471
FXUS65 KCYS 182110
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
310 PM MDT SAT OCT 18 2025
KEY MESSAGES
- A STRONG COLD FRONT WILL MOVE THROUGH SATURDAY LEADING TO
FREEZING TEMPERATURES ACROSS THE ENTIRE REGION SATURDAY NIGHT
INTO SUNDAY MORNING. FREEZE WATCHES HAVE BEEN UPGRADED TO
FREEZE WARNINGS.
- STRONG WINDS LOOK TO RETURN SUNDAY AFTERNOON INTO EARLY NEXT
WEEK. HIGH WIND WARNINGS HAVE BEEN HOISTED FOR THE BORDEAUX
AND ARLINGTON WIND PRONE ZONES AS WELL AS THE FOOTHILLS
STARTING LATER IN THE MORNING. THIS BREEZY PATTERN EXPECTED
TO CONTINUE THROUGH MONDAY.
SHORT TERM /THROUGH SUNDAY NIGHT/
ISSUED AT 307 PM MDT SAT OCT 18 2025
THE UPPER LEVEL TROUGH IS PUSHING EAST AS A SHORT LIVED RIDGE MAKES
ITS WAY INTO THE INTERMOUNTAIN WEST. THE ATTENDANT COLD FRONT PUSHED
THROUGH LATE THIS MORNING TURNING THE WINDS TO THE NORTHWEST
EFFECTIVELY TURNING OFF OUR HIGH WINDS FOR OUR AREA. CLEARING SKIES
ARE EXPECTED BEHIND THE COLD FRONT AND DEPARTING UPPER-LEVEL TROUGH
AS AN UPPER-LEVEL RIDGE STARTS TO BUILD IN. TEMPERATURES BEHIND THE
FRONT WILL REMAIN FAIRLY COOL, AS THE WARMEST AIR FROM THE UPPER-
LEVEL RIDGE DOES NOT ARRIVE UNTIL SUNDAY MORNING. WITH CLEAR SKIES,
RADIATIONAL COOLING WILL QUICKLY TANK TEMPERATURES INTO THE 20S AND
30S ACROSS THE ENTIRE CWA. AS A RESULT, THE FREEZE WATCHES FOR THE
REMAINING COUNTIES WERE UPGRADED TO A FREEZE WARNING FOR SATURDAY
NIGHT INTO EARLY SUNDAY MORNING.
TEMPERATURES WILL REBOUND QUICKLY SUNDAY AFTERNOON, WITH HIGHS
RETURNING TO THE 60 AND 70S ONCE MORE. AS IS TYPICAL WITH COOL
SEASON SYSTEMS, THE UPPER-LEVEL RIDGE WILL FLATTEN OUT OVER THE CWA
WITH INCREASING HEIGHT GRADIENTS AT 700MB AS A 700MB LOW DEVELOPS
OVER SOUTHERN CANADA. THE 700MB JET WILL ONCE AGAIN STRENGTHEN TO
AROUND 50 TO 55 KTS. LAPSE RATES ARE FAVORABLE FOR THESE STRONG
WINDS TO MIX DOWN TO THE SURFACE IN THE WIND PRONE REGIONS OF
SOUTHEAST WYOMING. SUBSIDENT FLOW IS ALSO STRONG AS DEPICTED IN THE
GFS OMEGA FIELD WHICH HELPS MIX DOWN THOSE STRONGER WINDS TO THE
SURFACE. OUR IN HOUSE HIGH WIND ALGORITHMS HAS FAIRLY HIGH
PROBABILITIES FOR OUR WIND PRONE AREAS. THERE ARE ALSO FAIRLY STRONG
NEGATIVE OMEGA VALUES OVER THE FOOTHILLS AS WELL SO THE HIGH WIND
WATCH WAS UPGRADED TO HIGH WIND WARNINGS WITH THE FOOTHILLS INCLUDED
AS WELL BUT STARTING AT 10AM INSTEAD OF 3AM SUNDAY. OUR WIND PRONE
AREAS LIKE ARLINGTON AND BORDEAUX HAVE THEIR HIGH WIND WARNINGS
STILL STARTING AT 3AM. THIS WAS BASED UPON TIMING OF THE STRONG
SUBSIDENCE MOVING OVER THE AREA WHILE UNDER THE STRONGER 700MB JET.
LONG TERM /MONDAY THROUGH SATURDAY/
ISSUED AT 307 PM MDT SAT OCT 18 2025
AT THE START OF THE LONG TERM PERIOD, ACTIVE WEATHER WILL ONCE AGAIN
PLAGUE THE CWA AS A 500MB TROUGH SWEEPS ACROSS THE REGION. THIS
SYSTEM WILL PROVIDE ENOUGH ENERGY ALOFT TO HELP SUPPORT CHANCES OF
PRECIPITATION (RAIN AT LOWER ELEVATIONS) FOR MONDAY MORNING
PRIMARILY ACROSS CONVERSE AND NIOBRARA COUNTIES ALONG WITH SNOW
CHANCES AT HIGHER ELEVATIONS OF THE SNOWY AND SIERRA MADRE RANGES.
GUIDANCE IS HINTING TO THE POSSIBILITY OF ANOTHER HIGH WINDS EVENT
IN OUR TYPICAL WIND PRONE AREAS MONDAY. BY MONDAY NIGHT, WINDS WILL
HAVE DIMINISHED AND SKIES CLEARED, WITH A COOL AIRMASS IN PLACE, IF
YOU HAVEN'T ALREADY YOU WILL SEE A HARD FREEZE AS YOU WAKE UP TUESDAY
MORNING. BY TUESDAY AFTERNOON, THE AFOREMENTIONED TROUGH WILL EJECT
TO OUR EAST AS A WEAK 500MB RIDGE MOVES RIGHT IN ON ITS HEELS. THIS
WILL BRING DRY CONDITIONS ALONG WITH INDUCING AN EVER SO SLIGHTLY
WARMING TREND THROUGH THE REMAINDER OF THE LONG TERM PERIOD. SOME
GUIDANCE IS TRYING TO BRING MOISTURE INTO OUR CWA WEDNESDAY THROUGH
THURSDAY AS A WEAK UPPER LEVEL LOW SLIDES EAST JUST TO OUR SOUTH;
HOWEVER, IT APPEARS NOW THAT MOST OF THE PRECIPITATION SHOULD REMAIN
OUT OF OUR CWA. AT THE TAIL END OF NEXT WEEK, RIDGING WILL ONCE
AGAIN MAKE A TRIUMPHANT RETURN AND DOMINATE CONDITIONS INTO NEXT
WEEKEND.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 1144 AM MDT SAT OCT 18 2025
A COLD FRONT IS DIVING SOUTH ACROSS THE CWA, BRINGING GUSTY
WINDS ALONG WITH LIGHT SNOW, LOWER CIGS, AND DECREASED VIS FOR A
FEW TERMINALS (KCYS AND KLAR). THIS FRONT SHOULD BE OUT OF OUR
CWA BY 22Z, WITH PRECIPITATION CHANCES ENDING. HOWEVER, WINDS
WILL LINGER A BIT LONGER, SO EXPECT GUSTY CONDITIONS UNTIL 00Z
SUNDAY, WITH WINDS CONTINUING A DOWNWARD TREND ALONG WITH SKIES
CLEARING THROUGH THIS EVENING. BY EARLY MONDAY MORNING, WEST
WINDS WILL RAMP UP, PRIMARILY AFFECTING TERMINAL WEST OF I-25,
AND REMAIN GUSTY THROUGH END OF THIS TAF PERIOD.
CYS WATCHES/WARNINGS/ADVISORIES
WY...HIGH WIND WARNING FROM 3 AM TO 6 PM MDT SUNDAY FOR WYZ106-110.
HIGH WIND WARNING FROM 10 AM TO 6 PM MDT SUNDAY FOR WYZ117.
NE...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 7 AM MDT SUNDAY FOR
NEZ019-021-055.
SHORT TERM...MM
LONG TERM...RZ
AVIATION...RZ
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