789
FXUS65 KCYS 170517
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1017 PM MST SAT NOV 16 2024
KEY MESSAGES
- BREEZY CONDITIONS AND SNOW SHOWERS ARE EXPECTED THIS
AFTERNOON. CANNOT RULE OUT SNOW SQUALLS FOR AREAS WEST OF THE
LARAMIE RANGE.
- HIGH WIND POSSIBLE LATE TONIGHT INTO SUNDAY AFTERNOON. A HIGH
WIND WARNING HAS BEEN ISSUED FOR THE SOUTHEAST WYOMING WIND
PRONES.
- A POTENT COLD FRONT WILL BRING ANOTHER ROUND OF STRONG WINDS BEGINNING
MONDAY, FOLLOWED BY MUCH COLDER TEMPERATURES AND A CHANCE FOR
SNOW SHOWERS MONDAY PM INTO TUESDAY.
- STRONG WINDS ARE EXPECTED TO CONTINUE INTO AT LEAST WEDNESDAY,
AND POSSIBLY THROUGH THE END OF THE WEEK.
SHORT TERM /THROUGH SUNDAY NIGHT/
ISSUED AT 120 PM MST SAT NOV 16 2024
FORECAST CONCERNS DEAL WITH SNOW SQUALLS THIS
AFTERNOON...FOLLOWED BY STRONG WINDS IN THE WIND PRONE AREAS
TONIGHT INTO SUNDAY. CURRENTLY...CWA IN THE CYCLONIC NORTHWEST
FLOW BEHIND A SURFACE LOW OVER SOUTH CENTRAL NORTH DAKOTA. A
FAIRLY UNSTABLE DAY TODAY IN THIS NORTHWEST FLOW. LATEST SB CAPE
ACROSS CARBON AND ALBANY COUNTIES RIGHT AROUND 250J/KG. THIS
HAS BEEN CAUSING SNOW SHOWERS/SNOW SQUALLS TO DEVELOP NEAR
ARLINGTON THIS MORNING AND EARLY AFTERNOON. NAM SNOW SQUALL
PARAMETER UP TO AROUND 5 UNITS CURRENTLY ACROSS THE NORTH
LARAMIE RANGE SOUTHWEST TO NEAR LARAMIE. THAT CONTINUES THROUGH
21Z AND EVENTUALLY ENDS AT 00Z. IN THE MEANTIME...WILL HAVE TO
KEEP A CLOSE EYE ON WYDOT WEBCAMS AND RADAR FOR ANY FURTHER
ISSUANCES OF SNOW SQUALL WARNINGS.
ATTENTION TURNS TO STRONG WINDS TONIGHT. UPPER TROUGH MOVES
THROUGH THE CWA BETWEEN 00Z AND 06Z WITH WINDS TURNING WESTERLY
BEHIND THE DEPARTING TROUGH. CRAIG TO CASPER 850/700MB HEIGHT
GRADIENTS INCREASE TO 50/47MTRS BY 06Z TONIGHT AS 700MB WINDS
INCREASE TO 40-45KTS. BY 12Z SUNDAY...GRADIENTS UP 57/55MTRS AND
700MB WINDS UP TO 50-55KTS. RANDOM FOREST HIGH WIND GUIDANCE
SHOWING VERY GOOD PROBABILITIES FOR BOTH ARLINGTON AND BORDEAUX
UP TO 80 PERCENT FOR ARLINGTON AND 50 PERCENT FOR BORDEAUX.
CURRENT HIGH WIND WARNINGS LOOK IN GOOD SHAPE.
AM CONCERNED WITH THE SOUTH LARAMIE RANGE THIS EVENING AND
OVERNIGHT. DOES APPEAR THE STRONGER 700/750MB WINDS ARE FURTHER
NORTH OVER THE CENTRAL LARAMIE RANGE. RANDOM FOREST IS NOT ALL
THAT EXCITED ABOUT VEDAUWOO WITH ONLY A 30 PERCENT CHANCE. WILL
CONTINUE TO MONITOR WIND TRENDS THIS EVENING.
GET A BREAK IN GRADIENTS SUNDAY FOR A BRIEF PERIOD...BUT THEY
BEGIN TO INCREASE ONCE AGAIN SUNDAY NIGHT INTO MONDAY. WILL
LIKELY NEED WIND HEADLINES FOR MONDAY.
LONG TERM /MONDAY THROUGH SATURDAY/
ISSUED AT 340 AM MST SAT NOV 16 2024
AN ACTIVE WEATHER PATTERN IS EXPECTED TO CARRY THROUGH MOST OF NEXT
WEEK, BUT THIS WILL MANIFEST MORE AS VOLATILE TEMPERATURES AND
SEVERAL STRONG WIND EVENTS, WITH PRECIPITATION CHANCES REMAINING
LIMITED. ON MONDAY, OUR AREA WILL BE SANDWICHED IN BETWEEN TWO STORM
SYSTEMS: A VIGOROUS CLOSED LOW EJECTING OVER THE SOUTHERN PLAINS TO
OUR SOUTHEAST, AND THE NEXT TROUGH MOVING IN FROM THE NORTHWEST. THE
CLOSED LOW WILL BE TOO FAR EAST TO BRING PRECIPITATION TO OUR AREA,
BUT ONCE IT GETS FAR ENOUGH NORTH TO START RECONNECTING WITH THE
MAIN FLOW, MODEL GUIDANCE SHOWS 700-MB STREAMLINES WRAPPING INTO THE
CLOSED LOW IN ADVANCE OF THE TROUGH AXIS. AS A RESULT, WE'LL BE
LOOKING AT WIND SPEEDS INCREASING THROUGH MONDAY AND INTO MONDAY
NIGHT. IN-HOUSE GUIDANCE IS SHOWING ABOUT A 40 TO 60% CHANCE OF HIGH
WINDS IN THE WIND PRONE AREAS, WITH THE HIGHEST PROBABILITY OVER THE
I-80 SUMMIT THANKS TO THE WNW ORIENTATION OF THE 700-MB FLOW
WRAPPING INTO THE LOW TO THE EAST. DECENT CLOUD LEVEL MOISTURE
SHOULD ALLOW FOR OROGRAPHIC SNOW SHOWERS TO DEVELOP DURING THE DAY
MONDAY CONTINUING THROUGH EARLY TUESDAY. ADDITIONALLY, VORTICITY
ADVECTION ALOFT SHOULD SUPPORT INCREASING SNOW SHOWER COVERAGE
MONDAY PM INTO MONDAY NIGHT MAINLY IN CARBON AND CONVERSE COUNTIES.
HOWEVER, MODELS ARE IN FAIRLY GOOD AGREEMENT ON THIS TROUGH PASSING
THROUGH AS A DOUBLE VORT-MAX, WITH ONE CENTROID JUST TO OUR NORTH,
AND A SECONDARY VORT-MAX SLIGHTLY DELAYED AND CLOSER TO THE FOUR
CORNERS. WHILE DECENT MOISTURE SWINGS OVER THE I-80 CORRIDOR WITH
THE SOUTHERN FEATURE, THE VORT-MAX TO THE NORTH WILL MOST LIKELY
PREVENT ISENTROPIC LIFT JUST AHEAD OF THE SOUTHERN VORT-MAX FROM
REACHING THIS FAR NORTH. IT SEEMS LIKE THE HIGH PLAINS WILL AGAIN
STRUGGLE TO GET MUCH PRECIPITATION OUT OF THIS SYSTEM. TEMPERATURES
WILL BE MUCH COLDER ON TUESDAY AS 700-MB TEMPERATURES PLUMMET TO
AROUND -12 TO -14C. HIGHS WILL STRUGGLE TO GET TO FREEZING IN
WYOMING, AND WILL REMAIN STUCK IN THE 30S IN NEBRASKA.
WIND SPEEDS ARE EXPECTED TO EASE SLIGHTLY DURING THE DAY TUESDAY,
BUT THE BREAK WILL PROBABLY BE FAIRLY SHORT-LIVED. AS THE NORTHERN
TROUGH DIVES INTO THE CENTRAL CONUS, IT WILL ABSORB THE EJECTING
SOUTHERN CLOSED LOW, AND THEN RAPIDLY STRENGTHEN INTO A POWERFUL
OCCLUDED CYCLONE OVER THE GREAT LAKES REGION. THE RAPID DROP IN
PRESSURE/HEIGHT TO OUR EAST WILL CAUSE GRADIENTS TO SPIKE TUESDAY
NIGHT INTO WEDNESDAY. ENSEMBLE MEDIAN 700-MB WINDS OVER KCYS REACH
46 KNOTS EARLY WEDNESDAY, AND REMAIN OVER 40 KNOTS THROUGH EARLY
THURSDAY. GFS-BASED IN-HOUSE GUIDANCE IS INDICATING HIGH
PROBABILITIES OF HIGH WINDS IN THE WIND PRONE AREAS, WITH ADJACENT
AREAS POSSIBLY IN PLAY ALSO, WHICH IS FAIRLY CONSISTENT WITH THE
CURRENT STATE OF THE MODEL SUITE. THE BRIGHT SIDE OF THIS IS THAT WE
ARE NOW EXPECTING FAIRLY RAPID WARM AIR ADVECTION WEDNESDAY INTO
THURSDAY. ENSEMBLES HAVE COME INTO BETTER AGREEMENT ON THE FURTHER
EAST POSITIONING OF THE POWERFUL CLOSED LOW, WHICH WILL ALLOW
RIDGING TO CREEP BACK INTO THE ROCKIES REGION. ABOUT 90% OF GRAND
ENSEMBLE MEMBERS HOW SHOW 700-MB TEMPERATURES RECOVERING TO ABOVE 0C
BY THURSDAY MORNING, SO CONFIDENCE IS INCREASING IN TEMPERATURES
RAPIDLY RETURNING TO ABOVE NORMAL VALUES BY THURSDAY EVEN IF THE
WIND KEEPS THINGS FEELING CHILLIER. THE END OF THE WEEK LOOKS TO BE
CHARACTERIZED BY A LOW AMPLITUDE RIDGE OVER THE WEST WITH A STRONG
JET STREAM MOVING OVER TOP OF THIS RIDGE AND THEN UNDERNEATH THE
EASTERN US CLOSED LOW. THE MOST LIKELY SCENARIO IS THAT THE JET
STAYS JUST FAR ENOUGH NORTH TO KEEP PRECIPITATION AND PASSING COLD
FRONTS OUT OF THE AREA, BUT NOT FAR ENOUGH TO KNOCK DOWN WIND
SPEEDS, LEADING TO AN EXTENDED MILD AND WINDY PERIOD. HOWEVER, THE
STORM TRACK WILL BE CLOSE ENOUGH THAT IT WON'T TAKE A VERY BIG
CHANGE IN THE MODEL SUITE TO ALLOW FOR SHORTWAVE TROUGHS TO COME
CLOSE ENOUGH TO BRING SNOWFALL AND/OR COLDER TEMPERATURES TOWARDS
THE END OF THE WEEK.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1014 PM MST SAT NOV 16 2024
LIGHT WINDS EXPECTED OVERNIGHT WITH THE EXCEPTION OF KRWL.
RAWLINS LIKELY TO SEE INCREASING WINDS BY 09 TO 10Z THAT WILL
CONTINUE THROUGH MOST OF SUNDAY. OTHER SOUTHEAST WYOMING
AIRPORTS WILL SEE WINDS INCREASING AFTER SUNRISE. VFR
CONDITIONS THROUGH THE NEXT 24 HOURS.
CYS WATCHES/WARNINGS/ADVISORIES
WY...HIGH WIND WARNING UNTIL 3 PM MST SUNDAY FOR WYZ106-110.
NE...NONE.
SHORT TERM...GCC
LONG TERM...MN
AVIATION...GCC
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