469  
FXUS65 KPIH 232001  
AFDPIH  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE POCATELLO ID  
101 PM MST TUE JAN 23 2018  
   
SHORT TERM
 
TONIGHT THROUGH FRIDAY.  
WILL HAVE MAINLY DRY CONDITIONS TONIGHT AND WEDNESDAY WITH ONLY  
SOME ISOLATED TO SCATTERED SNOW SHOWERS IN UPPER SNAKE RIVER  
HIGHLANDS. NEXT PACIFIC SYSTEM AND ASSOCIATED COLD FRONT WILL MOVE  
THROUGH SOUTHEAST IDAHO ON THURSDAY WITH SNOW MOVING BACK INTO THE  
CENTRAL MOUNTAINS WEDNESDAY NIGHT AND WILL QUICKLY OVERSPREAD THE  
REMAINDER OF THE REGION THURSDAY MORNING. THE SPEED OF THE SYSTEM  
SHOULD LIMIT SNOW AMOUNTS WITH FORECASTS RIGHT NOW OF 2 TO 5  
INCHES IN THE MOUNTAINS AND AROUND AN INCH IN THE SNAKE RIVER  
PLAIN EXPECTED. SHOULD SEE SOME WINDY CONDITIONS AND SOME AREAS OF  
BLOWING SNOW AS WELL. A WEAKER SYSTEM WILL KEEP LIGHT SNOW IN THE  
FORECAST FOR FRIDAY AS WELL AFTER A BRIEF BREAK THURSDAY NIGHT.  
LIGHT ACCUMULATIONS ARE EXPECTED AGAIN WITH THIS SYSTEM MAINLY IN  
THE MOUNTAINS. TEMPERATURES WILL BE QUITE WARM WEDNESDAY AHEAD OF  
THE COLD FRONT WITH WIDESPREAD 40S FOR HIGH TEMPERATURES IN THE  
VALLEYS. IT WILL BE MUCH COOLER BEHIND THE FRONT THURSDAY AND  
FRIDAY.  
GK  
   
LONG TERM
 
FRI NIGHT THROUGH NEXT TUE NIGHT. LONGWAVE PATTERN FOR  
THIS PERIOD AT 500MB STARTS WITH A FAIRLY DEEP TROUGH CLOSE TO THE  
WEST COAST AND A LOW-AMPLITUDE RIDGE OVER THE GREAT PLAINS. THIS  
PATTERN SLOWLY RETROGRADES, AND ENDS UP WITH THE LOW TO THE WEST OF  
140W LONGITUDE AND THE UPPER LEVEL RIDGE AXIS OVER THE FORECAST  
AREA. THAT DEVELOPS BY MON. THAT KIND OF SHIFT WOULD LINE UP WITH  
YESTERDAY'S ECMWF SOLUTION THAT DRIED OUT THE FORECAST AT THE VERY  
END. ALSO, NO MAJOR SNOW STORM WOULD BE EXPECTED, SINCE THE EARLY  
PORTION OF THE TIME WOULD HAVE VERY MILD TEMPERATURES AND HIGH SNOW  
LEVELS, AND THE LATTER PORTION WOULD HAVE TO HAVE A REALLY STRONG  
STORM TO BREAK DOWN THE RIDGE. FACTORING IN THE SHORTWAVES, THERE  
ARE POTENTIALLY TWO FEATURES DURING THE PERIOD THAT COULD BRING  
MODERATE TO HEAVY AMOUNTS OF PRECIPITATION: SAT NIGHT/SUN, AND  
TUE/TUE NIGHT. THEN THERE IS THE FRI STORM FROM THE SHORT TERM  
FORECAST WRAPPING UP ON FRI NIGHT. BOTH THE GFS AND THE ECMWF ARE  
VERY CLOSE WHEN IT COMES TO TIMING. THE ONLY ISSUE IS THE AMOUNT OF  
PRECIPITATION. AT FIRST THE ECMWF IS DRY, THEN AFTER THE PAUSE IN  
SHORTWAVES ON SUN NIGHT THROUGH MON NIGHT, THE ECMWF IS WETTER,  
THOUGH IT LOOKS LIKE IT IS DUE TO THE LOW RESOLUTION OUT AT THAT  
TIME. THE ONE THING LACKING DURING THIS EXTENDED FORECAST PERIOD IS  
THAT RUN TO RUN CONSISTENCY IS SOMEWHAT LACKING. SO HAVE LOWERED THE  
RANGE OF EXTREMES ON BOTH ENDS TO MATCH UP WITH NEIGHBORS. MESSICK  
 

 
   
AVIATION
 
THE LOW STRATUS HAS CLEARED IN MOST LOCATIONS, SAVE  
KDIJ. LOOK FOR IMPROVING CIGS AND UNLIMITED VSBY. DO NOT EXPECT A  
RETURN OF FOG TO ANY OF THE 5 AIRDROMES WE FOR WHICH WE FORECAST; IT  
COULD RETURN TO PLACES IN THE CENTRAL IDAHO MOUNTAINS. THIS IS GOING  
AGAINST THE VERY LOW CIGS FORECAST BY BOTH THE NAM AND GFS FOR KIDA.  
THE MOS GUIDANCE HAS BEEN OVERLY PESSIMISTIC WITH THIS STORM AND THE  
TIME-HEIGHT CROSS SECTIONS NOWHERE INDICATE ENOUGH MOISTURE FOR  
STRATUS. MESSICK  
 

 
   
PIH WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  

 
 

 
 
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