866  
FXUS65 KCYS 181927  
AFDCYS  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CHEYENNE WY  
127 PM MDT FRI JUL 18 2025  
   
KEY MESSAGES
 
 
- SCATTERED PM SHOWERS AND THUNDERSTORMS ARE EXPECTED ACROSS THE  
AREA ON BOTH FRIDAY AND SATURDAY. A FEW STORMS WILL HAVE THE  
POTENTIAL TO BECOME STRONG TO SEVERE, MAINLY IN THE NE  
PANHANDLE.  
 
- QUITE WARM CONDITIONS PERSIST FOR SUNDAY THROUGH FRIDAY, WITH  
ALMOST DAILY CHANCES FOR ISOLATED TO SCATTERED LATE DAY  
SHOWERS AND THUNDERSTORMS.  
 

 
   
SHORT TERM /THROUGH SATURDAY NIGHT/
 
 
ISSUED AT 100 PM MDT FRI JUL 18 2025  
 
EARLY AFTERNOON VISIBLE SATELLITE IMAGERY REVEALS DEVELOPING  
CONVECTIVE CUMULUS CLOUD COVERAGE OVER THE HIGHER TERRAIN OF  
SOUTHEAST WYOMING. WIDELY SCATTERED MID AND UPPER-LEVEL CLOUD  
COVER CONTINUES TO DRIFT FROM SOUTHWEST TO NORTHEAST OVER THE  
REGION, EVIDENCE IN SEASONABLY HIGH MID-LEVEL MOISTURE ALSO  
SHOWN IN FORECAST SOUNDINGS. ALOFT, A LIGHT ZONAL-FLOW PATTERN  
IS PRESENT OVER WYOMING AND NEBRASKA, WITH THE CORE OF STRONGER  
FLOW ALOFT LOCATED WELL TO THE NORTH IN THE DAKOTAS AND MONTANA.  
FORECAST SOUNDINGS REVEAL A VERY SHALLOW LAYER OF UPSLOPE FLOW  
IN AREAS EAST OF THE HIGH PLAINS WHICH IS CONFIRMED BY SURFACE  
OBSERVATIONS AS OF 19Z. OVERALL, A VERY MARGINAL CONVECTIVE  
SETUP IS IN PLACE TODAY. WEST OF I-25, FORECAST SOUNDINGS SHOW  
FAIRLY LARGE DEWPOINT DEPRESSIONS AND GENERALLY STRAIGHT BUT  
SHORT HODOGRAPHS. ISOLATED INSTANCES OF GUSTY WIND IN THE 40-60  
MPH RANGE ARE POSSIBLE WITH ANY STRONGER CORES, WITH ISOLATED  
SHOWER ACTIVITY CONTINUING OVERNIGHT AS A WEAK MONSOONAL PLUME  
OF MID-LEVEL MOISTURE CONTINUES TO SIT OVER THE CENTRAL ROCKIES.  
FARTHER EAST IN THE WYOMING HIGH PLAINS AND NEBRASKA PANHANDLE,  
THUNDERSTORMS WILL HAVE A BIT MORE LOW-LEVEL MOISTURE TO WORK  
WITH, WITH SMALLER TD DEPRESSIONS AND SMALL BUT SLIGHTLY MORE  
CURVING HODOGRAPHS SEEN IN FORECAST SOUNDINGS. CAM GUIDANCE IS  
IN GENERALLY GOOD AGREEMENT SHOWING A WEAK CLUSTERED STORM MODE  
AND THE POSSIBILITY OF A FEW CELLS CONTAINING PEA TO PENNY  
SIZED HAIL AND WIND GUSTS UP TO 60 MPH. THE CORRIDOR OF GREATEST  
CONCERN APPEARS TO BE FROM TORRINGTON/LUSK THROUGH CHADRON  
WHERE LOCALLY BACKED AND ENHANCED SURFACE FLOW MAY HELP TO  
SUSTAIN A STRONGER STORM OR TWO THROUGH AROUND 3Z TONIGHT.  
ELSEWHERE, EXPECT A FEW ISOLATED SHOWERS TO CONTINUE THROUGH THE  
EVENING AS THE AFOREMENTIONED MONSOONAL PLUME REMAINS IN PLACE  
IN THE MID LEVELS OVER ALL OF SOUTHEAST WYOMING AND FAR WESTERN  
NEBRASKA.  
 
AFTER A MILD AND PARTLY CLOUDY OVERNIGHT PERIOD, CONVECTION WILL  
ONCE AGAIN BE A THREAT ON SATURDAY. THE 500MB JET WILL DIP  
SOUTHWARD THROUGH THE MORNING AND EARLY AFTERNOON, WITH H5 FLOW  
AROUND 25-35 KNOTS OVER MOST OF THE HIGH PLAINS EAST OF THE  
LARAMIE RANGE BY 18Z. SURFACE FLOW WILL REMAIN OUT OF THE WEST  
IN THE HIGH-BASINS OF SOUTHEAST WYOMING. TO THE EAST, A BATTLE  
BETWEEN DRIER WESTERLY SURFACE FLOW AND LINGERING UPSLOPE WILL  
TAKE PLACE, WITH A DIFFUSE DRYLINE SETTING UP SOMEWHERE  
ALONG/EAST OF THE WY/NE STATE LINE IN THE NE PANHANDLE. EXACTLY  
WHERE THIS DRYLINE SETS UP AND HOW SHARP IT BECOMES WILL  
ULTIMATELY DETERMINE THE CONVECTIVE THREAT IN THE PANHANDLE ON  
SATURDAY. A SHARPER DRYLINE WITH MORE POTENT MOISTURE RETURN  
(EVIDENCED IN CAMS SUCH AS THE NAM NEST/WRF ARW WOULD SUPPORT A  
GREATER THUNDERSTORM THREAT IN THE PANHANDLE. SUPERCELLS WOULD  
BE POSSIBLE IN THE CWA WITH LARGE HAIL OVER 1 INCH AND GUSTY  
OUTFLOW WINDS POSSIBLE. HOWEVER, MODELS SUCH AS THE HRRR, FV3,  
AND RRFS FAVOR A MORE DEEPLY MIXED BOUNDARY LAYER AND THUS A  
MORE DIFFUSE DRYLINE FARTHER EAST OF THE CDR/AIA/SNY LINE. THIS  
OUTCOME WOULD LIKELY RESULT IN ONLY WEAKER, HIGH-BASED  
CONVECTION FOR MUCH OF THE CWA WITH ONLY A MINOR HIGH-WIND  
THREAT. THE CURRENT TREND OF MOST HREF GUIDANCE FAVORS THE  
FARTHER EAST DRYLINE AND LOWER SEVERE WEATHER THREAT FOR THE  
EASTERN PORTIONS OF THE CWA ON SATURDAY AND POPS/POT GUIDANCE  
HAS BEEN ADJUSTED ACCORDINGLY. STILL, FOLKS HEADED OUTSIDE TO  
ENJOY SUMMERTIME RECREATION WEEKEND ACTIVITIES SHOULD BE ON THE  
LOOKOUT FOR BRIEFLY GUSTY WINDS AND ISOLATED LIGHTNING WITH ANY  
THUNDERSTORMS THAT DO FORM.  
 

 
   
LONG TERM /SUNDAY THROUGH THURSDAY/
 
 
ISSUED AT 100 PM MDT FRI JUL 18 2025  
 
SUNDAY...LOW AMPLITUDE SHORTWAVE RIDGING ALOFT DEVELOPS. WITH DRIER  
AIR MOVING IN AT LOW AND MID LEVELS, ONLY ISOLATED AFTERNOON  
THUNDERSTORMS WILL BE POSSIBLE NEAR THE SOUTHERN LARAMIE RANGE,  
OTHERWISE DRY. 700 MB TEMPERATURES NEAR 17 CELSIUS WILL YIELD HIGH  
TEMPERATURES FROM THE MID 80S TO UPPER 90S.  
 
MONDAY...CONTINUED HOT WITH SOUTHWEST FLOW ALOFT AND 700 MB  
TEMPERATURES NEAR 16 CELSIUS. OTHER THAN ISOLATED LATE DAY  
THUNDERSTORMS, WARM TEMPERATURES ALOFT WILL PRODUCE ENOUGH  
CONVECTIVE INHIBITION TO LIMIT CONVECTIVE DEVELOPMENT.  
 
TUESDAY...WITH SLIGHTLY MORE ATMOSPHERIC MOISTURE, AND COOLER  
TEMPERATURES ALOFT, WE EXPECT TO SEE A LITTLE UPTICK IN LATE DAY  
SHOWERS AND THUNDERSTORMS, ALONG WITH SLIGHTLY COOLER TEMPERATURES.  
 
WEDNESDAY...AS THE FLOW ALOFT TURNS WESTERLY, ATMOSPHERIC MOISTURE  
INCREASES, WITH A CORRESPONDING INCREASE IN LATE DAY SHOWERS AND  
THUNDERSTORMS, ALONG WITH COOLER TEMPERATURES.  
 
THURSDAY...SIMILAR TEMPERATURES COMPARED TO WEDNESDAY WITH WEAK  
RIDGING ALOFT. STILL LOOKS LIKE ADEQUATE LOW AND MID LEVEL MOISTURE  
FOR ISOLATED TO SCATTERED AFTERNOON AND EVENING THUNDERSTORMS.  
 
FRIDAY...A FEW DEGREES WARMER THAN THURSDAY AS 700 MB TEMPERATURES  
PEAK NEAR 18 CELSIUS. ADEQUATE ATMOSPHERIC MOISTURE FOR ISOLATED TO  
SCATTERED LATE DAY SHOWERS AND THUNDERSTORMS, MAINLY EAST OF  
I-25.  
 

 
   
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
 
 
ISSUED AT 1134 AM MDT FRI JUL 18 2025  
 
SHOWERS AND STORMS WILL BE FAIRLY WIDESPREAD THIS AFTERNOON AND  
EVENING. SHOWERS ARE MOSTLY EXPECTED FOR OUR WYOMING TERMINALS  
AS A BOUNDARY LOOKS TO SET UP JUST EAST OF THE LARAMIE RANGE.  
THIS BOUNDARY WILL PRODUCE BETTER CHANCES FOR OUR NEBRASKA  
TERMINALS TO RECEIVE THUNDERSTORMS AFTER 00Z. SHOWER  
DEVELOPMENT LOOKS TO BE RIGHT AROUND 21-22Z FOR THE WYOMING  
TERMINALS. AFTER 03Z THERE LOOKS TO BE ANOTHER ROUND OF SHOWERS  
THAT COULD CONTINUE UNTIL EARLY SATURDAY MORNING.  
 

 
   
CYS WATCHES/WARNINGS/ADVISORIES
 
 
WY...NONE.  
NE...NONE.  
 

 
 

 
 
SHORT TERM...MAC  
LONG TERM...RUBIN  
AVIATION...MM  
 
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