102
FXUS65 KRIW 201141
AFDRIW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
441 AM MST THU FEB 20 2025
KEY MESSAGES
- QUICK MOVING WINTER STORM WILL PUSH ACROSS SOUTHERN COUNTIES,
MAINLY ALONG AND SOUTH OF THE I-80 CORRIDOR.
- MINOR TRAVEL IMPACTS TO I-80 WITH ADVISORY LEVEL SNOW
EXPECTED.
- WARMING AND DRY TREND THROUGH THE WEEKEND AND INTO EARLY NEXT
WEEK AHEAD OF THE NEXT UPPER LEVEL DISTURBANCE.
DISCUSSION
ISSUED AT 1245 AM MST THU FEB 20 2025
CURRENT IR DEPICTS THE NEXT QUICK MOVING SHORTWAVE ACROSS THE
NV/ID/UT TRIPOINT AS IT PUSHES EAST. WV SHOWS A WEAK FINGER OF
THE PFJ SUPPORTING IT OFF THE PACIFIC NORTHWEST COAST AS THE
MAIN PFJ EXTENDS OUT OF CANADA INTO THE GREAT PLAINS, WHERE THE
COLDEST OF THE AIR IS LOCATED. A LEESIDE LOW OUT OF IDAHO WILL
SLOWLY PUSH INTO FAR SOUTHWESTERN REACHES OF THE STATE THROUGH
THE EARLY THURSDAY MORNING HOURS WITH A WEAK SURFACE BOUNDARY
EXTENDING TO THE SOUTH OVER NORTHEASTERN UT INTO NORTHWESTERN
CO. THIS WILL KEEP MUCH OF THE MOISTURE MAINLY ALONG AND SOUTH
OF THE I-80 CORRIDOR THROUGH MUCH OF THURSDAY. HIGHEST SNOW
RATES WILL BE ACROSS THE HIGHER TERRAIN OF SOUTHERN LINCOLN
COUNTY BEFORE SUNRISE THROUGH MOST OF THE MORNING BUT MORE
LIMITED IN MINOR ACCUMULATIONS FURTHER EAST ALONG THE I-80
CORRIDOR. 60-70 PERCENT PROBABILITIES OF 2 INCHES OR MORE IN THE
LOWER ELEVATIONS FROM KEMMERER TO RKS WITH A FEW POCKETS OF
BETTER 4 INCH ACCUMULATIONS SOUTH OF RKS IN SOUTHWESTERN PARTS
OF SWEETWATER COUNTY. THIS IS WHERE THERE WILL BE THE VERY LOW
CHANCE (<10%) FOR ANY 6 INCHES OR MORE TO WARRANT THE ONGOING
ADVISORIES TO BE UPGRADED TO A WARNING. REGARDLESS, MINOR TRAVEL
IMPACTS ALONG I-80 FROM ALMOST TO WAMSUTTER AND INTO UINTA
COUNTY CAN BE EXPECTED. NORTH OF WEST WIND GUSTS UP TO 20 TO 30
MPH AFTER NOON IN THIS AREA WILL CREATE A BIT OF A CROSSWIND
THAT COULD LIMITED VISIBILITY WITH THE LINGERING SNOW IN THE
AFTERNOON. OTHERWISE, SNOW WILL TAPER OFF TOWARDS SUNSET AND
PUSH EAST AND SOUTHEAST BY MIDNIGHT.
FOR OTHER AREAS OF THE CWA, SOME PATCHY FOG ACROSS THE WIND
RIVER BASIN IS POSSIBLE (30-40%) AFTER THIS RECENT SNOW BUT WILL
ALL BE DEPENDENT ON CLOUD COVER AND IF IT CLEARS ENOUGH BY
DAYBREAK THURSDAY MORNING. THIS WILL BE MORE PREVALENT COME
FRIDAY MORNING WITH MORE CLEARING AS RIDGING BUILDS IN LATER
THURSDAY AND THROUGH THE WEEKEND AS WELL. THE MAIN TAKEAWAY FOR
WEEK'S END AND THE WEEKEND WILL BE WARMING AND DRY CONDITIONS
EXPECTED. A WIDER SPREAD OF 40S EAST OF THE DIVIDE SATURDAY WITH
30S WEST TO EVEN SOME 50S TO THE EAST SUNDAY. NBM INPUT SEEMS A
BIT HIGH AT THIS POINT BUT EVEN BLENDING IN SOME OTHER MORE
RELIABLE MODEL DATA, STILL HAS SOME OF THESE VALUES MORE LIKELY
THAN NOT EVEN THROUGH MONDAY AHEAD OF THE NEXT SYSTEM.
THE UPPER LEVEL RIDGE STARTS TO BREAK DOWN AND BROADEN COME
SUNDAY AS THE PFJ DIPS BACK A FURTHER SOUTH THROUGH MONTANA THAT
WILL OPEN UP THE NORTHWEST PACIFIC ONCE AGAIN FOR THE WESTERN
MOUNTAINS INTO EARLY NEXT WEEK. THIS WILL INCREASES SNOW
CHANCES WEST OF THE DIVIDE THROUGH MID WEEK BEFORE THE MAIN
TROUGH PUSHES EAST OVERNIGHT TUESDAY INTO WEDNESDAY. THIS WILL
BRING SOME SNOW CHANCES AND COOLER TEMPERATURES EAST OF THE
DIVIDE BUT WARMING ONCE AGAIN BY WEEK'S END. THIS FAR OUT,
LONGER TERM MODELS DO NOT SUGGEST ANYTHING SIGNIFICANT IN TERMS
OF SNOWFALL BUT MINOR ACCUMULATIONS FOR MOST AREAS WEST OF THE
DIVIDE AND SPREADING TO THE BIGHORNS WEDNESDAY. EVEN AS THE
SYSTEM PUSHES EAST, IT MIGHT EVEN JUST BE LIQUID PRECIPITATION
WITH THE ABOVE FREEZING TEMPERATURES (EVEN THOUGH COOLER) FOR
THE LOWER BASINS EAST OF THE DIVIDE. TIME WILL TELL, BUT MARCH
IS NEAR WITH THE START OF SPRING NOT THAT FAR INTO THE FUTURE.
AVIATION /12Z TAFS THROUGH 12Z FRIDAY/
ISSUED AT 439 AM MST THU FEB 20 2025
WEST OF THE DIVIDE...KBPI/KJAC/KPNA/KRKS TERMINALS.
A WINTER WEATHER SYSTEM IS MAKING ITS WAY INTO SOUTHERN WYOMING AND
WILL BRING SNOW CHANCES AND MVFR CEILINGS TO THE WEST OF THE DIVIDE
TERMINALS. KRKS WILL SEE THE GREATEST IMPACTS WITH THIS SYSTEM, WITH
MVFR TO IFR FLIGHT CONDITIONS DUE TO SNOW. BREAKS BETWEEN SNOW
SHOWERS COULD ALLOW FOR BRIEF PERIODS OF IMPROVEMENT TO VFR FLIGHT
CONDITIONS THIS AFTERNOON, HOWEVER CONFIDENCE IN TIMING AND
OCCURRENCE IS TOO LOW TO INCLUDE A PREVAILING VFR GROUP AT THIS
TIME. LIGHT SNOW CHANCES SHOULD DIMINISH AT KJAC AROUND 15Z,
WITH LINGERING MVFR CEILINGS THROUGH MID-DAY. MOUNTAIN
OBSCURATION CAN BE EXPECTED WITH LOWER CEILINGS AND
VISIBILITIES.
KPNA AND KBPI HAVE A 30% CHANCE OF SEEING SNOW STARTING AROUND 20-
21Z AND LINGERING THROUGH 02-03Z. THERE IS POTENTIAL (AROUND A 20%
CHANCE) FOR A LOW CLOUD DECK TO DEVELOP LATE IN THE TAF PERIOD AT
KBPI AND KPNA, HOWEVER, CONFIDENCE IS TOO LOW TO INCLUDE A
PREVAILING GROUP OF REDUCED FLIGHT CONDITIONS AT THIS TIME.
EAST OF THE DIVIDE...KCOD/KCPR/KLND/KRIW/KWRL TERMINALS.
MOST EAST OF THE DIVIDE TERMINALS CAN EXPECT VFR FLIGHT
CONDITIONS THIS TAF PERIOD WITH INCREASING CLOUDS. KLND HAS THE
GREATEST CHANCE (30%) OF SEEING LIGHT SNOW BETWEEN 18-24Z WITH A
WEATHER SYSTEM THAT IS MOVING INTO SOUTHERN WYOMING. I CANNOT
RULE OUT KRIW AND KCPR SEEING VERY ISOLATED LIGHT SNOW BETWEEN
16-20Z, HOWEVER CONFIDENCE IN IMPACTS IS TOO LOW (AROUND 10%) TO
INCLUDE IN TAF AT THIS TIME. WINDS AT ALL EAST OF THE DIVIDE
TERMINALS ARE FORECAST TO BE LESS THAN 10 KNOTS.
PLEASE SEE THE AVIATION WEATHER CENTER AND/OR CWSU ZDV AND ZLC FOR
THE LATEST INFORMATION ON ICING AND TURBULENCE FORECASTS.
RIW WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY UNTIL 11 PM MST THIS EVENING FOR
WYZ027>030.
DISCUSSION...LOWE
AVIATION...GERHARDT
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