181  
FXUS65 KCYS 231726  
AFDCYS  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CHEYENNE WY  
1125 AM MDT SUN APR 23 2017  
   
SHORT TERM
 
(TODAY THROUGH TUESDAY)  
ISSUED AT 200 AM MDT SUN APR 23 2017  
 
A FEW FORECAST CHALLENGES IN THE SHORT TERM. STRONG WINDS A  
CONCERN TODAY AND MONDAY WITH PRECIP TIMING/TYPE AS A FRONT MOVES  
INTO THE AREA.  
 
CURRENTLY...WATER VAPOR SHOWING A PRETTY STRONG SYSTEM MOVING INTO  
OREGON THIS MORNING, JUST ABOUT TO MOVE INTO WESTERN IDAHO. RIDGE  
AXIS JUST ABOUT OVERHEAD AT THIS TIME. RADAR IS PPINE AT THIS TIME  
WITH CLEAR SKIES OVER THE CWFA AT THIS TIME.  
 
FOR TODAY...RIDGE AXIS SHIFTS EAST AND SOUTHWEST WINDS BEGIN TO  
INCREASE. GFS SOUNDINGS FOR RAWLINS SHOWING POSSIBILITY OF MIXING  
WINDS FROM 550MBS THIS AFTERNOON, WHICH ARE AROUND 45KTS. CRAIG TO  
CASPER 850/700MB GRADIENTS INCREASE TO 32/35MTRS RESPECTIVELY  
THIS AFTERNOON AND UP TO 44/41MTRS MONDAY. SO DEFINITELY A WINDY  
DAY ESPECIALLY OUT WEST. DID BUMP UP WINDS, BUT KEPT WINDS AROUND  
40-45KTS ON GUSTS. AT THE SAME TIME, INCREASING CLOUDS AND MID  
LEVEL MOISTURE SHOULD BEGIN TO LIMIT MIXING.  
 
CONVECTION SPREADS INTO THE CWFA FROM WEST TO EAST THIS EVENING  
INTO MONDAY. MOUNTAINS OUT WEST (SNOWY/SIERRA MADRE) GETTING HIT  
PRETTY GOOD ON GFS AND ECMWF MONDAY AFTERNOON INTO THE EVENING  
HOURS. LATEST HPC SNOW FORECAST FOR THESE MOUNTAINS AROUND 8-10  
INCHES FOR SNOWFALL THROUGH 12Z WEDNESDAY. LATER SHIFTS WILL NEED  
TO CONSIDER ADVISORIES FOR THESE TWO ZONES.  
   
LONG TERM
 
(TUESDAY NIGHT THROUGH SATURDAY)  
ISSUED AT 1213 AM MDT SUN APR 23 2017  
 
TUESDAY NIGHT/WEDNESDAY...INITIAL SHORTWAVE TROUGH ALOFT CONTINUES  
TO MOVE TO OUR SOUTHEAST WITH DECREASING AREAL COVERAGE OF SHOWERS  
AFTER MIDNIGHT, CONFINED MAINLY TO THE MOUNTAINS. ON WEDNESDAY, THE  
NEXT SHORTWAVE TROUGH ALOFT MOVES ACROSS WESTERN WYOMING, SPREADING  
CLOUDS AND SHOWERS FROM WEST TO EAST ACROSS OUR COUNTIES, ESPECIALLY  
IN THE AFTERNOON, WITH DECENT OROGRAPHICS EXPECTED OVER OUR SNOWY  
AND SIERRA MADRE RANGES.  
 
THURSDAY...QUITE A WET PATTERN SETTING UP AS THE INITIAL SHORTWAVE  
TROUGH ALOFT MOVES OFF TO OUR EAST, WITH ANOTHER STRONGER SHORTWAVE  
DEVELOPING OVER WESTERN WYOMING IN THE AFTERNOON, AND DECENT UPPER  
LEVEL DIFFLUENCE SETTING UP OVER SOUTHEAST WYOMING ALONG WITH PLENTY  
OF LOW AND MID LEVEL MOISTURE, SETTING THE STAGE FOR SCATTERED TO  
NUMEROUS SHOWERS TO DEVELOP LATE IN THE DAY.  
 
FRIDAY...MODELS SIMILAR IN DEPICTING A SLOW MOVING UPPER LOW OVER  
WESTERN COLORADO WITH DEEP AND MOIST LOW AND MID LEVEL UPSLOPE FLOW  
OVER OUR COUNTIES, PRODUCING SCATTERED TO NUMEROUS SHOWERS WITH  
MOUNTAIN SNOWS. QUITE A COOL AND RAW DAY WITH PLENTY OF RAIN  
FALLING. IF THIS PATTERN VERIFIES, WE WILL EXPECT A COOL AND CLOUDY  
DAY WITH WIDESPREAD SHOWERS AND PLENTY OF SNOW FOR THE MOUNTAINS.  
 
SATURDAY...THE SLOW MOVING UPPER LOW PROGGED TO MOVE TO NORTHEAST  
COLORADO BY LATE IN THE DAY, WITH SCATTERED TO NUMEROUS SHOWERS TO  
CONTINUE ACROSS OUR COUNTIES IN THE WRAPAROUND PRECIPITATION BAND.  
CONTINUED QUITE COOL WITH TEMPERATURES HOVERING MAINLY IN THE 40S AT  
LOWER ELEVATIONS.  
 

 
   
AVIATION
 
(FOR THE 18Z TAFS THROUGH MONDAY MORNING)  
 
VFR CONDITIONS WILL PREVAIL TODAY AND TONIGHT ACROSS THE SOUTHEAST  
WYOMING AND WESTERN NEBRASKA TERMINALS. GUSTY SOUTH TO SOUTHWEST  
WINDS ARE EXPECTED THIS AFTERNOON AND INTO EARLY THIS EVENING ACROSS  
SOUTHEAST WYOMING, WITH WINDS REMAINING BETWEEN 15 TO 25 KNOTS  
ACROSS PORTIONS OF WESTERN NEBRASKA THROUGH MIDNIGHT TONIGHT. BANDS  
OF RAIN SHOWERS WILL BRIEFLY LOWER CIGS, BUT LITTLE IF ANY AVIATION  
IMPACTS ARE EXPECTED AT THIS TIME.  
 

 
   
FIRE WEATHER
 
 
ISSUED AT 200 AM MDT SUN APR 23 2017  
 
STRONG WINDS TODAY AS HIGH PRESSURE MOVES OFF TO OUR EAST AND A  
FRONT BEGINS TO MOVE IN FROM THE WEST. COULD SEE SOUTHWEST WINDS  
GUSTING CLOSE TO 50 MPH IN THE WIND PRONE AREAS TODAY.  
FORTUNATELY, AFTERNOON HUMIDITIES SHOULD REMAIN ABOVE CRITICAL  
THRESHOLDS. AS THE FRONT MOVES INTO CARBON COUNTY LATE THIS  
AFTERNOON, WE WILL SEE INCREASING CHANCES FOR WETTING RAINS AND  
MOUNTAIN SNOW. PRETTY UNSETTLED WEATHER FOR MOST OF THE UPCOMING  
WEEK WITH DAILY CHANCES FOR WETTING RAINS AND MOUNTAIN SNOW.  
 

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

 
 

 
 
SHORT TERM...GCC  
LONG TERM...RUBIN  
AVIATION...TJT  
FIRE WEATHER...GCC  
 
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