099
FXUS65 KCYS 190947
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
347 AM MDT THU JUN 19 2025
KEY MESSAGES
- A WARMING AND DRYING TREND WILL TAKE OVER WEDNESDAY THROUGH
SATURDAY. NEAR RECORD HIGH TEMPERATURES ARE POSSIBLE ON FRIDAY
AND SATURDAY.
- COOLER TEMPERATURES EXPECTED FOR MOST OF NEXT WEEK WITH A
RETURN OF SHOWERS AND THUNDERSTORMS.
SHORT TERM /THROUGH SATURDAY/
ISSUED AT 300 AM MDT THU JUN 19 2025
DRY AND BENIGN WEATHER EXPECTED OVER THE NEXT FEW DAYS AS AN
UPPER LEVEL RIDGE AXIS SLIDES EASTWARD ACROSS THE AREA, AND THEN
INTO THE GREAT PLAINS BY FRIDAY AFTERNOON. THE DRIER AIRMASS
WILL ORIGINATE FROM THE DESERT SOUTHWEST WITH DEWPOINTS LOWERING
INTO TEENS AND 20S ALONG AND WEST OF THE I-25 CORRIDOR, WITH
WESTERN NEBRASKA IN THE 30S FOR DEWPOINTS. THIS WILL RESULT IN
HIGH BASED FAIR WEATHER CUMULUS WITH A VERY LOW POTENTIAL FOR
ANY DEEP CONVECTION AS CAPE WILL GENERALLY BE UNDER 300 J/KG. IT
WILL BECOME HOT STARTING TODAY AND CONTINUE THROUGH SATURDAY AS
700MB TEMPERATURES INCREASE TO +20C. MOST MODELS HAVE 700MB
TEMPS ABOVE 18C TO 20C, SO BLENDED FORECAST HIGH TEMPERATURES
WITH THE NBM AND GRAND ENSEMBLE 75TH TO 90TH PERCENTILE. THIS
PUTS HIGH TEMPERATURES WELL INTO THE 80S TO MID 90S FOR MOST
SOUTHEAST WYOMING AND WESTERN NEBRASKA FOR TODAY
(THURSDAY)...WARMEST BELOW ELEVATIONS OF 5000 FEET. FRIDAY AND
SATURDAY WILL BE EVEN WARMER AS SOUTHWEST FLOW DEVELOPS BEHIND
THE UPPER LEVEL RIDGE AXIS. HIGHS IN THE UPPER 80S TO MID 90S
ARE EXPECTED ALONG AND WEST OF THE INTERSTATE 25 CORRIDOR WITH A
FEW PLACES, SUCH AS WHEATLAND, APPROACHING 100 DEGREES FRIDAY
AFTERNOON. EAST OF THE I-25 CORRIDOR, HIGHS BETWEEN 100 TO 105
ARE EXPECTED. THOUGHT ABOUT ISSUING A HEAT ADVISORY FOR THE
WESTERN NEBRASKA PANHANDLE, BUT OVERNIGHT LOWS SHOULD BE COOL
ENOUGH (UPPER 50S TO UPPER 60S) NOT TO WARRANT AN ADVISORY, BUT
WILL CONTINUE TO MONITOR TEMPERATURE TRENDS OVER THE NEXT FEW
DAYS.
THE ONLY MINOR FORECAST CONCERN OVER THE NEXT 48 HOURS WILL BE
GUSTY AND LOCALLY STRONG WINDS, ESPECIALLY FRIDAY AFTERNOON AND
POSSIBLY INTO FRIDAY NIGHT FOR THE WIND PRONE AREAS. THIS IS IN
RESPONSE TO A PACIFIC COLD FRONT SLOWLY TRACKING EAST INTO
WYOMING BY LATE FRIDAY...AND A (THERMAL) SURFACE LOW TRACKING
NORTHEAST OVER CENTRAL AND NORTHERN WYOMING. WILL HAVE TO KEEP
AN EYE ON CARBON AND ALBANY COUNTIES SINCE GUIDANCE IS STARTING
TO SHOW SUSTAINED WINDS OF 30 TO 40 MPH WITH HIGHER GUSTS LIKELY
WITH DEEP BOUNDARY LAYER MIXING UP TO 500MB. SOME MODELS, INCLUDING
THE GFS, SHOW WINDS ALOFT AROUND 60 TO 65KTS AROUND THE 500MB
LEVEL. IF MODEL TRENDS CONTINUE, MAY NEED BRIEF HIGH WIND
HEADLINES WEST OF THE LARAMIE RANGE. ATTENTION WILL THEN SHIFT
TO THE WIND PRONE AREAS FRIDAY NIGHT AND INTO SATURDAY AS THE
COLD FRONT NUDGES EASTWARD INTO CENTRAL WYOMING. IN-HOUSE WIND
GUIDANCE SHOWS ELEVATED WINDS WITH A LOW PROBABILITY OF HIGH
WIND CRITERIA. INCREASED WINDS A BIT BUT KEPT THEM SHY OF HIGH
WIND CRITERIA AT THIS TIME. LIGHT WINDS ARE EXPECTED FURTHER
EAST TOWARDS WESTERN NEBRASKA WITH GUSTS OF 30 MPH ARE POSSIBLE.
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
ISSUED AT 345 AM MDT THU JUN 19 2025
NO MAJOR CHANGES TO THE LONG TERM PORTION OF THE FORECAST WITH
MUCH COOLER TEMPERATURES AND THE RETURN OF SHOWERS AND
THUNDERSTORMS BEING THE MAIN CONCERN FOR MOST OF NEXT WEEK.
UPPER LEVEL RIDGE AXIS WILL SHIFT EAST INTO THE GREAT PLAINS AND
GREAT LAKES REGION ON SUNDAY AS THE PACIFIC COLD FRONT FINALLY
MOVES EAST AND THEN SOUTH ACROSS THE REGION INTO LATE SUNDAY AND
SUNDAY NIGHT. HIGH TEMPERATURES ON SUNDAY WILL STILL BE ABOVE
AVERAGE FOR MOST OF THE DAY, BUT AS THE FRONT DIGS SOUTH AND
WINDS SHIFT INTO THE NORTH, TEMPERATURES WILL LIKELY DECREASE
THROUGH THE MID TO LATE AFTERNOON HOURS AFTER LATE MORNING/EARLY
AFTERNOON HIGHS IN THE MID 70S TO NEAR 80 DEGREES NORTH OF
INTERSTATE 80, AND LOW TO UPPER 80S ALONG AND SOUTH OF
INTERSTATE 80. CAN'T RULE OUT ISOLATED SHOWERS AND THUNDERSTORMS
BEHIND THE FRONT, BUT WITH A VERY DRY BOUNDARY LAYER, MOISTURE
ADVECTION AND BOUNDARY LAYER COOLING WILL LIKELY TAKE SOME TIME.
BY SUNDAY, THE UPPER-LEVEL RIDGE WILL BE ON ITS WAY OUT, BUT IT WILL
STILL MANAGE TO GET INTO THE UPPER 80S IN THE NEBRASKA PANHANDLE. IT
WILL CONTINUE TO BE PRECIP FREE UNTIL THE TROUGH MOVES IN LATER IN
THE DAY. THIS TROUGH WILL BRING MUCH COOLER TEMPERATURES AND A CHANCE
FOR MORE RAIN, WITH THE HIGHEST CHANCES EAST OF I-25. THIS WILL
BE NOTHING LIKE THE RECENT HEAVY RAIN EVENTS, WITH ONLY A FEW
HUNDREDTHS OF QPF EXPECTED. THE SLOW MOVING NATURE OF THIS TROUGH
WILL CONTINUE THE SHOWER AND STORM CHANCES THROUGH THE EARLY
WEEK, WITH UP TO A QUARTER INCH POSSIBLE IN THE PANHANDLE TUESDAY
NIGHT. THE HEAVIER AMOUNTS SHIFT SLIGHTLY WEST ON WEDNESDAY,
WITH A QUARTER TO HALF INCH POSSIBLE ALONG I-25. HIGHS MONDAY
THROUGH WEDNESDAY WILL BE BACK IN THE 70S BEFORE THINGS WARM
BACK UP NEAR THE END OF THE PERIOD AND THE 90S RETURN. DELAYED
THE HIGHEST PRECIP AND THUNDERSTORM PROBABILITIES UNTIL SUNDAY
EVENING AND SUNDAY NIGHT.
MUCH COOLER MONDAY THROUGH WEDNESDAY BEHIND THE FRONT. SURFACE
WINDS WILL SHIFT INTO THE EAST OR SOUTHEAST WITH EXCELLENT
MOISTURE ADVECTION NEAR THE SURFACE. THIS WILL LIKELY RESULT IN
LOW STRATUS ACROSS THE EASTERN HIGH PLAINS AND CLOUDY SKIES FOR
MUCH OF MONDAY AND EARLY TUESDAY. HOWEVER, THIS MAY ALSO LIMIT
CONVECTION A BIT WITH THE BEST CHANCE OF THUNDERSTORMS CONFINED
TO AREAS WEST OF THE LARAMIE RANGE FOR AT LEAST MONDAY. MODELS
SHOW THE STATIONARY COLD FRONT LIFTING NORTHEAST AS A WARM FRONT
LATER ON TUESDAY WITH INCREASED FRONTOGENESIS AND LIFT. THIS
LOOKS LIKE THE MOST FAVORABLE PERIOD (TUESDAY THROUGH TUESDAY
NIGHT) FOR WIDESPREAD SHOWERS AND THUNDERSTORMS FOR THE AREA.
ALTHOUGH 700MB TEMPERATURES INCREASE TUESDAY AND WEDNESDAY, LOW
TO MIDLEVEL CLOUD COVER AND THE PRESENCE OF A PACIFIC UPPER
LEVEL TROUGH WILL LIKELY KEEP TEMPERATURES NEAR OR SLIGHTLY
BELOW AVERAGE FOR THE MIDDLE OF NEXT WEEK. CAN'T RULE OUT THE
POTENTIAL FOR STRONG OR SEVERE THUNDERSTORMS AFTER MONDAY, BUT
COVERAGE AND CONFIDENCE ARE PRETTY LOW AT THIS TIME WITH
MARGINAL CONVECTIVE PARAMETERS.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 1135 PM MDT WED JUN 18 2025
UPPER LEVEL RIDGE AXIS IS FORECAST TO MOVE INTO THE REGION
OVER THE NEXT 24 HOURS AND REMAIN OVER THE FRONT RANGE THROUGH
FRIDAY. DRY AND BENIGN WEATHER IS EXPECTED WITH INCREASING WINDS
AS WE HEAD INTO FRIDAY.
HAZARDS/WEATHER TRENDS: VFR CONDITIONS WILL CONTINUE THROUGH 00Z
FRIDAY. SOME LLWS EXPECTED FOR KCDR BETWEEN 08Z AND 12Z DUE TO A
STRENGTHENING LOW LEVEL JET.
CYS WATCHES/WARNINGS/ADVISORIES
WY...NONE.
NE...NONE.
SHORT TERM...TJT
LONG TERM...TJT/WFO CYS
AVIATION...TJT
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