669  
FXUS65 KCYS 191745  
AFDCYS  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CHEYENNE WY  
1145 AM MDT SUN APR 19 2015  
   
UPDATE
 
 
ISSUED AT 1023 AM MDT SUN APR 19 2015  
 
NO BIG CHANGES TO THE FORECAST TODAY...ONLY TYPICAL MINOR  
ADJUSTMENTS. RADAR IS SHOWING SOME ECHOS OVER THE FORECAST  
AREA...BUT LITTLE IN THE WAY OF ACTUAL PRECIPITATION HITTING THE  
GROUND. MAY SEE A FEW LIGHT SPRINKLES OR FLURRIES BUT CHANCES FOR  
MEASURABLE PRECIPITATION VERY LOW. THE ONLY EXCEPTION BEING OVER  
THE SNOWY AND SIERRA MADRE RANGES WHERE AN INCH OR SO OF SNOW IS  
POSSIBLE.  
 

 
   
SHORT TERM
 
(TODAY THROUGH TUESDAY)  
ISSUED AT 330 AM MDT SUN APR 19 2015  
 
LATEST WATER VAPOR IMAGERY SHOWED THE CLOSED UPPER LOW OVER WESTERN  
KS...WITH A TROUGH TRAVERSING THE NORTHERN PLAINS. A STRONG SURFACE  
COLD FRONT EXTENDED FROM NORTHWEST NE TO THE CO-WY BORDER SOUTH OF  
CHEYENNE. 6HRLY PRESSURE RISES OF 3-4 MB BEHIND THE FRONT GENERATED  
GUSTY NORTH TO NORTHWEST WINDS OF 25-40 MPH ACROSS THE HIGH PLAINS.  
REGIONAL RADARS INDICATED MOST OF THE PRECIPITATION MOVED SOUTHEAST  
INTO NORTH AND NORTHEAST CO...WITH SOME LIGHT SNOW SHOWERS LINGERING  
OVER THE SNOWY AND SOUTH LARAMIE RANGES AND ADJACENT FOOTHILLS.  
TEMPERATURES RANGED FROM THE MID 20S TO MID 40S.  
 
THERE IS GOOD AGREEMENT WITH THE 00Z DETERMINISTIC MODEL GUIDANCE  
PROGGING THE CENTRAL PLAINS UPPER LOW TO WEAKEN TO A TROUGH AS  
IT TRACKS EAST TOWARD THE MID MS VALLEY THROUGH TONIGHT. MEANWHILE...  
THE TROUGH OVER THE DAKOTAS ENTERS THE UPPER MIDWEST TONIGHT. A  
NORTHWEST FLOW ALOFT WILL PREVAIL WITH A FEW WEAK SHORTWAVES  
PASSING THROUGH THE CWA. THE MODELS HOLD ONTO SOME MOISTURE AND  
UPSLOPE TO PRODUCE ISOLATED TO SCATTERED RAIN/SNOW SHOWERS MAINLY  
ALONG AND WEST OF THE LARAMIE RANGE FOR THE NEXT 24 TO 36 HOURS.  
A DRIER AND MORE STABLE AIR MASS WILL PRECLUDE SHOWER ACTIVITY  
MONDAY NIGHT...WITH ISOLATED AFTERNOON SHOWERS POSSIBLE SNOWY AND  
SIERRA MADRES WITH ANOTHER PASSING WAVE TUESDAY.  
 
GUSTY NORTH TO NORTHWEST WINDS OF 25-40 MPH WILL PREVAIL EAST OF  
THE LARAMIE RANGE TODAY...THEN DIMINISH THIS EVENING WITH RELAXING  
PRESSURE GRADIENT. NORTHWEST WINDS WILL NOT BE AS GUSTY MONDAY  
AFTERNOON FOR THE HIGH PLAINS. EVEN LIGHTER WINDS ARE FORECAST  
FOR TUESDAY. HIGH TEMPERATURES TODAY WILL SLIGHTLY COOLER COMPARED  
TO YESTERDAY WITH 40S TO LOWER 50S. LOWS TONIGHT AND MONDAY NIGHT  
WILL MAINLY BE IN THE 20S. A GRADUAL WARMING TREND COMMENCES EARLY  
THIS WEEK WITH HIGHS MONDAY IN THE UPPER 40S TO MID 50S...AND UPPER  
50S TO MID 60S TUESDAY.  
   
LONG TERM
 
(TUESDAY NIGHT THROUGH SATURDAY)  
ISSUED AT 330 AM MDT SUN APR 19 2015  
 
MILD BUT SOMEWHAT UNSETTLED WEATHER IS EXPECTED ACROSS THE CWA  
THIS PERIOD WITH SEVERAL DISTURBANCES PASSING ACROSS IN A  
GENERALLY PROGRESSIVE UPPER FLOW PATTERN. INITIALLY THE CWA WILL  
BE UNDER A CONFLUENT UPPER PATTERN BETWEEN NORTHERN AND SOUTHERN  
STREAMFLOWS BEFORE BECOMING MORE WEST TO SWLY FRIDAY THROUGH  
SATURDAY. A PUSH OF COOLER CANADIAN AIR WILL SINK DOWN THE PLAINS  
WEDS AND BACK UP AGAINST THE MTNS WEDS NIGHT AND THURSDAY BEFORE  
ERODING BACK EAST ON FRIDAY. MODEST UPSLOPE FLOW WILL HELP TO SET  
OFF SCTD SHOWERS LATE WEDS AND AGAIN LATE THURSDAY THEN AN  
APPROACHING UPPER TROUGH WILL BRING SOME MORE ACTIVITY FRIDAY AND  
SATURDAY.  
 

 
   
AVIATION
 
(FOR THE 18Z TAFS THROUGH MONDAY MORNING)  
 
VFR CONDITIONS ARE EXPECTED THIS AFTERNOON AND INTO THIS EVENING  
WITH NORTH TO NORTHWEST WINDS GUSTING UP TO 40 KNOTS ACROSS THE  
EASTERN PLAINS...INCLUDING THE WESTERN NEBRASKA TERMINALS. A WEAK  
DISTURBANCE ALOFT MAY BRING SOME SCATTERED RAIN/SNOW SHOWERS AND  
MVFR CIGS AND VIS TO PORTIONS OF SOUTHEAST WYOMING LATE TONIGHT  
 

 
   
FIRE WEATHER
 
 
ISSUED AT 300 AM MDT SUN APR 19 2015  
 
THE UPPER LEVEL LOW PRESSURE SYSTEM THAT LINGERED OVER THE DISTRICTS  
FOR THE PAST SEVERAL DAYS WILL BE WEAKENING AS IT MOVES EAST ACROSS  
THE CENTRAL PLAINS TODAY. AS A RESULT...RAIN AND SNOW SHOWERS WILL  
BE MORE SCATTERED AND CONFINED TO THE HIGHER TERRAIN ALONG AND WEST  
OF THE LARAMIE RANGE FOR THE NEXT FEW DAYS. A COLD FRONT WILL PUSH  
THROUGH THE REGION EARLY THIS MORNING WITH GUSTY NORTH TO NORTHWEST  
WINDS TODAY. TEMPERATURES WILL BEGIN TO MODERATE WITH LOWERING  
DAYTIME HUMIDITIES EARLY THIS WEEK.  
 

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

 
 

 
 
UPDATE...SML  
SHORT TERM...MJ  
LONG TERM...RE  
AVIATION...TJT  
FIRE WEATHER...MJ  
 
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