062
FXUS65 KCYS 030009
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
505 PM MST SUN FEB 2 2025
KEY MESSAGES
- HIGH WINDS CONTINUE THROUGH MONDAY MORNING FOR OUR WESTERN
ZONES THROUGH THE I-25 CORRIDOR AND JUST EAST WITH HIGH WIND
WARNINGS ONGOING.
- SPLIT TEMPERATURES FROM A SAGGING FRONTAL BOUNDARY EXPECTED TO
START THE WEEK WITH CHILLY, SUB-FREEZING HIGHS FOR
NORTHEASTERN PORTIONS OF THE CWA, WHILE THE REST OF THE LOWER
ELEVATIONS SEE SEASONABLY WARM TEMPERATURES WITH MILD
AFTERNOON HIGHS.
- WIDESPREAD ELEVATED TO STRONG WINDS CONTINUE INTO NEXT WEEK
WITH MILD TEMPERATURES.
SHORT TERM /THROUGH TUESDAY/
ISSUED AT 230 PM MST SUN FEB 2 2025
ANOTHER HIGH WIND EVENT IS UNDERWAY ACROSS THE CWA AND VERIFYING
QUITE NICELY FOR THE MOST PART, WITH A FEW PEAK GUSTS FROM THIS
MORNING AND EARLY AFTERNOON IN THE 60-70 MPH RANGE. MODEL
GUIDANCE CONTINUES TO ADVERTISE A STRONG JET AT 700 MB WITH
SUBSIDENT FLOW BRINGING THESE STRONG WINDS DOWN, AND IN-HOUSE
GUIDANCE REMAINS ON TRACK WITH A 50-75% PROBABILITY OF GUSTS 60+
MPH FOR OUR WIND PRONE AREAS THROUGH AROUND 12-15Z BEFORE
PROBABILITIES TAPER OFF AS THE JET THEN WEAKENS AND LIFTS NORTH
AS WE MOVE INTO A MORE RIDGE PATTERN.
AT THE SURFACE, A WEAK FRONTAL BOUNDARY IS EXPECTED TO SAG AND
SHIFT WITH THE FLOW, ALLOWING FOR A WIDE SWATH OF TEMPERATURES
ACROSS THE CWA AS WE MOVE INTO MONDAY. PORTIONS OF THE CHEYENNE
RIDGE UP INTO THE LOWER HIGH PLAINS AND WESTWARD WILL SEE
NOTABLE WARMTH FOR THE LOWER ELEVATIONS AS TEMPERATURES REMAIN
SIGNIFICANTLY ABOVE NORMAL, IN THE 40'S TO SOME LOW 60'S.
MEANWHILE, THE BULK OF THE NORTH PLAINS INTO THE THE NORTHERN
NEBRASKA PANHANDLE WILL SEE QUITE THE CHILL AS TEMPERATURES
PLUMMET BACK INTO THE 20'S TO 30'S FOR HIGHS. THEN ON TUESDAY,
TEMPERATURES FOR THOSE COOLER LOCATIONS SHOULD SEE A BUMP BY
ABOUT 8 TO 10 DEGREES AS A MORE MILD AIRMASS OVERSPREADS.
OTHERWISE, CONDITIONS SHOULD LARGELY BE NON-IMPACTFUL ONCE THE
HIGH WIND WARNINGS HAVE SUBSIDED, THOUGH CONTINUED BREEZY WINDS
FOR OUR WIND PRONE SPOTS ARE EXPECTED, BUT NOT NEARLY AT THE
LEVEL WE'RE SEEING TODAY. A SURGE OF MOISTURE WILL BE MAKING ITS
WAY INTO THE CWA AS WELL ON TUESDAY, BUT ONLY A FEW LIGHT
MOUNTAIN SNOW SHOWERS FOR THE SIERRA MADRES AND SNOWY RANGES ARE
EXPECTED DURING THE MORNING AND EARLY AFTERNOON, AS THE BULK OF
THE STRONGER QPF WON'T BE ARRIVING TO OUR REGION UNTIL THE LONG
TERM PERIOD.
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/
ISSUED AT 230 PM MST SUN FEB 2 2025
NOT MUCH CHANGE IN THE LONG-TERM FORECAST PERIOD WITH TODAY'S
ENSEMBLE GUIDANCE RUNS. A BROAD AREA OF FAST ZONAL WESTERLY FLOW OUT
OF THE PACIFIC WILL REMAIN IN PLACE OVER MUCH OF THE WESTERN CONUS
FROM TUESDAY NIGHT THROUGH THE END OF THE WEEK. THIS FEATURE,
GENERALLY GUIDED BY AN UPPER-LEVEL LOW OVER THE CANADIAN PACIFIC
COAST, WILL PUMP AN ANOMALOUSLY MILD AIRMASS EASTWARD OVER THE
CENTRAL ROCKIES AND HIGH PLAINS. EXPECT ABOVE-AVERAGE CONDITIONS TO
CONTINUE ON WEDNESDAY AS THE GENERAL SUBTROPICAL MOISTURE STREAM
REMAINS WELL TO THE NORTH OF THE CWA. BY WEDNESDAY NIGHT INTO
THURSDAY, A WEAK SHORTWAVE WILL EJECT EASTWARD ALONG THE NORTHERN
EDGE OF THE JET STREAM, BRIEFLY PUSHING THE MOISTURE STREAM
SOUTHWARD AND ALLOWING FOR A PERIOD OF MOUNTAIN SNOW IN THE SIERRA
MADRE AND SNOWY RANGES AS WELL AS IN THE NORTHERN LARAMIE RANGE. A
SURFACE COLD FRONT WILL ATTEMPT TO SWING SOUTHWARD ALONG THE HIGH
PLAINS/FRONT RANGE EARLY ON THURSDAY MORNING. HOWEVER, GUIDANCE HAS
BACKED OFF ON THE SOUTHWARD PROGRESSION OF THIS BOUNDARY AND IT MAY
BE THAT THIS FRONT ULTIMATELY STALLS AND DIFFUSES AROUND THE
CHEYENNE RIDGE/NE PANHANDLE. WHILE TEMPERATURES WILL COOL OFF A BIT
ON THURSDAY, A MORE POTENT FRONTAL SYSTEM WITH EASTERLY UPSLOPE
PRECIPITATION IS NOW MUCH LESS LIKELY ON THURSDAY. HEIGHT RISES
ASSOCIATED WITH A BRIEF RETREAT OF THE JET STREAM TO THE NORTH WILL
RESULT IN ANOTHER WARM DAY ON FRIDAY. BY FRIDAY NIGHT, THE BROAD
WEST-COAST TROUGH WILL FINALLY EJECT EASTWARD THROUGH THE GREAT
BASIN AND ROCKY MOUNTAINS. THIS WILL REDIRECT THE PACIFIC MOISTURE
PLUME SOUTHWARD INTO THE SOUTHEAST WYOMING/NORTHERN COLORADO
MOUNTAINS, SETTING THE STAGE FOR HEAVY AND MOISTURE-LADEN MOUNTAIN
SNOWS FROM FRIDAY NIGHT THROUGH SATURDAY. ANOTHER SURFACE COLD FRONT
WILL MAKE ITS WAY SOUTH ALONG THE HIGH PLAINS WITH THIS TROUGH
EJECTION. HOWEVER, FORECAST SOUNDINGS DO NOT SHOW MUCH IN THE WAY OF
SATURATION IN THE LOWER LEVELS EAST OF THE LARAMIE RANGE.
ADDITIONALLY, SURFACE WIND VECTORS DO NOT SUPPORT APPRECIABLE
UPSLOPE AND THUS QPF IS QUITE LIMITED EAST OF THE MOUNTAINS. THIS IS
ESPECIALLY TRUE IN NAEFS PRODUCTS, WITH THE ECMWF ENSEMBLE A BIT
MORE OPTIMISTIC FOR PRECIPITATION IN THE HIGH PLAINS DUE TO A
QUICKER FRONTAL PASSAGE. FORECAST CONFIDENCE STILL REMAINS QUITE LOW
WITH REGARD TO PRECIPITATION CHANCES AND TEMPERATURES FROM
FRIDAY/SATURDAY ONWARD, GIVEN BROAD SPREAD IN BOTH FRONTAL TIMING
AND MOISTURE POSITIONING AMONG ENSEMBLE MEMBERS. TEMPERATURES WILL
LIKELY REMAIN ABOVE AVERAGE UNTIL SATURDAY THROUGHOUT THE LONG-TERM
PERIOD.
AVIATION /00Z TAFS THROUGH 00Z TUESDAY/
ISSUED AT 505 PM MST SUN FEB 2 2025
VERY WINDY CONDITIONS WILL CONTINUE TONIGHT AND EARLY MONDAY FOR ALL
SOUTHEAST WYOMING TERMINALS AS ZONAL FLOW ALOFT REMAINS OVER THE
AREA. A STRONG BACKDOOR COLD FRONT IS EXPECTED TO BECOME NEARLY
STATIONARY TONIGHT ACROSS THE NORTHERN NEBRASKA PANHANDLE, MAINLY
EFFECTED KCDR AND KAIA WITH PERIODS OF LOW CIGS AND FOG.
HAZARDS/WEATHER TRENDS: FOR MOST TERMINALS, VFR CONDITIONS WILL
CONTINUE WITH STRONG GUSTY WINDS AT TIMES FOR KRWL, KLAR, AND KCYS.
MOUNTAIN WAVE ACTIVITY ARE EXPECTED AT THESE TERMINALS...WITH
PERIODS OF LIGHTER WINDS AND LLWS...WHICH MAY BE FOLLOWED BY SUDDEN
GUSTY WINDS UP TO 50 KNOTS.
LOW CONFIDENCE TAF FOR THE NORTHERN NEBRASKA PANHANDLE TERMINALS,
INCLUDING KAIA AND KCDR. DENSE FOG HAS MOVED INTO KCDR THIS EVENING.
IT IS UNCLEAR HOW LONG THIS FOG WILL LAST OR IF IT WILL LIFT
SHORTLY. KEPT THE FOG OUT OF KAIA FOR NOW, BUT CAN'T RULE IFR
CONDITIONS IN LOW CIGS. CONFIDENCE IS AROUND 20% TO 30% AT THIS TIME
AND WILL WAIT UNTIL HIGH RESOLUTION GUIDANCE IS IN BETTER AGREEMENT.
CYS WATCHES/WARNINGS/ADVISORIES
WY...HIGH WIND WARNING UNTIL 8 AM MST MONDAY FOR WYZ101-106>108-
115>118.
HIGH WIND WARNING UNTIL 11 AM MST MONDAY FOR WYZ104-109-110-
113.
NE...NONE.
SHORT TERM...CG
LONG TERM...MAC
AVIATION...TJT
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