868
FXUS65 KCYS 301735
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1135 AM MDT THU APR 30 2026
KEY MESSAGES
- CHANCES FOR SCATTERED RAIN AND SNOW SHOWERS WILL CONTINUE FOR
PORTIONS OF SOUTHEAST WYOMING THROUGH THIS EVENING. ISOLATED
THUNDER REMAINS POSSIBLE.
- WARMER AND DRIER CONDITIONS ARE EXPECTED TO RETURN FOR FRIDAY
INTO THE WEEKEND.
SHORT TERM /THROUGH FRIDAY NIGHT/
ISSUED AT 300 AM MDT THU APR 30 2026
MOSTLY CLOUDY SKIES ARE OVER THE AREA THIS MORNING AS A WEAK UPPER
LEVEL SHORTWAVE SLOWLY PROGRESSES THROUGH. AN EXPANSIVE, BUT
RELATIVELY WEAK SURFACE HIGH PRESSURE IS FILLING IN BEHIND THE UPPER
LEVEL FEATURES, PUSHING DOWN FROM THE NORTH THIS WEEKEND. THE
FRONTAL BOUNDARY WAS RELATIVELY DIFFUSE BUT MOST OF THE AREA IS NOW
SEEING WEAK NORTHERLY WINDS AS SURFACE PRESSURE SLOWLY RISES.
UPSLOPE FLOW AND WEAK FRONTOGENESIS ARE SUPPORTING SOME SHOW SHOWER
ACTIVITY MAINLY IN CARBON AND ALBANY COUNTIES. THIS IS TIED TO THE
SURFACE FRONT SLOWING AS IT PUSHES UP AGAINST THE HIGHER TERRAIN.
SNOW SHOWERS ARE LEADING TO SLICK SPOTS AND REDUCED VISIBILITY ALONG
I-80. A SPECIAL WEATHER STATEMENT HAS BEEN ISSUED THROUGH 6AM, BUT
ACCUMULATIONS ARE EXPECTED TO BE SUB-ADVISORY. STILL, TRAVELERS MAY
ENCOUNTER SLICK OR HAZARDOUS CONDITIONS THIS MORNING. EXPECT THIS TO
IMPROVE QUICKLY ONCE THE STRONG APRIL SUN RISES. COVERAGE OF SNOW
SHOWER ACTIVITY SHOULD ALSO COME DOWN AROUND SUNRISE, BUT THEN
PICK UP AGAIN AROUND MIDDAY WITH MINIMAL CONVECTIVE INSTABILITY
EXPECTED TO DEVELOP. WE MAY ALSO SEE A FEW RUMBLES OF THUNDER
WITH THIS ACTIVITY. THE HIGH PLAINS NORTH AND EAST OF CHEYENNE
WILL SEE LITTLE TO NO MOISTURE FROM THIS EVENT, AND EVEN MOST OF
CARBON, ALBANY, AND WESTERN LARAMIE COUNTIES WILL BE FAIRLY
LIMITED. THE HIGHER PEAKS OF THE SNOW RANGE AND THE NORTHERN AND
EASTERN FOOTHILLS HAVE THE BEST CHANCE FOR SEEING OVER 0.10" OF
LIQUID PRECIPITATION THROUGH THIS EVENING.
DRIER AIR WILL WORK IN ALOFT OVERNIGHT TONIGHT, AND BRING ANY
LINGERING SHOWER ACTIVITY TO AN END. SKIES WILL CLEAR FROM NORTH TO
SOUTH, WITH MOSTLY CLEAR SKIES EXPECTED BY DAYBREAK FRIDAY. TODAY'S
SLOPPY SHORTWAVE TROUGH WILL GET STUCK TO OUR SOUTH OVER THE FOUR
CORNERS STATES BY TOMORROW MORNING. A NARROW RIDGE WILL TRY TO SNEAK
BACK INTO THE NORTHERN ROCKIES, BOOSTING TEMPERATURES ONCE AGAIN.
EXPECT HIGHS ON FRIDAY TO BE RELATIVELY CLOSE TO SEASONAL AVERAGES,
GENERALLY MID 50S TO MID 60S. WINDS WILL REMAIN FAIRLY LIGHT EVEN AS
HUMIDITY DROPS AGAIN, WHICH SHOULD KEEP FIRE WEATHER CONCERNS FROM
ESCALATING TOO MUCH.
LONG TERM /SATURDAY THROUGH WEDNESDAY/
ISSUED AT 300 AM MDT THU APR 30 2026
UPPER LEVEL RIDGING WILL REMAIN IN PLACE OVER THE AREA FOR SATURDAY
AND SUNDAY. 700-MB TEMPERATURES WILL CLIMB TO AROUND +2 TO +6C
ACROSS THE AREA FOR THE WEEKEND, SUPPORTING DAYTIME HIGH
TEMPERATURES ABOVE SEASONAL AVERAGES. FORECAST HIGHS IN THE MID
60S TO MID 70S EACH DAY WILL BE ABOUT 10F ABOVE AVERAGE. WITH
WINDS REMAINING LIGHT, IT SHOULD BE A VERY PLEASANT WEEKEND FOR
OUTDOOR ACTIVITIES. SATURDAY WILL REMAIN VERY DRY ACROSS THE
AREA WITH RH AS LOW AS 10%, BUT MOISTURE WILL BEGIN TO RECOVER
ON SUNDAY. ELEVATED MOISTURE OVERTOP A DRY AND DEEP BOUNDARY
LAYER WILL RETURN HIGH- BASED VIRGA SHOWERS TO THE FORECAST
SUNDAY AFTERNOON AND EVENING, BUT THE CHANCE FOR RAINFALL WILL
BE FAIRLY LOW.
ANOTHER SUBTLE UPPER LEVEL SHORTWAVE ROUGH MOVING DOWN FROM THE
NORTH ON SUNDAY INTO MONDAY WILL BE ACCOMPANIED BY A SURFACE COOL
FRONT. THE TEMPERATURE DROP WILL BE SUBTLE, WITH MONDAY'S HIGHS
EXPECTED TO BE JUST A FEW DEGREES COOLER THAN SUNDAY, BUT SURFACE
MOISTURE SHOULD IMPROVE SIGNIFICANTLY. MEANWHILE, A SPRAWLING UPPER
LEVEL LOW WILL SLOWLY MOVE INLAND FROM THE WEST COAST ON MONDAY,
WHICH WILL SET THE STAGE FOR AN UNSETTLED BUT EXTREMELY MESSY
WEATHER PATTERN BEGINNING MONDAY AND CONTINUING THROUGH THE MIDDLE
OF NEXT WEEK. MONDAY LOOKS TO BE PRIMARILY CONVECTIVE. SYNOPTIC
FORCING IS MUDDLED AND WEAK, BUT WE SHOULD SEE AMPLE MOISTURE IN
PLACE WITH DECENT INSTABILITY. TUESDAY LOOKS LIKE A MIX OF
CONVECTIVE AND SYNOPTIC FORCING FOR PRECIPITATION AS A STRONGER
SHORTWAVE ALOFT DROPS DOWN FROM THE NORTH AND INITIATES A COMPLEX
INTERACTION WITH THE WEST COAST CLOSED LOW.
THE PRIMARY UNCERTAINTY NEXT WEEK IS HOW FAR WEST THIS NORTHERN
BRANCH SHORTWAVE WILL TRAVEL. ENSEMBLES ARE FAIRLY EVENLY SPLIT
BETWEEN TWO SCENARIOS. THE FIRST FEATURES A STRONGER TROUGH
POSITIONED FURTHER WEST, WHICH SHOULD LEAD TO 700-MB
TEMPERATURES AROUND -6 TO -10C AND SUPPORT WELL-BELOW AVERAGE
TEMPERATURES. THE SECOND KEEPS THE COOLER AIR FURTHER EAST, AND
ONLY FEATURES A MODEST COOL DOWN WITH 700-MB TEMPERATURES
DROPPING TO BETWEEN 0 AND -4C. IT IS SOMEWHAT UNCLEAR WHICH
SCENARIO WOULD LEAD TO MORE WIDESPREAD PRECIPITATION. EACH
CLUSTER CONTAINS SEVERAL MEMBERS WITH NOTABLE PRECIPITATION
AMOUNTS EXCEEDING 0.25" FOR MUCH OF THE AREA. EACH SCENARIO ALSO
INCLUDES SEVERAL ENSEMBLE MEMBERS WITH LITTLE TO NO
PRECIPITATION AS WELL. THE OFFICIAL FORECAST INCLUDES POPS IN
THE 40 TO 70% WHICH SEEMS APPROPRIATE AT THIS LEAD TIME. THE
PRECIPITATION OUTCOME WILL DEPEND ON THE INTERACTION BETWEEN THE
WEST COAST CLOSED LOW AND THE NORTHERN BRANCH SHORTWAVE, AND
THAT WILL BE VERY DIFFICULT TO ACCURATELY FORECAST OUTSIDE OF A
FEW DAYS LEAD TIME.
AVIATION /18Z TAFS THROUGH 18Z FRIDAY/
ISSUED AT 1127 AM MDT THU APR 30 2026
NORTH NORTHWEST FLOW ALOFT WILL CONTINUE, WHILE A WEAK WEATHER
DISTURBANCE MOVES TO THE SOUTH OF THE TERMINALS, HELPING CLOUDS
TO CLEAR OUT FROM NORTH TO SOUTH THIS AFTERNOON AND EVENING.
WYOMING TAFS...HIGH CONFIDENCE IN CEILINGS RANGING FROM 4000 TO
7000 FEET THROUGH THE AFTERNOON, WITH OCCASIONAL SNOW SHOWERS
THROUGH 21Z, REDUCING THE VISIBILITY TO 4 MILES AND CEILINGS TO
1800 TO 2500 FEET, THEN SKIES WILL BECOME CLEAR THIS EVENING.
SUFFICIENT PRESSURE GRADIENTS WILL HELP WINDS GUSTING TO
25 KNOTS AT RAWLINS AND CHEYENNE UNTIL LATE AFTERNOON, THEN
WINDS WILL GUST TO 20 KNOTS AT CHEYENNE AFTER 15Z FRIDAY.
NEBRASKA TAFS...HIGH CONFIDENCE IN SCATTERED CLOUDS FROM 5000 TO
8000 FEET THROUGH EARLY EVENING, WITH SKIES BECOMING CLEAR
THEREAFTER. PRESSURE GRADIENTS SUGGEST WINDS GUSTING TO 25 KNOTS
AT ALLIANCE, SCOTTSBLUFF AND SIDNEY UNTIL 01Z, AND TO 22 KNOTS
AT SIDNEY AFTER 15Z FRIDAY.
CYS WATCHES/WARNINGS/ADVISORIES
WY...NONE.
NE...NONE.
SHORT TERM...MN
LONG TERM...MN
AVIATION...RUBIN
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