940  
FXUS65 KCYS 061200  
AFDCYS  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CHEYENNE WY  
500 AM MST WED NOV 6 2024  
   
KEY MESSAGES
 
 
- MUCH COLDER TEMPERATURES ARE EXPECTED WEDNESDAY WITH BRISK  
NORTHERLY WINDS FOR MOST AREAS. SNOW SHOWERS MAY LEAD TO LIGHT  
ACCUMULATIONS ACROSS CONVERSE, CARBON, AND ALBANY COUNTIES  
THROUGH WEDNESDAY AFTERNOON.  
 
- SNOW SHOWERS ASSOCIATED WITH A STRONGER STORM SYSTEM TO THE  
SOUTH MAY CREEP INTO THE SOUTHERN NEBRASKA PANHANDLE WEDNESDAY  
THROUGH WEDNESDAY NIGHT.  
 
- UNCERTAINTY STILL REMAINS CONCERNING THE POTENTIAL STORM  
SYSTEM ON FRIDAY INTO SATURDAY. SEE THE LONG TERM SECTION  
BELOW FOR MORE DETAILS.  
 

 
   
SHORT TERM /THROUGH THURSDAY NIGHT/
 
 
ISSUED AT 121 AM MST WED NOV 6 2024  
 
CLOUDY SKIES OVERHEAD TONIGHT IN THE WAKE OF THE COLD FRONT THAT  
PUSHED THROUGH THE REGION EARLIER TODAY. MOISTURE IS STREAMING IN  
ACROSS EASTERN PORTIONS OF THE CWA, PER MID-LEVEL WATER VAPOR  
IMAGERY FROM GOES16, WITH SIGNIFICANT MOISTURE PRESENT ACROSS EASTERN  
COLORADO AND CENTRAL NEBRASKA. WHILE CLOUDS ARE OVERHEAD WITH  
MOISTURE STREAMING INTO THE REGION, NO SNOW IS FALLING AS OF 09Z.  
THE BEST CHANCE FOR SNOW WOULD BE A SIDNEY, BUT THE DRY BOUNDARY  
LAYER OVERNIGHT IS PREVENTING ANY POTENTIAL PRECIPITATION FROM  
REACHING THE GROUND AT THIS TIME. TEMPERATURES ARE QUITE COOL,  
THOUGH NOT AS COOL AS THEY COULD BE THANKS TO THE CLOUD COVER  
OVERHEAD. TEMPERATURES CURRENTLY RANGE FROM THE LOW-20S TO THE WEST  
AND UPPER-30S TO THE EAST, SPECIFICALLY SIDNEY. WITH DEWPOINTS IN  
THE TEENS AND 20S AT THIS TIME, PRECIPITATION IS NOT FAVORED TO  
REACH THE GROUND BEFORE EVAPORATING.  
 
A VERY DYNAMIC PATTERN REMAINS OVERHEAD, AS A SPLIT FLOW REGIME IN  
THE MID-LEVELS OF THE ATMOSPHERE HAS DEVELOPED. THE NORTHERN PORTION  
OF THE SPLIT FLOW REGIME REMAINS OVER CENTRAL NORTH DAKOTA DOWN INTO  
WESTERN SOUTH DAKOTA AS OF 09Z PER GOES16 MID-LEVEL WATER VAPOR  
IMAGERY. THE SOUTHERN PORTION OF THE FLOW REGIME, AND THE  
POTENTIALLY IMPACTFUL SYSTEM IN A FEW DAYS, IS CURRENTLY OVER  
EASTERN UTAH AND WESTERN COLORADO. MOISTURE IS STREAMING OUT INTO  
EASTERN COLORADO AHEAD OF THE SOUTHERN FLANK OF THE TROUGH AT THIS  
TIME. SNOW IS ONGOING ACROSS MUCH OF COLORADO, BUT THE BEST MOISTURE  
HAS YET TO MAKE IT INTO WESTERN NEBRASKA. AS SUCH, NO SNOW HAS  
FALLEN THUS FAR AT SIDNEY, DESPITE SHORT RANGE, HIRES MODELS  
SUGGESTING SNOW STARTING TO FALL A FEW HOURS AGO. DUE TO THIS, DID  
LOWER SNOW TOTALS AT SIDNEY FOR WEDNESDAY, AS THE BOUNDARY LAYER IS  
MUCH DRIER THAN WHAT IS CURRENTLY BEING PROJECTED IN MOST MODELS.  
BETTER ISENTROPIC LIFT IS PROGGED TO DEVELOP AROUND 12Z AT AND JUST  
SOUTH OF CHEYENNE COUNTY WITH ADDITIONAL MOISTURE SURGING INTO THE  
REGION. THIS LOOKS TO BE THE BEST TIME TO GET PRECIPITATION TO BEGIN  
FALLING ACROSS I-80 IN CHEYENNE AND POTENTIALLY KIMBALL COUNTIES.  
HOWEVER, WITH THE OVERLY MOIST BOUNDARY LAYERS IN THE CURRENT  
MODELS, LESS PRECIPITATION MAY FALL THAN IS CURRENTLY MODELED IN THE  
GFS, ECMWF, AND NAM. THE HRRR HAS THE BEST GRASP ON THE CURRENT  
BOUNDARY LAYER AND SUGGESTS ONLY ABOUT AN INCH OF SNOW AT SIDNEY  
THROUGH THE MORNING AND AFTERNOON HOURS. THEREFORE, TRENDED SNOWFALL  
DOWN CLOSER TO THE VALUE MODELED BY THE HRRR. THE BEST ISENTROPIC  
LIFT ADVECTS OUT OF THE REGION BY 18Z TODAY, THEREFORE, SNOWFALL IS  
EXPECTED TO TAPER OFF QUICKLY AFTER 18Z. VERY COLD 700MB  
TEMPERATURES WILL REMAIN OVERHEAD, USHERED IN BY CONTINUED NORTHERLY  
FLOW. TEMPERATURES AT 700MB WILL REMAIN IN THE -10 TO -12C RANGE  
THROUGHOUT THE DAY TODAY, LEADING TO SURFACE HIGH TEMPERATURES  
STRUGGLING TO HIT FREEZING IN SOUTHEAST WYOMING AND IN THE MID-30S  
IN WESTERN NEBRASKA. ADDITIONAL CLOUD COVER THROUGHOUT THE DAY WILL  
FURTHER PREVENT THESE TEMPERATURES FROM RAISING SIGNIFICANTLY  
THROUGHOUT THE DAY.  
 
NORTHERLY FLOW AT 700MB WILL ENABLE COLD TEMPERATURES TO REMAIN  
OVERHEAD, WITH 700MB TEMPERATURES EXPECTED TO BE IN THE -7 TO -9C  
RANGE EARLY THURSDAY MORNING. CLOUDS WILL CLEAR DURING THE OVERNIGHT  
HOURS DUE TO THE SOUTHERN PORTION OF THE SPLIT FLOW REGIME REMAINING  
STATIONARY JUST SOUTH OF THE FOUR CORNERS REGION. AS A RESULT,  
TEMPERATURES ARE EXPECTED TO TANK THURSDAY MORNING, WITH MORNING  
LOWS IN THE SINGLE DIGITS TO TEENS. LIGHT WINDS OVERNIGHT WILL MAKE  
MOST LOCATIONS FEEL MUCH COLDER, WITH APPARENT TEMPERATURES IN THE  
LOW SINGLE DIGITS FOR MOST LOCATIONS THURSDAY MORNING. THIS WILL  
EASILY BE THE COLDEST AIR OF THE SEASON THUS FAR. THE CLEARING SKIES  
WILL HELP WARM TEMPERATURES UP DECENTLY FOR THURSDAY AS THE UPPER-  
LEVEL LOW CONTINUES TO CHURN ACROSS SOUTHERN NEW MEXICO.  
TEMPERATURES EXPECTED TO INCREASE INTO THE MID-30S TO MID-40S AREA  
WIDE, WITH CHADRON POTENTIALLY SEEING 50F THURSDAY AFTERNOON.  
OVERALL, THE COLD TEMPERATURES TO START THE DAY WILL QUICKLY MOVE  
OUT OF THE REGION. SOUTHERLY SURFACE FLOW WILL ALSO HELP USHER IN  
SLIGHTLY WARMER TEMPERATURES FOR THURSDAY. THERE ARE LIMITED  
PRECIPITATION CHANCES FOR THURSDAY, AS THE 700MB LOW REMAINS MUCH  
TOO FAR SOUTH TO HAVE ANY SIGNIFICANT IMPACT TO THE REGION. HOWEVER,  
THERE IS STILL A SLIGHT CHANCE (15-19%) FOR ISOLATED SHOWERS ALONG  
THE I-80 CORRIDOR IN CHEYENNE AND KIMBALL COUNTIES. NOT MUCH  
ACCUMULATION, IF ANY AT ALL, IS EXPECTED WITH ANY SHOWERS THAT  
DEVELOP IN THIS REGION ON THURSDAY.  
 
PRECIPITATION CHANCES COME TO AN END THURSDAY NIGHT INTO THE EARLY  
MORNING HOURS THURSDAY AS ISENTROPIC DOWNGLIDE DOMINATES THE REGION  
AND THE 700MB LOW CONTINUES TO CHURN WELL OFF TO THE SOUTH OVER  
EASTERN NEW MEXICO. TEMPERATURES THURSDAY NIGHT INTO FRIDAY MORNING  
WILL CONTINUE TO BE COLD, THOUGH WARMER THAN THURSDAY MORNING AS  
700MB TEMPERATURES APPROACH 0C. LOWS ARE EXPECTED IN THE TEENS TO  
LOW-20S AREA WIDE.  
 

 
   
LONG TERM /FRIDAY THROUGH TUESDAY/
 
 
ISSUED AT 121 AM MST WED NOV 6 2024  
 
STILL SOME UNCERTAINTY ON WHATS GOING TO HAPPEN THIS WEEKEND.  
THE ECMWF HAS BEEN VERY CONSISTENT WITH A VERTICALLY STACKED LOW  
TRACKING ACROSS SOUTHERN COLORADO. THAT WOULD PUT THE NORTHERN  
WRAP AROUND MOISTURE OVER THE CHEYENNE CWA. NOT AN OVERLY COLD  
LOW AS ECMWF 700MB TEMPERATURES OVER THE CWA RIGHT AROUND 0C  
AND SLIGHTLY WARMER. WHERE THE WRAP AROUND MOISTURE IS MOST  
PREVALENT...THE NEBRASKA PANHANDLE...A LOT OF THIS MOISTURE  
WILL FALL AS RAIN.  
 
GFS HAS THE LOW FURTHER SOUTH IN NORTHERN NEW MEXICO AND TRACKS  
IT NORTHEAST INTO CENTRAL NEBRASKA SATURDAY AND IOWA ON SUNDAY.  
THIS WOULD BE A WARMER AND DRIER SOLUTION FOR WEATHER HERE IN  
SOUTHEAST WYOMING.  
 
WENT WITH THE MORE CONSISTENT ECMWF SOLUTION FOR THE FRIDAY  
THROUGH SUNDAY FORECAST. LOOKS LIKE RAIN BELOW 6K FEET AND SNOW  
ABOVE. AGAIN MOST OF THE FORECAST QPF IS OVER THE PANHANDLE...SO  
HEAVIER SNOW ACCUMULATIONS ARE NOT EXPECTED AT THIS TIME.  
 
NICE WARM UP FOR SUNDAY AS A SHORTWAVE RIDGE MOVES ACROSS THE  
CWA. LOOKING AT 700MB TEMPERATURES CLIMBING TO +8C...SO  
AFTERNOON HIGHS IN THE 60S LOOKING LIKELY FOR THE PANHANDLE WITH  
40S AND 50S ACROSS SOUTHEAST WYOMING.  
 
RIDGE DOESN'T STICK AROUND VERY LONG AS IT TRACKS INTO THE  
CENTRAL PLAINS AND THE NEXT SHORTWAVE TROUGH APPROACHES FROM THE  
WEST. MONDAY WILL BE A NICE DAY WITH INCREASING CLOUDS AHEAD OF  
THAT NEXT SHORTWAVE. THIS SYSTEM TRACKS INTO OUR WESTERN CWA  
TUESDAY WITH VERY COLD 700MB TEMPERATURES BEHIND THE TROUGH.  
SNOW WOULD BE A PRETTY GOOD BET AS 700MB TEMPERATURES FALL TO -6  
TO -8C.  
 

 
   
AVIATION /12Z TAFS THROUGH 12Z THURSDAY/
 
 
ISSUED AT 456 AM MST WED NOV 6 2024  
 
RADAR SHOWING AN AREA OF SNOW MOVING NORTH OUT OF NORTHEAST  
COLORADO THIS MORNING. IT WILL BRING IFR VISIBILITIES AND  
CEILINGS TO KSNY AND ALONG THE I-80 CORRIDOR WEST TO KCYS AND  
KLAR. MOST OF THE MORNING WILL BE DOWN IN SNOW THROUGH AT LEAST  
17 TO 18Z AT THESE THREE AIRPORTS. SNOW THEN IS FORECAST TO  
SLOWLY SHIFT EAST AND OUT OF OUR AREAS.  
 

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

 
 

 
 
SHORT TERM...AM  
LONG TERM...GCC  
AVIATION...GCC  
 
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