617
FXUS65 KCYS 172025
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
225 PM MDT FRI JUL 17 2026
KEY MESSAGES
- HOT, DRY, AND BREEZY CONDITIONS CONTINUE THROUGH SUNDAY BEFORE
A MUCH AWAITED COLD FRONT ARRIVES FOR THE START OF THE WEEK.
- MONDAY LOOKS TO BE THE LAST 100+ DAY FOR THE UPCOMING WEEK OR
SO, WITH REDUCED FIRE CONCERNS ALSO ARRIVING WITH COOLER
WEATHER.
- MONSOONAL MOISTURE WILL ATTEMPT TO RETURN AS EARLY AS MONDAY,
LEADING TO INCREASED PRECIPITATION CHANCES THROUGH MUCH OF
NEXT WEEK.
SHORT TERM /THROUGH SATURDAY NIGHT/
ISSUED AT 220 PM MDT FRI JUL 17 2026
THE SHORT TERM SHOULD REMAIN FAIRLY SIMILAR TO THE LAST SEVERAL
DAYS AS HIGH PRESSURE RIDGING CONTINUES TO SIT OVER THE REGION
WITH WARM TEMPERATURES TODAY IN THE UPPER 80'S TO NEAR TRIPLE
DIGITS, INCREASING A FEW DEGREES WITH NEARLY WIDESPREAD 90'S TO
100'S ACROSS THE AREA ON SATURDAY. BECAUSE OF THIS INCREASE IN
COVERAGE OF TRIPLE DEGREE HEAT, A HEAT ADVISORY WAS ISSUED
BEGINNING SATURDAY FOR PORTIONS OF SIOUX AND DAWES COUNTIES,
WITH SEVERAL MORE ZONES ADDED IN BEGINNING ON SUNDAY. WE SHOULD
ALSO CONTINUE TO SEE ELEVATED FIRE WEATHER CONDITIONS AS
SURFACE RELATIVE HUMIDITY VALUES SIT IN THE 15-20% RANGE WHILE
BREEZY, DIURNALLY DRIVEN WINDS OF AROUND 20-25 MPH WILL BE
PRESENT, BUT IF ANY SITE IS ABLE TO REACH CRITICAL CRITERIA FOR
FIRE WEATHER CONDITIONS IT'S NOT EXPECTED TO PERSIST FOR 3 OR
MORE HOURS. FINALLY UPSLOPE FLOW TODAY MAY ONCE AGAIN FUEL AN
ISOLATED SHOWER OR STORM ACROSS OUR HIGH ELEVATION AND
MOUNTAINOUS LOCATIONS IN CARBON AND ALBANY COUNTIES, BUT WITH
INVERTED V SOUNDING PROFILES PRECIPITATION MAY STRUGGLE TO REACH
THE GROUND UNDER WEAKER CELLS, AND INSTEAD WE COULD SEE THE
POTENTIAL FOR A ROGUE DRY LIGHTNING STRIKE OR GUSTY OUTFLOW
WINDS. MONSOONAL MOISTURE ATTEMPTS TO FINALLY SWING INTO THE
REGION ON SATURDAY, BUT GUIDANCE HAS DIALED BACK OR
PRECIPITATION CHANCES WITH CARBON AND ALBANY COUNTY ONCE AGAIN
AT AN ISOLATED TO WIDELY SCATTERED PROBABILITY OF SEEING SOME
DEVELOPMENT. BETTER MOISTURE SHOULD RETURN JUST BEYOND THE SHORT
TERM ON SUNDAY AND THEREAFTER.
LONG TERM /SUNDAY THROUGH THURSDAY/
ISSUED AT 220 PM MDT FRI JUL 17 2026
SUNDAY...GFS PROGS THE RIDGE ALOFT OVER THE NORTHERN ROCKIES TO BE
FLATTENED SOMEWHAT WITH ZONAL FLOW DEVELOPING OVER MONTANA AND
NORTHERN WYOMING. A WEAK PERTURBATION, OR SHORTWAVE TROUGH ALOFT,
WILL MOVE ACROSS OUR COUNTIES IN THE AFTERNOON AND EVENING, WITH
MONSOONAL MOISTURE ADVECTING INTO OUR WESTERN COUNTIES WEST OF I-25,
WHERE WE ANTICIPATE SCATTERED SHOWERS AND THUNDERSTORMS TO DEVELOP
IN THE AFTERNOON WEST OF I-25, WITH THE GREATEST AREAL COVERAGE OVER
THE SNOWY, SIERRA MADRE AND NORTHERN LARAMIE RANGES. SO, MORE
BENEFICIAL RAIN WILL OCCUR.
MONDAY...MONSOONAL MOISTURE AT LOW AND MID LEVELS INCREASES FURTHER,
AIDING IN ANOTHER INCREASE IN LATE DAY SHOWER AND THUNDERSTORM
COVERAGE, AND BENEFICIAL RAINS, WITH COVERAGE INCREASING TO
SCATTERED 30 TO 60 PERCENT POPS, PROBABILITY OF MEASURABLE
PRECIPITATION, WITH THE GREATEST COVERAGE OVER AND NEAR OUR MOUNTAIN
ZONES.
TUESDAY-FRIDAY...A RELATIVELY SIGNIFICANT PATTERN CHANGE WILL OCCUR,
WITH "BEWARE" NORTHWEST FLOW ALOFT DEVELOPING ALONG WITH A DECENT
INCREASE IN LOW AND MID LEVEL MOISTURE AND UPSLOPE SOUTHEAST
MECHANICAL LIFT AT LOW LEVELS, AND OCCASIONAL PASSING SHORTWAVE
TROUGHS ALOFT, HELPING TO PRODUCE SCATTERED TO NUMEROUS SHOWERS, AND
SCATTERED THUNDERSTORMS IN THE AFTERNOONS AND EVENINGS, WITH
BENEFICIAL RAINFALL AND POSSIBLY SOME LOCALLY HEAVY RAINS FROM SOME
OF THE SLOWER MOVING THUNDERSTORMS. THE MOST LIKELY LOCATIONS FOR
LOCALLY HEAVY RAIN AND THE GREATEST AREAL COVERAGE MAY BE ALONG AND
EAST OF INTERSTATE 25. ON FRIDAY, THE GFS PROGS THE LAST OF THE
PASSING SHORTWAVE TROUGHS ALOFT TO MOVE INTO NEBRASKA BY EVENING,
WITH SHORTWAVE RIDGING ALOFT BULGING ACROSS WYOMING, THUS EXPECT AN
ATTENDANT DECREASE IN AREAL AFTERNOON AND EVENING SHOWER AND
THUNDERSTORM COVERAGE.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
ISSUED AT 1125 AM MDT FRI JUL 17 2026
A 5940 METER PLUS 500 MB RIDGE ALOFT WILL REMAIN PARKED OVER
OUR REGION THROUGH SATURDAY AFTERNOON, SQUELCHING ALL BUT
ISOLATED AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS OVER
THE SIERRA MADRE RANGE, WITH DRY CONDITIONS ELSEWHERE. AT THE
SURFACE, A SURFACE LOW PRESSURE TROUGH WILL DEVELOP LATE TONIGHT
FROM DOUGLAS TO ALLIANCE, WITH AN ATTENDANT WARM FRONT
EXTENDING EASTWARD IN THE AFOREMENTIONED TROUGH AXIS. NORTH OF
THE WARM FRONT, EASTERLY UPSLOPE WINDS WILL LIKELY AID IN THE
DEVELOPMENT OF LOW CLOUDS AND SOME FOG FOR KCDR AND KAIA LATE
TONIGHT AND EARLY SATURDAY MORNING.
WYOMING TAFS...CONFIDENCE IS HIGH IN VFR CONDITIONS PREVAILING
WITH ISOLATED LATE AFTERNOON AND EARLY EVENING SHOWERS AND
THUNDERSTORMS OVER THE SIERRA MADRE RANGE, AND DRY CONDITIONS
ELSEWHERE. SCATTERED HIGH BASED CUMULUS WILL OCCUR THROUGH EARLY
EVENING. MIX DOWN AND SURFACE PRESSURE GRADIENTS WILL AID IN
PRODUCING GUSTY WINDS OF 20 TO 30 KNOTS THROUGH EARLY THIS
EVENING, WITH WINDS THEN SUBSIDING.
NEBRASKA TAFS...HIGH CONFIDENCE IN VFR CONDITIONS PREVAILING
WITH SCATTERED HIGH BASED CUMULUS CLOUDS THROUGH EARLY EVENING.
A WARM FRONT WILL DEVELOP LATE TONIGHT FROM ROUGHLY DOUGLAS TO
ALLIANCE, WITH NORTHEAST TO SOUTHEAST LOW LEVEL WINDS PRODUCING
LIKELY MVFR CEILINGS AND VISIBILITIES IN LOW CLOUDS AND FOG AT
KCDR AND KAIA FROM 09Z TO 13Z. OTHERWISE, CLEAR SKIES WILL
PREVAIL. MIX DOWN AND SURFACE PRESSURE GRADIENTS WILL AID IN
PRODUCING GUSTY WINDS TO 22 KNOTS THROUGH EARLY EVENING, THEN
WINDS WILL SUBSIDE.
CYS WATCHES/WARNINGS/ADVISORIES
WY...HEAT ADVISORY FROM NOON SUNDAY TO 6 PM MDT MONDAY FOR WYZ101-
102-108.
NE...HEAT ADVISORY FROM NOON SATURDAY TO 6 PM MDT MONDAY FOR NEZ002-
095.
HEAT ADVISORY FROM NOON SUNDAY TO 6 PM MDT MONDAY FOR NEZ003-
019>021-096.
SHORT TERM...CG
LONG TERM...RUBIN
AVIATION...RUBIN
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