231
FXUS65 KCYS 120544
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1144 PM MDT THU SEP 11 2025
KEY MESSAGES
- DAILY CHANCES FOR AFTERNOON SHOWERS AND THUNDERSTORMS CONTINUE
THROUGH FRIDAY WITH GUSTY WINDS, DOWNPOURS, AND ISOLATED HAIL
POSSIBLE.
- A COLD FRONT WILL IMPACT THE AREA LATER THIS WEEK BRINGING
COOLER TEMPERATURES THROUGH THE WEEKEND.
SHORT TERM /THROUGH FRIDAY/
ISSUED AT 219 PM MDT THU SEP 11 2025
A DEEP UPPER LEVEL TROUGH RESIDES OVER THE PACIFIC NORTHWEST/WEST
COAST OF THE UNITED STATES. THIS TROUGH WILL SEND SHORTWAVES OVER
THE NEXT 48 HOURS TO AID IN THUNDERSTORM DEVELOPMENT. THE JETSTREAM
WILL RESIDE ACROSS THE SOUTHEAST WYOMING AREA TO AIDE IN DIVERGENCE
ALOFT ACROSS THE REGION. THIS DIVERGENCE REGION WILL HELP CONTRIBUTE
TO THE SYNOPTIC LIFT AS WELL AS PROVIDE SOME SUBSTANTIAL SHEAR TO
SUSTAIN THUNDERSTORMS ONCE DEVELOPED. HIGH-RES GUIDANCE SHOWS
WIDESPREAD THUNDERSTORM ACTIVITY ATTACHING ITSELF TO A SURFACE THETA-
E GRADIENT AS THE WAVE PUSHES THROUGH. THERE IS ALSO SOME LOCALLY
ENHANCED VORT-MAXES THAT RESIDE IN THE SOUTHERN PORTION OF LARAMIE
COUNTY AS WELL AS THE NEBRASKA PANHANDLE. IF THUNDERSTORMS INGEST
THIS VORTICITY THEN LARGE HAIL AND GUSTY WINDS LOOKS TO BE THE MAIN
THREATS AS THE STORMS PULSE UP AND DEVELOP STRONGER/MORE EFFICIENT
UPDRAFTS DUE TO THE LOCALIZED VORTICITY. MODEL SOUNDINGS DO SHOW A
LARGE INVERTED-V SOUNDING TO SUPPORT THE DEEPER MIXING AND GUSTY
WINDS. LOW-LEVEL WATER VAPOR SUPPORTS A DRY LAYER NEAR SURFACE WHILE
MID-LEVEL WATER VAPOR SHOWS MOISTURE ADVECTION FROM OUR
SOUTHWESTERLY FLOW FROM THE TILTED RIDGE THAT IS SLOWLY PULLING
EAST. THESE STORMS COULD POTENTIALLY LAST UNTIL EARLY FRIDAY MORNING
BUT WILL BEGIN TO LOSE THEIR INTENSITY AFTER THE SUN GOES DOWN AND
THE POTENTIAL ENERGY BECOMES DEPLETED. AFTER 03Z THE HREF HAS THE
CAPE LEVEL DIPPING BELOW 300 JOULES WITH THE BETTER INSTABILITY OFF
FURTHER EAST INTO NEBRASKA.
FRIDAY, THE SAME WIDESPREAD ACTIVITY IS EXPECTED AS THIS EVENING.
MODEL SOUNDINGS DO SHOW A STRONGER SIGNATURE FOR A WET MICROBURST
SCENARIO AS THE SATURATION LAYER IS DEEPER ABOVE THE INVERTED V AS
WELL AS THIN CAPE PROFILE SUGGESTING A HEAVIER RAINFALL POTENTIAL.
HOWEVER, THE SYNOPTIC FORCING WILL BE STRONGER AS THE UPPER LEVEL
TROUGH BEGINS TO LIFT INTO THE INTERMOUNTAIN WEST WHILE ALSO
INCREASING THE AMOUNT OF POTENTIAL VORTICITY ENHANCEMENT AS WELL.
THE DOWNFALL TO FRIDAY IS THE LACK OF PROGGED CAPE FOR THE AREA.
THIS IS LIKELY DUE TO THE PROJECTED TRACK OF THE LOW AND THE COOLER
TEMPERATURES FOLLOWING TO DECREASE THE REGIONS AVAILABLE
INSTABILITY. DUE TO THE STRONGER WET MICROBURST SIGNATURE GUSTY
WINDS CAN'T BE RULED OUT AS THE THUNDERSTORM WEAKEN AND COLLAPSE
THEIR UPDRAFTS. HOWEVER, THE OVERALL SEVERITY OF THE THESE
THUNDERSTORMS IS RATHER LOW BUT A COUPLE STRONG THUNDERSTORM ARE THE
MOST LIKELY SCENARIO WITH STRATIFORM RAIN TO FOLLOW THROUGH FRIDAY
EVENING.
LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/
ISSUED AT 219 PM MDT THU SEP 11 2025
AS WE START THE LONG TERM AND PROGRESS THROUGH THE WEEKEND,
TROUGHING DIGS IN AND SLIDES ACROSS OUR CWA AS RIDGING PUSHES OFF TO
THE EAST. WITHIN THE TROUGH, ENERGY ALOFT WILL MOVE THROUGH OUR CWA,
KICKING OFF A FEW ISOLATED TO SCATTERED THUNDERSTORMS ALONG WITH THE
POTENTIAL FOR HEAVY RAINFALL. THIS TROUGH WILL SLIDE OFF TO THE EAST
THROUGH SUNDAY, BRINGING THE GREATEST THREAT OF HEAVY PRECIPITATION
AND THUNDERSTORM POTENTIAL INTO THE NEBRASKA PANHANDLE. A BRIEF
REPRIEVE MONDAY AS A TRANSIT RIDGE MOVES IN, DECREASING
PRECIPITATION AND STORM POTENTIAL. THIS RIDGE WILL BRING IN THE
WARMEST TEMPERATURES FOR THE LONG TERM PERIOD, WITH HIGHS EAST OF
THE I-25 CORRIDOR SOARING ONCE AGAIN BACK INTO THE LOWER TO
MID/UPPER 80S AND INTO THE 70S ACROSS OUR WESTERN COUNTIES.
BEGINNING TUESDAY, WE WILL SEE A RETURN OF MOISTURE ALONG WITH
INCREASED PRECIPITATION CHANCES THAT REMAIN POSSIBLE INTO WEDNESDAY
AS ANOTHER ANOTHER UPPER LEVEL LOW ROTATES ACROSS OUR CWA. AT THE
TAIL END OF NEXT WEEK, NORTHWEST FLOW ALOFT MAKES A RETURN, USHERING
IN COOLER TEMPERATURES THAT MAY ONLY TOP OUT IN THE LOWER TO MID
70S. IN ADDITION, PRECIPITATION CHANCES DURING THIS TIME PERIOD
PREVIOUSLY MENTIONED, DWINDLES INTO NEXT WEEKEND.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 1143 PM MDT THU SEP 11 2025
A FEW STRAY SHOWERS POSSIBLE OVERNIGHT, OTHERWISE GENERALLY QUIET
CONDITIONS ARE EXPECTED. WINDS WILL BE FAIRLY LIGHT AND VARIABLE AT
NIGHT AT MOST TERMINALS. MID TO UPPER-LEVEL CLOUDS WILL MOVE ACROSS
THE AREA OVERNIGHT. MORE WIDESPREAD SHOWERS AND STORMS CAN BE
EXPECTED DURING THE DAY TOMORROW WITH VISIBILITY DROPS POSSIBLE DUE
TO HEAVY RAIN.
CYS WATCHES/WARNINGS/ADVISORIES
WY...NONE.
NE...NONE.
SHORT TERM...MM
LONG TERM...RZ
AVIATION...SF
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