656  
FXUS65 KPIH 051003  
AFDPIH  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE POCATELLO ID  
303 AM MST FRI MAR 5 2021  
   
SHORT TERM
 
TODAY THROUGH SUNDAY.  
 
EXPECT ANOTHER PLEASANT DAY WITH ABOVE NORMAL TEMPS,  
LIGHT WINDS AND NO PRECIPITATION. A WEAK COLD FRONT WILL ARRIVE ON  
SUNDAY. QUITE A BIT OF DRY AIR ACROSS THE REGION, SO MOST IF NOT ALL  
OF THE PRECIPITATION WITH THIS FRONT WILL OCCUR OVER THE HIGH  
COUNTRY. PRECIPITATION WILL BE MAINLY CONFINED TO THE FRONT AS WELL,  
SO MOST OF IT WILL OCCUR SATURDAY AFTERNOON. SNOW LEVELS ARE BETWEEN  
5500-6500 FT WITH THIS SYSTEM. AMOUNTS LOOK VERY LIGHT WITH AN INCH  
OR LESS LIKELY IN AREAS THAT RECEIVE SNOW. POSSIBLY UP TO 2 INCHES  
NEAR PASSES SUCH AS GALENA AND BANNER SUMMITS. EXPECT WINDY  
CONDITIONS SATURDAY AFTERNOON BUT PERHAPS NOT QUITE TO WIND ADVISORY  
LEVELS. WITH THE SNOWPACK RECEDING AND THE DRY WINDY WEATHER  
EXPECTED SATURDAY WOULDN'T BE SURPRISED TO SEE A COUPLE BRUSH FIRES  
POP UP.  
 
TEMPERATURES COOL OFF A COUPLE DEGREES BEHIND THE FRONT ON SUNDAY  
WITH DRY WEATHER ACROSS THE REGION.  
 
13  
   
LONG TERM
 
MONDAY THROUGH NEXT FRIDAY NIGHT. MONDAY WILL SIGNAL  
THE BEGINNING OF A PATTERN CHANGE ACROSS THE REGION AS AN AREA OF  
LOW PRESSURE AND ATTENDANT STRONG COLD FRONT APPROACHES FROM THE  
WEST. DETERMINISTIC AND ENSEMBLE MODEL GUIDANCE ARE ALL IN  
REASONABLY GOOD AGREEMENT, WHICH AIDS FORECASTER CONFIDENCE. FOR THE  
DAYLIGHT HOURS ON MONDAY, CENTRAL AND EASTERN IDAHO WILL RESIDE ON  
THE WARM SIDE OF THIS SYSTEM, WITH THE COLD FRONT LURKING TO THE  
WEST. SNOW SHOWERS WILL DEVELOP ACROSS THE CENTRAL IDAHO MOUNTAINS  
MONDAY MORNING, WITH ACTIVITY EXPANDING ACROSS THE MONTANA BORDER  
REGION AND ISLAND PARK AREAS BY LATE AFTERNOON/EARLY EVENING. A  
NORTHEAST TO SOUTHWEST BAND OF PRECIPITATION FORCED BY UPPER JET/MID-  
LEVEL FRONTAL FORCING IS THEN EXPECTED TO DEVELOP ACROSS THE EASTERN  
HIGHLANDS OR EASTERN SNAKE PLAIN (THERE REMAINS SOME UNCERTAINTY ON  
PLACEMENT) MONDAY EVENING. THIS BAND OF PRECIPITATION IS LIKELY TO  
CONTINUE INTO TUESDAY MORNING. SNOW LEVELS ARE INITIALLY EXPECTED TO  
BE BETWEEN 6-6,500 FEET WHEN PRECIPITATION BEGINS, BUT A COMBINATION  
OF COLD ADVECTION AND DIABATIC COOLING WILL CAUSE SNOW LEVELS TO  
FALL TO VALLEY FLOORS AROUND OR SHORTLY AFTER MIDNIGHT. AS THE LONG  
TERM PORTION OF THE FORECAST PERIOD PROGRESSES, A BROAD LONGWAVE  
TROUGH IS EXPECTED TO TAKE UP RESIDENCE ACROSS THE WESTERN CONUS IN  
THE TUESDAY-THURSDAY TIMEFRAME BEFORE IT IS REPLACED WITH BROAD  
NORTHWEST FLOW BY LATE WEEK. WITH THE PRESENCE OF THE TROUGH AND  
ASSOCIATED COLD AIR ALOFT, ANY DECENT DURATION OF SUNSHINE WILL  
STEEPEN LAPSE RATES AND PROMOTE DIURNALLY-ENHANCED SHOWERS,  
ESPECIALLY FROM MID AFTERNOON THROUGH EARLY EVENING. OTHERWISE, NO  
STRONG FORCING MECHANISMS WILL BE IN PLACE TO FORCE, ORGANIZED  
WIDESPREAD PRECIPITATION FROM TUESDAY-THURSDAY, SO ACTIVITY WILL BE  
ESPECIALLY DIURNALLY ENHANCED. A WEAK SHORTWAVE IS FORECAST TO BE  
SLIDING SOUTHEAST THROUGH THE NORTHWEST FLOW ALOFT BY FRIDAY,  
PROMOTING HIGH-ELEVATION SNOW SHOWER ACTIVITY.  
 
AD  
 

 
   
AVIATION
 
VFR CONDITIONS ARE EXPECTED TO PERSIST THROUGH THE  
PERIOD AS A RIDGE OF HIGH PRESSURE SLIDES OFF TO THE EAST. AN  
APPROACHING TROUGH WILL STRENGTHEN THE PRESSURE GRADIENT TONIGHT INTO  
SATURDAY MORNING, AND AS SUCH, MID-UPPER LEVEL FLOW WILL INCREASE.  
FORECAST SOUNDINGS INDICATE SSW WINDS INCREASING INTO THE 35-45KT  
RANGE BETWEEN 1-2KFT SATURDAY MORNING SHORTLY AFTER SUNRISE -- WITH  
A SIMILAR REGIME INDICATED FOR KBYI, KIDA AND KDIJ. THEREFORE, WILL  
NEED TO ADD A WIND SHEAR MENTION FOR THESE SITES AT THE TAIL-END OF  
THE FORECAST. WINDS WILL INCREASE JUST OFF THE SURFACE AT KSUN AS  
WELL, BUT ARE SHOWN TO CLOCK IN JUST BELOW WIND SHEAR THRESHOLDS.  
 
AD  
 

 
   
PIH WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  

 
 

 
 
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