272
FXUS65 KCYS 082055
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
255 PM MDT WED APR 8 2026
KEY MESSAGES
- MULTIPLE, WEAKER COLD FRONT WILL PUSH THROUGH OVER THE NEXT
COUPLE OF DAYS, LEADING TO SLIGHTLY COOLER TEMPERATURES AND
INCREASING PRECIPITATION CHANCES HEADING INTO THE WEEKEND.
- THE FIRST STRONG THUNDERSTORMS COULD ARRIVE AS EARLY AS
SATURDAY AFTERNOON TO THE WESTERN NEBRASKA PANHANDLE.
SHORT TERM /THROUGH FRIDAY NIGHT/
ISSUED AT 254 PM MDT WED APR 8 2026
LOOKING AT MID-LEVEL WATER VAPOR, THE UPPER LEVEL LOW THAT WAS
TRAVERSING ACROSS THE CANADIAN PROVIDENCES IS NOW SLOWLY DIVING
SOUTH INTO THE NORTHERN PLAINS. AS THIS KIND OF WOBBLES ALONG THE
CANADIAN/US BORDER, A STREAM OF VORTICITY WILL PUSH THROUGH OUR CWA
LATER TONIGHT. THIS VORTICITY WILL HELP DEVELOP SOME LIGHT SHOWERS
WITH THE INCREASED SYNOPTIC LIFT HOWEVER, LOOKING AT THE QPF FIELDS
AND MODEL SOUNDINGS VERY LITTLE PRECIPITATION IS EXPECTED TO REACH
THE GROUND IF ANY AT ALL. THE PROBABILITIES WERE KEPT AT 15 PERCENT
OR LESS WITH THE GREATEST CHANCE FOR 0.01 INCHES BEING AROUND
CHADRON TONIGHT AT A WHOPPING 20 PERCENT. ANOTHER SHORTWAVE OR BROAD
TROUGH WILL PASS THROUGH THE CANADIAN PROVIDENCES THURSDAY TURNING
OUR WINDS MORE WESTERLY. THESE WESTERLY WINDS WILL PUT US IN A DRY
DOWNSLOPE REGIME. MODEL SOUNDINGS SHOW THE MID TO UPPER LEVELS
BECOMING SATURATED BUT THE LOWER LEVELS REMAIN QUITE DRY. WINDS WILL
BE LIGHT IN THE MORNING AND GRADUALLY INCREASE THURSDAY AFTERNOON.
WHILE HIGH WINDS AREN'T EXPECTED, THE WINDS WILL BE STRONG ENOUGH TO
REINFORCED THAT DRY LAYER NEAR THE SURFACE SEVERELY LIMITING THE
AMOUNT OF PRECIPITATION IF ANY TO REACH THE SURFACE. THIS BROAD
TROUGH WILL PUT UP A GOOD FIGHT AS MULTIPLE LOBES OF VORTICITY
COMBINED WITH THE INCREASED MID-LEVEL MOISTURE AND WARM AIR
ADVECTION (WAA) TO INCREASE THE SYNOPTIC FORCING TO PROVIDE A
FIGHTING CHANCE FOR SOME PRECIPITATION THURSDAY AFTERNOON AND
INCREASING CHANCES LATER THAT EVENING. CURRENTLY THE GREATEST
CHANCES FOR PRECIPITATION FOR THE REGION LIES NEAR THE WYOMING
COLORADO BORDER AND THE SIERRA MADRE MOUNTAINS AS THE WESTERLY WINDS
CREATE A FAVORABLE UPSLOPE ENHANCING THE CHANCES FOR PRECIPITATION
FOR THE MOUNTAINS. A COLD FRONT IS PROGGED TO TRANSIT THROUGH THE
FORECAST AREA THURSDAY EVENING INTO THE OVERNIGHT HOURS. WITH THE
COLD FRONT PASSING THROUGH THE LATER PORTION OF THE DAY, THE
ATMOSPHERE WILL HAVE BEGUN TO SATURATE DUE TO THE FALLING
TEMPERATURES AND THUS PROVIDE MORE MOISTURE PARCELS TO BE LIFTED BY
THE FRONT. POPS WERE GRADUALLY INCREASED THROUGHOUT THE AFTERNOON
AND INTO THE OVERNIGHT PERIOD TO REFLECT THIS. SOUTHWESTERLY FLOW IS
ANTICIPATED TO RETURN FOR FRIDAY AFTERNOON AS THE UPPER-LEVEL TROUGH
STARTS TO PUSH INTO THE WEST COAST AND DIGS ACROSS CENTRAL AND
SOUTHERN CALIFORNIA. THE WEAK, UPPER-LEVEL RIDGE WILL START TO PUSH
INTO THE CWA LATE FRIDAY MORNING WITH THE APEX OF THE RIDGE MOVING
THROUGH BY THE EARLY AFTERNOON HOURS. ONCE THE APEX MOVES THROUGH,
SOUTHWESTERLY FLOW RETURNS ON THE WESTERN SIDE OF THE RIDGE. WITH
THE STRONG TROUGH ACROSS THE WEST COAST, SOUTHWESTERLY FLOW ACROSS
THE CWA WILL ACT TO ADVECT IN PACIFIC MOISTURE, WITH NAEFS TO SHOW
MEAN PW VALUES TO BE IN THE 90-97TH CLIMATOLOGICAL PERCENTILE ACROSS
SOUTHEAST WYOMING AND THE WESTERN NEBRASKA PANHANDLE AREA. MULTIPLE
500MB VORTICITY LOBES WILL EJECT OUT AHEAD OF THE APPROACHING
TROUGH, FAVORING INCREASING SYNOPTIC ASCENT ACROSS THE CWA FOR
FRIDAY AFTERNOON AND EVENING. 700MB WARM AIR ADVECTION WILL INCREASE
SIGNIFICANTLY FRIDAY MORNING INTO THE EARLY AFTERNOON HOURS, WITH
EVEN STRONGER WAA EXPECTED OVERNIGHT FRIDAY. WITH A SURFACE HIGH
OVER MINNESOTA AND LOWER PRESSURE WEST OF THE ROCKY MOUNTAINS, A
STRONG SURFACE PRESSURE GRADIENTS WILL DEVELOP, LEADING TO EASTERLY
WINDS AS WIND FLOW FROM THE HIGHER PRESSURE TOWARDS THE LOWER
PRESSURE. AS A RESULT, MOIST, UPSLOPE FLOW IS EXPECTED EAST OF THE
LARAMIE RANGE, INCREASING PRECIPITATION CHANCES ONCE AGAIN. ISOLATED
TO SCATTERED SHOWERS AND POTENTIALLY A RUMBLE OR TWO OF THUNDER IS
EXPECTED THROUGHOUT THE AFTERNOON AND EVENING ON FRIDAY. ONCE AGAIN,
THIS DOES NOT LOOK TO BE A DROUGHT BUSTING EVENT, BUT ANOTHER 0.03
TO 0.10 IN OF PRECIPITATION IS POSSIBLE ACROSS MOST OF THE AREA.
LONG TERM /SATURDAY THROUGH TUESDAY/
ISSUED AT 254 PM MDT WED APR 8 2026
UNSETTLED WEATHER WILL CONTINUE INTO THE EARLY PART OF NEXT WEEK
ACROSS THE REGION. BY THIS WEEKEND, THE WEATHER PATTERN ON THE
SYNOPTIC SCALE WILL FEATURE A BROAD, STRENGTHENING UPPER LEVEL RIDGE
OVER THE CENTRAL AND EASTERN CONUS, WITH TROUGHING OVER THE WEST
COAST. A SERIES OF UPPER LEVEL SHORTWAVES MOVING THROUGH THE
SOUTHWEST FLOW ALOFT ACROSS THE ROCKIES WILL KEEP PRECIPITATION
CHANCES AND THE POTENTIAL FOR STRONGER WINDS IN THE FORECAST.
FIRST, SATURDAY IS CONTINUING TO BE A DAY TO WATCH FOR THE POTENTIAL
FOR A FEW STRONG THUNDERSTORMS. THE RIDGE AXIS WILL PEAK OVERHEAD ON
SATURDAY BEFORE STARTING TO SHIFT EASTWARD LATER IN THE PERIOD. 700-
MB TEMPERATURES PEAK AROUND +6 TO +8C. LOOK FOR SATURDAY TO BE THE
WARMEST DAY OF THE PERIOD AS A RESULT, WITH WIDESPREAD UPPER 60S TO
70S EXPECTED. A FEW LOW 80S COULD SHOW UP IN THE LOWEST ELEVATIONS
TOO. AT THE SURFACE, WE WILL OPEN UP SATURDAY WITH SOUTH TO
SOUTHEAST FLOW OVER THE HIGH PLAINS AROUND THE PERIPHERY OF A VERY
LARGE SURFACE HIGH PRESSURE SYSTEM POSITIONED WELL TO THE EAST. GULF
MOISTURE ADVECTION LOOKS TO BE EXCELLENT FOR THIS TIME OF YEAR, WITH
DEWPOINTS EXPECTED TO REACH INTO THE LOW 40S FOR ALL ALONG AND EAST
OF I-25. MORNING LOW CLOUDS AND/OR FOG LOOK LIKE A GOOD BET, BUT FOG
WAS NOT ADDED TO THE FORECAST YET SINCE WE ARE STILL A FEW DAYS OUT.
FORECAST SOUNDINGS SHOW A FAIRLY POTENT SUBSIDENT DRY LAYER ON TOP
OF THE SHALLOW SURFACE MOISTURE, WHICH WILL PLAY A ROLE IN THE
POTENTIAL FOR AFTERNOON CONVECTION. BROAD SOUTHWEST FLOW ALOFT WILL
SUPPORT LEE CYCLOGENESIS ACROSS CENTRAL WYOMING DURING THE DAY ON
SATURDAY. AS THIS ADVANCES EASTWARD, WE SHOULD SEE THE DRYLINE WHICH
WILL BE POSITIONED ALONG THE LARAMIE RANGE MOVE EASTWARD THROUGH THE
DAY. HOW FAR THE MOISTURE RETREATS TO THE EAST WILL BE THE MAIN
UNCERTAINTY CONCERNING THUNDERSTORM POTENTIAL. AN APPROACHING VORT-
MAX WILL ENHANCE SYNOPTIC LIFT DURING THE AFTERNOON AND EVENING
HOURS, WHICH SHOULD KICK OFF SOME SCATTERED PM SHOWERS AND ISOLATED
THUNDERSTORMS. THE RIGHT BALANCE BETWEEN THE CAPPING INVERSION
WEAKENING, AND THE BOUNDARY LAYER NOT DRYING OUT TOO MUCH WILL NEED
TO BE STRUCK IN ORDER TO GET MORE ORGANIZED THUNDERSTORM POTENTIAL.
THIS IS POSSIBLE, BUT FAR FROM A GUARANTEE. WITH GOOD VERTICAL WIND
SHEAR IN PLACE, A FEW STRONG THUNDERSTORMS WILL BE POSSIBLE, BUT
UNCERTAINTY IS CONSIDERABLE AT THIS LEAD TIME.
SUNDAY WILL BE A FEW DEGREES COOLER THAN SATURDAY BEHIND THE INITIAL
SHORTWAVE TROUGH ALOFT. THERE WILL STILL BE A CHANCE FOR PM SHOWERS
AND THUNDERSTORMS, BUT COVERAGE AND INTENSITY LOOKS TO BE MORE
LIMITED. THERE WILL ALSO BE A SHORT WINDOW FOR HIGH WINDS IN THE
WIND PRONE AREAS SATURDAY NIGHT INTO SUNDAY MORNING AS WE SEE A BRIEF
SURGE IN 700-MB HEIGHT GRADIENTS AND WINDS BEHIND THE DEPARTING VORT-
MAX. LOW-LEVEL MOISTURE WILL BE REDUCED SIGNIFICANTLY FOR SUNDAY,
SUCH THAT ELEVATED TO NEAR CRITICAL FIRE WEATHER CONCERNS MAY RETURN
TO THE PICTURE TOO. PRECIPITATION CHANCES WILL INCREASE AGAIN MONDAY
INTO WEDNESDAY NEXT WEEK AS THE BROAD UPPER LEVEL LOW OVER THE WEST
COAST FINALLY MOVES INLAND. WHILE THERE IS GOOD AGREEMENT ON THE
OVERALL SYNOPTIC EVOLUTION, THE DEVIL IS IN THE DETAILS. THE EXACT
TRACK AND STRENGTH OF THE UPPER LEVEL LOW COMBINED WITH THE
POTENTIAL FOR INTERFERENCE FROM OTHER SHORTWAVE TROUGHS EITHER
EJECTING AHEAD OF THE MAIN SYSTEM OR RIDING TO THE NORTH WILL
DETERMINE PRECIPITATION AMOUNTS. UNFORTUNATELY FOR OUR DROUGHT
STRICKEN AREA, THE PROBABILITY FOR SIGNIFICANT, WIDESPREAD RAINFALL
OR SNOWFALL CONTINUES TO DECREASE. WHILE THE DETERMINISTIC ECMWF
CONTINUES TO SHOW A PROMISING TRACK WITH PLENTIFUL PRECIPITATION, IT
APPEARS TO BE AN OUTLIER AMONGST ITS OWN ENSEMBLE SYSTEM. CLUSTER
ANALYSIS SUGGESTS THAT THE PROBABILITY OF A SYSTEM CAPABLE OF
MEANINGFULLY IMPROVING THE DROUGHT (0.5" OR MORE OVER A LARGE AREA)
IS ONLY AROUND 10 TO 20% PER THE LREF. DEPENDING ON THE EXACT TRACK
OF THE UPPER LEVEL LOW, THERE WILL ALSO BE A POTENTIAL FOR HIGH
WINDS IN THE WIND PRONE AREAS DURING THIS PERIOD.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 1142 AM MDT WED APR 8 2026
MAINLY A WIND FORECAST FOR THE UPCOMING TAF PERIOD. AT ALL
TERMINALS EXCEPT RWL, WINDS WILL VEER THROUGH NEARLY THE ENTIRE
COMPASS OVER THE NEXT 24 HOURS. NORTH TO NORTHEAST WINDS THIS
AFTERNOON WILL TURN EAST AND THEN SOUTHEAST OVERNIGHT. A BRIEF
SURGE OF SOUTHERLY WINDS IS EXPECTED THURSDAY MORNING, BEFORE
WINDS FLIP BACK TO THE WEST OR NORTHWEST NEAR THE END OF THE
PERIOD.
IN ADDITION, SOME ISOLATED VIRGA SHOWERS LATE THIS
AFTERNOON THROUGH THE EVENING MAY LEAD TO BRIEF GUSTY AND
ERRATIC WINDS. VIS OR CIG DROPS ARE NOT EXPECTED. EXPECT
INCREASING MID TO UPPER LEVEL CLOUD COVER. A FEW LOW CLOUDS
CANNOT BE RULED OUT THURSDAY MORNING, BUT THE PROBABILITY (10%)
IS TOO LOW TO ADD TO THE TAF.
CYS WATCHES/WARNINGS/ADVISORIES
WY...NONE.
NE...NONE.
SHORT TERM...MM
LONG TERM...MN
AVIATION...MN
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