434
FXUS65 KCYS 040349
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
949 PM MDT THU SEP 3 2026
KEY MESSAGES
- RED FLAG WARNING IN EFFECT FOR CONVERSE AND NIOBRARA
COUNTIES.
- WARMING AND DRYING TREND EXPECTED THROUGH THE END OF THE WEEK.
- PRECIPITATION CHANCES RETURN FOR THE BEGINNING OF NEXT WEEK.
SHORT TERM /THROUGH FRIDAY/
ISSUED AT 139 PM MDT THU SEP 3 2026
TONIGHT…DRY SOUTHWEST FLOW ALOFT PREVAILS WITH A QUIET NIGHT ON TAP AND
COOL OVERNIGHT MINIMAL TO PRODUCE GOOD SLEEPING CONDITIONS FOR
OPENING UP WINDOWS.
FRIDAY…THE MAIN WEATHER STORY WILL BE THE HEAT, WITH SOUTHWEST WINDS
ALOFT AND SURFACE LOW PRESSURE AND A THERMAL RIDGE AXIS OVER OUR
COUNTIES. WITH 700 MB TEMPERATURES NEAR 15 CELSIUS AND DOWNSLOPE
WINDS AND LITTLE IF ANY CLOUD COVER, MAXIMUM TEMPERATURES WILL
SOAR INTO THE MID 80S TO NEAR 90 DEGREES WEST OF I-25, WITH
BLISTERING HEAT FURTHER EAST OF I-25, WITH MAXIMUM TEMPERATURES
IN THE 90S, TO NEAR 100 DEGREES OVER THE NEBRASKA PANHANDLE.
RECORD HIGH TEMPERATURES, YEAR AND FORECAST HIGH TEMPERATURES FOR
SEPTEMBER 4…
RAWLINS 95/1998…83
LARAMIE 89/2022…84
CHEYENNE 94/2022…90
CHADRON 104/1978…101
ALLIANCE 101/1998…96
SCOTTSBLUFF 102/1998…99
SIDNEY…100/1998…99
FRIDAY NIGHT…A WEAK SHORTWAVE TROUGH ALOFT MOVES TO OUR SOUTHERN
COUNTIES BY DAWN, SPAWNING ISOLATED TO SCATTERED SHOWERS NEAR
A CHEYENNE TO TORRINGTON LINE, OTHERWISE DRY AND COOL.
LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/
ISSUED AT 145 PM MDT THU SEP 3 2026
WEAK SOUTHWESTERLY UPPER-LEVEL FLOW IS ANTICIPATED FOR SATURDAY
WITH LAX PRESSURE GRADIENTS BETWEEN TROUGHING OVER THE PACIFIC
NORTHWEST AND A RIDGE TO THE SOUTHEAST. THE MAJORITY OF AREA
WILL BE CAPPED THROUGH THE EARLY AFTERNOON. A WEAK UPPER LEVEL
SHORTWAVE WOULD PROMOTE A FEW MORNING SHOWERS AND GENERAL
CLOUDINESS BEFORE MOVING THROUGH IN THE EARLY AFTERNOON. A FEW
SHOWERS AND THUNDERSTORMS MAY BE POSSIBLE IN THE MOUNTAINS AND ALONG I-25
EARLY ON WITH A FEW STORMS DEVELOPING IN THE NE PANHANDLE AREAS
LATER ON. A STORM OR TWO MAY BE MARGINALLY SEVERE, THOUGH
LIMITED BULK SHEAR (25-35 KT) AND CAPE (1000-1500 J/KG) WILL
KEEP MOST ACTIVITY ON THE WEAKER SIDE. PWAT VALUES ARE SLIGHTLY
ELEVATED COMPARED TO CLIMATE AVERAGE DUE TO SOME MONSOONAL FLOW,
SO, STORMS MAY BE BETTER ABLE TO PRODUCE BENEFICIAL RAIN WERE
THEY OCCUR. OUTSIDE OF STORMS AFTERNOON HIGH TEMPERATURES ARE
EXPECTED TO MAKE IT INTO THE 90S EAST OF I-25 AND 80S TO THE
WEST. MINIMUM RELATIVE HUMIDITY VALUES IN THE LOW 20S AND UPPER
TEENS COULD LEND ITSELF TO ELEVATED FIRE POTENTIAL THOUGH OVERNIGHT
RECOVERIES ARE GOOD.
SUNDAY IS MUCH THE SAME AS MONDAY. THE TROUGH OVER THE PACIFIC NW
WILL INCH CLOSER TO OUR AREA ALLOWING FOR SLIGHTLY BETTER FORCING
AND ADVECTION OF MONSOON. THEREFORE, THE ODDS OF STORMS INCREASE.
THE FORECASTED POPS ARE ABOUT 40-60% AREA WIDE, WHILE MODEL ENSEMBLES
ARE A LITTLE MORE GIVING WITH 50-75% CHANCES OF RAIN. PW VALUES
OF AN INCH TO 1.5 OVER SOUTHEAST WYOMING AND THE NEBRASKA
PANHANDLE MAY LEAD TO A SNEAKY FLOODING POTENTIAL. CORFIDI
VECTORS ARE IN THE 15 TO 20 KNOT RANGE WITH BUNKERS RIGHT MOTION
BEING NEARLY STATIONARY. THESE PARAMETERS ARE SENSITIVE TO DETAILS
THAT ARE HARD TO RESOLVE AT THIS RANGE, BUT THE CHANCE OF SLOW
MOVING AND HEAVY RAINFALL PRODUCING STORMS IS POSSIBLE.
THE TREND OF SHOWERS AND THUNDERSTORMS CONTINUE THROUGH MONDAY
AND TUESDAY AS THE STUBBORN TROUGH TO THE NORTHWEST FINALLY
EJECTS INTO THE CENTRAL PLAINS. WHILE MOISTURE WILL REMAIN
HIGH, A LOBE OF DRIER AIR ASSOCIATED WITH A RIDGE TO THE EAST
MAY BE PULLED IN AHEAD OF THE TROUGH WHICH WOULD REDUCE RAIN
POTENTIAL. HOWEVER, SINCE THE TROUGH IS EJECTING IT IS POSSIBLE
THAT CYCLOGENESIS OCCURS NEARBY INCREASING THE SEVERE WEATHER
POTENTIAL. SOME MACHINE LEARNING MODELS ARE HIGHLIGHTING AN
UPTICK IN THAT POTENTIAL FOR THE NEBRASKA PANHANDLE AREA.
THE DETAILS OF HOW THIS UNFOLDS WILL BE IRONED OUT AS WE GET
CLOSER.
THE REMAINDER OF THE LONG TERM IS IN A DRYING TREND. THE
RIDGE NOSES IN. THIS WOULD NOT COMPLETELY SHUT DOWN STORM
ACTIVITY.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 945 PM MDT THU SEP 3 2026
HIGH CONFIDENCE THAT VFR CONDITIONS REMAIN IN PLACE THROUGH THE TAF
PERIOD AS SOUTHEASTERN WYOMING AND THE NEBRASKA PANHANDLE REMAIN
UNDER THE INFLUENCE OF AN UPPER-LEVEL RIDGE LOCATED TO OUR EAST,
GIVING US MOSTLY DRY CONDITIONS. EXPECT THE TYPICAL ONSET OF
SHALLOW, HIGH-BASED CUMULUS HUMILIS LATE MORNING THROUGH THE
AFTERNOON BEFORE DISSIPATING INTO THE EVENING. FOR THE WYOMING
TERMINALS, ANTICIPATING GUSTY SW WINDS OF 15-20 KNOTS AND PEAK GUSTS
OF 25-25 KNOTS BEGINNING MID-MORNING. FURTHER EAST, THE NEBRASKA
TERMINALS ARE EXPECTED TO SEE THE ONSET OF A 35-40 KNOT 850 MB LOW-
LEVEL JET WITHIN A COUPLE OF HOURS AFTER SUNSET, MAINLY AT KSNY,
KAIA, AND KCDR. CONFIDENCE ISN'T HIGH ENOUGH AT THIS TIME TO INCLUDE
LLWS IN THE TAFS, BUT THIS MAY HAVE TO BE INTRODUCED IN THE ROUTINE
12Z ISSUANCE.
CYS WATCHES/WARNINGS/ADVISORIES
WY...NONE.
NE...NONE.
SHORT TERM...SF
LONG TERM...RV
AVIATION...NB
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