957
FXUS65 KCYS 011051
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
451 AM MDT TUE JUL 1 2025
KEY MESSAGES
- THERE IS A MARGINAL RISK OF STRONG TO SEVERE THUNDERSTORMS
THIS AFTERNOON FOR PORTIONS OF WESTERN NEBRASKA AND FAR
EASTERN WYOMING.
- WARM TEMPERATURES AND DAILY CHANCES FOR PM SHOWERS AND
THUNDERSTORMS WILL CONTINUE LATE THIS WEEK AND INTO NEXT
WEEKEND.
SHORT TERM /THROUGH THURSDAY/
ISSUED AT 440 AM MDT TUE JUL 1 2025
CLEAR SKIES AND QUIET CONDITIONS EARLY THIS MORNING AS AN UPPER LEVEL
RIDGE AXIS REMAINS OVER THE REGION TODAY. WARMER TEMPERATURES
ARE EXPECTED THIS AFTERNOON WITH HIGHS IN THE 80S TO LOW 90S,
WARMEST BELOW 4500 FEET. ALTHOUGH IT SHOULD BE PRETTY NICE DAY
ACROSS THE AREA, MODEL ANALYSIS SHOWS A WEAK UPPER LEVEL
SHORTWAVE/VORTICITY MAX NEAR THE WYOMING AND MONTANA BORDER.
THIS VORT FEATURE IS EXPECTED TO DRIFT SOUTHEAST THROUGH THIS
AFTERNOON. CURRENT SURFACE OBSERVATIONS SHOW AMPLE LOW LEVEL
MOISTURE WITH DEWPOINTS IN THE 50S ALONG AND EAST OF THE LARAMIE
RANGE. COMBINED WITH SOME FORCING NEAR THE UPPER LEVEL SHORTWAVE
AND WEAK SURFACE CONVERGENCE DUE TO LEE-SIDE TROUGHING...SHOWERS
AND THUNDERSTORMS ARE EXPECTED TO DEVELOP AROUND OR SHORTLY
AFTER NOON. THERE IS A MARGINAL RISK FOR STRONG TO SEVERE
THUNDERSTORMS EAST OF THE I-25 CORRIDOR. 0-6KM SHEAR VALUES ARE
GENERALLY AROUND 25 KNOTS AND SLOWLY INCREASE TOWARDS 30 KNOTS
BY THE END OF THE DAY. THIS SHOULD BE ENOUGH SHEAR TO JUSTIFY A
FEW STRONG THUNDERSTORMS, BUT COVERAGE WILL BE LIMITED AS THE
UPPER LEVEL RIDGE AXIS AND ASSOCIATED MIDLEVEL SUBSIDENCE WILL
REMAIN OVER THE AREA. KEPT POP AND PROB OF THUNDER BETWEEN 15 TO
30 PERCENT INTO THIS EVENING. PRIMARY CONCERNS WILL BE HAIL UP
TO QUARTER SIZED AND GUSTY WINDS. A DEVELOPING LOW LEVEL JET MAY
ENHANCE THIS THUNDERSTORM ACTIVITY IN THE EVENING HOURS, BUT
MOST OF THE ACTIVITY MAY BE MOVING INTO CENTRAL NEBRASKA BY
THEN.
FOR WEDNESDAY AND THURSDAY, A PRETTY TYPICAL SUMMER WEATHER
PATTERN SETS UP ACROSS THE REGION AS A SLOW MOVING UPPER LEVEL
RIDGE MOVES EAST OF THE AREA. HIGH TEMPERATURES WILL REMAIN IN
THE 80S WEST OF I-25, AND UPPER 80S TO MID 90S EAST OF I-25.
SECONDARY 590 DM RIDGE AXIS WILL PUSH INTO THE AREA WEDNESDAY.
WITH INCREASING MIDLEVEL SUBSIDENCE AND THE LACK OF ANY NOTABLE
FORCING, KEPT MENTION OF PRECIPITATION WEST OF THE LARAMIE
RANGE. SHOWERS AND THUNDERSTORMS WILL RETURN TO MOST OF THE
REGION ON THURSDAY AS A BROAD EASTERN PACIFIC TROUGH MOVES INTO
THE GREAT BASIN REGION AND FINALLY INTO THE INTERMOUNTAIN WEST
THURSDAY AFTERNOON. THIS FEATURE IS EXPECTED TO BRING SOME
SUBTROPICAL MOISTURE TO THE AREA AS PWATS INCREASE BETWEEN 1.00
TO 1.50 INCHES. CONTINUED TO INCREASE POP ACROSS SOUTHEAST
WYOMING WITH SOME HEAVY RAINFALL POSSIBLE. HIGH TEMPERATURES
WILL BE SLIGHTLY COOLER THURSDAY AFTERNOON DUE TO CLOUD COVER,
BUT STILL NEAR OR SLIGHTLY ABOVE AVERAGE FOR THIS TIME OF THE
YEAR.
LONG TERM /THURSDAY NIGHT THROUGH MONDAY/
ISSUED AT 455 AM MDT TUE JUL 1 2025
MODELS SHOW THE PACIFIC UPPER LEVEL TROUGH CONTINUING TO LIFT
NORTHEAST ACROSS THE AREA FRIDAY WITH ANOTHER ROUND OF SHOWERS
AND THUNDERSTORMS. THUNDERSTORM COVERAGE IS FORECAST TO LOWER
THIS WEEKEND DUE TO THE LACK OF FORCING AS WEAK ZONAL FLOW
DEVELOPS ACROSS THE INTERMOUNTAIN WEST AND ACROSS THE ROCKY
MOUNTAIN REGION.
TEMPERATURES REMAIN IN THE UPPER 70'S TO THE MID 80'S ACROSS THE
FORECAST AREA. 700MB TEMPERATURES STAY AROUND 16 CELSIUS WHICH
TRANSLATE SURFACE TEMPERATURES INTO THE LOW TO MID 80'S FOR THE
LOWER ELEVATIONS AND UPPER 70'S TO LOW 80'S FOR OUR MORE MOUNTAINOUS
REGIONS.
AS WE HEAD INTO NEXT WEEK, MODELS SHOW ANOTHER SLOW WARMING
TREND AS A 595 TO 600DM UPPER LEVEL HIGH DEVELOPS NEAR THE FOUR
CORNERS REGION. THE POSITION OF THIS HIGH IS A BIT FAR SOUTH, SO
ANY SHORTWAVE ACTIVITY DIGGING SOUTH OF OF CANADA WILL BE ENOUGH
TO TRIGGER SHOWERS AND THUNDERSTORMS EACH AFTERNOON. KEPT
THUNDERSTORMS IN THE FORECAST MONDAY AND TUESDAY AS ALL MODELS
DO NOT SHOW THIS UPPER LEVEL HIGH DRIFTING NORTHWARD UNTIL THE
MIDDLE OF NEXT WEEK.
AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/
ISSUED AT 1145 PM MDT MON JUN 30 2025
UPPER LEVEL RIDGE AXIS WILL REMAIN OVER THE REGION THIS MORNING
THROUGH TUESDAY. WIDELY SCATTERED THUNDERSTORMS ARE POSSIBLE ACROSS
MOST TERMINALS AFTER 19Z AS A WEAK DISTURBANCE ALOFT SLOWLY DRIFTS
SOUTHEAST ACROSS THE HIGH PLAINS.
HAZARDS/WEATHER TRENDS: VFR CONDITIONS WILL PREVAIL OVER THE NEXT 24
HOURS WITH BRIEF MVFR VIS POSSIBLE IN THUNDERSTORM AND SHOWER
ACTIVITY THIS AFTERNOON. KEPT SOME LLWS OVER THE WESTERN NEBRASKA
TERMINALS FROM 08Z TO 12Z THIS MORNING. THESE WINDS MAY OCCASIONALLY
MIX DOWN TO THE SURFACE BUT WINDS BELOW 15KT SHOULD PREVAIL.
CYS WATCHES/WARNINGS/ADVISORIES
WY...NONE.
NE...NONE.
SHORT TERM...TJT
LONG TERM...TJT/MM
AVIATION...TJT
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