999  
FXUS65 KCYS 290415  
AFDCYS  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CHEYENNE WY  
1015 PM MDT THU MAR 28 2024  
   
KEY MESSAGES
 
 
- HIGH WIND WARNING FOR CENTRAL CARBON COUNTY AS WELL AS AREAS  
NEAR ARLINGTON AND ELK MOUNTAIN UNTIL 6 PM MDT THIS EVENING  
FOR OCCASIONAL WIND GUSTS 55 TO 60 MPH.  
 
- SNOW SQUALLS ARE POSSIBLE ACROSS CARBON AND ALBANY COUNTIES  
DURING THE EARLY TO MID EVENING HOURS TODAY. THE HEAVIEST  
BANDS COULD PRODUCE SNOWFALL AMOUNTS IN EXCESS OF 3 INCHES.  
 
- A PROLONGED PERIOD OF UNSETTLED WEATHER IS EXPECTED FRIDAY  
THROUGH MONDAY WITH DAILY CHANCES FOR RAIN AND SNOW, BUT THE  
PROBABILITY OF A HIGH IMPACT WINTER STORM IS DECREASING.  
 

 
   
SHORT TERM /THROUGH FRIDAY NIGHT/
 
 
ISSUED AT 230 PM MDT THU MAR 28 2024  
 
WIND GUSTS 55 TO 60 MPH HAVE DEVELOPED ACROSS PORTIONS OF CARBON  
COUNTY (INCLUDING BOTH RAWLINS AND ARLINGTON) THIS AFTERNOON, IN  
RESPONSE TO STRONG LOW-LEVEL GRADIENTS AND DEEP LOW-LEVEL MIXING  
ACROSS THE REGION. OPTED FOR THE ISSUANCE OF A HIGH WIND WARNING  
IN AN EARLIER UPDATE, WHICH IS VALID UNTIL 6 PM MDT THIS EVENING  
WITH WINDS EXPECTED TO DIMINISH TOWARD SUNSET. SNOW SHOWERS WILL  
BEGIN TO INCREASE IN COVERAGE AND INTENSITY ACROSS WESTERN AREAS  
BY 00Z THIS EVENING AS A COLD FRONT BLASTS EASTWARD ACROSS SOUTH  
CENTRAL AND SOUTHEAST WYOMING. LINEAR FORCING ALONG THIS FRONTAL  
ZONE, COUPLED WITH AMPLE INSTABILITY COURTESY OF VERY STEEP MID-  
LEVEL LAPSE RATES SHOULD SUPPORT A CONVECTIVE PRECIPITATION MODE  
THROUGH THE EARLY TO MID EVENING HOURS, WITH LINEAR SEGMENTS AND  
LOCALLY ENHANCED PRECIPITATION RATES. GIVEN 700-800 HPA FLOW AT/  
ABOVE 40 KNOTS, THIS ACTIVITY MAY ALSO BE ACCOMPANIED BY LOCALLY  
ENHANCED WIND GUST AND THUS POTENTIAL FOR SNOW SQUALLS. COULD BE  
A CHANCE FOR A COUPLE OF LIGHTNING STRIKES AS WELL. THE MAJORITY  
OF AREAS SHOULD SEE FAIRLY MODEST ACCUMULATIONS, BUT SNOW SQUALL  
ACTIVITY OR LOCALIZED BANDS COULD PRODUCE A QUICK 2 TO 4 INCHES,  
PERHAPS MORE OVER THE SNOWYS & SIERRA MADRES. AFTER A BRIEF LULL  
ON FRIDAY MORNING, MODELS DEPICT THE NEXT WAVE LIFTING NORTH AND  
EAST ACROSS THE CWA BY LATE FRIDAY AFTERNOON IN AHEAD OF A DEEP/  
VIGOROUS UPPER-LEVEL LOW SPINNING OFF THE CA COASTLINE. THIS MAY  
SUPPORT A WIDESPREAD SHIELD OF LIGHT TO MODERATE SNOW ACROSS THE  
MAJORITY OF THE CWA W/ THE BEST CHANCE OF MORE SUBSTANTIAL SNOW-  
FALL ACCUMULATIONS OVER THE SNOWY AND SIERRA MADRE MOUNTAINS. WE  
MAY NEED TO EXPAND CURRENT WINTER WX ADVISORIES IN BOTH TIME AND  
SPACE WITH LATER UPDATES, AS ANOTHER 6 TO 12 INCHES APPEARS VERY  
POSSIBLE WITH THIS NEXT WAVE.  
 

 
   
LONG TERM /SATURDAY THROUGH THURSDAY/
 
 
ISSUED AT 230 PM MDT THU MAR 28 2024  
 
A MESSY STORM SYSTEM ASSOCIATED WITH A CLOSED LOW DROPPING SOUTH  
JUST OFF THE CALIFORNIA COAST THIS WEEKEND WILL LEAD TO SEVERAL DAYS  
OF UNSETTLED WEATHER. PICKING UP ON SATURDAY, THE LOW WILL STILL BE  
JUST WEST OF THE SAN FRANCISCO BAY, BUT MOISTURE LADEN SOUTHWEST  
FLOW WILL BE STRETCHING OUT AHEAD OF IT, WITH DEEP MOISTURE  
STREAMING OVER OUR AREA IN A STRONG AND BROAD JET STREAM ALOFT.  
CONFLUENT FLOW ON THE EASTERN EDGE OF THIS TROUGH WILL KEEP A  
FRONTAL BOUNDARY STALLED SOMEWHERE CLOSE TO OUR AREA THROUGH THE  
WEEKEND. DOWNSTREAM AMPLIFICATION AHEAD OF THE TROUGH WILL HELP TO  
LIFT THE FRONTAL BOUNDARY NORTH THROUGH THE DAY ON FRIDAY, ALLOWING  
FOR FAIRLY STRONG WARM AIR ADVECTION ACROSS MOST OF THE AREA.  
GUIDANCE SHOWS FAIRLY CONSISTENT ISENTROPIC LIFT OVERRUNNING THE  
FRONTAL BOUNDARY, PARTICULARLY STRONG WHEN ONE OF A SERIES OF VORT-  
MAXES TRAVERSES OVERTOP THE BOUNDARY. THE STRATIFORM PRECIPITATION  
SHOULD LIFT MOSTLY NORTH OF OUR AREA DURING THE DAY SATURDAY, BUT AS  
THAT OCCURS, SHOWERY TYPE PRECIPITATION WILL DEVELOP IN THE NARROW  
WARM SECTOR OF THE STORM SYSTEM. THUS, STILL HAVE DECENT POPS ACROSS  
THE AREA SATURDAY AFTERNOON AND EVENING EVEN AS THE FRONTAL BOUNDARY  
SHIFTS NORTH. A VORT-MAX MOVES TO THE EAST LATE SATURDAY EVENING,  
SHOULD ALLOW THE FRONTAL BOUNDARY TO SAG SOUTHWARD SLIGHTLY IN ITS  
WAKE.  
 
SUNDAY LOOKS LIKE A FAIRLY SIMILAR SETUP TO SATURDAY, JUST WITH THE  
FRONTAL BOUNDARY SLIGHTLY FURTHER SOUTH. ANOTHER ROUND OF SHOWERY  
TYPE PRECIPITATION SHOULD DEVELOP IN THE WARM SECTOR, THEN FOCUSED A  
LITTLE FURTHER SOUTH CLOSER TO THE I-80 CORRIDOR AND UP TO THE  
CENTRAL PORTION OF THE FORECAST AREA. ENSEMBLE MEANS SHOW A FEW  
HUNDRED J/KG OF CAPE ACROSS THE SOUTHERN HALF OF THE AREA ON SUNDAY  
AFTERNOON. COMBINED WITH FRONTOGENESIS AND ANOTHER ROUND OF  
OVERRUNNING, WE SHOULD SEE PRETTY GOOD PRECIPITATION COVERAGE SUNDAY  
AFTERNOON AND EVENING, WITH SOME EMBEDDED THUNDER POSSIBLE. SUNDAY  
EVENING AND OVERNIGHT LOOKS QUITE COMPLEX, WITH RAPID COLD AIR  
ADVECTION AS A SURFACE CYCLONE OVER EAST CENTRAL COLORADO DRAWS THE  
COLD FRONT BACK TO THE SOUTH AND EJECTS TO THE EAST. EXPECT RAIN TO  
CHANGE OVER TO SNOW RAPIDLY AS COLD AIR SPILLS SOUTHWARD. HOWEVER,  
THE DYNAMICS IN THE WRAP-AROUND FLOW DON'T LOOK THAT FAVORABLE FOR  
WIDESPREAD STRATIFORM PRECIPITATION. THIS LEAVES SOME CONSIDERABLE  
UNCERTAINTY IN THE COLD PHASE OF THIS SYSTEM STILL, BUT THE VAST  
MAJORITY OF ENSEMBLE MEMBERS ARE CONSOLIDATING AROUND A LESS-SNOWY  
SCENARIO AT THIS TIME. STILL LOOKING AT SOME FAIRLY WIDESPREAD LIGHT  
ACCUMULATIONS SUNDAY NIGHT INTO MONDAY, AND COULD SEE SOME  
ADVISORIES BEING NEEDED.  
 
MUCH COLDER ON MONDAY WITH 700-MB TEMPERATURES DROPPING TO NEAR -8C  
FOR MUCH OF THE AREA WITH BRISK NORTHERLY WINDS. THIS COLD SNAP  
SHOULD BE SHORT-LIVED WITH A STRONG RIDGE PUSHING IN ON TOP OF THE  
DEPARTING TROUGH AS WE HEAD INTO TUESDAY. WE SHOULD WARM TO NEAR  
AVERAGE TUESDAY, AND THEN ABOVE AVERAGE WEDNESDAY AND THURSDAY.  
 

 
   
AVIATION /00Z TAFS THROUGH 00Z SATURDAY/
 
 
ISSUED AT 1011 PM MDT THU MAR 28 2024  
 
WEST SOUTHWEST FLOW ALOFT WILL PREVAIL, WHILE A COLD FRONT  
SWEEPS FROM WEST TO EAST ACROSS THE TERMINALS TONIGHT.  
 
WYOMING TAFS...AT RAWLINS, CEILINGS WILL RANGE FROM 3500 TO  
6000 FEET WITH OCCASIONAL SNOW REDUCING VISIBILITIES TO 3 MILES  
AND CEILINGS TO 2500 FEET THROUGH 09Z. WINDS WILL GUST TO  
25 KNOTS UNTIL 12Z.  
 
AT LARAMIE AND CHEYENNE, CEILINGS WILL RANGE FROM 3500 TO  
10000 FEET, WITH SHOWERS IN THE VICINITY AFTER 00Z.  
 
NEBRASKA TAFS...CEILINGS WILL RANGE FROM 6000 TO 15000 FEET.  
WINDS WILL GUST TO 25 KNOTS FROM 15Z TO 00Z.  
 

 
   
CYS WATCHES/WARNINGS/ADVISORIES
 
 
WY...WINTER WEATHER ADVISORY UNTIL 6 AM MDT FRIDAY FOR WYZ112.  
NE...NONE.  
 

 
 

 
 
SHORT TERM...CLH  
LONG TERM...MN  
AVIATION...RUBIN  
 
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