278   
FXUS65 KGGW 180802  
AFDGGW  
  
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GLASGOW MT  
202 AM MDT THU SEP 18 2025  
   
DISCUSSION  
  
KEY MESSAGES:  
- ISOLATED PATCHY FOG MAY BE POSSIBLE IN THE FAR NORTHEAST THIS  
  MORNING.   
  
- A WEAK LIFT ZONE ASSOCIATED WITH EXITING LOW PRESSURE WILL  
  GENERATE ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS  
  THROUGHOUT THE DAY TODAY.    
   
- DRY AND WARMING CONDITIONS ARE EXPECTED FRIDAY THROUGH SUNDAY.   
  
WEATHER PATTERN OVERVIEW:  
TODAY: THE LOW PRESSURE COMPLEX IS STARTING TO FINALLY MORPH INTO  
ONE SINGLE CIRCULATION, THE CENTER OF WHICH IS NOW MOVING   
SOUTHEASTWARD THROUGH CENTRAL SOUTH DAKOTA. A NW OUTER BAND OF   
ISOLATED THUNDERSTORMS IS MOVING WESTWARD ALONG THE HI-LINE EARLY   
THIS MRONIGN AND IS EXPECTED TO DROP SOUTH INTO PHILLIPS AND   
GARFIELD CLOOUTY THIS AFTERNOON. WITH PEAK DIURNAL HEATING THIS   
LIFT ZONE WILL EXPAND IN SIZE, BUT OVERALL RAINFALL TOTALS UNDER   
THESE SMALL CELLS WILL LIKELY BE UNDER A WETTING RAIN(0.10") FOR   
MOST LOCATIONS THAT DO GET HIT BEFORE IT EXITS TO THE SOUTHEAST   
TONIGHT.  
  
EARLY MORNING FOG IS HINTED AT BY GLAMP DATA IN PATCHY LOCATIONS   
OVER THE BIG SHEEP TOPS AND ALONG THE BIG MUDDY AND MISSOURI RIVER  
VALLEY BOTTOMS. THIS ACTIVITY SHOULD DISAPPEAR BY ABOUT 9-10 AM.   
  
SATURDAY THROUGH MONDAY, A NEW WESTERN STATES RIDGE OF HIGH  
PRESSURE WILL MOVING INTO OUR REGION, BRINGING WARMER THAN AVERAGE  
TEMPERATURES AND MUCH DRIER CONDITIONS THROUGH SUNDAY. IT WILL BE  
WISE TO MONITOR EARLY NEXT WEEK FOR MARGINAL FIRE WEATHER   
CONDITIONS. AFTERWARD, THE RIDGE WILL TOPPLE OVER BY A COLD FRONT  
SUNDAY NIGHT AND MONDAY, WHICH COULD BRING SCATTERED SHOWERS AND   
THUNDERSTORMS ALONG WITH SLIGHTLY STRONGER WINDS BEHIND IT.   
  
MONDAY NIGHT ONWARD: ONCE THE COLD AIR ASSOCIATED WITH THE COLD  
FRONT MOVES THROUGH THE AREA THE RIDGE TO THE SWOYUTHWEST LOOKS  
LIKE IT WILL BEGIN TO BUILD AGAIN BRINGING MORE WARMING AND DRY   
CONDITIONS.   
  
FORECAST CONFIDENCE & DEVIATIONS:  
DEVIATIONS WERE GENEREATED TODAY OVER NORTHERN VALLEY COUNTY INTO  
NORTHERN GARFIELD COUNTY IN THE HOURLY POPS TO ACCOUNT FOR THE   
LOW PRESSURE EXTERIOR LIFT ZONE THAT IS GENERATING A FEW   
THUNDERSTORMS ON RADAR AND NLDN DATA EARLY THIS MORNING. THIS LIFT  
ZONE WAS NOT ADEQUATELY CAPTURED BY THE NBM WITH NEAR ZERO POPS   
UNTIL IT MOVES OVER SOUTHERN PHILLIPS AND NORTHERN GARFIELD LATER   
THIS AFTERNOON. THEREFORE, HAD TO RAISE POPS TO ACCOUNT FOR THIS   
MIGRATION AND BRIDGE RADAR TRENDS FROM THIS MORNING TO THE LARGER   
AREA OF COVERAGE THIS AFTERNOON.   
  
CONFIDENCE IS AVERAGE FOR PRECIPITATION TIMING, AND AMOUNTS.  
CONFIDENCE IS HIGH FOR THE TEMPERATURE FORECAST.  
  
GAH  
  
  
   
AVIATION  
  
UPDATE: 0800Z  
  
FLIGHT CAT RANGE: VFR - IFR  
  
DISCUSSION: THE ENTIRE REGION REMAINS UNDER THE INFLUENCE OF A  
MIGRATING LOW PRESSURE SYSTEM WHICH IS EXITING TO THE SOUTHEAST.   
EXPECT LOW CLOUDS AND ISOLATED PRECIPITATION TO ENCROACH WESTWARD  
FROM NORTH DAKOTA INTO NE MONTANA THIS MORNING AND THEN BLOSSOM   
INTO SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND   
EVENING. IFR LEVEL FOG WILL BE POSSIBLE NEAR THE KOLF AND KSDY   
TERMINALS FROM 11 TO 16Z THIS MORNING.   
  
WIND: E TO SE AND UNDER 10 KTS THIS MORNING. RISING TO 5 TO 15 KTS  
AFTER SUNRISE THROUGH THE DAY. CALMING TO LESS THAN 10 KTS AFTER  
MIDNIGHT/06Z THROUGH THE REMAINDER OF THE CYCLE.   
  
EQUIPMENT: COMMS ISSUES WITH THE KSDY OBSERVATION REMAIN. AMD NOT  
SKED WILL REMAIN IN PLACE UNTIL METARS ARE AVAILABLE.  
  
  
   
GGW WATCHES/WARNINGS/ADVISORIES  
  
NONE.  
  
  
  
  
  
WEATHER.GOV/GLASGOW  
 
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