894
FXUS65 KCYS 080010
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
505 PM MST WED JAN 7 2026
KEY MESSAGES
- HIGH WINDS WILL CONTINUE THROUGH THIS MORNING IN THE WIND
PRONE AREAS, INTERMITTENTLY SPILLING INTO ADJACENT ZONES.
- ELEVATED GRASSLAND FIRE DANGER IS EXPECTED TODAY OVER THE
HIGH PLAINS.
- THE NEXT STORM SYSTEM WILL BRING A CHANCE FOR SNOW SHOWERS AND
A RETURN TO BELOW AVERAGE TEMPERATURES THIS EVENING INTO
FRIDAY.
SHORT TERM /THROUGH THURSDAY NIGHT/
ISSUED AT 304 PM MST WED JAN 7 2026
THE WINDS SHOULD START DIEING OFF BY 00Z AS THE UPPER LEVEL SUPPORT
MOVES WITH THIS INCOMING TROUGH. RIGHT NOW RH VALUES ARE KIND OF LOW
WITH VALUES IN THE MID TO UPPER 20'S. IT WILL TAKE A LITTLE BIT FOR
THE LOWER ELEVATIONS EAST OF I-25 DUE TO THE DOWNSLOPING WINDS
TODAY. FORCING ALSO ISN'T THE GREATEST AS WE HAVE ISENTROPIC DESCENT
LATER TONIGHT COUPLED WITH THE STRONGER FGEN MOVING OFF TO THE EAST
CREATING A LITTLE BIT OF A TIMING ISSUE WITH THE MOISTURE
AVAILABILITY AND THE FORCING NEEDED TO CREATE THE LARGER SNOW
AMOUNTS. THE QPF TOTALS AND SNOW TOTALS WERE CUT DOWN FROM NBM
GUIDANCE DUE TO THIS MISMATCH IN TIMING. HOWEVER, THERE IS SOME
CONVERGENCE IN THE NEBRASKA PANHANDLE TO HELP LIFT THE MOISTURE
PARCELS FOR THE DEVELOPMENT OF SOME POSSIBLE SNOW. THE RECENT RUNS
OF THE HRRR ALSO CUT SNOW TOTALS COMPARED TO PREVIOUS ONES LIKELY
PICKING UP ON THE LACK OF SIGNIFICANT SUPPORT. CHEYENNE MAY SEE
BETWEEN 1-2 INCHES ON THURSDAY AS THE TROUGH PUSHES THROUGH BUT
SIDNEY MAY ONLY SEE HALF AN INCH. IF THE ENVIRONMENT WERE TO
SATURATE IN TIME TO UTILIZE THE STRONGER FORCING THEN WE COULD SEE
SNOW TOTALS FOR THE LOWER ELEVATIONS INCREASE BY 1-2 INCHES. BY
THURSDAY EVENING THE TROUGH IS EXPECTED TO PUSH EAST INTO THE PLAINS
AREA BUT ANOTHER WEAK SHORTWAVE IS EXPECTED TO PUSH THROUGH THE
INTERMOUNTAIN WEST THURSDAY EVENING INTO FRIDAY MORNING. THIS
SHORTWAVE SHOULD PROVIDE ENOUGH FORCING TO PRODUCE ANOTHER COUPLE
TENTHS OF SNOW.
THE GOOD NEWS IS THAT AN ARCTIC AIRMASS FOLLOWS THE TROUGH TONIGHT
LEADING TO MORE SEASONABLE TEMPERATURES THURSDAY. OVERNIGHT
TEMPERATURES WILL DROP INTO THE TEENS THURSDAY NIGHT INTO FRIDAY. SO
THE SNOW THAT FALLS SHOULD STAY AROUND A LITTLE BIT LONGER THAN
PREVIOUS TIMES TO HOPEFULLY HAVE SNOW ON THE GROUND THURSDAY THROUGH
FRIDAY MORNING.
LONG TERM /FRIDAY THROUGH WEDNESDAY/
ISSUED AT 304 PM MST WED JAN 7 2026
THE AXIS OF A SPLIT TROUGH WILL MOVE ACROSS THE AREA ON FRIDAY.
EXPECT SNOW SHOWERS TO LINGER OVER THE AREA, ESPECIALLY IN THE
MOUNTAINS, INTO FRIDAY, BUT OUR AREA IS POSITIONED SOMEWHAT
UNFAVORABLY (FOR SIGNIFICANT PRECIPITATION) BETWEEN TWO UPPER LEVEL
LOWS BOTH TO OUR NORTH AND TO OUR SOUTH. AN ELONGATED BAND OF
ELEVATED VORTICITY ALOFT WILL MOVE THROUGH FRIDAY, AND SINCE WE WILL
CONTINUE TO HAVE STEEP LOW-LEVEL LAPSE RATES IN PLACE, WE SHOULD SEE
SOME LIMITED CONVECTIVE-TYPE SNOW SHOWER ACTIVITY CONTINUE INTO
FRIDAY. A STRONG REINFORCING SURFACE COLD FRONT WILL RIDE ALONG THE
UPPER LEVEL TROUGH AXIS, PUSHING THROUGH THE AREA BY DAYBREAK
FRIDAY. EXPECT FAIRLY RAPID PRESSURE RISES THROUGH THE DAY AS A
SURFACE HIGH PRESSURE SETTLES IN OVER THE NORTHERN ROCKIES. THIS
WILL KEEP A POTENT PRESSURE GRADIENT OVER MUCH OF THE AREA, AND
RETURN GUSTY WINDS INTO THE FORECAST FOR FRIDAY. THE PROBABILITY FOR
HIGH WINDS IS FAIRLY LOW (20%) BUT FAIRLY WIDESPREAD GUSTS OF 30 TO
45 MPH ARE ANTICIPATED. TEMPERATURES WILL BE CONSIDERABLY COLDER
TOO, AS 700-MB TEMPERATURES BOTTOM OUT AROUND -15C BEHIND THE COLD
FRONT. THIS WILL SUPPORT HIGHS MAINLY IN THE 20S TO LOW 30S, WITH
THE WINDS KEEPING APPARENT TEMPERATURES IN THE SINGLE DIGITS WEST OF
THE LARAMIE RANGE AND IN THE TEENS TO LOWER 20S TO THE EAST.
DEPENDING ON HOW MUCH SNOW FALLS TONIGHT AND THURSDAY, BLOWING SNOW
MAY BE A CONCERN ON FRIDAY, EVEN OUTSIDE OF THE TYPICAL WIND PRONE
AREAS.
THIS STORM WILL HELP COMPLETE A PATTERN SHIFT INTO A DRY NORTHWEST
FLOW PATTERN THAT WILL DOMINATE MUCH OF NEXT WEEK. THE SYNOPTIC
PATTERN LOOKS TO BE DOMINATED BY A STRONG WEST COAST RIDGE, AND
BROAD CENTRAL/EASTERN CONUS TROUGH. THE MAIN WEATHER MAKERS FOR OUR
AREA DURING THIS PERIOD WILL BE A SERIES OF CLIPPER SYSTEMS DIVING
DOWN THE WESTERN FLANK OF THE TROUGH. THE FIRST OF THESE IS EXPECTED
AROUND THE SATURDAY TIME PERIOD AS A SUBTLE VORT-MAX DIVES DOWN FROM
THE NORTH AND GETS WRAPPED INTO THE STRENGTHENING UPPER LEVEL LOW
OVER THE NORTHERN PLAINS. AT THE SAME TIME, THE WESTERN RIDGE WILL
TRY TO ADVANCE EASTWARD, LIKELY PRODUCING SOME OVERRUNNING ON TOP OF
THE RETREATING ARCTIC FRONTAL BOUNDARY. AS A RESULT, WE HAVE A
CHANCE FOR SNOW SHOWERS MAINLY OVER OUR NORTHERN AND EASTERN ZONES
(AND IN THE MOUNTAINS) SATURDAY AS THIS DISTURBANCE MOVES THROUGH.
IN ADDITION, THIS SYSTEM WILL TIGHTEN THE PRESSURE GRADIENT ACROSS
OUR GAP AREAS ONCE AGAIN, INCREASING WIND SPEEDS. THIS EVENT LOOKS
FAIRLY MARGINAL AT THIS TIME, WITH OVERALL WIND PARAMETERS NEAR
TYPICAL THRESHOLDS FOR HIGH WIND WARNING ISSUANCE. AT THIS TIME, THE
PROBABILITY FOR WINDS REACHING HIGH WIND CRITERIA IS ABOUT 60% IN
THE I-80 WIND PRONE AREAS, AND 20 TO 40% FOR THE I-25 CORRIDOR.
THE RIDGE WILL EVENTUALLY WIN BY SUNDAY, PUSHING THE ARCTIC AIR OFF
TO THE EAST. 700-MB TEMPERATURES WILL RECOVER TO AROUND -2C BY THE
END OF THE DAY SUNDAY, WHICH WILL PUT HIGHS BACK AROUND 10F ABOVE
AVERAGE FOR THIS TIME OF YEAR. EXPECT MILD TEMPERATURES WITH LITTLE
TO NO CHANCE FOR PRECIPITATION SUNDAY THROUGH MONDAY NIGHT AND
POSSIBLY LONGER. WE SHOULD GET A BREAK FROM THE WIND ON SUNDAY, AND
ENSEMBLE MEMBERS DIFFER IN HOW QUICKLY THEY RETURN. LOOK FOR AT
LEAST ELEVATED WINDS TO RETURN BY AROUND TUESDAY. THE NEXT CHANCE
FOR PRECIPITATION WILL BE WITH A WEAK CLIPPER SYSTEM TUESDAY NIGHT.
ENSEMBLE MEMBERS ARE FAIRLY EVENLY SPLIT, WITH ABOUT HALF OF LREF
MEMBERS (MAINLY FROM THE ECMWF ENSEMBLE) SHOWING THE CLIPPER TAKING
A MORE WESTWARD TRACK THAT BRINGS COLDER TEMPERATURES AND A CHANCE
FOR SNOW TUESDAY INTO WEDNESDAY, WHILE THE OTHER HALF (MAINLY FROM
THE GEFS) KEEP THE SYSTEM JUST TO OUR EAST, WHICH WOULD MEAN
CONTINUED MILD AND DRY CONDITIONS.
AVIATION /00Z TAFS THROUGH 00Z FRIDAY/
ISSUED AT 505 PM MST WED JAN 7 2026
GUSTY WINDS WILL EASE THIS EVENING AS A PACIFIC COLD FRONT MOVES
INTO THE REGION TONIGHT. CLOUDS ARE EXPECTED TO LOWER AND THICKEN
WITH PERIODS OF LIGHT SNOW, ESPECIALLY FOR THE INTERSTATE 80
CORRIDOR AND TERMINALS NEAR THE COLORADO BORDER.
HAZARDS/WEATHER TRENDS: VFR CONDITIONS WILL CONTINUE OVER THE NEXT 6
HOURS FOR MOST TERMINALS WITH INCREASING MID TO HIGH LEVEL
CLOUDINESS AHEAD OF THE COLD FRONT. ANY GUSTY WINDS WILL DIMINISH BY
03Z. HIGH RES MODELS SHOW SNOW INITIALLY DEVELOPING ACROSS CARBON
COUNTY AND KRWL BETWEEN 03Z AND 06Z WITH NEAR MVFR CONDITIONS. LOW
CONFIDENCE ON HOW WIDESPREAD THIS SNOW WILL BE OR WHAT THE SNOWFALL
RATES WILL BE DUE TO LOW LEVEL DRY AIR AND LIMITED DYNAMIC FORCING.
FURTHER EAST, SNOW WILL GRADUALLY DEVELOP AS THE FRONT MOVES
SOUTHEAST WITH KLAR, KCYS, AND KSNY LIKELY SEEING SOME LIGHT SNOW
BETWEEN 10Z AND 18Z THURSDAY. IFR CONDITIONS ARE MORE LIKELY AT
THESE TERMINALS WITH BETTER MODEL AGREEMENT.
CYS WATCHES/WARNINGS/ADVISORIES
WY...NONE.
NE...NONE.
SHORT TERM...MM
LONG TERM...MN
AVIATION...TJT
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