575
FXUS65 KCYS 011737
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1037 AM MST SAT FEB 1 2025
KEY MESSAGES
- HIGH WIND WARNINGS AND IN EFFECT TODAY FOR THE SOUTHEAST
WYOMING WIND PRONES AND ADJACENT AREAS. ANOTHER ROUND OF HIGH
WINDS ARE EXPECTED DURING THE DAY SUNDAY.
- WINTER STORM WARNINGS ISSUED FOR THE SIERRA MADRE AND SNOWY
RANGES SATURDAY MORNING THROUGH SUNDAY FOR HEAVY ACCUMULATING
SNOW AND WINDY CONDITIONS. WINTER WEATHER ADVISORIES ARE ALSO
IN PLACE FOR RAWLINS AND THE ARLINGTON AREA.
- WIDESPREAD ELEVATED TO STRONG WINDS CONTINUE INTO NEXT WEEK.
SHORT TERM /THROUGH SUNDAY NIGHT/
ISSUED AT 445 AM MST SAT FEB 1 2025
WINDS REMAIN ELEVATED EARLY THIS MORNING, WITH FREQUENT GUSTS OVER
60 MPH. MOST OF THE ZONES UNDER A HIGH WIND WARNING HAVE VERIFIED,
WITH SOME OF THE STRONGEST WINDS SO FAR OCCURRING BY MUDDY GAP
AND IN CONVERSE COUNTY. STILL WAITING ON THE FOOTHILLS ZONE AND
CENTRAL LARAMIE COUNTY TO VERIFY, HOWEVER, WINDS ARE STARTING TO
PICK UP IN THESE ZONES WITH THE GFS STILL SUPPORTING HIGH WINDS
IN THESE AREAS. HIGH WIND WARNINGS STILL LOOK ON TRACK FOR
TODAY, THEREFORE NO CHANGES WERE MADE TO THE HEADLINES. WINDS
ALOFT WILL GRADUALLY DECREASE THROUGHOUT THE DAY AS THE 250 MB
JET LIFTS NORTHWARD. THIS WILL EVER SO SLIGHTLY ALTER THE WIND
DIRECTION TO A MORE WEST-NORTHWEST POSITION WHICH IS NOT AS
FAVORABLE FOR HIGH WINDS. MSLP GRADIENTS WILL ALSO RELAX,
CAUSING WINDS ALOFT TO WEAKEN. AS A RESULT, SOME HIGH WIND
WARNINGS MAY BE ABLE TO BE CANCELLED EARLY THIS AFTERNOON AS THE
STRONGEST WINDS ARE EXPECTED THIS MORNING.
A POTENTIAL BRIEF LULL IN HIGH WINDS WILL BE POSSIBLE SATURDAY
NIGHT. WHILE AREAS OUTSIDE OF THE WIND PRONES CAN EXPECT A BREAK,
CANNOT RULE OUT A FEW ROGUE GUSTS OVER 58 MPH AROUND ARLINGTON,
BORDEAUX AND THE MUDDY GAP AREA. WINDS RETURN IN FULL FORCE ONCE
AGAIN ON SUNDAY AS THE 250 MB JET FLATTENS OUT OVER WYOMING AND
WINDS BECOME MORE WESTERLY. MSLP GRADIENTS WILL ONCE AGAIN TIGHTEN,
HELPING TO STRENGTHEN WINDS ALOFT. WITH 700 MB WINDS MAXING OUT AT
60 TO 70 KTS WITH GREAT SUBSIDENCE AND A STRONG MOUNTAIN WAVE
SIGNATURE, HIGH WIND HEADLINES WILL LIKELY NEED TO BE HOISTED ONCE
AGAIN. OPTED TO NOT ISSUE ANYTHING AT THIS TIME, SINCE ACTIVE HIGH
WIND WARNINGS ARE CURRENTLY IN EFFECT. HOWEVER, HEADLINES WILL
LIKELY BE NEEDED FOR THE WIND PRONES AND WIND PRONE ADJACENT AREAS
SUNDAY AND POTENTIALLY INTO THE DAY MONDAY.
A HEAVY MOUNTAIN SNOW EVENT STILL LOOKS ON TRACK FOR THE SIERRA
MADRE AND SNOWY RANGES TODAY THROUGH SUNDAY. MID-LEVEL MOISTURE WILL
BE FUNNELED INTO THE CWA FROM THE PACIFIC, WHICH WILL INCREASE PWS
ACROSS THE SOUTHERN HALF OF THE CWA SATURDAY MORNING THROUGH SUNDAY.
PWS WILL RISE ABOVE THE 90TH PERCENTILE FOR NAEFS CLIMATOLOGY ON
SATURDAY, AND MAX OUT SUNDAY AFTERNOON IN THE 99.5TH PERCENTILE OVER
THE MOUNTAIN ZONES. IVT VALUES OVER THIS TIME ARE EQUALLY IF NOT
MORE IMPRESSIVE, WITH A PROLONGED PERIOD OF VALUES AT CLIMATOLOGICAL
MAX. ALL THIS TO SAY THAT AMPLE MOISTURE IS AVAILABLE TO THE
MOUNTAINS FOR A HEAVY SNOW EVENT. GIVEN THE FAIRLY "MILD"
TEMPERATURES AND PACIFIC MOISTURE, SNOW RATIOS WILL PROBABLY BE
LOWER THAN THEY TYPICALLY ARE, WITH A HEAVY WET SNOW POSSIBLE. THIS
COULD AFFECT TOTALS, HOWEVER, WINTER STORM WARNINGS STILL LOOK ON
TRACK WITH OVER A FOOT OF SNOW EXPECTED FOR THE MOUNTAINS. SNOW WILL
ALSO CREEP INTO THE LOWER ELEVATIONS OF CARBON COUNTY WHERE A WINTER
WEATHER ADVISORY IS IN PLACE FOR RAWLINS AND ARLINGTON. WEBCAMS
ALREADY SHOW SOME LIGHT SNOW FALLING AROUND THE ARLINGTON AREA EARLY
THIS MORNING. THESE LOWER ELEVATION AREAS CAN EXPECT TO SEE ANYWHERE
FROM 1 TO 5 INCHES OF SNOW, WITH THE HIGHEST AMOUNTS EXPECTED IN THE
NORTH SNOWY RANGE FOOTHILLS. PRECIPITATION WILL LIKELY STAY CONFINED
TO AREAS WEST OF THE LARAMIE RANGE TODAY AND TONIGHT DUE TO THE
DRYING DOWNSLOPING WINDS EXPECTED TO THE EAST.
LONG TERM /MONDAY THROUGH FRIDAY/
ISSUED AT 445 AM MST SAT FEB 1 2025
THE UPPER LEVEL IS ZONAL WITH A STREAM OF MOISTURE
BEING FUNNELED IN FROM THE PACIFIC. THE AIRMASS OVER THE ROCKY
MOUNTAINS WILL BE RATHER TROPICAL IN A SENSE GIVEN THE AMOUNT OF
MOISTURE THE ATMOSPHERIC RIVER ADVECTED INTO THE REGION THE PREVIOUS
DAYS. HOWEVER, RECENT MODEL TRENDS ARE PUSHING THE JETSTREAM FURTHER
NORTH AND PUSHING THAT MOISTURE STREAM FURTHER NORTH AS WELL.
LOOKING AT THE GLOBAL MODELS OMEGA FIELDS, THERE'S A SIGNAL FOR
CONTINUAL MOUNTAIN WAVE ACTIVITY THROUGHOUT MOST OF NEXT WEEK. THIS
COULD LEAD TO MORE POSSIBLE HIGH WIND HEADLINES ESPECIALLY FOR THE
WIND PRONE AREAS. MONDAY, THE HIGH WINDS LOOK TO CONTINUE TO
DOMINATE THE WIND PRONE AREAS AS A 60 TO 70KT 700MB JET LOOKS TO
SUSTAIN OUR HIGH WINDS UNTIL AT LEAST THE AFTERNOON. AROUND 18Z OUR
WINDS SHIFT TO THE SOUTHWEST TO CREATE SOME PRECIPITATION CHANCES
FOR THE SIERRA MADRE AND SNOWY RANGES. GIVEN THE NAEFS STILL SHOWS
SOME MOISTURE BEING ADVECTED INTO THE REGION AS THE ATMOSPHERIC
RIVER PUSHES INTO NORTHERN WYOMING. THERE IS STILL A SLIGHT CHANCE
FOR THE MOUNTAINS TO SEE SOME SNOW DEVELOPMENT. HOWEVER, IT IS STILL
UNCERTAIN HOW MUCH IF ANY WILL FALL GIVEN OUR MOISTURE STREAM IS
EXPECTED TO BE MUCH FARTHER NORTH. TUESDAY AND WEDNESDAY WILL BE
RATHER WARM AS A SMALL BUT BROAD RIDGE DEVELOPS OVER THE WESTERN
UNITED STATES. EARLY MORNING THURSDAY THERE LOOK TO A TROUGH MOVING
THROUGH THE ROCKY MOUNTAINS AS THE LOW RESPONSIBLE START TO DIP
SOUTH INTO MONTANA AND INTO THE NORTHERN PLAINS. THERE IS A BIT OF
UNCERTAINTY WITH THE EFFECTS OF THIS TROUGH AS THERE IS DISAGREEMENT
AMONG THE MODELS AS TO HOW FAR THE ARCTIC AIRMASS THAT FOLLOW THIS
TROUGH DESCENDS SOUTHWARD. THE GFS KEEPS THE ARCTIC AIRMASS OUT OF
SOUTHEAST WYOMING AS 700MB TEMPS STAY BETWEEN 0 AND -2 WHILE THE
EURO AND CANADIAN BRINGS THAT ARCTIC AIRMASS OVER US TO DROP 700MB
TEMPS INTO THE NEGATIVE TEENS. THIS DISAGREEMENT ALSO SHOWS UP INTO
THE NBM SURFACE TEMPS AS THE DAYTIME HIGHS ARE 30 DEGREES FOR THE
25TH PERCENTILE AND 50 DEGREE FOR THE 75TH. HOWEVER, AT NIGHT IS
WHERE THE COLDER TEMPERATURES MAY REALLY BE FELT AS SOME OF THE
ENSEMBLE MEMBERS PROJECT THE OVERNIGHT LOWS TO BE INTO THE TEENS.
FRIDAY AND INTO THE WEEKEND THERE MAY BE A PATTERN CHANGE AS THE
UPPER LEVELS BECOME AMPLIFIED WITH ITS RIDGES AND TROUGHS AND
SUGGEST ANOTHER ACTIVE PATTERN PERIOD FOR SOUTHEASTERN WYOMING AND
NEBRASKA PANHANDLE.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 1026 AM MST SAT FEB 1 2025
VFR CONDITIONS WILL DOMINATE THIS AFTERNOON OVER THE NE
PANHANDLE TERMINALS AS WELL AS AT CYS. FARTHER WEST, PERIODS OF
LIGHT TO MODERATE SNOW WILL AFFECT RWL AND OCCASIONALLY AT LAR.
RWL WILL BE MOST IMPACTED WITH CIG AND VIS LOWERING TO MVFR AND
POSSIBLY BRIEF IFR CONDITIONS LATER THIS AFTERNOON. LAR WILL SEE
BRIEF PERIODS OF LIGHT SNOW WITH CIG AND VIS LOWERING INTO THE
MVFR RANGE, WITH SNOW CHANCES DECREASING AFTER 6Z TONIGHT.
CYS WATCHES/WARNINGS/ADVISORIES
WY...HIGH WIND WARNING UNTIL 5 PM MST THIS AFTERNOON FOR WYZ101-
106>108-116>118.
HIGH WIND WARNING UNTIL 5 AM MST SUNDAY FOR WYZ104-110.
WINTER WEATHER ADVISORY UNTIL 5 PM MST SUNDAY FOR WYZ109-110.
WINTER STORM WARNING UNTIL 5 PM MST SUNDAY FOR WYZ112-114.
HIGH WIND WATCH UNTIL 5 PM MST THIS AFTERNOON FOR WYZ119.
NE...NONE.
SHORT TERM...SF
LONG TERM...MM
AVIATION...MAC
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