828
FXUS65 KCYS 040525
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1025 PM MST MON FEB 3 2025
KEY MESSAGES
- SPLIT TEMPERATURES FROM A SAGGING FRONTAL BOUNDARY EXPECTED TO
START THE WEEK WITH CHILLY, SUB-FREEZING HIGHS FOR EASTERN
PORTIONS OF THE CWA, WHILE AREAS TO THE WEST WILL SEE
SEASONABLY WARM TEMPERATURES WITH MILD AFTERNOON HIGHS.
- WIDESPREAD ELEVATED TO STRONG WINDS CONTINUE INTO NEXT WEEK
WITH MILD TEMPERATURES.
SHORT TERM /THROUGH TUESDAY NIGHT/
ISSUED AT 236 PM MST MON FEB 3 2025
LATEST UPPER AIR ANALYSIS DEPICTS ZONAL FLOW ACROSS THE CENTRAL TO
EASTERN CONUS, WITH WEAK UPPER LEVEL RIDGING BEGINNING TO DEVELOP
ACROSS THE INTERMOUNTAIN WEST. OBSERVATIONS THROUGHOUT THE DAY HAVE
BEEN FAIRLY TRICKY, WITH A COLD FRONT DROPPING SOUTH ACROSS THE CWA
BEFORE BEING CAUGHT UP ALONG THE ROCKIES AND STALLING ALONG THE I-80
CORRIDOR FROM CHEYENNE TO LARAMIE IN SOUTHEAST WYOMING. BEHIND THIS
BOUNDARY, TEMPERATURES HAVE DROPPED WELL BELOW FREEZING WITH SINGLE
DIGITS CURRENTLY REPORTED IN CHADRON NE. INTO THE WARM SECTOR,
TEMPERATURES ARE QUITE A BIT WARMER WITH A STRONG WESTERLY COMPONENT
TO THE WIND INCREASING TEMPERATURES INTO THE THE MID-50S FOR LARAMIE
AND RAWLINS. HOWEVER, WHAT REMAINS THE MOST IMPRESSIVE IS THE 20F
TEMPERATURE JUMP FROM 11AM MST TO 12PM MST FOR CHEYENNE AS THE FRONT
OSCILLATED ACROSS LARAMIE COUNTY SWITCHING WIND DIRECTION FROM THE
NORTH/NORTHWEST TO THE WEST, GREATLY AIDED BY THE STRONG DOWNSLOPING
WIND. TEMPERATURES WILL REMAIN THE MOST DIFFICULT TODAY DUE TO THIS
OSCILLATION WITH AREAS EAST OF THE I-25 CORRIDOR REMAINING WELL
BELOW FREEZING, AND A TIGHT TEMPERATURE GRADIENT FROM CARPENTER TO
HAWK SPRINGS KEEPING AREAS TO THE WEST IN THE 50S. OTHER THAN
TEMPERATURES, ADDITIONAL CONCERNS IN THE NEAR TERM FORECAST
WILL REMAIN CENTERED ON THE WIND THREAT ACROSS THE I-80 CORRIDOR
WITH ELEVATED WINDS OBSERVED OBSERVED THROUGHOUT THE LATE
MORNING AND INTO THE EARLY AFTERNOON HOURS, WITH A TIGHT SURFACE
GRADIENT AND STRONGER WESTERLY WINDS ASSOCIATED WITH THE FRONT
KICKING UP WINDS TO AROUND 50 TO 55 MPH FROM LARAMIE TO RAWLINS.
LOCAL IN-HOUSE MODEL GUIDANCE, COMBINED WITH CRAIG TO CASPER
GRADIENTS, BEGIN TO EASE THESE WINDS WITHIN THE NEXT HOURS. WILL
HOLD OFF ON ANY ADDITIONAL HIGH WIND HEADLINES TODAY, BUT WILL
NEED TO CLOSELY MONITOR OBSERVATIONS OVER THE NEXT SEVERAL HOURS
FOR ANY SHORT-FUSED HEADLINES THAT MIGHT BE NEEDED. INTO
TOMORROW, THE FRONT IS EXPECTED TO REMAIN STALLED ACROSS THE
LARAMIE RANGE WITH A NORTHWEST TO SOUTHEAST ORIENTATION INTO
NORTHEAST COLORADO. AS A RESULT, WILL SEE A VERY SIMILAR
TEMPERATURE GRADIENT AGAIN, WITH AREAS ALONG AND WEST OF THE
I-25 CORRIDOR HAVING DAYTIME HIGHS IN THE MID TO UPPER 50S AND A
20 DEGREE TEMPERATURE DROP INTO THE NEBRASKA PANHANDLE.
LONG TERM /WEDNESDAY THROUGH MONDAY/
ISSUED AT 236 PM MST MON FEB 3 2025
THE FORECAST AREA WILL SPEND MOST OF MID TO LATE WEEK IN QUASI-ZONAL
FLOW ALOFT AS A COUPLE WAVES BRUSH BY. A DEEPER TROUGH DIGS INTO THE
GREAT PLAINS OVER THE WEEKEND, TRANSITIONING THE PATTERN TO MORE
NORTHWEST FLOW. AT THE SURFACE, A COUPLE COOL FRONTS CROSS THE
REGION, WITH THE FIRST BEING LATE WEDNESDAY AND THE NEXT COMING LATE
FRIDAY. OVERALL, TEMPERATURES WILL BOUNCE BETWEEN VERY MILD AND
SEASONABLE THROUGH FRIDAY, THEN BECOME MORE WINTRY OVER THE WEEKEND.
THE ACTIVE PATTERN ALSO KEEPS PRECIP CHANCES AROUND, ESPECIALLY OVER
THE MOUNTAINS. A GREATER POTENTIAL FOR HIGH WINDS ALSO ACCOMPANIES
EACH COLD FRONT PASSAGE.
WEDNESDAY... WELL ABOVE NORMAL TEMPS ARE STILL ON TRACK, PRIMARILY
FOR AREAS NEAR AND EAST OF THE LARAMIE RANGE. A LOW LEVEL THERMAL
RIDGE CUTS UP THE HIGH PLAINS AS SHOWN BY H85 TEMPS PUSHING 15C IN
THE NEB PANHANDLE. H7 TEMPS ALSO EXCEED 0C OVER EASTERN WYO. NAEFS
AND ECM CLIMO ENSEMBLES BOTH INDICATE HIGH CONFIDENCE OF AN
ANOMALOUS EVENT, WITH THE FORMER SHOWING 90%ILE H7 TEMPS AND THE
LATTER WITH AN EFI OF 0.8/1 FOR MAX TEMPS. STRONG WESTERLY DOWNSLOPE
FLOW WILL AID IN MIXING THE MILD TEMPS ALOFT TOWARD THE SURFACE.
MADE LITTLE CHANGE TO THE NBM MEAN FOR FORECAST MAX TEMPS AS THE
ENVELOPE IS FAIRLY SMALL. VALUES RANGE FROM THE 30S AND 40S WEST OF
I-25 TO 50S AND PERHAPS LOWER 60S TO THE EAST. A SIGNIFICANT
MOUNTAIN WAVE ACCOMPANIES THE SURFACE FRONT, AND MID TO UPPER LEVEL
MOISTURE STEADILY INCREASES. KEPT LIKELY POP WEST OF I-25 WHERE
THERE WILL BE SIGNIFICANT UPSLOPE FLOW IN AREAS. WITH MILD TEMPS IN
PLACE, MUCH OF THAT MOISTURE MAY COME AS RAIN OR RAIN/SNOW MIX. AS
FOR WINDS, GUIDANCE IS SUGGESTING A MARGINAL HIGH WIND EVENT.
SURFACE PRESSURE CHANGES MAY SURPASS 10MB IN 6 HRS, WHILE A PV
ANOMALY BRUSHES THE NORTHERN TIER OF THE STATE. CRAIG-CASPER HEIGHT
GRADIENTS MAX OUT AROUND 67M AT H85 AND 58M AT H7, WHEREAS 60+ AT
EACH LEVEL IS A DECENT THRESHOLD FOR WARNINGS. ADDITIONALLY,
INTERNAL GUIDANCE SUGGESTS 50-50 PROBS FOR THE USUAL SPOTS (BORDEAUX
AND ARLINGTON). HELD OFF ON A NEW HEADLINE (WATCH) FOR NOW AND WILL
MONITOR TRENDS IN LATER GUIDANCE.
THURSDAY AND BEYOND... A BRIEF COOLDOWN IS IN STORE FOR THURSDAY IN
THE WAKE OF THE COOL FRONT, BEFORE TEMPS JUMP AGAIN FRIDAY WITH
ANOTHER HIGH PLAINS THERMAL RIDGE. MAX TEMPS SHOULD BE ABLE TO TOP
50F FOR PARTS OF EASTERN WYO PLAINS AND WESTERN/SOUTHERN NEB
PANHANDLE. ENERGY REALLY INCREASES LATE WEEK WITH THE ARRIVAL OF A
140+ KT H3 JET, STRONG MID-LEVEL SHORTWAVE, AND A SURFACE COOL
FRONT. A WAVE OF MID/UPPER LEVEL MOISTURE CORRESPONDS TO THE GREATER
LIFT, AND WITH NEARLY CONSISTENT WESTERLY FLOW, THE SOME HEFTY
MOISTURE TOTALS WILL BE POSSIBLE IN THE MOUNTAINS. ECM EFI IS
HINTING AT ANOMALOUS SNOWFALL ON FRIDAY WHERE UPSLOPE FLOW WILL BE
REALIZED. WINTER HEADLINES MAY BE NEEDED FOR THE SNOWY AND SIERRA
MADRE RANGES, ALONG WITH PARTS OF THE LARAMIE RANGE. MAINTAINED
LOWER POP OVER THE PLAINS, AND CONFIDENCE IS LOWER REGRADING
ACCUMULATIONS THERE AS WELL. WHILE ANY PRECIP MAY BEGIN AS RAIN FOR
THE PLAINS ON FRIDAY, ANY LEFTOVER MOISTURE BEYOND FRIDAY EVENING
WILL BE SNOW AS H7 TEMPS DROP BELOW -10C. GUIDANCE ALSO SUGGESTS
SOME GUSTIER WINDS IN THE PRONE AREAS LATE FRIDAY INTO SATURDAY, BUT
A HIGH WIND EVENT IS FAR FROM SLAM-DUNK.
AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/
ISSUED AT 1019 PM MST MON FEB 3 2025
IFR CEILINGS WILL PERSIST AT CYS OVER THE NEXT 2-4 HOURS AS A
MOIST UPSLOPE AIRMASS CONTINUES WITH SOUTHEASTERLY FLOW. EXPECT
HIGH CONFIDENCE IN IFR CEILINGS UNTIL AROUND 9Z WITH DECREASING
CONFIDENCE AFTERWARD AS SOME GUIDANCE INDICATES SCATTERING OF
THE LOW LEVEL DECK AFTER 10Z. ELSEWHERE IN THE NE PANHANDLE, LOW
CEILINGS WILL REMAIN SCATTERED ENOUGH TO AVOID IFR CRITERIA
TONIGHT. WIND SHEAR WILL BE PRESENT ALOFT WITH VERY FAST
SOUTHWEST FLOW ALOFT OVER TOP OF LIGHTER SURFACE WINDS. DRY
WEATHER IS EXPECTED AT ALL TERMINALS DESPITE CLOUD COVER.
CYS WATCHES/WARNINGS/ADVISORIES
WY...NONE.
NE...NONE.
SHORT TERM...MRD
LONG TERM...DS
AVIATION...MAC
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