173
FXUS65 KCYS 051738
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1138 AM MDT TUE AUG 5 2025
KEY MESSAGES
- RED FLAG WARNINGS REMAIN IN EFFECT THROUGH FRIDAY DUE TO LOW AFTERNOON
RELATIVE HUMIDITY AND POOR OVERNIGHT HUMIDITY RECOVERIES.
- HOT AND DRY CONDITIONS REMAIN ON TRACK, WITH THURSDAY BEING
THE WARMEST DAY OF THE WEEK.
SHORT TERM /THROUGH WEDNESDAY/
ISSUED AT 146 AM MDT TUE AUG 5 2025
A FEW ISOLATED SHOWERS AND STORMS ONGOING TONIGHT ACROSS WESTERN
NEBRASKA. THE STORMS HAVE REMAINED MOSTLY WEAK, EXCEPT FOR A FEW
STRONGER STORMS THAT OCCURRED ACROSS NORTHERN NIOBRARA COUNTY
EARLIER THIS EVENING. STORMS WILL NOT STICK AROUND LONG, AS THEY ARE
MOVING OFF TO THE EAST AT A REASONABLE SPEED. MOST APPEAR TO BE
ELEVATED IN NATURE, SO WHETHER OR NOT ANY PRECIPITATION REACHES THE
GROUND IS YET TO BE SEEN. HOWEVER, WITH THE LOW-LEVEL JET IN PLACE
ACROSS THE PANHANDLE, SOME OF THESE STORMS MAY STRENGTHEN OVER THE
NEXT FEW HOURS. BREEZY CONDITIONS ACROSS THE PANHANDLE WILL
ACCOMPANY THIS LOW-LEVEL JET AND THUNDERSTORM ACTIVITY, WITH SOME
SITES GUSTING TO AROUND 30 MPH. TEMPERATURES ARE VERY WARM IN THE
PANHANDLE, IN THE UPPER-60S TO MID-70S IN CHADRON WHERE STRONG
DOWNSLOPING IS OCCURRING. SOUTHEAST WYOMING IS COOLER, THOUGH STILL
MILD, WITH TEMPERATURES IN THE UPPER-50S TO LOW-70S NEAR RAWLINS.
HOT AND DRY CONDITIONS CONTINUE TODAY AS THE UPPER-LEVEL RIDGE
BEGINS TO FLATTEN OUT THROUGH THE MORNING AND EARLY AFTERNOON HOURS
AND GETS PUSHED TO THE EAST. ZONAL FLOW REMAINS IN THE UPPER-LEVELS
FROM THE AFTERNOON THROUGH THE EVENING AND OVERNIGHT HOURS WITH A
FEW LOBES OF 500MB VORTICITY ADVECTING ACROSS THE REGION.
SIMILARLY, A SUBTLE SHORTWAVE IS VISIBLE ACROSS THE ROCKY MOUNTAINS
AT THE 250MB LEVEL, INDICATING A SLIGHT POTENTIAL FOR PERHAPS SOME
WEAK MOUNTAIN WAVE ACTIVITY THIS AFTERNOON AS WESTERLY FLOW
CONTINUES TO DOMINATE. FLOW WILL SLOWLY DECREASE AT 700MB DURING THE
MORNING HOURS AS THE LOW-LEVEL JET WEAKENS AND THE ATMOSPHERE
REMAINS COUPLED. WESTERLY FLOW ARRIVES IN THE 700MB LAYER ACTING TO
INCREASE WINDS ALONG THE LARAMIE RANGE AND CONTINUALLY DRY OUT THE
WESTERN ZONES TODAY. AFTERNOON RELATIVE HUMIDITY VALUES WILL PLUMMET
INTO THE SINGLE DIGITS AS WINDS INCREASE SIGNIFICANTLY FOR THE
AFTERNOON. RED FLAG WARNINGS CONTINUE THROUGHOUT THE DAY TODAY DUE
TO THESE EXTREMELY FAVORABLE CONDITIONS FOR RAPID FIRE STARTS AND
RAPID FIRE SPREAD. TEMPERATURES WARM INTO THE LOW- TO MID-90S ACROSS
THE EASTERN HALF OF THE CWA, WITH THE WESTERN HALF ONLY A LITTLE
BEHIND IN THE MID-80S. THERE IS A SLIGHT CHANCE FOR AFTERNOON
SHOWERS AND STORMS IN THE FURTHEST EAST REACHES OF THE CWA AS A
SUBTLE 700MB SHORTWAVE MOVES THROUGH. HOWEVER, WITH DRY CONDITIONS
SEVERE WEATHER WILL BE DIFFICULT TO GET. THE STORM PREDICTION CENTER
HAS HIGHLIGHTED THE EASTERN MOST REGIONS IN A MARGINAL RISK (LEVEL 1
OF 5) FOR THE ISOLATED CHANCE FOR SEVERE WEATHER THIS AFTERNOON.
HOT AND DRY CONDITIONS CONTINUE FOR WEDNESDAY WITH CRITICAL FIRE
WEATHER CONDITIONS REMAINING ACROSS THE REGION. THE RED FLAG
WARNINGS WILL REMAIN IN PLACE THROUGH FRIDAY, AS POOR CONDITIONS ARE
EXPECTED THROUGH THE REST OF THE WEEK. TEMPERATURES WILL BE WARM
ONCE MORE, WITH HIGHS IN THE LOW- TO MID-90S EAST OF THE LARAMIE
RANGE ONCE MORE AND UPPER-80S WEST OF THE LARAMIE RANGE.
PRECIPITATION LOOKS MINIMAL DUE TO VERY DRY FLOW ALOFT AND NEAR THE
SURFACE. HOWEVER, AN ISOLATED SEVERE STORM ONCE AGAIN CANNOT BE
RULED OUT AS A SUBTLE SHORTWAVE PUSHES THROUGH WEDNESDAY AFTERNOON.
THERE IS ONCE AGAIN A MARGINAL RISK (LEVEL 1 OF 5) FOR A VERY SMALL
PORTION OF THE REGION ON WEDNESDAY, MAINLY FROM CHADRON SOUTH TO
BRIDGEPORT AND POINTS EAST.
LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/
ISSUED AT 311 PM MDT MON AUG 4 2025
WEDNESDAY THROUGH MOST OF FRIDAY WILL BE CHARACTERIZED BY DRY,
HOT CONDITIONS. A STOUT HIGH PRESSURE SYSTEM ANCHORED OVER THE
DESERT SOUTHWEST WILL PROMOTE MID-/UPPER-LEVEL RIDGING AND
RESULTING SUBSIDENCE ACROSS THE COUNTY WARNING AREA (CWA).
BELOW-AVERAGE PWAT VALUES WILL PREVAIL DURING THIS TIME FRAME,
AND WHEN COMBINED WITH LARGE-SCALE SUBSIDENCE, THE POTENTIAL FOR
RAIN EACH DAY IS QUITE LOW (AROUND 15% OR LESS). THIS SYNOPTIC
SETUP WILL SUPPORT HIGH TEMPERATURES IN THE MID-90S TO LOWER
100S EAST OF THE LARAMIE RANGE, AND UPPER 80S TO LOWER 90S WEST.
RELATIVE HUMIDITY IS PROGGED TO DROP AS LOW AS 5% TO 15% ACROSS
PORTIONS OF THE CWA, ESPECIALLY ACROSS THE WESTERN FIRE ZONES.
ADDITIONALLY, WINDS MAY GUST TO 20-30 KTS ACROSS THE WESTERN
FIRE ZONES. AS SUCH, A RED FLAG WARNING REMAINS IN EFFECT ACROSS
ALL OF CARBON COUNTY, ALL ALBANY COUNTY, AND THE FAR WESTERN
PORTION OF LARAMIE COUNTY -- WITH THE ADDITION OF A PORTION OF
PLATTE COUNTY AND SOUTHERN CONVERSE COUNTY -- FROM TUESDAY
EVENING THROUGH FRIDAY EVENING.
AN MID-/UPPER-LEVEL SHORTWAVE TROUGH IS PROGGED TO PUSH THROUGH THE
PACIFIC NORTHWEST ON THURSDAY, THEN SHIFT EASTWARD ACROSS THE
NORTHERN GREAT PLAINS ON FRIDAY. FAVORABLE MID-/UPPER-LEVEL DYNAMICS
WITH THE PASSING TROUGH AND EMBEDDED DISTURBANCES -- COUPLED WITH
ATTENDANT MOISTURE -- WILL SUPPORT THE POTENTIAL FOR SHOWERS AND
THUNDERSTORMS ACROSS A PORTION OF THE CWA ON FRIDAY EVENING AND
OVERNIGHT. THE PEAK WINDOW FOR SHOWERS AND STORMS WITH THIS SYSTEM
MAY SHIFT 6-12 HOURS EARLIER OR LATER IN SUBSEQUENT FORECAST
PACKAGES, AS THE TIMING OF THE TROUGH PASSAGE VARIES BETWEEN THE
GLOBAL MODELS. SPECIFICALLY, THE GFS PUSHES THE TROUGH EAST OF THE
CWA FASTER THAN THE ECMWF, WITH THE LATTER DEVELOPING A MORE LARGE-
SCALE, PERSISTENT TROUGHING PATTERN OVER NORTHERN GREAT PLAINS.
WHILE THE GFS TRANSITIONS THE MID-/UPPER-LEVEL PATTERN TO
NORTHWESTERLY FLOW BY SATURDAY EVENING, IT BRINGS A DISTURBANCE
SOUTHEASTWARD OUT OF IDAHO ON SUNDAY AND SKIRTS IT BY THE CWA. BOTH
MODEL SOLUTIONS SUPPORT THE INCLUSION OF 20% TO 40% POPS ON SATURDAY
AND SUNDAY. ANY DISTURBANCES THAT TRAVERSE THE FLOW IN BOTH MODEL
OUTCOMES COULD AID IN ORGANIZATION/INTENSIFICATION OF CONVECTION,
BUT FOR NOW, THE PROBABILITY FOR WIDESPREAD SEVERE WEATHER IS
LOW.
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 1128 AM MDT TUE AUG 5 2025
MAINLY CLEAR SKIES ARE EXPECTED FOR THE FORECAST PERIOD ASIDE
FROM A FEW MID TO HIGH LEVEL CLOUDS FILTERING THROUGH. LOOK FOR
WESTERLY WINDS GUSTING TO AROUND 25 TO 30 KNOTS AT WY TERMINALS
THIS AFTERNOON, WHICH SHOULD EASE AROUND SUNDOWN.
THERE IS A SLIGHT CHANCE FOR LOW CIGS TO CREEP INTO THE NE
PANHANDLE WEDNESDAY MORNING, BUT THE PROBABILITY WAS TOO LOW TO
ADD TO THE TAF. LASTLY, AREAS OF SMOKE MAY DRIFT BACK INTO
KRWL/KLAR TONIGHT INTO WEDNESDAY MORNING, BUT VIS SHOULD REMAIN
OVER 6 MILES.
CYS WATCHES/WARNINGS/ADVISORIES
WY...RED FLAG WARNING UNTIL 6 PM MDT THIS EVENING FOR WYZ417-418.
RED FLAG WARNING UNTIL 6 PM MDT FRIDAY FOR WYZ419>421-427>429.
RED FLAG WARNING UNTIL 6 PM MDT FRIDAY FOR WYZ422>426.
NE...NONE.
SHORT TERM...AM
LONG TERM...WFOCYS
AVIATION...MN
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