793
FXUS65 KCYS 142108
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
308 PM MDT SUN SEP 14 2025
KEY MESSAGES
- SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE OVER FAR
EASTERN WYOMING AND WESTERN NEBRASKA THROUGH THE EARLY
EVENING.
- WARMER TEMPERATURES ARE EXPECTED MONDAY WITH A FEW ISOLATED PM
SHOWERS AND THUNDERSTORMS CAPABLE OF PRODUCING GUSTY WINDS.
- ANOTHER COLD FRONT WILL PUSH ACROSS WYOMING ON TUESDAY,
RESULTING IN COOLER TEMPERATURES AND A DAILY CHANCE FOR
SHOWERS AND ISOLATED THUNDERSTORMS.
SHORT TERM /THROUGH TUESDAY/
ISSUED AT 300 PM MDT SUN SEP 14 2025
THE LATEST GOES SATELLITE IMAGERY SHOWS THE UPPER LEVEL LOW
CIRCULATING NEAR THE NEBRASKA/SOUTH DAKOTA BORDER AS IT LOWLY EJECTS
TO THE NORTHEAST. FAIRLY POTENT LOW TO MID-LEVEL ISENTROPIC LIFT /
POSITIVE THETA-E ADVECTION HAS BEEN ANALYZED OVER WESTERN NEBRASKA,
WHICH IS SUPPORTING ONGOING SHOWER ACTIVITY IN THIS AREA. HOWEVER,
THIS FORCING IS ON A WEAKENING TREND, AND SHOULD BE GONE BY ABOUT 6
TO 7 PM OR SO. HOWEVER, MODEST INSTABILITY REMAINS IN THE WAKE OF
THE SYSTEM OVER THE HIGH PLAINS. SBCAPE IS AROUND 500 TO 1000 J/KG,
AND WE HAVE FAIRLY DECENT LOW LEVEL CONVERGENCE PROVIDING SOME
FORCING OVER PLATTE, GOSHEN, AND LARAMIE COUNTIES AS WELL AS INTO
THE NEBRASKA PANHANDLE. MOST OF THIS CONVECTION IS FAIRLY LOW-
TOPPED, AND THUS THE PROBABILITY OF SEVERE WEATHER IS QUITE LOW.
STILL, WE COULD SEE SOME ISOLATED GUSTY WINDS AND PEA SIZED HAIL.
SURFACE VORTICITY IN PLACE ALSO MEANS A BRIEF, WEAK LANDSPOUT CAN'T
BE RULED OUT. EXPECT CLEARING SKIES OVERNIGHT TONIGHT AS THIS SYSTEM
FINALLY DEPARTS.
THE WEATHER PATTERN WILL REMAIN ACTIVE HEADING INTO MONDAY. THE NEXT
UPPER LEVEL LOW IS ALREADY APPARENT MOVING OVER THE PACIFIC
NORTHWEST THIS AFTERNOON. A TRANSIENT RIDGE WILL MOVE OVER THE AREA
TONIGHT INTO MONDAY AHEAD OF THIS NEXT SYSTEM, SUPPORTING ONE WARM
DAY IN BETWEEN SYSTEMS. WEST-SOUTHWEST FLOW ALOFT WILL SUPPORT WARM
AIR ADVECTION ACROSS THE AREA, BOOSTING TEMPERATURES BACK ABOVE
AVERAGE FOR THIS TIME OF YEAR. DRY AIR WILL ALSO WORK IN TONIGHT,
BUT MOISTURE ADVECTION ALOFT IS EXPECTED TO RETURN AS EARLY AS LATE
MORNING MONDAY. FORECAST SOUNDINGS SHOW FAIRLY DRY INVERTED-VS IN
THE LOW LEVELS WITH MOISTURE INCREASING ALOFT OVERTOP OF THE DRY
BOUNDARY LAYER. WITH SOME WEAK FORCING ANTICIPATED, WE SHOULD BE
LOOKING AT ISOLATED TO WIDELY SCATTERED HIGH BASED SHOWERS AND
THUNDERSTORMS MOVING RAPIDLY ACROSS THE AREA AHEAD OF THE UPPER
LEVEL LOW. COVERAGE IS NOT EXPECTED TO BE ALL THAT HIGH, BUT WE WILL
NEED TO WATCH FOR STRONG GUSTY WINDS WITH THIS ACTIVITY DUE TO THE
DRY LOW-LEVELS AND FAIRLY STRONG WINDS (FOR THIS TIME OF YEAR) ALOFT.
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/
ISSUED AT 300 PM MDT SUN SEP 14 2025
TUESDAY...THE SHORTWAVE TROUGH ALOFT MOVES OVERHEAD NEAR PEAK
HEATING, SPARKING SCATTERED SHOWERS AND THUNDERSTORMS IN THE
AFTERNOON AND EVENING. SOMEWHAT COOLER IN THE WAKE OF A COLD FRONT
AND WITH MORE CLOUD COVER AND PRECIPITATION COVERAGE.
WEDNESDAY...THE NEXT SHORTWAVE TROUGH ALOFT MOVES ACROSS WYOMING,
AND WITH ADEQUATE LOW AND MID LEVEL MOISTURE, WE EXPECT TO SEE
SCATTERED AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS. SOMEWHAT
COOLER WITH EXTENSIVE CLOUD COVER.
THURSDAY...NORTH FLOW ALOFT DEVELOPS, WITH DRIER AIR MOVING IN AT
LOW AND MID LEVELS, PRODUCING A DRIER DAY. 700 MB TEMPERATURES NEAR
5 CELSIUS WILL PRODUCE A WARMER DAY.
FRIDAY...SOMEWHAT DRIER AIR MOVES IN WITH NORTHWEST FLOW ALOFT,
PRODUCING A DRY DAY. 700 MB TEMPERATURES RISE SLIGHTLY, PRODUCING A
WARMER DAY.
SATURDAY...RIDGING ALOFT BUILDS OVER WESTERN WYOMING. WE MAY SEE
ISOLATED LATE DAY SHOWERS AND THUNDERSTORMS WITH JUST ENOUGH LOW AND
MID LEVEL MOISTURE.
SUNDAY...NORTHWEST FLOW ALOFT CONTINUES, AND WITH ENOUGH LOW AND MID
LEVEL MOISTURE, WE ANTICIPATE ISOLATED TO WIDELY SCATTERED AFTERNOON
AND EVENING SHOWERS AND THUNDERSTORMS. 700 MB TEMPERATURES NEAR 12
CELSIUS WILL YIELD MAXIMUM TEMPERATURES IN THE 70S.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1139 AM MDT SUN SEP 14 2025
AVIATION CONDITIONS ARE IMPROVING FOR WYOMING TERMINALS AS THE
STORM SYSTEM DEPARTS. EXPECT GRADUALLY CLEARING SKIES AND
OCCASIONALLY GUSTY WEST TO NORTHWEST WINDS. OVERNIGHT, WE WILL
SEE WINDS BEGIN TO INCREASE AROUND 2 KFT AGL AND THEN MIX TO THE
GROUND AROUND MID MORNING, PRODUCING SOME GUSTY WEST TO
SOUTHWEST WINDS.
IN NEBRASKA, SHOWER ACTIVITY IS EXPECTED TO CONTINUE FOR A FEW
MORE HOURS. ONCE THE STRATIFORM RAINFALL DEPARTS, WE WILL HAVE A
FEW MORE HOURS OF POTENTIAL FOR SCATTERED THUNDERSTORMS TO
DEVELOP IN MARGINAL INSTABILITY AND IMPACT NE TERMINALS WITH
LIGHTNING, RAIN, AND GUSTY WINDS. EXPECT GRADUAL CLEARING
OVERNIGHT TONIGHT.
CYS WATCHES/WARNINGS/ADVISORIES
WY...NONE.
NE...NONE.
SHORT TERM...MN
LONG TERM...RUBIN
AVIATION...MN
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