895  
FXUS65 KPIH 222039  
AFDPIH  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE POCATELLO ID  
139 PM MST WED JAN 22 2020  
   
SHORT TERM
 
TONIGHT THROUGH SATURDAY. EARLY AFTERNOON SATELLITE  
IMAGERY WAS SHOWING A LOW PRESSURE TROUGH WORKING INTO NW CANADA AND  
THE MEAN HIGH PRESSURE RIDGE AXIS POSITIONED OVER THE NW COAST.  
NUMERICAL MODELS SUGGEST THAT TRAILING MOISTURE AND ENERGY WILL TOP  
THE RIDGE AND SPILL INTO THE REGION TONIGHT IN THE NW FLOW ALOFT.  
THUS, LIGHT UPSLOPE SNOWFALL IS EXPECTED ON THE NW FACING ASPECTS OF  
THE CNTRL AND ERN MOUNTAINS TONIGHT AND THEN GRADUALLY TAPERING OFF  
THURSDAY AS THE RIDGE AXIS SHIFTS EAST INTO IDAHO AHEAD OF THE NEXT  
INCOMING PACIFIC STORM SYSTEM. PEAK SNOWFALL ACCUMULATIONS ARE  
EXPECTED RUN FROM 1 TO 3 INCHES OVER THE NEXT 24-HOURS, FALLING WELL  
BELOW ADVISORY LEVELS. THE NEXT INCOMING STORM ADVANCES THROUGH THE  
NW COAST FRIDAY MORNING AS ATTENDING PRECIPITATION SPREADS ACROSS SE  
IDAHO THROUGHOUT THE DAY EXITING EAST OF THE WYOMING BORDER BY  
FRIDAY EVENING. HERE AGAIN, WITH A FAIRLY FAST MOVING SYSTEM  
SWEEPING EAST THROUGH THE MEAN RIDGE AXIS, SNOW ACCUMULATIONS ARE  
EXPECTED TO RANGE FROM 1 TO 5 INCHES IN THE CNTRL AND ERN MOUNTAINS  
FALLING BELOW ADVISORY CRITERIA. IMPROVING CONDITIONS ARE  
ANTICIPATED FRIDAY NIGHT AND SATURDAY AS THE RIDGE REBOUNDS ACROSS  
THE REGION AHEAD OF YET ANOTHER PACIFIC STORM ADVANCING TOWARD THE  
NW COAST (MORE ON THAT BELOW). WITH ALL THE ACTIVITY, TEMPERATURES  
SHOULD REMAIN ABOVE CLIMATOLOGICAL NORMS THROUGH THE FORECAST  
PERIOD WITH GOOD ATMOSPHERIC MIXING. HUSTON  
   
LONG TERM
 
SATURDAY NIGHT THROUGH NEXT WEDNESDAY. UPPER RIDGING  
WILL BEGIN TO SHIFT EASTWARD SATURDAY NIGHT. AN UPSTREAM SHORTWAVE  
TROUGH WILL BEGIN TO MAKE ITS WAY TOWARDS IDAHO, WITH MODELS  
CONTINUING TO PUSH SOME SIGNIFICANT MOISTURE INTO THE AREA. WITH A  
SOUTHWESTERLY FLOW DEVELOPING BEHIND THE RIDGE, THE WESTERN SLOPES  
OF THE CENTRAL MOUNTAINS WILL BE A PRIME AREA FOR SOME MODERATE TO  
HEAVY SNOWFALL. AS FORCING AHEAD OF THE TROUGH NEARS--SOMETIME  
AROUND SUNDAY AFTERNOON--PRECIPITATION WILL LIKELY BE MORE  
WIDESPREAD. SNOW LEVELS AROUND 5000 TO 6000 WILL BE PRESENT OVER  
MOST OF THE SNAKE PLAIN AT THAT TIME, SO THE INTERSTATE CORRIDORS  
SHOULD SEE ONLY RAIN. THIS WILL LIKELY CHANGE OVER TO SNOW LATE  
SUNDAY NIGHT/MONDAY MORNING, THEN A MIX MONDAY AFTERNOON. MODELS ARE  
SHOWING FAIR AGREEMENT WITH THE TIMING OF THE TROUGH, THOUGH THE GFS  
IS SLIGHTLY FASTER. THE SYSTEM SHOULD DEPART BY TUESDAY MORNING, BUT  
WILL LIKELY BE FOLLOWED UP BY SOME MORE MOISTURE AS MODELS SHOW  
EVIDENCE OF ANOTHER WARM FRONT PUSHING INTO THE AREA, AND TAPPING  
INTO SOME OF THAT ATMOSPHERIC RIVER MOISTURE IN THE PACIFIC.  
HINSBERGER  

 
   
AVIATION
 
A WARM FRONT WILL PUSH NORTHEASTWARD ACROSS THE REGION  
TONIGHT, THOUGH PRECIP WILL LIKELY FAVOR THE MOUNTAINS. MODELS ARE  
KEEPING PRECIP AWAY FROM THE TERMINALS TONIGHT, THOUGH HAVE INCLUDED  
VCSH MENTION AT ALL BUT KSUN, WHICH MAY REMAIN 'PRECIP-SHADOWED'  
TONIGHT. THERE IS INDICATION IN MOS GUIDANCE AND FORECAST SOUNDINGS  
THAT CEILINGS WILL LOWER AS THE FRONT NEARS. KIDA MAY GET TO IFR  
CONDITIONS TONIGHT AND POSSIBLY LIFR BY TOMORROW MORNING. HINSBERGER  

 
   
PIH WATCHES/WARNINGS/ADVISORIES
 
NONE.  

 
 

 
 
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