546  
FXUS65 KCYS 282330  
AFDCYS  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CHEYENNE WY  
530 PM MDT THU AUG 28 2025  
   
KEY MESSAGES  
 
- SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WILL CONTINUE  
THROUGH THE EVENING HOURS TODAY. ISOLATED TORRENTIAL RAINFALL  
AND HAIL ARE THE PRIMARY HAZARDS.  
 
- WIDELY SCATTERED THUNDERSTORMS ARE EXPECTED AGAIN DURING THE  
PM HOURS ON FRIDAY AND SATURDAY.  
 
- WARMING TREND STARTS SUNDAY ONWARDS, WITH FIRE WEATHER  
CONCERNS SLOWLY CREEPING UP TO START THE WORK WEEK.  
 
 
   
SHORT TERM /THROUGH FRIDAY NIGHT/  
 
ISSUED AT 300 PM MDT THU AUG 28 2025  
 
THUNDERSTORM ACTIVITY GOT OFF TO AN EARLY START THIS AFTERNOON. GOES  
WATER VAPOR SATELLITE IMAGERY SHOWS OUR AREA SANDWICHED BETWEEN A  
HEALTHY PLUME OF MONSOON MOISTURE STREAMING IN FROM THE SOUTHWEST,  
AND LINGERING MOISTURE ASSOCIATED WITH THE VERY DISORGANIZED UPPER  
LEVEL LOW OVER THE NORTHERN ROCKIES. THE FEATURE PASSING TO OUR  
NORTH IS HELPING TO PRODUCE MODEST OVERRUNNING WARM AIR ADVECTION,  
STRONGEST GENERALLY ALONG A CASPER TO PINE BLUFFS LINE. WHILE  
CONVECTIVE PARAMETERS ARE FAIRLY MARGINAL, THE FORCING APPEARS TO BE  
ENOUGH TO KICK OFF SCATTERED TO NUMEROUS THUNDERSTORMS, WITH  
ISOLATED STRONG TO SEVERE STORMS. THE PRIMARY HAZARDS SO FAR ARE  
TORRENTIAL RAINFALL AND SMALL TO MARGINALLY SEVERE HAIL, BUT AN  
ISOLATED LANDSPOUT AND/OR DAMAGING WIND GUST CANNOT BE RULED OUT.  
SOUNDINGS ARE EXTREMELY MOIST ONCE AGAIN, BUT WE HAVE A LITTLE BIT  
OF DRIER AIR FILTERING IN ABOVE 500-MB THAT MAY BE HELPING TO  
PRODUCE A LITTLE MORE HAIL AND LIGHTNING COMPARED TO YESTERDAY. THE  
ISOLATED SEVERE THREAT SHOULD BE MAINLY CONFINED TO THE AREAS WHERE  
THE FORCING IS STRONGER, WHICH WEAKENS QUICKLY PAST FAR WESTERN  
NEBRASKA. EXPECT THIS ACTIVITY TO GROW UPSCALE FOR FEW HOURS, AND  
THEN BEGIN A SLOW DOWN TREND THROUGH THE EVENING, WITH MOST ACTIVITY  
CONCLUDED BY 9PM ASIDE FROM LINGERING LATE EVENING CONVECTION IN  
CONVERSE/NIOBRARA COUNTIES.  
 
WINDS WILL GAIN A LIGHT WESTERLY COMPONENT OVERNIGHT IN SOUTHEAST  
WYOMING, WHICH WILL KEEP THE LOW CLOUD/FOG CONFINED TO MAINLY THE  
NEBRASKA PANHANDLE, BUT THIS COULD SPREAD INTO NORTHERN GOSHEN AND  
NIOBRARA COUNTIES TOO. THE AIRMASS IN THE WESTERLY FLOW WILL STILL BE  
FAIRLY MOIST THOUGH, SO THIS WON'T EXACTLY BE A WELL DEFINED  
DRYLINE. FOR FRIDAY, THE DISORGANIZED UPPER LEVEL LOW WILL CONTINUE  
TO LINGER NEAR THE AREA AS IT CONTINUES ITS VERY SLOW PROGRESSION  
OVER THE OP OF THE WEAK SOUTHWEST CONUS RIDGE. MODELS SHOW A VERY  
MESSY 500-MB VORTICITY PATTERN, WITH NUMEROUS VORT-MAXES FLOATING  
AROUND THE AREA. THIS WILL PROVIDE SOME FORCING, BUT OVERALL IT  
LOOKS WEAKER THAN TODAY WHICH SHOULD DECREASE THUNDERSTORM COVERAGE.  
STORMS SHOULD BE MORE IN THE WIDELY SCATTERED CATEGORY. DRY AIR  
SHOULD REDUCE THE CHANCE FOR STORMS IN NORTHERN CARBON AND ALBANY  
COUNTIES, BUT MOST OF THE REST OF THE AREA WILL BE FAIR GAME.  
CONVECTIVE PARAMETERS ARE MARGINAL ONCE AGAIN BUT ISOLATED SEVERE  
HAIL AND/OR WIND CANNOT BE ENTIRELY RULED OUT. FRIDAY ALSO LOOKS  
LIKE THE WARMEST DAY OF THE WEEK, THANKS TO MORE WIDESPREAD SUNSHINE  
COMPARED TO THE LAST WEEK OR SO. A REINFORCING COOL FRONT WILL SLIP  
ACROSS THE HIGH PLAINS FRIDAY NIGHT, POSSIBLY ENHANCING SOME LATE  
EVENING THUNDERSTORM ACTIVITY AND BRINGING IN ANOTHER ROUND OF  
MORNING LOW CLOUDS AND/OR FOG.  
 
 
   
LONG TERM /SATURDAY THROUGH THURSDAY/  
 
ISSUED AT 300 PM MDT THU AUG 28 2025  
 
NORTHWEST FLOW CONTINUES THROUGH SATURDAY CONTINUING OUR  
CHANCES FOR AFTERNOON AND EVENING. SUNDAY, THE UPPER LEVEL RIDGE  
STARTS TO BUILD BACK OVER THE INTERMOUNTAIN WEST. THIS WILL  
SLOWLY START TO DECREASE THE MOISTURE OVER THE REGION. A WEAK  
DISTURBANCE DOES GIVE US A SLIGHT CHANCE FOR AN ISOLATED SHOWER  
BUT THE PROBABILITY LOOKS LOW ENOUGH TO NOT INCLUDE IN THE  
GRIDS. MONDAY AND TUESDAY LOOKS TO KEEP US DRY AS THE RIDGE  
SHIFT BACK OVER THE INTERMOUNTAIN WEST AS A LOW PRESSURE SYSTEM  
ENTERS THE PACIFIC NORTHWEST. CLUSTER ANALYSIS DOES SHOW SOME  
UNCERTAINTY AS TO THE TIMING OF THE LOW PRESSURE SYSTEM WHICH  
MAY BREAK DOWN THE RIDGE BY TUESDAY AFTERNOON BUT NBM LOOKS TO  
SIDE MORE WITH THE GEFS AND PAINTS A 20 PERCENT CHANCE OF  
SHOWERS. HOWEVER, IF THE RIDGE DOESN'T BREAK DOWN UNTIL TUESDAY  
EVENING AS 70 PERCENT OF THE GRAND ENSEMBLE MEMBERS (GEFS, EURO,  
CANADIAN GEPS) THEN WE SHOULD STAY DRY UNTIL WEDNESDAY.  
WEDNESDAY, THE INTERMOUNTAIN WEST BECOMES SANDWICHED BETWEEN AN  
UPPER LEVEL RIDGE AND LOW PRESSURE SYSTEM NEAR THE GREAT LAKES  
REGION. THIS WILL GIVE US GUSTY WINDS FOR THE REST OF THE WEEK  
AND AFTERNOON PRECIPITATION CHANCES UNTIL AT LEAST THE END OF  
THE WORK WEEK.  
 
 
   
AVIATION /00Z TAFS THROUGH 00Z SATURDAY/  
 
ISSUED AT 524 PM MDT THU AUG 28 2025  
 
WEST FLOW ALOFT WILL CONTINUE.  
 
WYOMING TAFS...SCATTERED TO BROKEN CLOUDS FROM 5000 TO  
10000 FEET WILL PREVAIL. OCCASIONAL THUNDERSTORMS WILL OCCUR AT  
CHEYENNE UNTIL 01Z, PRODUCING WIND GUSTS TO 35 KNOTS. OUTSIDE  
OF THUNDERSTORMS, WINDS WILL GUST TO 25 KNOTS AT RAWLINS AND  
CHEYENNE UNTIL 01Z, AND TO 24 KNOTS AT ALL TERMINALS AFTER  
15Z TO 17Z FRIDAY.  
 
NEBRASKA TAFS...SCATTERED TO BROKEN CLOUDS FROM 5000 TO  
10000 FEET WILL PREVAIL, WITH CEILINGS NEAR 800 FEET AT  
ALLIANCE AND SIDNEY FROM 11Z TO 16Z, AND OCCASIONAL  
THUNDERSTORMS AT SIDNEY UNTIL 01Z, PRODUCING WIND GUSTS TO  
30 KNOTS AND VISIBILITIES TO 4 MILES.  
 
 
   
CYS WATCHES/WARNINGS/ADVISORIES  
 
WY...NONE.  
NE...NONE.  
 
 
 
 
 
SHORT TERM...MN  
LONG TERM...MM  
AVIATION...RUBIN  
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