171
FXUS65 KCYS 161047
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
347 AM 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 SATURDAY NIGHT INTO SUNDAY AFTERNOON.
A HIGH WIND WATCH 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 340 AM MST SAT NOV 16 2024
CURRENT SURFACE ANALYSIS AND SATELLITE WATER VAPOR IMAGERY SHOWS THE
COLD FRONT ABOUT HALFWAY THROUGH THE CWA. BY THE TIME DAYBREAK ROLLS
AROUND, THE FRONT SHOULD BE THROUGH THE CWA AND ALMOST INTO CENTRAL
NEBRASKA. THIS WILL LEAD TO AN ACTIVE 36 HOUR PERIOD ACROSS MUCH OF
THE AREA. BEHIND THE FRONT, WINDS WILL INCREASE, LEADING TO A BREEZY
DAY FOR THE FORECAST AREA. THE USUAL SOUTHEAST WYOMING WIND PRONES
CAN EXPECT THE STRONGEST WINDS, BUT AREAS OUTSIDE OF THIS CAN STILL
EXPECT TO SEE 30 MPH GUSTS. NEXT, THE PRECIPITATION WILL ARRIVE. HI-
RES GUIDANCE IS IN GOOD AGREEMENT WITH MOUNTAIN SNOW DEVELOPING THIS
MORNING AND CONTINUING THROUGH THE AFTERNOON. SNOW SHOWERS WILL
LIKELY BEGIN TO DEVELOP IN THE LOWER ELEVATIONS/PLAINS OF
CARBON COUNTY AND NORTHERN ALBANY COUNTY BY THE AFTERNOON AS
INSTABILITY INCREASES. THE RAP SHOWS IMPRESSIVE SURFACE CAPE
VALUES FOR NOVEMBER. CAPE VALUES UP TO 400 J/KG CERTAINLY LEAD
TO THE CONCERN OF POSSIBLE SNOW SQUALLS THIS AFTERNOON, OR AT
LEAST SQUALL-LIKE SHOWERS. MODEL SNOW SQUALL PARAMETER VALUES
ARE LUCKILY ON THE LOWER SIDE, RANGING FROM 2 TO 3.5, HOWEVER,
THIS DOES NOT MEAN THAT SNOW SQUALLS WON'T BE POSSIBLE. THE
ELEVATED INSTABILITY, COOLER TEMPERATURES BEHIND THE FRONT, AND
ALREADY WINDY CONDITIONS DEFINITELY COULD LEAD TO AREAS OF LOW
VISIBILITY AND SLICK ROAD CONDITIONS IN ANY SNOW SHOWERS THAT DO
POP-UP. THE AREA OF GREATEST CONCERN FOR SNOW SQUALLS THIS
AFTERNOON WILL BE ALONG THE INTERSTATE 80 CORRIDOR BETWEEN
LARAMIE AND RAWLINS. SNOW BOTH IN THE MOUNTAINS AND PLAINS WILL
QUICKLY TAPER BY THIS EVENING. WHILE NO SNOW ACCUMULATION IS
EXPECTED IN THE PLAINS, THE SNOWY AND SIERRA MADRE RANGES COULD
BOTH PICK UP A FEW INCHES OF SNOW. WINDS WILL ALSO BRIEFLY TAPER
OFF LATE THIS AFTERNOON BEFORE QUICKLY PICKING UP LATER
SATURDAY NIGHT.
WITH THE DEPARTING TROUGH THAT BROUGHT THE COLD FRONT PUSHING
FURTHER EAST, MSLP GRADIENTS ALONG AND WEST OF THE LARAMIE RANGE
WILL TIGHTEN AS HIGH PRESSURE BUILDS IN WESTERN WYOMING. CAG-CPR 700
MB HEIGHT GRADIENTS WILL ALSO RESPOND, WITH VALUES ABOVE 50 METERS
LATE SATURDAY NIGHT INTO SUNDAY MORNING. WINDS ALOFT WILL ALSO
INCREASE, MAXING OUT AT 55 TO 60 KTS OVER THE USUAL SOUTHEAST
WYOMING WIND PRONES. SUBSIDENCE OVER THESE AREAS WILL ALSO BE
GREAT WHICH WILL LIKELY LEAD TO THESE WINDS MAKING IT DOWN TO
THE SURFACE. THERE IS ALSO A SLIGHT HINT AT A MOUNTAIN WAVE
SIGNATURE IN THE OMEGA FIELD. AS A RESULT OF THESE SIGNALS, AND
IN-HOUSE GUIDANCE SUGGESTING HIGH WIND POTENTIAL, DID ISSUE A
HIGH WIND WATCH FOR ARLINGTON/ELK MOUNTAIN AND BORDEAUX. THE
WATCH IS IN EFFECT FROM 11 PM SATURDAY UNTIL 2 PM SUNDAY
AFTERNOON. WINDS WILL EASE AFTER THIS, LEAVING A DRY, BUT STILL
BREEZY SUNDAY AFTERNOON AND EVENING.
LONG TERM /MONDAY THROUGH FRIDAY/
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 /00Z TAFS THROUGH 00Z SUNDAY/
ISSUED AT 943 PM MST FRI NOV 15 2024
CLEAR SKIES OVERNIGHT. LOOK FOR WINDS TO PICK UP AGAIN ACROSS
SOUTHEAST WYOMING AIRPORTS SATURDAY WITH GUSTS 30 TO 35 KTS
LIKELY. SHORT TERM GUIDANCE SHOWING THE POSSIBILITY OF SNOW
SHOWERS OUT BY KRWL SATURDAY AFTERNOON. WENT AHEAD WITH VCSH
WORDING IN THE KRWL TAF LATE MORNING THROUGH THE AFTERNOON.
CYS WATCHES/WARNINGS/ADVISORIES
WY...HIGH WIND WATCH FROM THIS EVENING THROUGH SUNDAY AFTERNOON FOR
WYZ106-110.
NE...NONE.
SHORT TERM...SF
LONG TERM...MN
AVIATION...GCC
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