584
FXUS65 KCYS 051740
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1040 AM MST WED NOV 5 2025
KEY MESSAGES
- WINDY, MILD, AND DRY CONDITIONS EXPECTED THROUGHOUT MUCH OF
THE WEEK DUE TO A ZONAL FLOW PATTERN.
- STRONG WINDS AND COOLING TEMPERATURES EXPECTED DURING THE
WEEKEND.
SHORT TERM /THROUGH THURSDAY NIGHT/
ISSUED AT 242 AM MST WED NOV 5 2025
THERE IS AN UPPER LEVEL LOW OVER THE GREAT LAKES REGION AND ANOTHER
PUSHING IN THE PACIFIC NORTHWEST. THAT PUTS THE INTERMOUNTAIN WEST IN
A SHORT LIVED AMPLIFIED RIDGING PATTERN ON WEDNESDAY. AS THE DAY
PROGRESSES THE RIDGING PATTERN WILL START TO PUSH EAST LOSING SOME
OF ITS AMPLIFICATION IN THE PROCESS AS THE LOW PUSHES FURTHER INTO
THE PACIFIC NORTHWEST. AS THAT LOW PUSHES EAST AND FLATTEN THE RIDGE
OVER US, IT WILL SEND A WEAK SHORTWAVE THROUGH THE INTERMOUNTAIN
WEST WEDNESDAY NIGHT INTO THURSDAY. DURING THIS TIME BOTH THE
PRESSURE GRADIENTS AT THE SURFACE AND AT 700MB WILL BEGIN TO
TIGHTEN, AND CONTINUE THE WYOMING HIGH WIND FESTIVAL WE ALL KNOW AND
LOVE. BOTH THE GFS AND THE RRFS SHOW THE 700MB JET MEETING HIGH WIND
CRITERIA AROUND BETWEEN 55 TO 65KTS STARTING AROUND 06Z ON THURSDAY.
BUT BY 12Z THURSDAY THE RRFS HAS THE 700MB JET DECREASING IN
INTENSITY TO AROUND 50KTS. THE GFS HAS IT WEAKENING AROUND 15Z JUST
SLIGHTLY LATER THAN THE RRFS. NOW PERUSING THE GFS OMEGA FIELD, THE
STRONG SUBSIDENT FLOW DOESN'T COME INTO EFFECT UNTIL 12Z RIGHT WHEN
THE JET IS SUPPOSED TO BE WEAKENING AND THE SHORTWAVE IS MOVING
THROUGH THE INTERMOUNTAIN WEST. SO THERE'S A LITTLE UNCERTAINTY IF
THE WINDS WILL BE STRONG ENOUGH TO MIX DOWN TO JUSTIFY A HIGH WIND
WARNING FOR THE WIND FESTIVAL WE HAVE OCCURRING. AROUND 18Z THE
OMEGA FIELD SHOWS MAXED VALUES FOR SUBSIDENT FLOW OVER THE WIND
PRONE AREAS ESSENTIALLY SHOWING THE TIMING FOR OUR MOUNTAIN WAVE
ACTIVITY REALLY TAKING EFFECT. WINDS AT THAT TIME AROUND SHOWING TO
BE AROUND 50KTS WHICH ISN'T EXACTLY STRONG ENOUGH FOR US TO JUSTIFY
A HIGH WIND WARNING (BUT ITS STILL GOING TO BE GUSTY ALL DAY
THURSDAY). OUR IN HOUSE ALGORITHM HAS ABOUT A 40 TO 60 PERCENT FOR
ELEVATED TO HIGH WINDS STARTING AT 06Z OVER ARLINGTON. IT HAS
BORDEAUX REACHING HIGH WIND CRITERIA AROUND 15Z AND THE SUMMIT AT
18Z. THEN IN LIKE TRUE MOUNTAIN WAVE FASHION THERE ARE LULLS WHERE
THE WINDS DIE DOWN FOR A BIT BEFORE RAMPING UP BACK INTO POSSIBLY
HIGH WIND CRITERIA. SO FOR NOW THE HIGH WIND WARNING WILL BE PASSED
BACK TO THE DAY SHIFT FOR THEIR FINAL DETERMINATION.
THE SECOND PART OF THIS WAVE IS OUR INCREASE IN PRECIPITATION
CHANCES. WEDNESDAY WE WILL REMAIN DRY AS THE AMPLIFIED RIDGE AXIS IS
OVER US. HOWEVER, WEDNESDAY NIGHT THAT TROUGH WILL ADVECT IN SOME
PACIFIC MOISTURE INTO THE MOUNTAINS. WHILE THERE ISN'T A TON OF
MOISTURE ADVECTING IN WITH THIS WAVE THERE DOES LOOK TO BE ENOUGH TO
SATURATE THE DRY AIR OVER THE MOUNTAINS AND HAVE SOME ACCUMULATING
SNOWFALL OCCUR IN THE SIERRA MADRE AND SNOWY RANGE. LOOKING AT MODEL
SOUNDINGS AT LARAMIE AND RAWLINS IT DOESN'T APPEAR TO BE ENOUGH TO
OVERCOME THE DRY LAYER IN THOSE LOCATIONS. SO POPS WILL MAINLY
FOCUSED ON THE MOUNTAINS WITH 10 TO 15 POPS OVER RAWLINS AND LARAMIE
AND CONTINUING THOSE LOW POPS OVER THE NORTHERN LARAMIE RANGE AND
INTO OUR NORTHERN COUNTIES. SOME OF THE HI-RES GUIDANCE HAD SOME
WEAK DEVELOPMENT OCCURRING IN THOSE AREAS WITH SOME SLIGHTLY
STRONGER DEVELOPMENT IN NORTHEASTERN WYOMING. SO LOW POPS SEEMED TO
ADEQUATELY CAPTURE THOSE OUTLIERS. LOW AND MID LEVEL WATER VAPOR
ALSO VERIFIES THE MOISTURE CURRENTLY ADVECTING IN WITH THE GREATER
POOL OF MOISTURE BEHIND IT. OUTSIDE OF THE MOUNTAINOUS REGIONS EAST
OF I-25, THE SOUNDINGS SHOW THE DRY LAYER REMAINING IN PLACE SO NO
POPS WERE ADDED FOR THESE AREAS. GIVEN THAT WESTERLY FLOW WILL STILL
BE THE DOMINANT REGIME, ITS ALMOST EXPECTED THAT THE DRY AIR WONT BE
GOING ANYWHERE THANKS TO THE WARM DRY DOWNSLOPING EFFECT.
LONG TERM /FRIDAY THROUGH TUESDAY/
ISSUED AT 252 PM MST TUE NOV 4 2025
THE LONG TERM REMAINS ACTIVE AS WE SEE MULTIPLE DAYS IN A ROW
OF STRONG TO HIGH WINDS FROM SEVERAL SYSTEMS MOVING ACROSS THE
REGION WHILE ALSO COOLING US BACK DOWN FROM OUR ABOVE NORMAL
TEMPERATURES BACK TO NEAR TO POSSIBLY EVEN BELOW NORMAL OVER THE
WEEKEND. THURSDAY STARTS AS A QUICK TROUGH SWINGS IN DURING THE
MORNING AND SHIFTS RIDGING OUT OF OUR AREA. THIS WILL CAUSE
TEMPERATURES WEST OF THE LARAMIE RANGE TO DROP BACK DOWN TO NEAR
NORMAL WITH HIGHS IN 40THE UPPER 40'S TO LOW 50'S, BUT
LOCATIONS EAST OF THIS WILL REMAIN WARM AS WE SEE 50'S TO MID
60'S LINGERING THROUGH FRIDAY. BUT THE ENHANCED PRESSURE
GRADIENT FROM THIS SYSTEM WILL PROMOTE WIDESPREAD 700MB WINDS IN
THE 50+ KNOT RANGE WITH FAVORABLE DOWNWARD OMEGA VALUES
BRINGING THESE SPEEDS DOWN TO THE SURFACE. AND THEN OVER THE
WEEKEND STRONG WINDS CONTINUE AS ANOTHER QUICK MOVING TROUGH
SWINGS DOWN AGAIN ON FRIDAY, FOLLOWED BY A DEEPER PACIFIC LOW
INTO SATURDAY, WITH POTENTIAL HIGH WIND WARNINGS ALL THE WAY
THROUGH SATURDAY, WHILE TEMPERATURES ARE NOW EXPECTED TO
ACTUALLY DESCEND BELOW NORMAL FOR THE WEEKEND AS THESE SYSTEMS
BRING IN A SURGE OF COLDER CANADIAN AIR FROM NORTHERLY TO
NORTHWESTERLY FLOW. WIDESPREAD HIGHS IN THE CWA ARE EXPECTED TO
BE STUCK IN THE 40'S TO POSSIBLY VERY LOW 50'S, WITH VERY COLD
MORNING LOWS IN THE TEENS TO 20'S SUNDAY MORNING. MEANWHILE THIS
PATTERN SHOULD SET OFF SOME LIGHT PRECIPITATION ON THURSDAY AND
AGAIN FRIDAY INTO EARLY SATURDAY, BUT WITH A LACK OF STRONGER
MOISTURE AND FORCING, EXPECT ANY SHOWERS THAT CAN OCCUR TO BE
LIMITED TO THE HIGH TERRAIN AND MOUNTAINS, WITH MINIMAL
ACCUMULATIONS OF SNOW AND/OR RAIN/SNOW MIX. EARLY NEXT WEEK WE
GET OUR NEXT ROUND OF RIDGING, WITH HIGHS RETURNING TO NEAR TO
ABOVE NORMAL TO START THE WEEK.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 1030 AM MST WED NOV 5 2025
VFR CONDITIONS WILL PREVAIL ACROSS ALL TERMINALS FOR THIS TAF
PERIOD. WINDS WILL RAMP UP AROUND 18Z, GUSTING UP TO 25 KNOTS,
WHILE KRWL WILL SEE GUSTS TOPPING OUT NEAR 35 KNOTS. OVERNIGHT
AND INTO TOMORROW, GUSTS INCREASE UP TO 35 KNOTS ACROSS THE
WYOMING TERMINALS; HOWEVER, THE NEBRASKA TERMINALS WILL SEE
SLIGHTLY WEAKER GUSTS TO NEAR 25 KNOTS. OUTSIDE OF KRWL, WIND
SHEAR MAY ALSO BE AN ISSUE ACROSS ALL TERMINALS LATE THIS
EVENING INTO TONIGHT.
CYS WATCHES/WARNINGS/ADVISORIES
WY...NONE.
NE...NONE.
SHORT TERM...MM
LONG TERM...CG
AVIATION...RZ
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page