670
FXUS65 KCYS 090542
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1142 PM MDT THU MAY 8 2025
KEY MESSAGES
- A WARMING TREND WILL BEGIN TODAY AND LAST THROUGH EARLY NEXT
WEEK WITH ISOLATED SHOWERS AND STORMS POSSIBLE IN THE HIGHER
TERRAIN OF SOUTHEAST WYOMING MOST AFTERNOONS.
- THE NEXT POTENTIAL STORM SYSTEM AROUND THE MIDDLE OF NEXT WEEK
WITH BRING COOLER TEMPERATURES, STRONGER WINDS, AND ANOTHER
CHANCE FOR SOME RAINFALL AND MOUNTAIN SNOW.
SHORT TERM /THROUGH FRIDAY NIGHT/
ISSUED AT 209 PM MDT THU MAY 8 2025
A TRANSITION IN THE WEATHER PATTERN OVER SOUTHEAST WYOMING AND
WESTERN NEBRAKSA CONTINUES TODAY. OUR LONG-DURATION EASTERLY
FLOW PATTERN HAS COME TO AN END AS THE UPPER-LEVEL LOW PRESSURE
SYSTEM RESPONSIBLE FOR THIS WEATHER HAS MOVED WELL TO THE EAST
AND SOUTH. WEAK RIDGING HAS BEGUN TO DEVELOP OVER THE
SOUTHWESTERN CONUS, PLACING OUR REGION IN A PATTERN OF LIGHT
NORTHERLY FLOW BETWEEN THESE TWO SYSTEMS. SOME LINGERING SURFACE
MOISTURE AND STRONG DAYTIME HEATING HAS RESULTED IN VERY LOW-
END INSTABILITY VALUES IN THE HIGHER TERRAIN OF SOUTHEAST
WYOMING, AND A FEW VERY ISOLATED SHOWERS AND WEAK THUNDERSTORMS
HAVE FORMED AS A RESULT. THESE SHOULD REMAIN CLOSELY TIED TO THE
HIGHER TERRAIN TODAY AND ANY PRECIPITATION AMOUNTS WILL BE LESS
THAN 0.1", EVEN UNDER THE STRONGER CORES. ELSEWHERE EXPECT A
MOSTLY SUNNY DAY AND CLEAR OVERNIGHT WITH TEMPERATURES RUNNING
AROUND 3-5 DEGREES ABOVE AVERAGE.
THE WARMING TREND CONTINUES ON FRIDAY AS RIDGING CONTINUES TO
BUILD EASTWARD OUT OF THE SOUTHWESTERN CONUS. EXPECT HIGHS TO
RUN AROUND 10 DEGREES ABOVE NORMAL. ONCE AGAIN, AFTERNOON
SHOWERS AND POSSIBLY A RUMBLE OF THUNDER OR TWO WILL BE POSSIBLE
IN THE HIGHER TERRAIN OF SOUTHEAST WYOMING. ONCE AGAIN, THIS
ACTIVITY WILL BE DRIVEN ENTIRELY BY SURFACE HEATING AND
LINGERING SURFACE MOISTURE, AND WILL QUICKLY DIMINISH TOWARD
SUNSET. VERY LITTLE CHANGES NEEDED TO MODEL BLENDS THROUGH THE
SHORT-TERM TODAY WITH EXCELLENT AGREEMENT IN HREF AND GLOBAL
ENSEMBLE BLENDS. FORECAST CONFIDENCE IS VERY HIGH.
LONG TERM /SATURDAY THROUGH THURSDAY/
ISSUED AT 209 PM MDT THU MAY 8 2025
THIS WEEKEND LOOKS PRETTY DRY EVEN WITH A SHORTWAVE PASSING THROUGH
TO GIVE EXTRA LIFT TO ANY LINGERING MOISTURE. THERE IS SOME WEAK
VORT-MAXES ASSOCIATED WITH THIS SHORTWAVE TO GIVE A SLIGHT CHANCE
FOR AFTERNOON SHOWERS BUT THE MOISTURE LOOKS VERY LIMITED AS
DEWPOINTS ARE IN THE LOW 20'S SATURDAY. THERE IS A PRETTY STOUT DRY
LAYER IN THE LOWER LEVELS SO ANY SHOWERS LOOK TO BE CONFINED NEAR
THE MOUNTAIN AND MOUNTAIN ADJACENT AREAS. THE RIDGE AXIS STARTS TO
SHIFT A LITTLE EAST AS A LOW PRESSURE SYSTEM PUSHES INTO THE PACIFIC
NORTHWEST. TEMPERATURES WILL BE IN MID 70'S WEST OF I-25 AND INTO
THE 80'S TO THE EAST. ON SUNDAY, THE NEBRASKA PANHANDLE HAS A CHANCE
FOR SOME 90'S MOSTLY FROM SCOTTSBLUFF TO ALLIANCE AND NORTH.
DURING THE NEXT WORK WEEK, AN UPPER LEVEL LOW STARTS TO MOVE INTO
THE INTERMOUNTAIN WEST TO GIVE SOME PRECIPITATION CHANCES MONDAY.
HOWEVER, THERE IS SOME UNCERTAINTY IN THE TIMING AND TRACK BETWEEN
THE GLOBAL MODELS. THE GFS HAS THE STORM PUSHING FURTHER NORTH
ALLOWING FOR THE NORTHERN PORTION OF WYOMING TO RECEIVE
PRECIPITATION WHILE OUR SOUTHEAST CORNER IS A LOT DRIER WITH ALMOST
NO PRECIPITATION. THE EURO AND CANADIAN BOTH HAVE THE RIDGE BREAKING
DOWN HOWEVER THE EURO BRINGS THE SYSTEM A LITTLE BIT MORE NORTH AND
WEAKER SHOWING A POSITIVELY TILTED TROUGH. THE CANADIAN HAS THE
RIDGE BREAKING DOWN A LITTLE BIT MORE WITH A SOUTHERN TRACK, WITH IT
BEING NEGATIVELY TILTED TROUGH INDICATING A STRONGER SYSTEM NEXT
WEEK. CLUSTER ANALYSIS GIVES ABOUT A 50/50 PROBABILITY OF BOTH
SCENARIOS BEING AS LIKELY TO OCCUR BETWEEN THE GLOBAL MODELS. MONDAY
AND WEDNESDAY LOOK TO BE OUR WINDY DAYS AS THE PRESSURE GRADIENT
GETS SQUEEZED ON MONDAY AND A STRONG JET MOVES OVER THE
INTERMOUNTAIN WEST. HOWEVER, WEDNESDAY IS STILL UP IN THE AIR AS THE
STRONGER JETSTREAK HAS BEEN PUSHED FURTHER NORTH WITH THE LATEST 12Z
RUN GIVING THE 70 KNOT JETSTREAK TO OUR NEIGHBORS WHILE WE GET
ELEVATED WINDS AT 45-50KTS.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 1140 PM MDT THU MAY 8 2025
VFR CONDITIONS EXPECTED THROUGH THE FRIDAY MORNING WITH JUST A
FEW MID TO HIGH LEVEL CLOUDS FILTERING THROUGH AND FAIRLY LIGHT
WINDS. WIDELY SCATTERED SHOWERS ARE EXPECTED TO DEVELOP EARLY
FRIDAY AFTERNOON ACROSS MUCH OF THE AREA. WHILE BASELINE WINDS
WILL BE FAIRLY WEAK FRIDAY, THESE SHOWERS MAY BRING LOCALLY
GUSTY AND ERRATIC WINDS AND A FEW RUMBLES OF THUNDER IF THEY
PASS NEAR OR OVER A TERMINAL. WIND GUSTS OF 30 TO 40 KNOTS WILL
BE POSSIBLE NEAR SHOWER ACTIVITY.
CYS WATCHES/WARNINGS/ADVISORIES
WY...NONE.
NE...NONE.
SHORT TERM...MAC
LONG TERM...MM
AVIATION...MN
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