111
FXUS65 KRIW 271954
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
1254 PM MST THU FEB 27 2020
SHORT TERM
THIS EVENING THROUGH SATURDAY
ISSUED AT 1253 PM MST THU FEB 27 2020
HIGH PRESSURE WILL BUILD INTO THE AREA FROM THE WEST AND BRING DRY
AND SETTLED WEATHER THROUGH SATURDAY. THERE COULD BE SOME VERY
ISOLATED SNOW SHOWERS IN THE NORTHWEST MOUNTAINS THIS AFTERNOON BUT
THEY WILL BRING LITTLE ACCUMULATION AND NOT IMPACTFUL. THE BIGGEST
CHALLENGES FOR THIS PERIOD WILL BE TEMPERATURE TRENDS AND WINDS AS
THE NEXT SYSTEM APPROACHES ON SATURDAY. VALLEY/BASIN INVERSIONS HAVE
BEEN HANGING TOUGH IN THE WEST AND SO AREAS LIKE AFTON AND BIG PINEY
HAVE BEEN SLOW TO WARM IN THE MORNING. THIS WILL LIKELY TRANSLATE TO
A LOWER HIGH TEMP UNTIL THE NEXT SYSTEM IS ABLE TO SCOUR OUT THE
INVERSIONS. AS THE UPPER LEVEL TROUGH MOVES FROM CANADA INTO THE
INTERMOUNTAIN WEST EXPECT BREEZY CONDITIONS ON FRIDAY AND STRONG WINDS
SATURDAY AFTERNOON IN THE WIND CORRIDOR FROM THE GREEN MOUNTAINS
THROUGH NATRONA COUNTY AND IN THE ABSAROKA MOUNTAINS.
THE NEXT WEATHER SYSTEM IN THE FORM OF A PACIFIC SYSTEM WILL BEGIN
TO APPROACH THE AREA ON SATURDAY. MODELS HAVE CONTINUED TO SLOW THE
PROGRESS OF THE SYSTEM AND IT NOW LOOKS LIKE ONLY THE FAR NORTHWEST
AREAS, YELLOWSTONE NP AND NORTHERN TETON MOUNTAINS, WILL SEE ANY
ACTIVITY SATURDAY EVENING. WE HAVE ADJUSTED POPS TO REFLECT THIS.
LONG TERM
SATURDAY NIGHT THROUGH THURSDAY
ISSUED AT 1253 PM MST THU FEB 27 2020
SATURDAY NIGHT HAS ALL OF THE MODELS SHOWING A TROUGH ACROSS THE
WESTERN U.S. INTO SOUTH-CENTRAL CANADA. MAIN UPPER LOWS ASSOCIATED
WITH THIS TROUGH ARE AROUND NORTHEASTERN OREGON AND ANOTHER IN
CENTRAL MANITOBA. WITH THE MAIN UPPER LOWS ROUGHLY ACROSS SOUTH-
CENTRAL MANITOBA AND N. CALIFORNIA. THE TROUGH WILL SPLIT/STRETCH
OUT SUNDAY WITH THE TROUGH AXIS PULLING ACROSS THE AREA SUNDAY NIGHT.
SEVERAL WEATHER ELEMENTS COMING TOGETHER SUNDAY FOR THE POTENTIAL OF
SIGNIFICANT SNOW MAINLY OVER CENTRAL AND SOUTHERN AREAS. MODELS ARE
HINTING A JET COUPLET BETWEEN THE POLAR AND SUBTROPICAL JET STREAM
AT 300MB, STRONG FRONTOGENESIS IN THE LOWER LEVELS PULLING SOUTH
SUNDAY, ISENTROPIC LIFT MAINLY OVER THE SOUTH, AND A DECENT
DENDRITIC GROWTH ZONE FOR A PERIOD OF TIME. THE MODELS HAVE COME
MUCH MORE IN LINE WITH THE SPLITTING OF THIS TROUGH, SO WE ARE
KEEPING THE HIGHER POPS AND SNOW AMOUNTS FROM THE PREVIOUS SHIFT.
STILL EXPECTING SOME HIGHLIGHTS OVER CENTRAL/SOUTHERN AREAS, LEANING
TOWARD ADVISORY AMOUNTS FOR NOW. THE SNOW WILL COME TO AN END FROM
NORTH TO SOUTH LATE SUNDAY NIGHT INTO EARLY MONDAY MORNING.
BEHIND THE FRONT, DRY CONDITIONS ARE EXPECTED, BUT WILL BE SHORT-
LIVED AS A NEW STORM SYSTEM WILL MOVE INTO THE FORECAST AREA. THIS
STORM, CURRENTLY IN THE GULF OF ALASKA, WILL RAPIDLY DRIVE SOUTHEAST
INTO THE PACIFIC NORTHWEST MONDAY NIGHT AND INTO THE ROCKIES EARLY
TUESDAY. SNOW WILL HIT NORTHWESTERN WYOMING LATE MONDAY AND SPREAD
EAST OF THE DIVIDE THROUGH TUESDAY INTO TUESDAY NIGHT. THERE IS THE
POTENTIAL FOR SIGNIFICANT SNOW OVER THE NORTHWEST BASED ON CURRENT
DATA, HOWEVER CENTRAL AND EASTERN AREAS WILL NOT SEE MUCH. ALSO
WINDY CONDITIONS ARE POSSIBLE WEDNESDAY FOR AREAS THAT FAVOR STRONG
NORTHWEST WINDS.
NORTHWEST FLOW IN THE WAKE OF THE TROUGH WEDNESDAY COULD RESULT IN A
RETURN TO SOME SNOW SHOWERS FALLING MAINLY OVER THE NORTHWEST.
THURSDAY WILL SEE DRIER CONDITIONS ACROSS THE REGION.
AVIATION
FOR THE 18Z TAFS THROUGH 18Z FRIDAY
ISSUED AT 1030 AM MST THU FEB 27 2020
EXPECT VFR CONDITIONS ACROSS THE AREA THROUGH THE TAF PERIOD WITH
VARIABLE MID TO HIGH LEVEL CLOUDS.
A GUSTY WEST TO SOUTHWEST WIND WILL CONTINUE AT KCPR THROUGH MUCH OF
THE TAF PERIOD. WINDS WILL SUBSIDE BELOW 15 KTS AT KCPR AFTER 00Z
FRIDAY, PICKING UP AGAIN AFTER 15Z FRIDAY. KRKS WILL SEE AN INCREASE
IN SPEED AFTER 21Z TODAY AND THEN DIMINISHING AFTER AROUND 04Z
FRIDAY.
FIRE WEATHER
ISSUED AT 1253 PM MST THU FEB 27 2020
EXPECT MOSTLY DRY CONDITIONS AND WARMING TEMPERATURES THROUGH
SATURDAY AS HIGH PRESSURE MOVES OVER THE AREA. A GUSTY WIND WILL
OCCUR IN THE FAVORED AREAS FROM ROCK SPRINGS THROUGH CASPER AND IN
THE ABSAROKAS. RELATIVE HUMIDITY WILL REMAIN ABOVE CRITICAL LEVELS
FOR THE NEXT SEVERAL DAYS. MIXING AND SMOKE DISPERSAL WILL BE
GENERALLY POOR TONIGHT AND FRIDAY. THE NEXT WEATHER SYSTEM ARRIVES
SATURDAY NIGHT INTO SUNDAY WITH SOME WIDESPREAD SNOW.
RIW WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...HULME
LONG TERM...SWANSON
AVIATION...SWANSON
FIRE WEATHER...HULME
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page