORTH ACROSS THE  
AREA TODAY WITH PRECIPITATION FAVORING NORTHERN LOCATIONS AND  
HIGHER TERRAIN. SIGNIFICANT PRECIPITATION IS ANTICIPATED WHEN THE  
SYSTEMS COLD FRONT MOVES THROUGH LATE TODAY AND OVERNIGHT.  
FORECAST MODELS ARE IN GOOD AGREEMENT THAT A CONSOLIDATED BAND OF  
PRECIPITATION WILL ACCOMPANY THE COLD FRONT, ALONG WITH DROPPING  
SNOW LEVELS. VALLEY LOCATIONS WILL GENERALLY SEE BETWEEN 0.15 AND  
0.25 INCHES OF PRECIPITATION, WHILE MOUNTAIN LOCATIONS WILL SEE  
BETWEEN 0.33 AND 0.75 INCHES. SNOW LEVELS WILL START OUT AROUND  
6000 FEET AND DROP CLOSER TO 5000 FEET BY EARLY MONDAY. THIS WILL  
ALLOW FOR MORE WHITENING OF THE HIGHER TERRAIN OF BOTH SE OREGON  
AND SW AND CENTRAL IDAHO. GUSTY NORTHWEST WINDS ARE ANTICIPATED  
BEHIND THE FRONT FOR MUCH OF THE DAY MONDAY. TEMPERATURES WILL  
GENERALLY BE AT TO SLIGHTLY ABOVE NORMAL TODAY, THEN SLIGHTLY  
BELOW NORMAL ON MONDAY.  
 
LONG TERM...MONDAY NIGHT THROUGH SATURDAY...A RIDGE WILL TRANSITION  
ACROSS THE AREA ON TUESDAY, WITH DRY CONDITIONS. ON WEDNESDAY, A  
TROUGH BEGINS TO DIG ALONG THE PACIFIC NW COAST, SETTING UP  
SOUTHWEST FLOW OVER EASTERN OREGON AND SW IDAHO. AS THIS SYSTEM  
APPROACHES, WARMER SOUTHWEST FLOW DEVELOPS BRINGING IN WARMER AIR ON  
WEDNESDAY. AN IMPRESSIVE MOISTURE FIELD DEVELOPS LATE WEDNESDAY  
NIGHT WITH WIDESPREAD PRECIPITATION ACROSS THE REGION. PRECIPITATION  
AMOUNTS ARE HEALTHY WITH THIS SYSTEM, AS THE CENTER OF THE TROUGH  
PASSES BY OVERHEAD, WITH THE MOUNTAINS RECEIVING 1.0 TO 1.5 INCHES  
OF LIQUID EQUIVALENT. ALTHOUGH SNOW LEVELS START OUT AT 7000-7500FT  
WITH THE ONSET OF PRECIPITATION, SNOW LEVELS BEGIN TO FALL TO AROUND  
5000FT MIDDAY ON THURSDAY. SIGNIFICANT SNOW WILL FALL ON THE PEAKS  
ABOVE 8000FT. RIDGING BUILDS INTO THE PACIFIC NW ON FRIDAY, BRINGING  
COOL NORTH-NORTHEASTERLY FLOW THROUGH SATURDAY. TEMPERATURES WILL  
GENERALLY BE BELOW NORMAL THROUGH THE EXTENDED PERIOD, WITH THE  
EXCEPTION OF WEDNESDAY.  
 

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

 
 

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