785
FXUS65 KCYS 280846
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
246 AM MDT TUE APR 28 2026
KEY MESSAGES
- SLICK CONDITIONS FROM OVERNIGHT SNOWFALL AND AREAS OF FOG WILL
LEAD TO LOCALLY HAZARDOUS TRAVEL CONDITIONS THIS MORNING.
- UNSETTLED WEATHER WILL CONTINUE THROUGH THE WORK WEEK WITH
DAILY CHANCES FOR SCATTERED RAIN AND SNOW SHOWERS. ISOLATED
THUNDER WILL BE POSSIBLE.
- WARMER AND DRIER CONDITIONS ARE EXPECTED TO RETURN FOR THE
WEEKEND.
SHORT TERM /THROUGH THURSDAY NIGHT/
ISSUED AT 245 AM MDT TUE APR 28 2026
UNSETTLED WEATHER CONTINUES OVER THE AREA THIS MORNING. THE CENTER
OF A VORTICITY MAXIMUM ALOFT IS TRAVERSING ACROSS THE AREA EARLY
THIS MORNING. MODEST ISENTROPIC LIFT AHEAD OF THE FEATURE ALONG WITH
VORTICITY ADVECTION ALOFT ARE SUPPORTING FAIRLY WIDESPREAD SHOWER
ACTIVITY ACROSS THE AREA. WITH TEMPERATURES HOVERING RIGHT AROUND
FREEZING FOR MOST OF THE AREA BUT COLDER TEMPERATURES ALOFT,
PRECIPITATION TYPE HAS TRANSITIONED TO MAINLY SNOW ACROSS THE AREA.
BELOW 6000 FT IN ELEVATION OR SO, SNOW WILL HAVE TROUBLE STICKING TO
ROADWAYS, BUT MANY MAY WAKE UP TO A COATING ON GRASSY OR ELEVATED
SURFACES. SNOW IS CAUSING SOME TRAVEL ISSUES AT HIGHER ELEVATION,
PRIMARY IN BETWEEN LARAMIE AND CHEYENNE ALONG THE SOUTHERN LARAMIE
RANGE. WEBCAMS INDICATE THAT SNOW HAS HAD NO TROUBLE STICKING EVEN
TO THE ROADWAYS. THE SHORTWAVE TROUGH AXIS ALOFT IS APPROACHING, AND
WE CAN EXPECT COVERAGE OF SNOW SHOWERS TO DECREASE SIGNIFICANTLY
AFTER THE AXIS PASSES THROUGH BETWEEN ABOUT 4 AM FOR OUR WESTERN
ZONES AND CLOSER TO NOON FURTHER EAST. WINTER WEATHER ADVISORIES
SHOULD BE ABLE TO EXPIRE ON TIME, BUT SLICK CONDITIONS ALONG WITH
AREAS OF FOG WILL LEAD TO LOCALLY HAZARDOUS TRAVEL THIS MORNING. THE
SURFACE TROUGH WILL NOT BE FAR BEHIND, AND WILL ALSO PROGRESS FROM
WEST TO EAST ACROSS THE AREA THIS MORNING. EXPECT A WIND SHIFT TO
THE NORTHWEST BEHIND THIS FEATURE, WITH GUSTS OF 20 TO 30 KNOTS
DEVELOPING MID MORNING INTO THE AFTERNOON.
WHILE SYNOPTICALLY FORCED PRECIPITATION ASSOCIATED WITH THIS
MORNING'S VORT-MAX SHOULD CLEAR OUT BY AROUND MIDDAY, WE WILL NOT
GET A CLEAR RADAR SCREEN ACROSS THE AREA FOR VERY LONG, IF AT ALL.
ANOTHER SUBTLE VORT-MAX ON THE BACKSIDE OF THE PRIMARY UPPER LEVEL
TROUGH WILL MOVE THROUGH THE AREA THIS AFTERNOON CONCURRENT WITH
CONVECTIVE INSTABILITY DEVELOPING. COLDER TEMPERATURES ALOFT WILL
WORK INTO THE AREA TODAY, SUPPORTING STEEP 700 TO 500-MB LAPSE RATES
AND DECENT INSTABILITY. EXPECT WIDELY SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS TO DEVELOP ACROSS THE AREA AROUND NOON AND MOVE
EASTWARD THROUGH AROUND SUNSET. WITH FAIRLY STRONG WINDS ALOFT,
STORMS WILL HAVE THE POTENTIAL TO MIX THIS DOWN AND PRODUCE LOCALLY
STRONG, GUSTY, AND ERRATIC WINDS AT THE SURFACE ALONG WITH SMALL
HAIL AND A BRIEF DOWNPOUR. WITH SNOW LEVELS HOVERING AROUND 6000 TO
7000 FT, SOME AREAS (MAINLY IN SOUTHEAST WYOMING) MAY NEED TO WATCH
FOR THE PRECIPITATION TYPE TO SUDDENLY SWITCH TO SNOW AND LEAD O
SLICK CONDITIONS AND REDUCED VISIBILITY.
RAIN AND SNOW SHOWER ACTIVITY IS EXPECTED TO DECREASE QUICKLY AFTER
SUNSET THIS EVENING, WITH CLEARING SKIES OVERNIGHT. LOW-LEVEL
MOISTURE WILL REMAIN HIGH ESPECIALLY OVER THE HIGH PLAINS, WHICH MAY
LEAD TO SOME PATCHY RADIATION FOG LATE TONIGHT INTO WEDNESDAY NIGHT.
THIS IS HINTED AT IN THE OFFICIAL FORECAST. SURFACE WINDS TURNING
WESTERLY TO NORTHWESTERLY WILL BURN OFF ANY REMAINING FOG AND LEAD
TO SURFACE DRYING. ANOTHER ROUND OF ISOLATED PM SHOWERS AND
THUNDERSTORMS CAN BE EXPECTED AGAIN ON WEDNESDAY, BUT THE COVERAGE
SHOULD BE A LITTLE MORE LIMITED COMPARED TO THE PRECEDING DAYS.
THE WEATHER WILL REMAIN UNSETTLED WEDNESDAY NIGHT INTO THURSDAY. A
DISORGANIZED UPPER LEVEL TROUGH WILL INCH ITS WAY SOUTHWARD ON THE
WEST SIDE OF THE BROAD UPPER LEVEL LOW PARKED OVER THE GREAT LAKES
REGION. MEANWHILE, A REINFORCING SURFACE HIGH PRESSURE WILL DIVE
DOWN FROM THE NORTH AND PUSH UP AGAINST THE MOUNTAINS, TURNING THE
SURFACE WINDS TO AN UPSLOPE DIRECTION. RECENT MODEL GUIDANCE HAS
CONTINUED TO TREND FURTHER SOUTH AND WEST WITH THE TRACK OF THE
UPPER LEVEL LOW, WHICH IS NOW PUTTING THE BEST SYNOPTIC FORCING FOR
ASCENT OUTSIDE OF OUR AREA. NAEFS MEAN 700-MB WINDS TURN EASTERLY
OVER CARBON, ALBANY, PLATTE, AND LARAMIE COUNTIES, BUT REMAIN WEAK
OR WESTERLY ELSEWHERE. ENSEMBLE SYSTEMS HAVE, UNFORTUNATELY,
DIVERGED APPROACHING THIS EVENT, WITH THE ECMWF ENSEMBLE MEAN
TRENDING QPF DOWNWARD TOWARDS ZERO. CONVERSELY, THE GEFS MEAN JUMPED
UP IN QPF IN THE RAWLINS TO CHEYENNE CORRIDOR, BUT QPF REMAINS LOW
FURTHER NORTH AND EAST. OVERALL, CURRENT PROBABILITIES FOR WETTING
RAINFALL (0.10" LIQUID OR MORE) ARE AROUND 40 TO 60% BETWEEN ELK
MOUNTAIN AND CHEYENNE, BUT DECREASE TO 30% OR LESS ALONG AND NORTH
OF THE NORTH PLATTE RIVER VALLEY. THE OFFICIAL FORECAST CURRENTLY
FAVORS THE DRIER ECMWF ENSEMBLE SOLUTION.
LONG TERM /FRIDAY THROUGH MONDAY/
ISSUED AT 245 AM MDT TUE APR 28 2026
BY FRIDAY, THE DISORGANIZED UPPER LEVEL LOW WILL BE MAINLY TO OUR
SOUTH. A MESSY RIDGE WILL TRY TO BUILD BACK INTO THE NORTHERN
ROCKIES FRIDAY INTO THE WEEKEND, BUT THIS WILL BE UNDERCUT BY THE
LINGERING UPPER LEVEL LOW MEANDERING OVER THE FOUR CORNERS STATES.
EXPECT WARM AIR ADVECTION AND REDUCED PRECIPITATION CHANCES ON
FRIDAY INTO SATURDAY. FRIDAY'S HIGHS WILL RETURN TO NEAR SEASONAL
AVERAGES, THEN CLIMB TO PERHAPS 10F WARMER THAN AVERAGE FOR
SATURDAY. RELATIVE HUMIDITY WILL DROP BACK DOWN TOWARDS CRITICAL
FIRE WEATHER THRESHOLDS, BUT CURRENTLY, THE WIND FORECAST LOOKS
MARGINAL FOR A POTENTIAL RED FLAG WARNING. PRECIPITATION ON BOTH
DAYS WILL MOST LIKELY BE LIMITED TO HIGH BASED VIRGA SHOWERS, IF
ANYTHING DEVELOPS AT ALL. PRECIPITABLE WATER WILL REACH A MINIMUM ON
SATURDAY, AND THEN RECOVER INTO EARLY NEXT WEEK. VALUES ARE EXPECTED
TO CLIMB BACK ABOVE SEASONAL AVERAGES BY SUNDAY AFTERNOON. THIS
SHOULD RETURN SLIGHT CHANCES FOR AFTERNOON SHOWER ACTIVITY INTO THE
AREA FOR SUNDAY WITH HIGH TEMPERATURES REMAINING ABOUT 10 DEGREES
ABOVE SEASONAL AVERAGES. THE INCREASED MOISTURE CONTENT SHOULD ALSO
NUDGE DEWPOINTS UPWARD FROM A SATURDAY MINIMUM.
LOOKING AHEAD INTO THE EARLY PART OF NEXT WEEK, WE OVERALL WEATHER
PATTERN IS EXPECTED TO TURN UNSETTLED ONCE AGAIN. TWO MAJOR PLAYERS
ON THE SYNOPTIC SCALE WILL BE ON THE TABLE, AND THE BEHAVIOR OF EACH
WILL DETERMINE THE SPECIFIC WEATHER OUTCOME FOR OUR AREA. THE FIRST
IS A SPRAWLING, CLOSED UPPER LEVEL LOW EXPECTED TO SLOWLY MEANDER
INLAND FROM THE WEST COAST DURING THE EARLY PART OF NEXT WEEK. THE
SECOND IS THE POTENTIAL FOR A NORTHERN BRANCH SHORTWAVE TROUGH
ROTATING AROUND THE BROAD AND UNSEASONABLY STRONG UPPER LEVEL LOW
FIXED OVER THE GREAT LAKES REGION TO DROP INTO OUR AREA FROM THE
NORTH. INDIVIDUAL ENSEMBLE MEMBERS ARE ALL OVER THE PLACE WITH THE
TREATMENT OF EACH OF THESE FEATURES, RESULTING IN WILDLY DIFFERENT
SCENARIOS FOR OUR AREA. WITH THIS MUCH UNCERTAINTY, IT IS IMPRUDENT
TO GET TOO FAR INTO THE DETAILS, BUT THIS WINDOW WILL NEED TO BE
WATCHED FOR ANOTHER POSSIBILITY (BUT FAR FROM A GUARANTEE) FOR
BENEFICIAL PRECIPITATION.
AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/
ISSUED AT 1142 PM MDT MON APR 27 2026
CHALLENGING AVIATION CONDITIONS WILL CONTINUE THROUGH TUESDAY
MORNING. A MIX OF RAIN AND SNOW SHOWERS ALONG WITH AREAS OF
REDUCED CIGS WILL LEAD TO FLUCTUATING FLIGHT CONDITIONS. PERIODS
OF IFR CAN BE ANTICIPATED AT ALL TERMINALS THROUGH MIDDAY. THE
MOST WIDESPREAD RAIN AND SNOW SHOWER ACTIVITY (AND THUS
POTENTIAL FOR REDUCED VISIBILITIES) WILL BE OVER THE NEXT 6
HOURS OR SO AS A BATCH OF MOISTURE MOVES OFF TO THE NORTHEAST
ACROSS THE AREA. LOW CIGS WILL CONTINUE PROBLEMS FOR A FEW MORE
HOURS AFTER, WITH ISOLATED RAIN AND SNOW SHOWERS POSSIBLY
LEADING TO LOCALIZED VISIBILITY REDUCTIONS. IFR TO LIFR WILL NOT
BE CONSISTENT THROUGH THE WHOLE TIME, AND BRIEF BREAKS OF VFR
CAN BE EXPECTED. HOWEVER, THESE WILL NOT LAST LONG.
CIGS WILL IMPROVE FROM WEST TO EAST TUESDAY MORNING INTO THE
EARLY AFTERNOON AS WINDS TURN NORTHWEST AND MIX IN DRIER AIR
WITH GUSTS OF 20 TO 30 KNOTS. ANOTHER ROUND OF WIDELY SCATTERED
RAIN AND SNOW SHOWERS CAN BE EXPECTED TUESDAY AFTERNOON, WHICH
IS HINTED AT WITH A FEW PROB30 GROUPS AT THIS TIME. LOCALIZED
VIS DROPS AND ISOLATED THUNDER WILL BE POSSIBLE.
CYS WATCHES/WARNINGS/ADVISORIES
WY...WINTER WEATHER ADVISORY UNTIL 3 PM MDT THIS AFTERNOON FOR
WYZ112-114.
WINTER WEATHER ADVISORY UNTIL 7 AM MDT THIS MORNING FOR WYZ116.
NE...NONE.
SHORT TERM...MN
LONG TERM...MN
AVIATION...MN
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