462
FXUS65 KCYS 141118
AFDCYS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
518 AM MDT MON APR 14 2025
KEY MESSAGES
- CONTINUED COOLER WEATHER TODAY WITH TEMPERATURES REBOUNDING
UPWARD ON TUESDAY AND WEDNESDAY.
- DRY WEATHER CONTINUES EACH DAY THROUGH MIDWEEK.
SHORT TERM /THROUGH TUESDAY NIGHT/
ISSUED AT 138 AM MDT MON APR 14 2025
OVERNIGHT SATELLITE IMAGERY REVEALS A DEPARTING CLOUD DECK
ASSOCIATED WITH THE FRONTAL SYSTEM THAT PASSED THROUGH THE
REGION ON SUNDAY. LIGHT NORTH TO NORTHWESTERLY SURFACE FLOW WILL
CONTINUE TO USHER IN A DRY AIRMASS BEHIND THIS SYSTEM, SETTING
THE STAGE FOR A MOSTLY SUNNY DAY THIS AFTERNOON. AFTERNOON HIGH
TEMPERATURES WILL CONTINUE TO RUN NEAR TO SLIGHTLY ABOVE AVERAGE
IN THE WAKE OF THIS COLD FRONT.
HEIGHTS WILL BEGIN TO RISE ON WEDNESDAY AS WEAK RIDGING MOVES IN
OVER THE SOUTHERN ROCKIES AHEAD OF AN UPPER-LEVEL LOW OFF OF THE
CALIFORNIA COAST. ANOTHER MOSTLY SUNNY DAY IS EXPECTED, WITH
TEMPERATURES RUNNING AT LEAST 10 DEGREES WARMER THAN ON MONDAY.
ADDITIONALLY, AFTERNOON RH VALUES WILL BE QUITE LOW, RUNNING AT
OR EVEN SLIGHTLY BELOW 10% IN MANY AREAS THROUGHOUT SOUTHEAST
WYOMING AND WESTERN NEBRASKA. FORTUNATELY, AFTERNOON WIND SPEEDS
WILL REMAIN QUITE LIGHT AND NO RED FLAG CONDITIONS ARE EXPECTED
FOR NOW. VERY LITTLE IMPACTFUL WEATHER IS EXPECTED THROUGH THE
SHORT TERM PERIOD AND VERY MINIMAL ADJUSTMENTS TO MODEL BLENDS
WERE MADE IN THIS FORECAST PACKAGE.
LONG TERM /WEDNESDAY THROUGH SUNDAY/
ISSUED AT 229 PM MDT SUN APR 13 2025
THE LONG TERM FORECAST WILL SEE A SWITCH TO A COOLER AND MORE ACTIVE
PATTERN LATER IN THE WEEK. STARTING WEDNESDAY NIGHT, BOTH THE GFS
AND ECMWF SHOW AN UPPER-LEVEL CLOSED LOW FROM CANADA DROPPING DOWN
INTO THE PACIFIC NORTHWEST. THIS LOW WILL SLOWLY DIVE SOUTH THROUGH
THE END OF THE WORK WEEK AND INTO THE WEEKEND AND LARGELY BE
RESPONSIBLE FOR THE COOLER TEMPERATURES AND PRECIPITATION CHANCES
DURING THIS TIME.
AHEAD OF THIS SYSTEM, A WEAK UPPER-LEVEL DISTURBANCE WILL PASS OVER
THE CWA WEDNESDAY NIGHT. MODELS ARE IN GOOD AGREEMENT, SHOWING SOME
LIGHT PRECIPITATION OVERNIGHT, MAINLY ALONG THE INTERSTATE 80
CORRIDOR AND WEST OF INTERSTATE 25. IMPACTS WILL LIKELY BE MINIMAL,
HOWEVER THE MOUNTAINS COULD SEE SOME LIGHT ACCUMULATIONS. HEADING
INTO THURSDAY, MODELS SHOW A BIT MORE DISAGREEMENT. DESPITE UPPER-
LEVEL LOW PLACEMENT BEING NEARLY IDENTICAL IN IDAHO, THE ECMWF IS
SPEEDIER TO PUSH THE COLD FRONT INTO THE CWA BY THURSDAY AFTERNOON.
THE GFS IS MUCH SLOWER, SHOWING FRONTAL PASSAGE BY EARLY FRIDAY
MORNING. THE SPEEDIER FRONT RESULTS IN A WETTER SOLUTION FOR
THURSDAY, WHILE THE SLOWER FRONT RESULTS IN A WETTER FRIDAY. BY
SATURDAY, THE UPPER-LEVEL LOW WILL DIVE INTO THE GREAT BASIN,
RESULTING IN MOSTLY DRY CONDITIONS. THE MOUNTAINS WILL LIKELY STILL
HANG ON TO SOME LINGERING MOISTURE WHICH COULD LEAD TO CONTINUED
LIGHT SNOW AT HIGHER ELEVATIONS.
TEMPERATURES WILL GRADUALLY DECREASE THROUGH THE END OF THE
WORK WEEK THANKS TO THE INCOMING COLD FRONT. TEMPERATURES WILL
START ABOVE AVERAGE ON WEDNESDAY, BUT DROP TO BELOW AVERAGE BY
FRIDAY AS 700 MB TEMPERATURES FALL BELOW 0C. GIVEN THESE COOLER
TEMPERATURES, IT IS POSSIBLE FOR SOME OF THE LOWER ELEVATION
LOCATIONS TO SEE SOME MINOR SNOW ACCUMULATION, ESPECIALLY AT
NIGHT WITH TEMPERATURES BELOW FREEZING. TEMPERATURES WILL WARM
UP TO ABOUT AVERAGE ON SATURDAY AS SOME OF THE COLD AIR ALOFT IS
KICKED OUT.
AVIATION /12Z TAFS THROUGH 12Z TUESDAY/
ISSUED AT 512 AM MDT MON APR 14 2025
SCATTER TO BROKEN STRATUS DECKS IN THE MVFR RANGE ARE POSSIBLE
FOR THE NEXT 1-2 HOURS AT CYS AND THE NEXT 2-4 HOUR AT SNY.
EXPECT CLEARING SKIES THIS MORNING AS DRY AIR CONTINUES TO WORK
IN FROM THE NORTHWEST. VFR IS EXPECTED THROUGH THE DAY AT ALL
TERMINALS AND AT CYS AND SNY AFTER MORNING CLOUDS CLEAR TO THE
SOUTH. GUSTY NORTHWEST WINDS ARE POSSIBLE THIS AFTERNOON AT ALL
TERMINALS BUT WILL QUICKLY DIMINISH AFTER SUNSET WITH A CLEAR
AND CALM OVERNIGHT EXPECTED WITH LIGHT DRAINAGE FLOW.
CYS WATCHES/WARNINGS/ADVISORIES
WY...NONE.
NE...NONE.
SHORT TERM...MAC
LONG TERM...SF
AVIATION...MAC
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