327  
FXUS65 KCYS 082359  
AFDCYS  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CHEYENNE WY  
450 PM MST THU DEC 8 2022  
   
SHORT TERM
 
(THIS EVENING THROUGH SUNDAY)  
ISSUED AT 215 PM MST THU DEC 8 2022  
 
FORECAST CONCERNS IN THE SHORT TERM DEAL WITH STRONG WINDS LEADING  
TO WIND HEADLINES THROUGH SATURDAY. MAJOR WINTER STORM STILL  
POSSIBLE THE START OF NEXT WEEK WITH SIGNIFICANT SNOWFALL AND  
STRONG WINDS POSSIBLE.  
 
CURRENTLY...FRONTAL BOUNDARY LAYS FROM WESTERN NEBRASKA NEAR  
MCCOOK TO GORDON NEBRASKA TO GILLETTE WYOMING UP INTO CENTRAL  
MONTANA THIS AFTERNOON. UPPER VORT MAX PUSHING INTO WESTERN  
NEBRASKA AT THIS TIME RIDING OVER THE FRONT. WINDS BEHIND THIS  
UPPER SHORTWAVE HAVE REALLY INCREASED. WE HAVE SEEN 60+MPH WINDS  
AT ARLINGTON...THE SUMMIT AND EASTERN FOOTHILLS FROM LATE MORNING  
THAT ARE CONTINUING THIS AFTERNOON. BORDEAUX HAS BEGUN TO INCREASE  
WITH 50MPH GUSTS REPORTED AT THE WYDOT SITE. NO PLANS ON CHANGING  
ANY OF THE CURRENT WIND WARNINGS AT THIS TIME. CURRENT CRAIG TO  
CASPER 850/700MB HEIGHT GRADIENTS NEAR 55/56MTRS  
RESPECTIVELY. GFS 700-800MB WINDS INCREASING TO 45 TO 50KTS  
THROUGH 00Z THIS AFTERNOON OVER CHEYENNE AND SOUTH LARAMIE RANGE.  
WIND GUSTS AT CHEYENNE CURRENTLY AT 40KTS. WITH THESE WINDS  
CONTINUING TO INCREASE THROUGH THE AFTERNOON...DO FEEL CHEYENNE IS  
GOING TO HIT.  
 
ONE NOTE OF CAUTION FOR THE EVENING SHIFT. MAY NEED TO EXTEND THE  
HIGH WIND WARNING A FEW MORE HOURS THIS EVENING AS GRADIENTS  
REMAIN HIGH THROUGH 06Z. MAY BE A LAST MINUTE UPDATE TO EXTEND  
WARNINGS BASED ON CURRENT OBSERVATIONS LATER TODAY.  
 
AS FOR WINTER HEADLINES...SNOTELS IN THE SIERRA MADRE HAVE  
REPORTED ROUGHLY .6 INCHES OF LIQUID. SNOWING PRETTY GOOD AT  
CHADRON. JUST GOT A REPORT AT CHADRON OF 3 INCHES WITH SNOW  
CONTINUING TO FALL. SO WILL KEEP THE ADVISORIES GOING AS THEY ARE.  
 
UPPER LOW TRACKS EAST THIS EVENING...WITH WINDS EASING OVERNIGHT.  
SHORTWAVE RIDGE MOVES FAIRLY RAPIDLY ACROSS THE CWA FRIDAY MORNING  
AS NEXT LOW PRESSURE SYSTEM MOVES INTO NORTHERN UTAH. LOOKING AT  
INCREASING CRAIG TO CASPER 850/700MB HEIGHT GRADIENTS FRIDAY  
EVENING AS UPPER SHORTWAVE MOVES INTO CENTRAL WYOMING. GFS  
700/750MB WINDS UP TO 50KTS FRIDAY EVENING OVER ARLINGTON AND  
BORDEAUX. DECIDED TO ISSUE A HIGH WIND WATCH FOR FRIDAY NIGHT INTO  
SATURDAY.  
IN WYOMING, THE MAIN AVIATION HAZARD WILL BE STRONG WINDS THIS  
AFTERNOON. KCYS AND KLAR CAN EXPECT FREQUENT WIND GUSTS BETWEEN 30  
AND 40 KTS, WITH OCCASIONAL GUSTS ABOVE 45 KTS. MVFR CIGS ARE  
LINGERING AT KRWL, BUT THIS SHOULD IMPROVE IN THE NEXT 1-2 HOURS  
WITH WIND GUSTS OF 30 TO 35 KNOTS LIKELY THIS AFTERNOON. WINDS WILL  
DIE DOWN AFTER SUNSET. A REPRIEVE IN THE WEATHER FOR SATURDAY  
AFTERNOON THROUGH SUNDAY AS UPPER RIDGE RESIDES OVER THE AREA. A  
VERY STRONG LOW PRESSURE SYSTEM MOVES INTO NORTHERN CALIFORNIA  
SUNDAY MORNING AND AFTERNOON. THIS IS THE LOW THAT COULD BRING  
SIGNIFICANT WINTER WEATHER TO OUR AREA FOR MONDAY THROUGH WEDNESDAY  
NEXT WEEK.  
   
LONG TERM
 
(SUNDAY NIGHT THROUGH THURSDAY)  
ISSUED AT 215 PM MST THU DEC 8 2022  
 
KEY MESSAGES:  
 
1) STRONG WINTER STORM REMAINS POSSIBLE IN THE LONG TERM FORECAST  
WITH WEATHER IMPACTS BEGINNING EARLY MONDAY MORNING AND LASTING  
THROUGH WEDNESDAY. PRIMARY HAZARDS WILL BE HEAVY SNOWFALL AND STRONG  
WINDS.  
 
2) UNCERTAINTY REMAINS HIGH AT THIS TIME AS EVEN A SLIGHT SHIFT  
NORTH OR EAST COULD LEAVE SOUTHEAST WYOMING AND THE NEBRASKA  
PANHANDLE RECEIVING MINIMAL IMPACTS.  
 
3) STRONG WINDS FOLLOWING THE INITIAL SNOWFALL POSSIBLE, RESULTING  
IN BLOWING SNOW, ESPECIALLY IN EAST CENTRAL WYOMING AND THE NEBRASKA  
PANHANDLE.  
 
DISCUSSION: THE PRIMARY FORECAST CONCERN FOR THE LONG TERM FORECAST  
PERIOD IS A POTENTIAL STRONG WINTER STORM STARTING MONDAY OVER  
WESTERN PORTIONS OF OUR CWA, LASTING THROUGH WEDNESDAY. CONFIDENCE  
IS HIGH THAT THE MAIN HAZARDS WITH THIS STORM WILL BE HEAVY SNOWFALL  
AND STRONG WINDS, HOWEVER CONFIDENCE IS LOW ON WHERE EXACTLY THESE  
IMPACTS WILL OCCUR. THE LOCATION WILL BE HEAVILY DEPENDENT ON HOW  
THE SYSTEM SETS UP SYNOPTICALLY. THE CURRENT GFS AND ECMWF  
DETERMINISTIC MODEL RUNS HAVE THE LOW DROPPING SOUTH ALONG THE  
WESTERN EDGE OF THE ROCKIES MONDAY, THEN SWINGING BACK NORTH TO THE  
BORDERS BETWEEN WY/NE/CO/KS, TAPPING INTO DEEP GULF MOISTURE, AND  
REMAINING ALMOST STATIONARY THROUGH WEDNESDAY NIGHT UNTIL IT EJECTS  
NORTHEASTWARD THURSDAY. IF THIS SET UP REMAINS CONSISTENT BETWEEN  
MODEL RUNS, EAST-CENTRAL WYOMING AND THE NEBRASKA PANHANDLE,  
PARTICULARLY THE PINE RIDGE AREA, WILL RECEIVE SIGNIFICANT IMPACTS  
DUE IN PART TO THE WRAP AROUND MOISTURE AND STRONG PRESSURE GRADIENT  
RESULTING IN HEAVY SNOWFALL AND VERY STRONG NORTHERLY WINDS.  
 
AS THIS SYSTEM IS STILL 5+ DAYS OUT, IT IS A GUARANTEE THAT THE  
FORECAST WILL CHANGE, EITHER TREND HIGHER OR LOWER DEPENDING ON  
WHERE THE MODELS SHOW THE LOW CLOSING OFF AND BECOMING STATIONARY.  
THE SNOWFALL ACCUMULATION FORECAST IS CURRENTLY NEAR GFS ENSEMBLE  
MEANS AND NBMV4.1 50TH PERCENTILE EVERYWHERE, EXCEPT THE PINE RIDGE,  
CHADRON TO DOUGLAS AREA, WHERE IT IS CLOSER TO THE NBMV4.1 75TH  
PERCENTILE. IN GENERAL WHAT THIS MEANS IS WE ARE MOST CONFIDENT IN  
THE PINE RIDGE, CHADRON TO DOUGLAS AREA, RECEIVING THE STRONGEST  
IMPACTS AND OUR CONFIDENCE DECREASES MOVING SOUTH.IN WYOMING, THE  
MAIN AVIATION HAZARD WILL BE STRONG WINDS THIS AFTERNOON. KCYS AND  
KLAR CAN EXPECT FREQUENT WIND GUSTS BETWEEN 30 AND 40 KTS, WITH  
OCCASIONAL GUSTS ABOVE 45 KTS. MVFR CIGS ARE LINGERING AT KRWL, BUT  
THIS SHOULD IMPROVE IN THE NEXT 1-2 HOURS WITH WIND GUSTS OF 30 TO  
35 KNOTS LIKELY THIS AFTERNOON. WINDS WILL DIE DOWN AFTER SUNSET.  
ANOTHER AREA TO NOTE IS THE LARAMIE VALLEY, MID-LEVEL WINDS APPEAR  
TO START OFF SOUTHERLY, TRANSITIONING TO EASTERLY BY TUESDAY,  
TURNING NORTHERLY BY WEDNESDAY. AS SOUTHERLY AND EASTERLY ARE BOTH  
DOWNSLOPING, THE LARAMIE VALLEY WILL START OFF SHADOWED BY THE  
MOUNTAINS, DECREASING THE SNOW POTENTIAL UNTIL THE WINDS TURN  
NORTHERLY, WHICH IS A MORE FAVORABLE DIRECTION.  
 
STAY TUNED IN THE COMING DAYS FOR FORECAST UPDATES!  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH FRIDAY AFTERNOON)  
ISSUED AT 455 PM MST THU DEC 8 2022  
 
SNOWFALL AND LOW CIGS WILL IMPACT KCDR EARLY THIS EVENING BEFORE  
CONDITIONS QUICKLY IMPROVE AROUND 03Z. SOUTHWEST FLOW EXPECTED  
TOMORROW WITH INCREASING MID TO HIGH CLOUDINESS THROUGH THE DAY.  
 
HAZARDS/WEATHER TRENDS: NEAR IFR CONDITIONS WILL CONTINUE AT KCDR  
WITH MAINLY MVFR VIS EXPECTED IN LIGHT SNOW. CONDITIONS ARE EXPECTED  
TO IMPROVE SHORTLY (BETWEEN 00Z AND 03Z) WITH VFR CONDITIONS AT ALL  
TERMINALS TONIGHT THROUGH FRIDAY MORNING. OTHERWISE, GUSTY WINDS UP  
TO 30 MPH THIS EVENING ACROSS THE EASTERN PLAINS TIN WYOMING, THE  
MAIN AVIATION HAZARD WILL BE STRONG WINDS THIS AFTERNOON. KCYS AND  
KLAR CAN EXPECT FREQUENT WIND GUSTS BETWEEN 30 AND 40 KTS, WITH  
OCCASIONAL GUSTS ABOVE 45 KTS. MVFR CIGS ARE LINGERING AT KRWL, BUT  
THIS SHOULD IMPROVE IN THE NEXT 1-2 HOURS WITH WIND GUSTS OF 30 TO  
35 KNOTS LIKELY THIS AFTERNOON. WINDS WILL DIE DOWN AFTER SUNSET.  
ERMINALS WILL LIKELY BECOME LIGHT AND VARIABLE AFTER 02Z.  
 

 
   
FIRE WEATHER
 
 
ISSUED AT 215 PM MST THU DEC 8 2022  
 
STRONG WINDS THIS AFTERNOON ACROSS THE WIND PRONE AREAS OF  
SOUTHEAST WYOMING. AFTERNOON HUMIDITY HAS REMAINED WELL ABOVE  
CRITICAL LEVELS THIS AFTERNOON...SO CRITICAL FIRE WEATHER  
CONDITIONS NOT EXPECTED. ANOTHER HIGH WIND EVENT FOR THE WIND  
PRONE AREAS OF SOUTHEAST WYOMING FRIDAY EVENING INTO SATURDAY WITH  
HIGH WIND WATCHES IN EFFECT. ANOTHER STRONG LOW PRESSURE SYSTEM  
FORECAST TO MOVE INTO THE CENTRAL ROCKIES SUNDAY INTO TUESDAY THAT  
COULD BRING SUBSTANTIAL SNOWFALL TO MUCH OF THE FORECAST AREA.  
SUBSTANTIAL SNOW AMOUNTS POSSIBLE TUESDAY AND WEDNESDAY WITH VERY  
STRONG NORTH TO NORTHWEST WINDS. STANDBY FOR FURTHER UPDATES OVER  
THIS WEEKEND.  
 

 
   
CYS WATCHES/WARNINGS/ADVISORIES
 
 
WY...HIGH WIND WARNING UNTIL 8 PM MST THIS EVENING FOR WYZ106-110-  
116>118.  
 
HIGH WIND WATCH FROM FRIDAY EVENING THROUGH SATURDAY MORNING FOR  
WYZ106-110-116-117.  
 
WINTER WEATHER ADVISORY UNTIL 5 PM MST THIS AFTERNOON FOR WYZ112.  
 
NE...WINTER WEATHER ADVISORY UNTIL 8 PM MST THIS EVENING FOR NEZ002.  
 

 
 

 
 
SHORT TERM...GCC  
LONG TERM...LK  
AVIATION...TJT  
FIRE WEATHER...GCC  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab WY Page
The Nexlab NE Page Main Text Page