466
FXUS65 KCYS 071750
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1050 AM MST FRI MAR 7 2025
KEY MESSAGES
- SNOWFALL WILL GRADUALLY END THROUGHOUT THE DAY AS THE SYSTEM
PUSHES EAST AND DEPARTS THE REGION.
- MILD AND DRY CONDITIONS EXPECTED TO START NEXT WEEK WITH A
RETURN OF WINDY CONDITIONS FOR MOST OF SOUTHEAST WYOMING.
- THE NEXT PACIFIC STORM SYSTEM IS FORECAST TO MOVE ACROSS
WYOMING THURSDAY.
SHORT TERM /THROUGH SATURDAY NIGHT/
ISSUED AT 324 AM MST FRI MAR 7 2025
IT IS STILL SNOWING IN MOST AREAS NORTH OF I-80 WITH THE EXCEPTION
OF RAWLINS WHERE IT IS STILL SNOWING. LOOKING AT RADAR THERE IS
STILL A BAND OF F-GEN JUST SOUTH OF CHUGWATER AND FURTHER WEST. AS
WE PROGRESS THROUGH THE DAY, THE SURFACE LOW OVER EASTERN COLORADO
WILL PUSH OFF EAST TAKING MAJORITY OF THE MOISTURE AND STRONGER
FORCING WITH IT. THE WARNING OVER CONVERSE AND NIOBRARA COUNTY WILL
EXPIRE ON TIME AT 12Z THIS MORNING BECAUSE OF THIS. AROUND THE
AFTERNOON THE DRY AIR WILL START TO FILTER IN AS THE UPPER LEVEL LOW
MOVES ACROSS SOUTHERN COLORADO. THIS UPPER LEVEL LOW WILL INJECT
SOME MOISTURE BUT SNOWFALL IS ONLY EXPECTED IN THE SOUTHERN MOUNTAIN
RANGES. AFTER 18Z OR 11 AM ALL THE WARNINGS AND ADVISORIES WILL BE
EXPIRED WITH THE EXCEPTION OF THE SNOWY AND SIERRA MADRE MOUNTAIN
RANGE. THE COMBINATION OF WEAK UPSLOPE AND ISENTROPIC LIFT OF THE
INJECTED MOISTURE SHOULD SUSTAIN LIGHT TO MODERATE SNOWFALL FOR OUR
SOUTHERN MOUNTAIN RANGES. BY 11PM THE SNOWFALL OVER THE MOUNTAINS
SHOULD HAVE STOPPED OR BE LIGHT ENOUGH THAT NO IMPACTS ARE CAUSED
FROM IT. SATURDAY MORNING SHOULD BE MOSTLY CLEAR SKIES AS THE UPPER
LEVEL RIDGE PUSHES INTO OUR REGION. TEMPERATURES ARE EXPECTED TO
REMAIN A LITTLE COOL AS MOST PLACES WILL HAVE A SNOWPACK FROM THIS
SYSTEM. TEMPERATURES WERE DROPPED A FEW DEGREES HOWEVER OUR SOUTHERN
COUNTIES EAST OF I-25 MAY REACH A COUPLE TEMPERATURES WARMER THAN
FORECAST SINCE THEIR SNOWPACK WILL MELT OFF A LIGHTER FASTER THAN
ANTICIPATED. FOR INSTANCE THE 1 INCH SNOW PACK IN CHEYENNE MAY BE
GONE BEFORE LUNCH AND THE TEMPERATURES MAY RAISE HIGHER THAN ALL THE
MODELS ANTICIPATE AND CHEYENNE REACHES A HIGH TEMPERATURE IN THE MID
40'S ON SATURDAY. THE HIGH TEMPERATURES WILL BE A LITTLE TRICKY TO
FORECAST SINCE THEY WILL BE HIGHLY INFLUENCE WITH HOW MUCH REMAINING
SNOW IS ON THE GROUND EACH DAY. ALSO AS A CONSEQUENCE OF THE
SNOWPACK THE OVERNIGHT TEMPERATURES LOOK TO BE INTO THE TEENS AND
20'S THIS WEEKEND.
LONG TERM /SUNDAY THROUGH THURSDAY/
ISSUED AT 324 AM MST FRI MAR 7 2025
NOT MANY CHANGES TO THE MEDIUM TO LONG RANGE FORECAST AS
MODELS AND ENSEMBLES REMAIN IN GOOD AGREEMENT THROUGH MOST OF
NEXT WEEK. QUIET AND BENIGN WEATHER IS FORECAST THROUGH
WEDNESDAY WITH ONLY WIND AND TEMPERATURE CONCERNS BEFORE THE
NEXT PACIFIC STORM SYSTEM MAKES ITS WAY INLAND WEDNESDAY NIGHT
AND THURSDAY. MAIN CONCERN ON SUNDAY WILL BE HIGH AND LOW
TEMPERATURES. THE FIRST FEW SNOWFALL REPORTS FROM THIS PART
STORM SHOW A GOOD SNOWPACK ALREADY ON THE GROUND FROM DOUGLAS TO
CHADRON WITH 8+ INCHES IN A FEW PLACES. HAVE A HARD TIME
BELIEVING THIS WILL MELT IN 3 DAYS, ESPECIALLY WITH VERY COLD
TEMPERATURES FOR THIS TIME OF THE YEAR EXPECTED FRIDAY AND
FRIDAY NIGHT. THEREFORE TRENDED THE TEMPERATURE FORECAST FOR
NORTH OF I-80 AND ALONG & NORTH OF THE NORTH PLATTE RIVER
VALLEY BELOW GUIDANCE AND TOWARDS THE COLDEST 25TH PERCENTILE OF
THE ENSEMBLE SPREADS FROM DOUGLAS OVER TO LUSK AND CHADRON, AND
AROUND RAWLINS AS WELL. EVEN ON SUNDAY, HIGHS WILL STRUGGLE TO
REACH THE MID TO UPPER 40S. ENSEMBLE SPREAD HAVE BEEN HINTING TO
THIS OUTCOME FOR SEVERAL DAYS, WITH VERY LOW SPREADS FURTHER
SOUTH NEAR THE COLORADO BORDER...WHICH HAD LITTLE SNOW WITH THIS
EVENT. ELSEWHERE, HIGHS IN THE 50S TO LOW 60S ARE EXPECTED
SUNDAY AFTERNOON WITH WINDS INCREASING SLIGHTLY THROUGH THE
AFTERNOON.
WARMING TREND WILL CONTINUE INTO MONDAY WITH HIGHS IN THE 50S
AND 60S, WITH EVEN A FEW PLACES AROUND 70 ACROSS THE SOUTHERN
NEBRASKA PANHANDLE. EVEN UP NORTH, EXPECT MOST LOCATIONS TO LOSE
MOST OF THEIR SNOWPACK BY MID MONDAY AFTERNOON WITH HIGHS
RETURNING TO THE 50S AND LOW 60S. PRIMARY FORECAST CONCERN EARLY
NEXT WEEK IS WINDY CONDITIONS AND THE POTENTIAL FOR LOCALLY
STRONG WINDS ACROSS THE WIND PRONE AREAS. ALL MODELS ARE A
LITTLE MORE FAVORABLE WITH SHOWING THE POTENTIAL FOR HIGH WIND
CRITERIA, AT LEAST ACROSS THE WIND PRONE AREAS. IN-HOUSE
WIND GUIDANCE ALSO SHOWS INCREASING PROBABILITIES FOR ARLINGTON,
BORDEAUX, AND EVEN NORTHERN PLATTE COUNTY NEAR COLEMAN ALONG
I-25. SYNOPTIC MODELS SHOW STRONGER SUBSIDENCE IN THE BOUNDARY
LATER BETWEEN LATE SUNDAY NIGHT THROUGH EARLY TUESDAY MORNING
WITH 700MB OVER 50 KNOTS. LOW LEVEL GRADIENTS ARE MARGINAL, BUT
ENOUGH TO WARRANT INCREASING WINDS OVER THE WIND PRONE AREAS.
NO PRECIPITATION IS EXPECTED FOR THIS TIME PERIOD SINCE MODELS
HAVE TRENDED FURTHER SOUTH WITH THE WEAK UPPER LEVEL TROUGH
MOVING EASTWARD OUT OF SOUTHERN CALIFORNIA.
AS WE HEAD INTO THURSDAY, MODELS ARE IN GOOD AGREEMENT, EVEN
FOR 7 DAYS OUT, AS THE NEXT PACIFIC STORM MOVES ONSHORE AND INTO
THE EASTERN GREAT BASIN REGION. THIS STORM IS FORECAST TO PUSH
INTO THE FRONT RANGE THURSDAY NIGHT AND FRIDAY WITH PRETTY GOOD
AGREEMENT ON TIMING, EVEN THOUGH THE GFS IS A BIT MORE
PROGRESSIVE THAN THE ECMWF AND CANADIAN. ENSEMBLES ARE MAINLY
SUGGESTING RAIN QUICKLY CHANGING TO SNOW LATE THURSDAY NIGHT AND
INTO EARLY FRIDAY MORNING. NBM POP WAS WAY TOO HIGH FOR 7 DAYS
OUT (NEARLY 95% IN SOME AREAS) AS THERE ARE SOME TIMING
DIFFERENCES, SO LOWERED POP BETWEEN 40 TO 60 PERCENT FOR NOW, AND
KEPT THEM SLIGHTLY HIGHER IN THE MOUNTAINS. WILL HAVE TO MONITOR
THIS STORM SINCE IT DOES TRACK OVER THE FOUR CORNERS REGION AND
LIFTS NORTHEAST INTO NORTHEAST COLORADO.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
ISSUED AT 1041 AM MST FRI MAR 7 2025
STAGNANT SURFACE HIGH PRESSURE WILL BE IN PLACE DURING THE NEXT
24HRS WHICH WILL TEND TO KEEP THE CLOUD COVER IN PLACE THROUGH
MUCH OF THE AFTERNOON WITH OCCASIONAL SNOW SHOWERS. THESE SNOW
SHOWERS SHOULD GRADUALLY DISSIPATE TOWARDS THE END OF THE DAY AS
THE DIURNAL EFFECTS BECOME LESS OF A FACTOR AS WELL AS WEAK
SUBSIDENCE. WE ARE A BIT CONCERNED ABOUT SOME PATCHY FOG
DEVELOPING IN THE VALLEYS SUCH AS KLAR. FOR NOW, WE WILL BRING
TO THE MVFR CATEGORY AND LET LATER SHIFTS TAKE ANOTHER LOOK AT
MODEL TRENDS.
CYS WATCHES/WARNINGS/ADVISORIES
WY...WINTER STORM WARNING UNTIL 11 PM MST THIS EVENING FOR WYZ112.
WINTER WEATHER ADVISORY UNTIL 11 PM MST THIS EVENING FOR
WYZ114.
NE...NONE.
SHORT TERM...MM
LONG TERM...TJT
AVIATION...REC
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