997  
FXUS65 KCYS 201134  
AFDCYS  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CHEYENNE WY  
534 AM MDT SUN OCT 20 2019  
   
SHORT TERM
 
(TODAY THROUGH TUESDAY)  
ISSUED AT 300 AM MDT SUN OCT 20 2019  
 
LOTS GOING ON THIS MORNING WITH STRONG WINDS AND SNOW THE PRIMARY  
FORECAST CHALLENGES WITH THIS FORECAST PACKAGE.  
 
CURRENTLY...IR IMAGERY SHOWING A FAIRLY STRONG LOW PRESSURE  
SYSTEM IN THE VICINITY OF WORLAND TO RIVERTON THIS MORNING. COLD  
FRONT ASSOCIATED WITH THE LOW EXTENDS SOUTH ALONG THE LARAMIE  
RANGE THIS MORNING. SEEING COOLING CLOUD TOPS ON IR IMAGERY AS A  
90+ KT JET FINGER BEGINS TO MOVE INTO NORTHWEST COLORADO AND  
SOUTHWESTERN CARBON COUNTY. WE HAVE SEEN A LITTLE BREAK IN THE  
SNOW OUT WEST EARLY THIS MORNING...BUT WITH THE COOLING CLOUD  
TOPS...WOULD EXPECT SNOW TO RETURN TO MUCH OF CARBON COUNTY OVER  
THE NEXT COUPLE HOURS.  
 
WINDS HAVE BEEN ON THE INCREASE BEHIND THE FRONT. COOPER COVE JUST  
HIT 58 MPH ON THEIR GUSTS. THE OTHER WYDOT SITES IN ZONE 114 ARE  
BEGINNING TO COME UP AS WELL...SO DO FEEL THE WIND EVENT IS GOING  
TO OCCUR. LATEST GFS HIGH WIND GUIDANCE SHOWING CRAIG TO CASPER  
850/700MB HEIGHT GRADIENTS INCREASING TO 76/71 MTRS BY 09Z AND  
90/87MTRS BY 12Z. SO WILL NOT CHANGE ANY WIND HEADLINES FOR TODAY.  
 
DID ADD A SNOW ADVISORY TO CONVERSE AND NIOBRARA COUNTY STARTING  
AT 12Z. WRAP AROUND MOISTURE FROM THE LOW LOOKS TO TRACK RIGHT  
OVER THAT AREA AND AM GETTING SOME FAIRLY HIGH SNOW TOTALS UP  
THERE. DAY SHIFT MAY NEED TO UPGRADE TO A BLIZZARD WARNING IF  
VISIBILITIES DO STAY DOWN.  
 
GRADIENTS BEGIN TO EASE AFTER 21Z THIS AFTERNOON AS THE LOW TRACKS  
INTO SOUTH DAKOTA. TIMING WISE...WILL KEEP ALL HEADLINES GOING AS  
THEY ARE.  
   
LONG TERM
 
(TUESDAY NIGHT THROUGH SATURDAY)  
ISSUED AT 300 AM MDT SUN OCT 20 2019  
 
WEDNESDAY...TURNING COLDER AS THE NEXT SHORTWAVE TROUGH ALOFT AND  
ITS ASSOCIATED COLD FRONT MOVE ACROSS OUR COUNTIES ON NORTHWEST FLOW  
ALOFT. SCATTERED TO NUMEROUS RAIN AND SNOW SHOWERS WILL SPREAD NORTH  
TO SOUTH ACROSS OUR COUNTIES.  
 
THURSDAY...DRYING OUT AND COLDER IN THE WAKE OF THE SHORTWAVE TROUGH  
ALOFT AND COLD FRONT PASSAGE. COLD MAXIMUM TEMPERATURES WITH 700 MB  
TEMPERATURES ONLY NEAR -11 CELSIUS.  
 
FRIDAY...WILL SEE A SIGNIFICANT WARMING TREND AS THE FLOW ALOFT  
BACKS TO NORTHWEST AND HEIGHTS AND THICKNESSES INCREASE  
SUBSTANTIALLY. SURFACE LEE TROUGHING DEVELOPS WITH DOWNSLOPE WARMING  
WEST WINDS HELPING TEMPERATURES TO RISE INTO THE 50S EAST OF  
INTERSTATE 25.  
 
SATURDAY...THE WEST NORTHWEST FLOW ALOFT STRENGTHENS SIGNIFICANTLY  
AS ANOTHER SHORTWAVE TROUGH ALOFT AND COLD FRONT APPROACH FROM OUR  
NORTH. IF THE COLD FRONTAL TIMING IS CORRECT, WE SHOULD SEE ONE MORE  
MILD DAY IN THE WARM SECTOR. PERHAPS A CHANCE FOR SHOWERS ALONG AND  
BEHIND THE APPROACHING COLD FRONT FOR OUR NORTHERN COUNTIES IN THE  
AFTERNOON.  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)  
ISSUED AT 531 AM MDT SUN OCT 20 2019  
 
WYOMING TAFS...VFR, EXCEPT OCCASIONAL MVFR AT RAWLINS AND LARAMIE  
UNTIL 16Z. WIND GUSTS TO 50 KNOTS UNTIL 01Z, THEN GUSTS UP TO 30  
KNOTS.  
 
NEBRASKA TAFS...VFR. WIND GUSTS TO 50 KNOTS UNTIL 02Z, THEN GUSTS  
UP TO 38 KNOTS.  
 

 
   
FIRE WEATHER
 
 
ISSUED AT 300 AM MDT SUN OCT 20 2019  
 
WIDESPREAD STRONG WIND EVENT WITH MOUNTAIN SNOW STILL EXPECTED  
TODAY AS A LOW PRESSURE SYSTEM TRACKS ACROSS CENTRAL WYOMING INTO  
SOUTHERN SOUTH DAKOTA THIS AFTERNOON. SNOW ALREADY OCCURRING OVER  
AREAS WEST OF THE LARAMIE RANGE AND WINDS ARE ON THE INCREASE.  
LOOKS LIKE WE COULD SEE SNOW ACROSS THE NORTHERN NEBRASKA  
PANHANDLE INTO CONVERSE AND NIOBRARA COUNTIES FROM AROUND NOON  
THROUGH 6 PM TODAY AS WELL. WINDS WILL BEGIN EASING BY LATE  
AFTERNOON. DRIER PATTERN TUESDAY AND WEDNESDAY BEFORE NEXT LOW  
PRESSURE SYSTEM APPROACHES FROM THE NORTHWEST.  
 

 
   
CYS WATCHES/WARNINGS/ADVISORIES
 
 
WY...HIGH WIND WARNING UNTIL 6 PM MDT THIS EVENING FOR WYZ101-102-  
104>109-115>119.  
 
WINTER WEATHER ADVISORY UNTIL 6 PM MDT THIS EVENING FOR WYZ101-  
102.  
 
WINTER STORM WARNING UNTIL NOON MDT MONDAY FOR WYZ103-112-114.  
 
BLIZZARD WARNING UNTIL 6 PM MDT THIS EVENING FOR WYZ110-113.  
 
NE...HIGH WIND WARNING UNTIL 6 PM MDT THIS EVENING FOR NEZ002-003-  
019>021-054-055-095-096.  
 

 
 

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