855  
FXUS65 KPIH 141938  
AFDPIH  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE POCATELLO ID  
138 PM MDT SAT SEP 14 2019  
   
DISCUSSION
 
TONIGHT THROUGH NEXT SATURDAY. A FLAT RIDGE OF HIGH  
PRESSURE WAS POSITIONED OVER THE REGION EARLY THIS AFTERNOON AS A  
DEEP BROAD UPPER LOW ADVANCED INTO THE CANADIAN COASTAL WATERS.  
NUMERICAL MODELS DRIVE THE LOW SOUTH THROUGH VANCOUVER ISLAND SUNDAY  
AS THE FLOW ALOFT OVER IDAHO BACKS FROM THE WEST TO SOUTHWEST AND  
REMAINS DRY. THE LOW MOVES ONSHORE SUNDAY NIGHT AND EASTWARD ACROSS  
OREGON AND WASHINGTON MONDAY AS ISOLATED SHOWERS LIFT NORTHWARD OUT  
OF UTAH INTO THE WYOMING BORDER REGION MONDAY AFTERNOON. LAST NIGHTS  
06Z NAM MODEL CYCLE WAS INDICATING A STRONGER TROUGH ADVANCING INTO  
NRN NEVADA MONDAY EVENING RESULTING IN THE POTENTIAL FOR SEVERE  
THUNDERSTORM ACTIVITY ACROSS THE SE IDAHO MOUNTAINS...AND THEN THE  
12Z MODEL RUN CAME IN MUCH WEAKER WITH THE TROUGH AND COMPLETELY  
DEVOID OF ANY ACTIVITY OVER THE SE MOUNTAINS. THUS, THE BRUNT OF THE  
STORM APPEARS TO SWEEP ACROSS SE IDAHO LATE MONDAY NIGHT AND TUESDAY  
WITH THUNDERSTORMS DEVELOPING OUT AHEAD OF THE TROUGH AND STRONG  
WINDS TRAILING INTO THE BURLEY AND POCATELLO AREAS BEHIND THE  
EXITING LOW TUESDAY AFTERNOON. WE SHOULD SEE A BRIEF DRY SPELL  
TUESDAY NIGHT AND WEDNESDAY BEFORE A SECOND PACIFIC LOW ADVANCES  
THROUGH THE NW STATES AND INTO SE IDAHO LATE THURSDAY AND FRIDAY  
BEFORE EXITING OFF TO THE NE SATURDAY. IT LOOKS LIKE FALL HAS  
ALREADY ARRIVED, WITH 15-20 DEGREE SWINGS IN DAYTIME HIGHS FROM ONE  
DAY TO THE NEXT ACCOMPANIED BY SHOWERS AND GUSTY WINDS. HUSTON  

 
   
AVIATION
 
HIGH PRESSURE CONTINUES TO EXERT CONTROL OVER SE IDAHO,  
PROVIDING HIGH CONFIDENCE IN VFR CIGS/VSBYS THROUGH AT LEAST MON  
EVE. AT THIS POINT, OUR AIRMASS IS TOO DRY TO SUPPORT FOG, OUTSIDE  
OF VERY ISOLATED DEVELOPMENT OVER WATER. DIURNALLY BREEZY CONDITIONS  
THIS AFTERNOON WILL TREND BREEZIER FOR SUN AND MON, WITH PREDOMINANT  
SW TRAJECTORIES NOT FAVORABLE FOR CROSSWINDS ON MAJOR TERMINAL  
RUNWAYS. TAF GROUPS LARGELY DELINEATE DIRECTIONAL WIND SHIFTS. -  
01/HUSTON  

 
   
FIRE WEATHER
 
HIGH PRESSURE WILL REMAIN THE PREDOMINANT FORCE  
CONTROLLING OUR WX THROUGH MON AFTERNOON, WITH A DRYING/WARMING  
TREND CONTINUING AND BREEZY CONDITIONS EACH AFTERNOON (PARTICULARLY  
ACROSS THE ARCO DESERT AND MID/UPPER SLOPES OF MOST ZONES). THESE  
WINDS WILL FLIRT WITH CRITICAL THRESHOLDS SUN ATOP RH VALUES  
DROPPING TO 10-16% ACROSS ALL ZONES EXCEPT 411. HOWEVER, IN ADDITION  
TO WINDS BEING BORDERLINE, THE BIG QUESTION REMAINS WHETHER OR NOT  
FUELS (ESPECIALLY FINER FUELS/GRASSES) WILL REACH CRITICAL AND BURN  
EFFECTIVELY. WITH THESE CONSIDERATIONS IN MIND, WILL CONTINUE TO  
HEADLINE THE NEAR-CRITICAL WX CONDITIONS IN THE FWF, BUT NOT ISSUE  
ANY RED FLAG PRODUCTS. OUR NEXT TROUGH IS STILL PROGGED TO SWING  
THROUGH MON NIGHT AND TUES, WITH A MASSIVE DROP IN TEMPS AND  
INCREASED HUMIDITY VALUES. WINDS MAY REMAIN BREEZY OVERNIGHT MON  
NIGHT. ANOTHER TROUGH IS LIKELY THURS OR FRI. - 01/HUSTON  

 
   
PIH WATCHES/WARNINGS/ADVISORIES
 
NONE.  

 
 

 
 
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