404
FXUS65 KCYS 091736
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1136 AM MDT SUN MAR 9 2025
KEY MESSAGES
- MILD AND DRY CONDITIONS EXPECTED THIS WEEKEND WITH THE RETURN
OF WINDY CONDITIONS FOR SOUTHEAST WYOMING ON MONDAY. HIGH
WIND WATCHES HAVE BEEN ISSUED FOR PORTIONS OF THE WIND PRONE
AREAS AND CONVERSE COUNTY.
- THE NEXT PACIFIC STORM SYSTEM IS FORECAST TO MOVE ACROSS
WYOMING AT THE END OF NEXT WEEK.
SHORT TERM /THROUGH MONDAY NIGHT/
ISSUED AT 435 AM MDT SUN MAR 9 2025
PRETTY QUIET WEATHER EARLY THIS MORNING WITH INTERVALS OF HIGH
CLOUDS MOVING SOUTH AND EAST ALONG THE NORTHERN PERIPHERY OF
THE RIDGE AXIS. THESE CLOUDS HAVE KEPT TEMPERATURES FROM FALLING
TOO LOW WITH TEMPERATURES THIS MORNING GENERALLY 10 TO 20
DEGREES HIGHER THAN THEY WERE LAST NIGHT. LOCALLY WINDY
CONDITIONS WITH AN OCCASIONAL STRONG WIND GUST HAVE BEEN
OBSERVED AT BORDEAUX ALONG I-25 EARLY THIS MORNING. EXPECT THESE
WINDS TO CONTINUE THROUGH SUNRISE, SO ISSUED A SPECIAL WEATHER
STATEMENT SINCE THE WIND SPEEDS HAVE BEEN FLUCTUATING RAPIDLY
AND ARE ONLY EXPECTED TO LAST A FEW MORE HOURS.
FOR THE REST OF THE WEEKEND, ALL MODELS SHOW THE UPPER LEVEL
RIDGE AXIS EXPANDING EASTWARD INTO THE HIGH PLAINS OF WYOMING
AND COLORADO THIS AFTERNOON. HIGH TEMPERATURES WILL BE TRICKY UP
NORTH DUE TO THE LINGERING SNOW PACK. WEBCAMS STILL SHOW A SOLID
SNOW PACK NORTH OF THE NORTH PLATTE RIVER VALLEY ACROSS THE
NEBRASKA PANHANDLE, AND CONVERSE AND NIOBRARA COUNTIES ACROSS
EAST CENTRAL WYOMING. KEPT THESE TEMPERATURES A FEW DEGREES
SHORT OF GUIDANCE AND BLENDED THE 25TH PERCENTILE WITH THE
PREVIOUS FORECAST. EXPECT A NICE DAY FURTHER SOUTH, WITH HIGHS
IN THE UPPER 50S TO MID 60S. AREAS WEST OF I-25 WILL ALSO REMAIN
IN THE 40S TO LOW 50S DUE TO SOME LINGERING SNOW PACK.
PRIMARY FORECAST CONCERN IS LOCALLY STRONG GUSTY WINDS OVER THE
WIND PRONE AREAS AND A FEW SUB-WIND PRONE REGIONS LIKE CONVERSE
COUNTY AND NORTHERN CARBON COUNTY TONIGHT THROUGH MONDAY. MODELS
CONTINUE TO SHOW STRONG 600MB TO 700MB SUBSIDENCE AND TRENDED A
LITTLE HIGHER ON 700MB WIND SPEEDS AND THE STRENGTH OF MOUNTAIN
WAVE ACTIVITY...MAINLY ACROSS CENTRAL WYOMING AND EAST CENTRAL
WYOMING. DECIDED TO UPGRADE ARLINGTON AND BORDEAUX AREAS TO A
WARNING WITH GUSTS AROUND 65 MPH. ADDED CONVERSE COUNTY TO THE
HIGH WIND WATCH DUE TO PEAK SUBSIDENCE TRENDING A BIT FURTHER
NORTH AND PEAK BOUNDARY LAYER WINDS OF 55 TO 60 KNOTS. DECIDING
FACTOR WAS THE STRONGER SURFACE PRESSURE GRADIENT AS A WEAK
PACIFIC DISTURBANCE AND TRAILING COLD FRONT PUSH SOUTHEAST
ACROSS THE REGION MONDAY. PLUS THIS LOCATION WILL HAVE ANOTHER
SHOT AT CRITERIA WITH BOUNDARY LAYER MIXING MONDAY AFTERNOON.
NORTHERN CARBON COUNTY OVER NEAR MUDDY GAP AND US HIGHWAY 287 IS
ANOTHER CONCERN WITH IN-HOUSE WIND MODELS SHOWING PROBABILITIES
OVER 70 PERCENT NOW. HOWEVER, COULDN'T GET MUCH OF THE ZONE
INTO CRITERIA AFTER USING THE NBM 90TH PERCENTILE AND MAV
GUIDANCE, SO DECIDED AGAINST EXTENDING THE WATCH TO THIS AREA.
EVEN THOUGH A COLD FRONT MOVES ACROSS THE PLAINS, INCREASED MAX
TEMPERATURES A FEW DEGREES. EXPECT THE FRONT TO BREAK ANY
REMAINING LOW LEVEL TEMPERATURE INVERSION OVER THE AREA,
INCLUDING AREAS WITH A LINGERING SNOW PACK. FORECAST HIGHS ARE
GENERALLY IN THE MID 50S TO MID 60S, WITH A FEW READINGS AROUND
70 DEGREES OVER THE CENTRAL AND SOUTHERN NEBRASKA PANHANDLE.
LONG TERM /TUESDAY THROUGH SATURDAY/
ISSUED AT 406 AM MDT SUN MAR 9 2025
AN UPPER LEVEL RIDGE KEEPS OUR REGION OF THE ROCKY
MOUNTAINS PRETTY DRY THROUGH THURSDAY. IN THE MORNING A WEAK
SHORTWAVE WILL START PUSH THROUGH THE REGION TO GIVE US SOME
ELEVATED WINDS THROUGHOUT THE DAY. A 40-50 KNOT JET WILL ACCOMPANY
THIS SHORTWAVE, ALTHOUGH THE HEIGHT GRADIENT CONTINUES TO NOT LOOK
IMPRESSIVE AT ONLY 30 TO 40 METERS. OUR IN HOUSE ALGORITHM ADDS
FURTHER CONFIDENCE BY GIVING A 30 PERCENT CHANCE FOR ELEVATED WINDS
BETWEEN 06Z TO 12Z THURSDAY. IT WILL BE SOMETHING TO KEEP A CLOSE
EYE ON TO SEE HOW THIS WAVE TRENDS OVER THE NEXT FEW RUNS.
LATE THURSDAY NIGHT THROUGH SATURDAY MORNING, A LARGE UPPER LEVEL
LOW PUSHES THROUGH THE INTERMOUNTAIN WEST TO CREATES SOME
POTENTIALLY WIDESPREAD PRECIPITATION CHANCES FOR THE SOUTHEAST
WYOMING AND NEBRASKA PANHANDLE AREA. LOOKING AT DETERMINISTIC MODEL
GUIDANCE FIRST, THERE IS A GENERAL CONSENSUS IN TIMING OF THE SYSTEM
BUT UNCERTAINTY OR DISAGREEMENT WITH THE STRENGTH AND TRACK OF THIS
SYSTEM. THE GFS IS DOUBLING DOWN ON THE POTENTIAL OF A BOMB CYCLONE,
(A 24-MB DROP IN 24 HOURS OR LESS) AND A LITTLE BIT OF A NORTHERN
COMPARED TO THE EURO AND CANADIAN. BOTH THE EURO AND CANADIAN KEEP
THE SYSTEM AS AN OPEN WAVE (THUS WEAKER SYSTEM) DURING THE SAME TIME
PERIOD AS THE GFS HAS THE UPPER LOW ALREADY CLOSED OFF. DEPENDING ON
THE TRACK OF THE SYSTEM WOULD GREATLY IMPACT HOW MUCH PRECIPITATION
OUR REGION WOULD RECEIVE. BY FRIDAY AFTERNOON IS WHEN THE EURO AND
CANADIAN CLOSE OFF THE UPPER LOW. HOWEVER, THE GFS MAINTAINS A
DEEPER LOW WITH A CENTRAL PRESSURE OF 265 COMPARED TO THE 277 AND
279 BY THE EURO AND CANADIAN RESPECTIVELY. WHEN LOOKING AT THE
ENSEMBLE CLUSTER ANALYSIS 77 PERCENT OF THE GEFS MEMBERS ARE
CHOOSING THE STRONGER SOLUTION WITH A STRONGER AND DEEPER TROUGH AND
76 PERCENT OF THE EURO MEMBERS ARE FAVORING A SHALLOWER AND WEAKER
SYSTEM. THE GEPS SHOWS A 40/60 SPLIT FOR THE STRONGER/WEAKER
SOLUTION. GIVEN HOW FAR OUT THE SYSTEM IS THIS COULD BE TAKEN AS A
50/50 SPLIT FROM THE CANADIAN ENSEMBLE. LOOKING AT NAEFS, IT DEPICTS
THE 90TH PERCENTILE FOR THE NORTHWEST PORTION OF SOUTHEAST WYOMING
AREA FOR INTEGRATED WATER VAPOR TRANSPORT AND 97TH TO 99TH
PERCENTILE OVER THE SIERRA MADRES AND SNOWY RANGE. THIS INCREASES
CONFIDENCE IN MORE IMPACTFUL WEATHER AS THE AMOUNT OF MOISTURE IS IN
THE 90TH PERCENTILE AND ABOVE COMPARED TO THE REGIONS CLIMATOLOGY.
CONTRAST TO THIS THEORY, THE LREF HAS THE 10TH AND 90 PERCENTILES AS
0 AND 5 INCHES OF SNOW FOR MUCH OF OUR FORECAST AREA WITH THE MEAN
SNOW ACCUMULATIONS BEING 2 INCHES. THERE ARE SOME ISOLATED AREAS
WHERE THE 90TH PERCENTILE IS AROUND 7 INCHES BUT, THAT BUBBLE LOOKS
TO HUG THE I-25 CORRIDOR AND CURVE BETWEEN SCOTTSBLUFF AND KIMBALL.
THE UNCERTAINTY WITH THESE AMOUNTS LIES WITH THE TIMING AND
TEMPERATURE OF THE GROUND THAT WILL LIKELY PREVENT THE HIGHER SNOW
ACCUMULATIONS FROM BEING REACHED. BUT NONETHELESS THIS SYSTEM NEEDS
TO BE CLOSELY MONITORED WITH THE POTENTIAL IMPACTS. ESPECIALLY ON
THE BACK END OF THIS SYSTEM WHERE TO COLDER AIR HUGS THIS SYSTEM AND
THE STRONGER FORCING FOR OUR AREA LIES. SATURDAY MORNING, THE GFS
CHOOSES VIOLENCE FOR 700MB WINDS. THE 00Z RUN DEPICTS AN 80 KNOT JET
PASSING OVER THE NEBRASKA PANHANDLE WHICH SHOULD BE TAKEN AS A
SIGNAL FOR STRONG WINDS AND NOT NECESSARILY 80 KNOT WINDS THIS FAR
OUT INTO THE FUTURE. WHICH GIVES EVEN MORE REASON TO MONITOR THIS
SYSTEM CLOSELY.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1131 AM MDT SUN MAR 9 2025
WEST FLOW ALOFT WILL CONTINUE. SKIES WILL BE MOSTLY CLEAR WITH
OCCASIONAL SCATTERED CLOUDS NEAR 15000 FEET. LOW LEVEL WIND
SHEAR OCCURS AT LARAMIE AND CHEYENNE FROM 04Z TO 15Z, AND AT
CHADRON, ALLIANCE AND SCOTTSBLUFF FROM 00Z TO 15Z. WINDS WILL
GUST TO 30 KNOTS AT ALL TERMINALS UNTIL 00Z, TO 38 KNOTS AT
RAWLINS AND LARAMIE AFTER 04Z, AND TO 32 KNOTS AT CHEYENNE AND
THE NEBRASKA TERMINALS AFTER 14Z MONDAY.
CYS WATCHES/WARNINGS/ADVISORIES
WY...HIGH WIND WATCH FROM MONDAY MORNING THROUGH MONDAY AFTERNOON
FOR WYZ101.
HIGH WIND WARNING FROM 6 PM THIS EVENING TO 6 PM MDT MONDAY
FOR WYZ106.
HIGH WIND WATCH FROM LATE TONIGHT THROUGH MONDAY AFTERNOON FOR
WYZ107.
HIGH WIND WARNING FROM 6 AM TO 6 PM MDT MONDAY FOR WYZ110.
NE...NONE.
SHORT TERM...TJT
LONG TERM...MM
AVIATION...RUBIN
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