130  
FXUS65 KPIH 230807  
AFDPIH  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE POCATELLO ID  
207 AM MDT SAT OCT 23 2021  
   
SHORT TERM
 
TONIGHT THROUGH MONDAY NIGHT.  
 
ATMOSPHERIC RIVER EVENT SETTING UP FOR THE WEEKEND.  
SHOULD SEE THE FIRST PUSH OF SHOWERS ACROSS THE REGION TODAY. SNOW  
LEVELS TODAY ARE SITTING ABOVE 6500FT. RAIN/SNOW AMOUNTS TODAY LOOK  
LIGHT. THE STRONG PUSH OF MOISTURE ARRIVES BY SUNDAY AFTERNOON.  
WE'LL SEE A WARM FRONT PUSH THROUGH THE REGION SUNDAY AFTERNOON AND  
EVENING. SNOW LEVELS ARE COMPLICATED FOR THIS EVENT. ACROSS THE  
CENTRAL MOUNTAINS WHERE THE HEAVIEST RAINFALL/SNOWFALL IS EXPECTED,  
SNOW LEVELS WILL START AT 6500 FT RISING SUNDAY NIGHT INTO MONDAY  
MORNING TO 7000-7500 FT. SNOW LEVELS ACROSS THE REST OF EAST IDAHO  
CLIMB MUCH HIGHER, PERHAPS OVER 9000 FT EVEN. STRONG SOUTHERLY WINDS  
ARE EXPECTED TO DEVELOP SUNDAY AFTERNOON AND EVENING WHICH MAY CUT  
INTO RAIN CHANCES AND AMOUNTS AROUND AMERICAN FALLS, POCATELLO, AND  
BLACKFOOT. HOWEVER, THE REAL FOCUS IS THE CENTRAL MOUNTAINS WHERE  
UPWARDS OF 2 INCHES OF LIQUID IS POSSIBLE. SNOW AMOUNTS OF UP TO 2  
FEET ARE POSSIBLE ABOVE 7000FT. ONCE AGAIN, SNOW AMOUNTS ARE HIGHLY  
DEPENDENT UPON WHERE SNOW LEVELS ACTUALLY FALL, AND THERE IS A FAIR  
AMOUNT OF UNCERTAINTY THERE. NOT SURPRISINGLY, WILL CONTINUE THE  
WINTER STORM WATCH FOR THE CENTRAL MOUNTAINS.  
 
ON MONDAY, THE TRAILING COLD FRONT POWERS THROUGH THE REGION AND WE  
SHOULD SEE THE BRUNT OF THE HEAVY PRECIPIATION SHIFT EAST WITH THE  
FRONT. THAT FRONT SHOULD PASS THROUGH EAST IDAHO MONDAY AFTERNOON  
AND MONDAY EVENING. RIGHT NOW, WE EXPECT MOST OF THE HEAVY  
PRECIPITATION TO FALL IN THE WARM SECTOR AS SNOW LEVELS FALL MONDAY  
AFTERNOON AND EVENING TO 6000-6500 FT. AS A RESULT, THIS IS EXPECTED  
TO MAINLY BE A RAIN EVENT FOR EAST IDAHO. STORM TOTAL RAINFALL  
AMOUNTS STARTING TODAY THROUGH MONDAY NIGHT ARE IMPRESSIVE WITH A  
1.00-1.50 INCHES POSSIBLE FOR EAST IDAHO AND THE MAGIC VALLEY AREA.  
ONCE AGAIN, THE CENTRAL MOUNTAINS, ESPECIALLY ALONG THE BIG WOOD AND  
UPPER SALMON AREAS, SHOULD DO VERY WELL WITH UP TO 2 INCHES LIQUID  
WITH THIS EVENT. SOME AREAS MAY EVEN OVERACHIEVE, ESPECIALLY ALONG  
SOME OF THE HIGHER RIDGES AND PEAKS. IN TERMS OF SNOWFALL, A STORM  
TOTAL OF 2 TO 3 FEET IS POSSIBLE ABOVE 7000 FT, WITH THE MORE  
IMPRESSIVE NUMBERS ON THE UPPER SLOPES AND RIDGELINE. ACROSS THE  
REMAINDER OF THE AREA, ONLY LOOKING AT 1 TO 6 INCHES MAINLY ALONG  
THE RIDGELINE.  
 
13  
   
LONG TERM
 
(TUESDAY - NEXT SATURDAY).  
TUESDAY MORNING LOOKS TO SEE THE FINAL REMNANTS OF AN UPPER LEVEL  
TROUGH THAT BROUGHT WIDESPREAD PRECIPITATION AND HIGH ELEVATION  
SNOWFALL TO SOUTHEAST IDAHO AS IT CONTINUES ITS PASSAGE FURTHER  
SOUTHEAST OF OUR REGION. PRECIPITATION THROUGHOUT THE DAY TUESDAY  
STAYS MOSTLY CONFINED TO OUR SOUTHERN AND EASTERN LOCATIONS, AS WELL  
AS THROUGH THE CENTRAL MOUNTAINS. SNOW LEVELS DROP TO VALLEY FLOORS  
IN THE CENTRAL MOUNTAINS TUESDAY MORNING, WHILE ELSEWHERE 5,500-  
6,000FT IS MORE LIKELY WITH MARGINAL WET BULB TEMPERATURES. CLUSTER  
ANALYSES MIDWEEK NEXT WEEK SHOW AGREEMENT AMONGST LONG TERM ENSEMBLE  
MODELS HAVING HIGH PRESSURE MAKING A PUSH FURTHER NORTH ASSOCIATED  
WITH A BUILDING RIDGE. CHANCES FOR LIGHT RAIN AND HIGH ELEVATION  
SNOW SHOWERS PERSIST MIDWEEK, WITH WIDESPREAD PRECIPITATION LIKELY  
OUT OF THE AREA BY WEDNESDAY. LINGERING SHOWERS ARE LIKELY MOSTLY  
FOR OUR NORTHERN LOCATIONS AND AREAS AT ELEVATION, WITH  
ACCUMULATIONS STAYING LIGHT. THIS IS COURTESY OF A FEW SHORTWAVE  
TROUGHS THAT PASS BY UP INTO MONTANA, KEEPING THOSE VERY SLIGHT  
CHANCES FOR PRECIPITATION THROUGH THE WEEK AND ELEVATED WINDS  
LIKELY. LOOKING TOWARDS THE START OF THE WEEKEND, THERE IS SLIGHT  
DISAGREEMENT AS TO WHEN THIS UPPER LEVEL RIDGE IS EXPECTED TO BREAK  
DOWN, WITH THE GFS BRINGING AN UPPER LEVEL CLOSED LOW IN FOR  
SATURDAY AND THE ECMWF LAGGING A BIT BEHIND FOR SUNDAY. TEMPERATURES  
FOR NEXT WEEK REMAIN SEASONABLE WITH HIGHS IN THE 40S AND 50S,  
WARMING UP TO AROUND 60 DEGREES NEXT FRIDAY ASSOCIATED WITH THAT  
BUILDING HIGH PRESSURE TREND DURING THE WEEK. CONDITIONS ARE  
EXPECTED TO SLIGHTLY COOL BY A FEW DEGREES NEXT WEEKEND, ASSOCIATED  
WITH THAT NEXT SYSTEM WHEN IT ARRIVES. MACKAY  
 

 
   
AVIATION
 
VFR REMAINS THE PREDOMINANT GROUP TO START OFF TODAY,  
WITH INCREASED CHANCES OF SCATTERED SHOWERS BUILDING SOUTHWEST TO  
NORTHEAST THROUGHOUT THE DAY FOR MUCH OF THE SOUTHERN AND EASTERN  
PORTIONS OF THE FORECAST AREA. MARGINAL VFR CIGS ARE EXPECTED  
ACROSS ALL TAF SITES AT TIMES DURING THE DAY ASSOCIATED WITH THESE  
RAIN SHOWERS EXCEPT AT KSUN. HERE, PRECIPITATION IS EXPECTED TO  
STAY LIGHT AND OUTSIDE OF THE TERMINAL UNTIL THE OVERNIGHT HOURS  
WHEN THE OUTER FRINGES OF THE NEXT LARGE SYSTEM MOVES IN. CHANCES  
FOR PRECIPITATION TAPER OFF DURING THE AFTERNOON AND EVENING  
HOURS. SOUTHWEST WINDS REMAIN ELEVATED TODAY WITH GUSTS AT KPIH,  
KIDA, AND KDIJ UP TO AROUND 20-25KTS. THIS AFTERNOON AND INTO  
TONIGHT, CEILINGS BEGIN TO IMPROVE SLIGHTLY BEFORE LOWERING INTO  
THE MVFR/IFR CATEGORIES AS THE NEXT LARGE SYSTEM BEGINS IMPACTING  
THE REGION SUNDAY INTO THE START OF NEXT WEEK, KEEPING WINDS  
ELEVATED AS THIS SYSTEM PASSES THROUGH. MACKAY  
 

 
   
PIH WATCHES/WARNINGS/ADVISORIES
 
 
WINTER STORM WATCH FROM SUNDAY AFTERNOON THROUGH MONDAY MORNING  
FOR IDZ069-071>074.  
 

 
 

 
 
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