502
FXUS65 KCYS 290006
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
605 PM MDT TUE APR 28 2026
KEY MESSAGES
- 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 FRIDAY/
ISSUED AT 201 PM MDT TUE APR 28 2026
AN AREA OR BUBBLE OF HIGH PRESSURE WILL MOVE OVER OUR PORTION OF THE
INTERMOUNTAIN WEST THIS EVENING AND INTO THE OVERNIGHT PERIOD. THIS
WILL START TO CLEAR OUT MOST OF THE SKY THROUGHOUT THE NIGHT AND
GIVE US A TEMPORARY BREAK IN RAIN/SNOW SHOWERS. THIS AREA OF HIGH
PRESSURE WILL CREATE A LOW LEVEL NOCTURNAL SURFACE INVERSION OVER
THE HIGH PLAINS. MODEL SOUNDINGS DEPICT THE ENVIRONMENT AS A SHALLOW
ALMOST SUPER ADIABATIC CLOSE TO THE SURFACE THAT WILL HELP TRAP ANY
LOW LEVEL MOISTURE PRODUCING RADIATIONAL FOG IN THE MORNING. RIGHT
NOW THE HIGHEST AREA OF CONFIDENCE IS THE NEBRASKA PANHANDLE BUT
PATCHY FOG MAY BE POSSIBLE FOR ALL AREAS EAST OF THE I-25 CORRIDOR
WITH THE RECENT MODERATE RAIN/SNOWFALL. HOWEVER, A DISORGANIZED
UPPER LEVEL TROUGH WILL INCH ITS WAY INTO THE INTO THE INTERMOUNTAIN
WEST AS THE PARENT BROAD UPPER LEVEL LOW REMAINS PARKED OVER THE
GREAT LAKES REGION. IN RESPONSE THE WINDS WILL SHIFT DIRECTIONS
THROUGHOUT THE DAY WEDNESDAY FROM OUR WEAK WESTERLIES TO A NORTHERLY
DIRECTION AND FINALLY AN EASTERLY UPSLOPE DIRECTION WEDNESDAY NIGHT
INTO THURSDAY MORNING. SOME LINGERING VORT-MAXES WILL ACCOMPANY THE
TROUGH TO AID THE SYNOPTIC SUPPORT TO PRODUCE SOME AFTERNOON AND
EVENING SHOWERS. WHILE THE MOUNTAINS MAY GET DECENT ACCUMULATIONS OF
A COUPLE TENTHS, MUCH LOWER VALUES OF A TENTH OR LESS IS EXPECTED
FOR AREAS EAST OF I-25. 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. HIGH TEMPERATURES FOR FRIDAY LOOK TO RETURN TO
NEAR SEASONAL AVERAGES OF 50'S AND 60'S FOR THE MAJORITY OF THE
FORECAST AREA.
LONG TERM /FRIDAY NIGHT THROUGH MONDAY/
ISSUED AT 201 PM MDT TUE APR 28 2026
LONG TERM REMAINS ACTIVE AS WE SEE A QUICK WARMING AND DRYOUT
OVER THE WEEKEND, BUT THE RETURN OF A MORE PROGRESSIVE PATTERN
NEXT WEEK SHOULD USHER BACK CHANCES OF RAIN AND POSSIBLY SPRING
THUNDERSTORMS TO THE AREA. FRIDAY BEGINS WITH THE REGION FALLING
IN BETWEEN SEVERAL PRIMARY FEATURES - A DEEP UPPER LEVEL LOW
COVERING THE EASTERN US, A SECONDARY TROUGH OVER THE DESERT
SOUTHWEST, AND A RIDGE MOVING INLAND ACROSS THE PACIFIC
NORTHWEST AND BEGINNING TO ENCROACH UPON OUR AREA. THIS SHOULD
HELP TO SWEEP OUT THE PRECIPITATION WE'LL BE SEEING DURING THE
WEEK OUT OF THE AREA AND USHER IN CLEARING AND WARMING, BUT NOT
BEFORE LINGERING MOISTURE AND THE INFLUENCE OF THE TROUGH TO OUR
SOUTH MAY PRODUCE AN ISOLATED MORNING SHOWER FOR THE DAY. BY THE
AFTERNOON, SKIES WILL CLEAR AND TEMPERATURES SHOULD REBOUND INTO
THE 50'S AND 60'S.
SATURDAY THE REGION WILL BE UNDER THE INFLUENCE OF THE MEAGER
RIDGE THAT WILL MOVE INTO THE AREA, ALLOWING FOR FURTHER WARM
AIR ADVECTION AND INCREASING TEMPERATURES, AS HIGHS BOUNCE INTO
THE 60'S AND 70'S. SUNDAY WILL SEE THE INFLUENCE OF THIS RIDGE
WANE AS SEVERAL SHORTWAVE IMPULSES RIDE ACROSS THE PERIPHERY OF
THIS SYSTEM SPURRED BY THE DEEP EASTERN US LOW, WITH A
CALIFORNIA LOW SANDWICHING THE OTHER SIDE AND HELPING TO
FLATTEN THE RIDGE MORE SOUTHWARD. WITH A COMBINATION OF SOME
PACIFIC AND MONSOONAL MOISTURE MOVING INTO THE AREA, PWATS
SHOULD BE ON THE RISE, UP TO NEAR TO JUST ABOVE NORMAL, ALLOWING
NEW DEVELOPMENT OF ISOLATED TO SCATTERED SHOWERS. FAVORABLE LOW
LEVEL LAPSE RATES AND SOME MEAGER POCKETS OF INSTABILITY MAY
ALSO INDUCE AN ISOLATED THUNDERSTORM OR TWO, BUT DON'T EXPECT
MUCH OUT OF THE DAY ASIDE FROM SOME RUMBLES OF THUNDER.
MONDAY LOOKS SIMILAR AS FURTHER MOISTURE MOVES INTO THE AREA AND
PWAT ANOMALIES INCREASE TO AROUND 0.1 INCH ABOVE NORMAL WITH A
WEAK SHORTWAVE PROMOTING FURTHER SCATTERED PRECIPITATION
DEVELOPMENT FOR THE DAY. THIS TIME SIMILAR LAPSE RATES AND A BIT
MORE WIDESPREAD WEAK INSTABILITY SHOULD ALLOW FOR BETTER CHANCES
OF THUNDERSTORMS, BUT ONCE AGAIN MOSTLY ANTICIPATING SOME WEAK
THUNDER ACTIVITY WITH MINIMAL CONCERNS FOR ANYTHING STRONGER.
OVERALL THIS ACTIVITY WILL NOT BE A DROUGHT BUSTER BY ANY MEANS,
BUT THE CHANCE OF A LOCALIZED STRONGER STORM COULD BRING A HIT
OF BENEFICIAL MOISTURE FOR ANYWHERE UNDERNEATH.
AVIATION /00Z TAFS THROUGH 00Z THURSDAY/
ISSUED AT 605 PM MDT FRI MAY 16 2025
WEAK UPPER LEVEL RIDGE AXIS WILL PUSH INTO THE AREA TONIGHT, GREATLY
LIMITING SHOWER COVERAGE OVER THE NEXT FEW HOURS AND OVERNIGHT.
SKIES ARE EXPECTED TO CLEAR WITH SOME FOG AND/OR LOW CLOUDS POSSIBLE
ACROSS WESTERN NEBRASKA AFTER 04Z.
HAZARDS/WEATHER TRENDS: VFR CONDITIONS WILL PREVAIL OVER THE
SOUTHEAST WYOMING TERMINALS WITH RELATIVELY LIGHT WINDS TONIGHT
THROUGH MOST OF WEDNESDAY. ANY REMAINING SHOWER ACTIVITY SHOULD
DIMINISH BY 02Z. FOR WESTERN NEBRASKA, THERE IS A MODERATE CHANCE
(20% TO 40%) OF LOW CLOUDS AND FOG LATE THIS EVENING THROUGH EARLY
WEDNESDAY MORNING (05Z TO 14Z). PROBABILITIES FROM HIGH RES ENSEMBLE
GUIDANCE HAVE INCREASED SLIGHTLY, SO ADDED SOME MENTION OF IFR
CONDITIONS OR VCFG.
CYS WATCHES/WARNINGS/ADVISORIES
WY...WINTER WEATHER ADVISORY UNTIL 3 PM MDT THIS AFTERNOON FOR
WYZ112-114.
NE...NONE.
SHORT TERM...MM
LONG TERM...CG
AVIATION...TJT
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