360
FXUS65 KCYS 021846
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1246 PM MDT TUE JUN 2 2026
KEY MESSAGES
- THERE IS A SLIGHT RISK (LEVEL 2 OF 5) OF SEVERE WEATHER ACROSS
THE EASTERN HIGH PLAINS TODAY. LARGE HAIL, SEVERE WIND, AND AN
ISOLATED TORNADO WILL BE POSSIBLE.
- THE POTENTIAL FOR A FEW AFTERNOON AND EVENING STRONG TO SEVERE
THUNDERSTORMS WILL CONTINUE THROUGH THE REMAINDER OF THE
WORK WEEK.
- TEMPERATURES WILL SLOWLY WARM TO WELL ABOVE SEASONAL AVERAGES
BY THE WEEKEND AS THUNDERSTORM CHANCES BECOME MORE ISOLATED.
SHORT TERM /THROUGH WEDNESDAY NIGHT/
ISSUED AT 1242 PM MDT TUE JUN 2 2026
LOOKING LIKE ANOTHER ACTIVE DAY ACROSS THE FORECAST AREA WITH
CONTINUED CHANCES FOR SEVERE THUNDERSTORMS THIS AFTERNOON AND
THROUGH THE EVENING HOURS. CURRENT MESOSCALE ANALYSIS FROM LATE THIS
MORNING SHOWS THE CAPPING INVERSION HAS BEEN VIRTUALLY ERODED ACROSS
MOST OF THE NEBRASKA PANHANDLE AND AREAS WEST OF THE LARAMIE RANGE.
THE INTERSTATE 25 CORRIDOR AS WELL AS CONVERSE AND NIOBRARA COUNTIES
REMAIN CAPPED, BUT ARE EXPECTED TO ERODE AWAY ANY SURFACE BASED CIN
WITHIN THE NEXT FEW HOURS. HEALTHY SOUTHERLY FLOW, STRONGER THAN
WHAT MODELS ORIGINALLY SUGGESTED, HAVE HELPED MIX THE ATMOSPHERE,
WITH DAYTIME HEATING NOW HELPING PRIME THE ENVIRONMENT FOR SEVERE
STORMS. MODEL SOUNDINGS AS WELL AS MESOSCALE ANALYSIS SHOW HEALTHY
AMOUNTS OF INSTABILITY THIS AFTERNOON, WITH MUCAPE VALUES RANGING
FROM ABOUT 1500 TO 2000 J/KG FOR AREAS EAST OF THE LARAMIE RANGE.
EFFECTIVE SHEAR VALUES ARE DECENT, AND WILL BE SUFFICIENT ENOUGH TO
GET SUPERCELLS AS WELL AS LARGE HAIL. HI-RES GUIDANCE SHOWS
INITIALLY DISCRETE CELLS WILL TRANSITION TO MORE OF A DISORGANIZED
LINE BY THIS EVENING. THIS LINE COULD PRODUCE DAMAGING WIND GUSTS AS
STORMS BECOME MORE OUTFLOW DOMINATE. CANNOT RULE OUT TORNADOES
IN TODAY'S SET UP WITH RATHER HIGH MLCAPE VALUES FOR OUR AREA,
BUT HIGHER LCLS MAY WORK TO COUNTERACT THIS. RADAR TRENDS
ALREADY SHOW SHOWER AND STORM DEVELOPMENT OVER THE HIGH TERRAIN
OUT WEST. ALBANY COUNTY ALSO SHOWS A RIPE ENVIRONMENT FOR SEVERE
WEATHER SO CANNOT RULE OUT SEVERE STORMS IN AND AROUND LARAMIE
THIS AFTERNOON. STORMS ARE ALSO EXPECTED TO FORM OFF A FRONTAL
BOUNDARY THAT IS PROGGED TO MOVE ACROSS EASTERN WYOMING LATER
TODAY. GREATEST CHANCE OF SEVERE STORMS IN WYOMING WILL BE
BETWEEN 2 PM AND 6 PM THIS AFTERNOON, WITH SEVERE STORMS
POSSIBLE IN NEBRASKA BETWEEN 5 PM AND 10 PM THIS EVENING.
ALTHOUGH SEVERE WEATHER CHANCES ARE STILL POSSIBLE ON
WEDNESDAY, IT WILL BE A BIT OF A BREAK FROM STORMS COMPARED TO
THE LAST FEW DAYS. WEAKER INSTABILITY WILL CREATE AN ENVIRONMENT
CONDUCIVE TO MARGINALLY SEVERE STORMS. THE FURTHER EASTWARD
EXTENT OF THE DRYLINE MODELED BY THE HRRR WILL ALSO CREATE A
SMALLER AREAL EXTENT FOR STORMS TO DEVELOP. HI-RES GUIDANCE
SHOWS THE SOUTHERN NEBRASKA PANHANDLE AS THE MOST LIKELY AREA
FOR SEVERE STORMS AS THIS IS WHERE THE HIGHEST INSTABILITY IS.
BOTH SEVERE HAIL AND WIND WILL BE POSSIBLE AS BOTH DISCRETE
CELLS AS WELL AS STORM CLUSTERS ARE FORECAST FOR WEDNESDAY. MID
TO LATE AFTERNOON IS THE MOST LIKELY TIMING FOR STORMS WITH
STORMS NOT EXPECTED TO STRAY TO LATE INTO THE EVENING HOURS.
LONG TERM /THURSDAY THROUGH MONDAY/
ISSUED AT 1242 PM MDT TUE JUN 2 2026
LOOKING AHEAD TO THURSDAY, ANOTHER UPPER LEVEL SHORTWAVE TROUGH
RIGHT ON THE HEELS OF THE DEPARTING PRIMARY LOW WILL MOVE ACROSS THE
NORTHERN ROCKIES. RECENT MODEL GUIDANCE HAS BEGUN TO PICK UP ON LEE
CYCLOGENESIS NEAR THE AREA IN ADVANCE OF THE APPROACHING UPPER LEVEL
FEATURE, BUT DIFFER IN ITS EXACT LOCATION. EXACTLY WHERE THIS SETS
UP WILL HELP DETERMINE WHERE THE MOST FAVORABLE AREA FOR STRONG TO
SEVERE THUNDERSTORMS WILL DEVELOP. CURRENTLY, THIS APPEARS MOST
LIKELY ALONG THE LUSK TO CHADRON CORRIDOR IN EAST CENTRAL WYOMING
AND INTO THE NORTHERN NEBRASKA PANHANDLE. THIS COULD ALSO EXTEND
INTO THE CHADRON TO SIDNEY CORRIDOR. BOTH OF THESE AREAS HAVE THE
HIGHEST CONFIDENCE IN DEWPOINTS REMAINING HIGH, WHEREAS MODEL
GUIDANCE HAS BEEN TRENDING TOWARDS A DRIER SURFACE AIRMASS ALONG
AND WEST OF THE I-25 CORRIDOR. FORCING WILL BE PROVIDED BY THE
APPROACHING UPPER LEVEL LOW WITH CURRENT CONVECTIVE PARAMETERS
APPEARING SUPPORTING OF AT LEAST ISOLATED STRONG TO SEVERE
THUNDERSTORMS THURSDAY AFTERNOON AND EVENING.
STORM CHANCES WILL DROP BACK SOMEWHAT FOR FRIDAY AS DRIER AIR PUSHES
EASTWARD TO ENCOMPASS MOST OF THE FORECAST AREA. A DEEP PACIFIC
TROUGH PUSHING INTO THE NORTHWEST CONUS WILL AMPLIFY THE DOWNSTREAM
RIDGE OVER THE ROCKIES AND PLAINS, PUSHING TEMPERATURES UPWARD INTO
THE WEEKEND. MOST AREAS WILL REACH THE 80S ON FRIDAY, WITH FAIRLY
WIDESPREAD 90S POSSIBLE SATURDAY AS THE RIDGE AXIS SHIFTS OVERHEAD.
700-MB TEMPERATURES PEAKING AROUND +12 TO +16C WILL BE AROUND THE
CLIMATOLOGICAL 90TH PERCENTILE. SUNDAY'S HIGHS MAY DROP SLIGHTLY FOR
OUR WESTERN ZONES, BUT SHOULD BE FAIRLY SIMILAR TO SATURDAY OVER THE
HIGH PLAINS, WITH WIDESPREAD MID 80S TO MID 90S. CURRENT FORECAST
REMAIN COMFORTABLY BELOW DAILY RECORD HIGHS, BUT IT WILL CERTAINLY
BE A WARM TO HOT FEW DAYS.
WHILE PRECIPITATION ON FRIDAY LOOKS VERY ISOLATED, MOISTURE WILL
BEGIN TO SLOWLY TICK UPWARDS AGAIN SATURDAY ONWARD. MOISTURE WILL
IMPROVE ALOFT FIRST, INCREASING ON SATURDAY. THIS COULD LEAD TO A
FEW ISOLATED HIGH-BASED SHOWERS AND POSSIBLY A DRY MICROBURST
HAZARD, BUT THIS IS FAIRLY LOW CONFIDENCE SEVERAL DAYS OUT. LOW-
LEVEL MOISTURE LOOKS TO RECOVER SUNDAY INTO EARLY NEXT WEEK, WHICH
WILL THEN ALLOW FOR HIGHER CHANCES FOR APPRECIABLE PRECIPITATION,
BUT ALSO STRONG TO SEVERE THUNDERSTORMS. AN EARLY LOOK FROM THE
ECMWF ENSEMBLE SUGGESTS FAIRLY POTENT INSTABILITY AND THUS MORE
PREVALENT THUNDERSTORM CHANCES ON MONDAY AND TUESDAY.
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 1139 AM MDT TUE JUN 2 2026
THUNDERSTORMS REMAIN THE PRIMARY AVIATION CONCERN THIS AFTERNOON
AND EVENING. STRONG SOUTHERLY WINDS WILL CONTINUE INTO THE
AFTERNOON HOURS, BUT EXPECT GUSTS TO EASE GRADUALLY.
THUNDERSTORMS WILL DEVELOP IN THE NEXT FEW HOURS AND THEN MOVE
OFF TO THE NORTHEAST THROUGH THE EARLY EVENING HOURS. CONFIDENCE
IN DIRECT IMPACTS TO EACH TERMINAL IS NOT HIGH ENOUGH FOR
PREVAILING GROUPS YET, BUT BE READY FOR POSSIBLE AMDS AS STORMS
APPROACH A TERMINAL. THE PRIMARY HAZARDS WILL BE FREQUENT
LIGHTNING, GUSTY WINDS, BRIEF DOWNPOURS, AND ISOLATED LARGE
HAIL.
STORMS SHOULD DEPART THE AREA BY AROUND 03Z OR SO, THOUGH A FEW
SHOWERS MAY LINGER OVERNIGHT. LATE EVENING THUNDERSTORMS CANNOT
BE RULED OUT, BUT THE PROBABILITY IS FAIRLY LOW. SOUTHEAST WINDS
WILL KICK UP AGAIN OVERNIGHT OVER THE HIGH PLAINS, BUT EXPECT
THIS TO WEAKEN WEDNESDAY MORNING AND BEGIN TO SHIFT MORE
WESTERLY AT ALL TERMINALS EXCEPT SNY.
CYS WATCHES/WARNINGS/ADVISORIES
WY...NONE.
NE...NONE.
SHORT TERM...SF
LONG TERM...MN
AVIATION...MN
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