050
FXUS65 KCYS 042058
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
258 PM MDT FRI JUL 4 2025
KEY MESSAGES
- AFTERNOON AND EVENING SHOWERS AND STORMS MAY IMPACT
INDEPENDENCE DAY FESTIVITIES. GUSTY WINDS AND LIGHTNING ARE
THE PRIMARY THREATS.
- SCATTERED PM THUNDERSTORMS WITH THE POTENTIAL TO BECOME STRONG
TO SEVERE WILL CONTINUE THROUGH THE WEEKEND AND INTO EARLY
NEXT WEEK.
- HOT TEMPERATURES ARE POSSIBLE BY MID TO LATE NEXT WEEK.
SHORT TERM /THROUGH SATURDAY NIGHT/
ISSUED AT 300 PM MDT FRI JUL 4 2025
STORMY WEATHER CONTINUES THIS INDEPENDENCE DAY ACROSS THE AREA.
CURRENT GOES WATER VAPOR IMAGERY SHOWS THE FIRST SHORTWAVE
RESPONSIBLE FOR THE NOCTURNAL AND MORNING SHOWER AND THUNDERSTORM
ACTIVITY EARLIER TODAY NOW MOVING EAST ACROSS CENTRAL NEBRASKA.
HOWEVER, ANOTHER UPPER LEVEL LOW CURRENTLY LOCATED OVER THE PACIFIC
NORTHWEST HAS A VORTICITY AXIS STRETCHING TO ITS SOUTHEAST, THE AXIS
OF WHICH IS NOW MOVING ACROSS WESTERN WYOMING. THIS IS TAPPING INTO
THE ABUNDANT MOISTURE LINGERING OVER THE AREA BEHIND YESTERDAY'S
SURGE OF MOISTURE OUT OF THE MONSOON REGION. DEWPOINTS WEST OF THE
LARAMIE RANGE REMAIN IN THE MID TO UPPER 40S, WHILE THE NEBRASKA
PANHANDLE IS PUSHING FROM THE MID 50S TO EVEN LOW 60S NEAR ALLIANCE.
DECENT SOUTHWEST FLOW IS APPARENT ALOFT, BUT WESTERLY SURFACE WINDS
ARE LIMITING THE SHEAR ON THE WYOMING SIDE. THE LATEST MESOANALYSIS
DEPICTS TWO AREAS OF SLIGHTLY GREATER INSTABILITY OVER ABOUT 1000
J/KG (SURFACE BASED): THE FIRST OVER CARBON INTO CONVERSE COUNTY
WHERE MID LEVEL LAPSE RATES ARE STEEP, AND THE SECOND OVER THE
NEBRASKA PANHANDLE WHERE LOW-LEVEL MOISTURE IS HIGHEST. ALL
TOGETHER, THIS IS PAINTING A FAIRLY MUDDY PICTURE FOR THIS AFTERNOON
AND EVENING'S CONVECTIVE ACTIVITY. WIDELY SCATTERED SHOWERS AND
THUNDERSTORMS HAVE ALREADY KICKED OFF AND WILL CONTINUE TO MOVE EAST
THROUGH THE EVENING WITH A FEW SUCCESSIVE ROUNDS POSSIBLE. WITH
FAIRLY SATURATED MID-LEVELS AND ONLY MODEST INSTABILITY, THE LARGE
HAIL THREAT TODAY ISN'T VERY HIGH, BUT STORMS WILL HAVE THE
POTENTIAL TO PRODUCE STRONG, GUSTY WINDS AND LIGHTNING, WHICH CAN
CERTAINLY BE A PROBLEM WITH MANY FOLKS OUTDOORS TODAY. ADDITIONALLY,
WE WILL NEED TO WATCH FOR THE DEVELOPMENT OF A MESO-HIGH. THIS IS
ALREADY APPARENT OVER NORTHWEST WYOMING ON THE LATEST
MESOANALYSIS. HI-RES MODEL GUIDANCE SHOWS THIS STRENGTHENING
AND MOVING EAST THROUGH THE EVENING. THIS MAY BE ABLE TO
ORGANIZE MORE LINEAR CONVECTION ALONG ITS LEADING EDGE, AND
PROVIDE A FOCUS FOR STRONGER WINDS WITH THUNDERSTORM ACTIVITY.
IF THIS MATERIALIZES, IT SHOULD CREEP INTO CARBON/CONVERSE
COUNTIES AROUND 5-6PM, REACHING THE US- 385 CORRIDOR BY 10-11PM.
CONFIDENCE IS FAIRLY LOW IN WHETHER A SYSTEM WILL ORGANIZE
ALONG THIS, BUT IT WILL WARRANT CLOSE WATCHING AS THAT WOULD BE
THE MAIN PIECE TO INTERFERE WITH EVENING FESTIVITIES.
MOST ACTIVITY SHOULD BE DONE BY MIDNIGHT, ASIDE FROM PERHAPS SOME
LINGERING SHOWERS WITH EMBEDDED THUNDER OVER CARBON COUNTY UNTIL
ABOUT 3AM OR SO. SKIES WILL TREND TOWARDS CLEAR SATURDAY MORNING AS
THE AXIS OF A MODEST UPPER LEVEL RIDGE PARKS OVERHEAD. THE PNW UPPER
LEVEL LOW WILL SHIFT EASTWARD TO THE NORTHERN ROCKIES BY TOMORROW,
AND ANOTHER BAND OF ELONGATED VORTICITY ON ITS SOUTHERN FLANK WILL
MOVE OFF OF THE MOUNTAINS DURING THE AFTERNOON HOURS. A SURFACE LOW
DEVELOPING OVER CENTRAL WYOMING WILL PULL DRIER AIR BACK INTO CARBON
COUNTY AND AMPLIFY THE DRYLINE ALONG THE LARAMIE RANGE WHICH SHOULD
PROVIDE A FOCUS FOR INITIATION OF AFTERNOON THUNDERSTORMS. FORECAST
SOUNDINGS SHOW STEEPER LAPSE RATES WITH MOISTURE REMAINING PLENTIFUL
ON SATURDAY, LEADING TO MORE INSTABILITY THAN WHAT WE SEE TODAY.
VERTICAL WIND SHEAR LOOKS MARGINAL BUT SUFFICIENT FOR A FEW STRONG
TO SEVERE THUNDERSTORMS TO DEVELOP.
LONG TERM /SUNDAY THROUGH THURSDAY/
ISSUED AT 300 PM MDT FRI JUL 4 2025
AN ACTIVE START TO THE LONG TERM IS EXPECTED AS A FEW SHORTWAVES
MOVE NORTH OF THE CWA. THE FIRST SHORTWAVE WILL GRAZE THE NORTHERN
PART OF THE FORECAST AREA ON SUNDAY. THIS SHORTWAVE WILL PROVIDE
NEEDED LIFT AND SOME OF THE MOISTURE TO PRODUCE THUNDERSTORMS ACROSS
THE AREA. MODEL SOUNDINGS SHOW A DECENT ENVIRONMENT FOR STRONG TO
SEVERE STORMS TO DEVELOP IN THE NEBRASKA PANHANDLE. SOUNDINGS SHOW
ABOUT 1800 J/KG OF MUCAPE WITH AROUND 35 KTS OF EFFECTIVE SHEAR.
DCAPE VALUES ARE ALSO HIGH WITH VALUES AROUND 1500 J/KG. THIS WILL
LEAD TO PRIMARILY A WIND AND HAIL THREAT IN STORMS THAT DEVELOP.
SEVERE CHANCES LOOK EVEN MORE FAVORABLE ON MONDAY. MODEL SOUNDINGS
IN THE NEBRASKA PANHANDLE SHOW UP TO 2500 J/KG OF MUCAPE WITH 35 TO
40 KTS OF SHEAR. THIS WILL SUPPORT A LARGE HAIL THREAT. DCAPE VALUES
ARE SIMILAR TO SUNDAY, SO DAMAGING WINDS WILL STILL BE A
POSSIBILITY. MLCAPE IS ALSO RATHER HIGH, AT ABOUT 1600 J/KG WITH SFC-
3KM SRH AT ABOUT 100 M^2/S^2. THIS COULD SUPPORT AN ISOLATED TORNADO
THREAT MONDAY AFTERNOON AS A SECONDARY SHORTWAVE PASSES NORTH OF THE
CWA.
THE 500 MB HIGH OVER THE FOUR CORNERS REGION WILL STRENGTHEN MID-
WEEK, ALSO STRENGTHENING THE RIDGE OVER THE ROCKIES. AS A RESULT, A
FAST WARM UP IS EXPECTED. HIGH TEMPERATURES WILL MAKE A RETURN TO
THE 90S FOR MOST LOCATIONS BY TUESDAY, WITH EVEN HOTTER TEMPERATURES
EXPECTED WEDNESDAY AS 700 MB TEMPERATURES CLIMB TO +20C!
PRECIPITATION CHANCES DURING THIS TIME WILL ALSO BE MINIMAL AS
DESERT AIR AND SUBSIDENCE UNDER THE RIDGE KEEP CONDITIONS DRY.
SLIGHTLY COOLER TEMPERATURES AND BETTER PRECIPITATION CHANCES RETURN
TO THE AREA ON THURSDAY AS A SHORTWAVE MOVES ACROSS THE AREA.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
ISSUED AT 1136 AM MDT FRI JUL 4 2025
MAIN AVIATION CONCERN WILL BE STRONG TO SEVERE THUNDERSTORMS IN
SOUTHEAST WYOMING AND THE NEBRASKA PANHANDLE THIS AFTERNOON AND
EVENING. STORMS COULD CONTAIN DAMAGING WINDS AND HAIL. HEAVY RAIN
COULD ALSO BE POSSIBLE LEADING TO REDUCED VISIBILITY AT TIMES. LOW
CIGS COULD ALSO BE POSSIBLE IN STORMS. STORMS WILL DISSIPATE LATER
TONIGHT, LEADING TO CALMER CONDITIONS.
CYS WATCHES/WARNINGS/ADVISORIES
WY...NONE.
NE...NONE.
SHORT TERM...MN
LONG TERM...SF
AVIATION...SF
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