807  
FXUS65 KPIH 231958  
AFDPIH  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE POCATELLO ID  
158 PM MDT WED SEP 23 2020  
   
SHORT TERM...TONIGHT THROUGH FRIDAY
 
SOUTHEAST FLOW IS FORECAST  
THIS PERIOD WITH HIGH PRESSURE SITUATED TO OUR SOUTH. CHANCES FOR  
PRECIPITATION IN CENTRAL IDAHO BEGIN THURSDAY WITH WEAK  
SHORTWAVES PULSING EASTWARD ASSOCIATED WITH A LOW PRESSURE TROUGH  
AND SUBSEQUENT COLD FRONT THURSDAY INTO FRIDAY. INCREASING WIND  
SPEEDS ARE EXPECTED THURSDAY AFTERNOON AND EVENING WITH GUSTS  
AROUND 40 MPH IN PORTIONS OF THE SNAKE PLAIN 30 TO 40 MPH AT  
RIDGETOPS. BECAUSE OF THESE ANTICIPATED STRONG WINDS, WE WILL  
ISSUE A WIND ADVISORY ACROSS THE UPPER SNAKE RIVER PLAIN AND ARCO  
DESERT ZONE AS WELL AS A LAKE WIND ADVISORY FOR AMERICAN FALLS  
RESERVOIR. THE FRONT ITSELF IS RATHER DRY AND SHOULD NOT ALLOW  
FOR WIDESPREAD CHANCES FOR SHOWERS AND THUNDERSTORMS.  
ND  
   
LONG TERM...SATURDAY THROUGH WEDNESDAY
 
A VERY MILD WEEKEND IS  
FORECAST UNDER ZONAL FLOW. THERE ARE SLIGHT CHANCES FOR SHOWERS IN  
THE ISLAND PARK/EAST IDAHO AREAS SATURDAY AS WEAK IMPULSES  
TRAVERSE THROUGH THE AREA. TEMPERATURES WILL BE MILD AND PLEASANT  
IN THE 70S; A TREND THAT WILL PERSIST THROUGH EARLY NEXT WEEK. A  
HIGH PRESSURE RIDGE WILL ONLY STRENGTH AS WE HEAD INTO THE MIDDLE  
PORTION OF NEXT WEEK, CONTINUING THE TREND OF FALL LIKE  
TEMPERATURES AND PRECIP-FREE DAYS.  
ND  
 

 
   
AVIATION
 
CONTINUED VFR CONDITIONS ARE AGAIN EXPECTED TODAY WITH  
BREEZY CONDITIONS LIKELY FOR PIH, IDA AND DIJ THIS AFTERNOON. THERE  
MAY BE BRIEF MVFR CONDITIONS THIS AFTERNOON FOR SMOKE, ESPECIALLY  
KSUN. BRIEF MVFR CONDITIONS MAY BE POSSIBLE AS WELL FOR SMOKE FOR  
THE SNAKE RIVER PLAIN INCLUDING KIDA, KPIH AND KBYI THIS EVENING  
INTO EARLY MORNING.  
TW  
 

 
   
FIRE WEATHER
 
EXPECT BREEZY WINDS AGAIN TODAY AHEAD OF A SYSTEM  
THAT WILL MOVE THROUGH THURSDAY INTO SATURDAY MORNING. BY  
THURSDAY AFTERNOON, WINDS WILL PICK UP GUSTING TO 25 TO 35 MPH  
WITH LOCALIZED AREAS OF 40 MPH MAINLY FOR THE ARCO DESERT AND SOME  
RIDGE TOPS AS THIS NEXT SYSTEM/WEAK COLD FRONT MOVES THROUGH. ON  
THURSDAY AFTERNOON RELATIVE HUMIDITY LOOKS TO BE AROUND 20 TO 30  
PERCENT FOR VALLEYS WITH THE LOWER AMOUNTS NEAR 20 PERCENT IN THE  
ARCO DESERT AND ALONG THE UTAH BORDER. HAINES INDEX WILL DROP TO 2  
AND 3 BY THURSDAY AFTERNOON AS WELL. DUE TO RELATIVE HUMIDITY  
ABOVE CRITICAL VALUES OF 15 PERCENT AND A LOW HAINES INDEX, HAVE  
NOT PUT OUT A RED FLAG. THIS IS COORDINATED WITH OUR FIRE WEATHER  
PARTNERS. THERE IS A SLIGHT CHANCE OF PRECIPITATION THURSDAY FOR  
MAINLY ZONES 475, 476 AND 411, THOUGH OVERALL AMOUNTS LOOK LIGHT.  
CHANCE OF WETTING RAIN LOOKS UNLIKELY AND CERTAINLY WOULD NOT BE  
WIDESPREAD IF OCCURS. FRIDAY CONTINUES TO BE WINDY, MEETING RED  
FLAG CRITERIA FOR A LOT OF AREAS WITH 20 TO 30 MPH GUSTS. THERE IS  
ANOTHER SLIGHT CHANCE OF PRECIPITATION FOR OUR NORTHERN AREAS.  
RELATIVE HUMIDITY DOES RISE EVEN MORE. AS A RESULT FRIDAY RELATIVE  
HUMIDITY WILL BE IN THE 25 TO 35 PERCENT RANGE AND TOO HIGH TO  
CONSIDER ANY RED FLAG WARNINGS. FRIDAY AND SATURDAY TEMPERATURES  
WILL DROP TO NEAR TO SLIGHTLY BELOW NORMAL. LATE SATURDAY INTO  
SUNDAY LOOK FOR HIGH PRESSURE TO BUILD BACK IN BRINGING WARMER AND  
DRIER CONDITIONS SUNDAY THROUGH THE BEGINNING OF NEXT WEEK.  
TW  
 

 
   
AIR STAGNATION
 
DEGRADED AIR QUALITY FROM WILDFIRE SMOKE IS LIKELY  
THIS AFTERNOON AND EVENING AS SOUTHWESTERLY FLOW IS FORECAST OVER  
OUR AREA. AT TIMES, SPEEDS WILL BE RATHER STRONG THIS AFTERNOON AND  
AGAIN THURSDAY AFTERNOON; ALLOWING THE SMOKE TO QUICKLY MOVE THROUGH  
THE AREA. THERE MAY BE LOCAL SMOKE INFLUENCE FROM BADGER/WOODHEAD  
FIRES UNDER THIS REGIME. CHANCES FOR PRECIPITATION IN CENTRAL IDAHO  
BEGINNING THURSDAY WOULD HELP ALLEVIATE THE DEGRADED AIR QUALITY. A  
PASSING COLD FRONT THURSDAY INTO FRIDAY SHOULD CLEAR OUT CONCERNS  
FOR SMOKE ACROSS OUR AREA.  
ND  
 

 
   
PIH WATCHES/WARNINGS/ADVISORIES
 
 
LAKE WIND ADVISORY FROM NOON TO 8 PM MDT THURSDAY FOR IDZ054.  
 
WIND ADVISORY FROM NOON TO 8 PM MDT THURSDAY FOR IDZ052-053.  
 

 
 

 
 
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