888
FXUS65 KBYZ 282139
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
339 PM MDT FRI MAR 28 2025
KEY MESSAGES
- COOLER & WETTER THROUGH THE WEEKEND, WITH AREAS OF RAIN AND WET
SNOW; GREATEST POTENTIAL FOR SNOW ACCUMULATION AT LOWER
ELEVATIONS IS SATURDAY NIGHT AND SUNDAY.
- UNSETTLED CONDITIONS ARE FORECAST TO PERSIST THROUGH NEXT WEEK
WITH MULTIPLE ROUNDS OF PRECIPITATION. THERE IS A MEDIUM CHANCE
(25-50%) FOR GREATER THAN 0.25 INCHES TUESDAY/WEDNESDAY.
DISCUSSION
THROUGH SATURDAY NIGHT...
SATELLITE IMAGERY SHOWS CLEAR SKIES ACROSS MUCH OF THE FORECAST
AREA. MORNING PRECIP IN OUR EAST HAS EXITED, BUT THERE REMAINS AN
AREA OF SLOWLY-DISSIPATING LOW CLOUDS EAST OF MILES CITY AND
BROADUS. TO THE WEST, WE ARE SEEING SHALLOW CONVECTION DEVELOP
WEST OF A BACKDOOR COLD FRONT, WHICH REACHED REED POINT THIS
MORNING BUT HAS SINCE STALLED. IN FACT, THE FRONTAL BOUNDARY SEEMS
TO BE A FOCUS FOR THE WEAK CONVECTION. PLACES LIKE HARLOWTON, BIG
TIMBER AND LIVINGSTON SHOULD SEE A FEW RAIN SHOWERS BETWEEN NOW
AND SUNSET.
BY THIS EVENING, THE FRONT SHOULD BACK ALL THE WAY TO OUR WESTERN
FOOTHILLS. AN APPROACHING SHORTWAVE, CURRENTLY OVER THE NORTHERN
GREAT BASIN, WILL LIFT THRU CENTRAL MT TONIGHT. AS THIS HAPPENS,
THE COMBINATION OF ASCENT WITH DEEPENING EAST WINDS SHOULD BRING A
PERIOD OF RAIN TO WET SNOW ESPECIALLY ON THE EAST SIDE OF THE
CRAZY MOUNTAINS. SNOW IN THE MOUNTAINS WILL CONTINUE THROUGH THE
WEEKEND AND HAVE ISSUED A WINTER STORM WARNING FOR THE CRAZIES
FROM 00Z THIS EVENING THROUGH SUNDAY. FOR THE MELVILLE FOOTHILLS,
HAVE ISSUED A WINTER WEATHER ADVISORY FROM 00Z TO 15Z SATURDAY
MORNING, AS TRAVEL ON US-191 MAY BE IMPACTED BY SOME SLUSHY
CONDITIONS AS RAIN CHANGES TO WET SNOW (SNOW LEVELS EXPECTED TO
FALL TO NEAR ~4500' TONIGHT, ABOVE THE MUSSELSHELL & YELLOWSTONE
VALLEYS THEMSELVES).
A WAVE FURTHER SOUTH OVER THE SOUTHERN GREAT BASIN WILL ALSO LIFT
TO THE NORTHEAST, EVENTUALLY TRACKING THRU WY/NE/SD, BRINGING SOME
RAIN AND WET SNOW TO SHERIDAN AND SOUTHEAST MT LATE TONIGHT AND
TOMORROW. SURFACE TEMPS AT SHERIDAN LOOK WARM ENOUGH TO KEEP
PRECIP TYPE AS RAIN (AT LEAST INITIALLY), BUT AIR MASS WILL BE
COLDER FURTHER NORTH, AND THE HIGHER HILLS OF SOUTHEAST MT SHOULD
SEE A LITTLE WET SNOW (AN INCH OR LESS ABOVE 3500').
THE OTHER ISSUE WILL BE STRATUS/FOG AS BOUNDARY LAYER MOISTURE
INCREASES W/ THE EASTERLY FLOW. THERE IS UNCERTAINTY HERE, AS
THERE ALWAYS IS WITH STRATUS & FOG, BUT AS IT APPEARS NOW THE
GREATEST POTENTIAL FOR FOG WILL BE ALONG UPSLOPE AREAS WEST OF
BILLINGS, WHILE STRATUS IS THE BETTER BET FOR THE REMAINING LOWER
ELEVATIONS. ALL OF THIS WILL NEED TO BE MONITORED, OF COURSE.
TEMPERATURES TODAY ARE MUCH COOLER THAN LAST NIGHT'S GUIDANCE, PER
THE BACKDOOR COOLING. TONIGHT WILL BE A COOLER NIGHT AND SATURDAY
WILL BE COOLER THAN TODAY. LOOK FOR HIGHS TOMORROW IN THE UPPER
30S TO MID 40S MOST PLACES.
NEXT STRONGER WAVE CURRENTLY OFF THE PACIFIC COAST WILL MOVE
INLAND AND PROVIDE ASCENT FOR ANOTHER PERIOD OF PRECIP BEGINNING
SATURDAY NIGHT AND LASTING THRU SUNDAY. THE AIR MASS WILL BE
COOLER AND EASTERLY WINDS WILL REMAIN, SO THERE IS POTENTIAL FOR
SOME WET SNOW TO ACCUMULATE CLOSE TO THE FOOTHILLS.
AFTER THURSDAY'S HOT DAY, WE ARE HEADING INTO A COUPLE DAYS OF
MUCH COOLER TEMPERATURES.
JKL
SUNDAY THROUGH FRIDAY...
ANOTHER TROUGH MOVES IN OFF THE PACIFIC LATE MONDAY INTO EARLY
TUESDAY WHICH WILL BE OUR NEXT CHANCE FOR PRECIPITATION. MODELS
HAVE COME INTO BETTER AGREEMENT WITH THE AMOUNT OF PRECIP FOR
MUCH OF THE AREA. THE ECMWF ENSEMBLE HAS BILLINGS RECEIVING
BETWEEN 0.3-0.4" QPF WITH THIS NEXT SYSTEM WITH THE NBM SHOWING A
40% CHANCE OF >0.25". WITH TEMPS JUST A TOUCH BELOW AVERAGE (HIGH
40'S OUTSIDE THE MOUNTAINS) ACROSS THE REGION SNOW SHOULD BE
PRIMARILY CONFINED TO THE HIGHER HILLS AND MOUNTAINS YET AGAIN.
MOUNTAIN TOPS SHOULD BE ABLE TO PICK UP ANOTHER FOOT WITH THIS
SYSTEM ADDING TO THE ALREADY HEALTHY SNOWPACK.
AS TEMPS SLOWLY WARM THROUGH THE END OF THE WEEK ANOTHER SYSTEM IS
PROGGED TO MOVE THROUGH THE INTERMOUNTAIN WEST. THERE IS MINIMAL
AGREEMENT AT ALL IN THE AMPLITUDE, TIMING, AND OVERALL STRENGTH
OF THIS SYSTEM. THE ECMWF HAS A MUCH STRONGER TROUGH THAT DIGS
MUCH DEEPER THAN WHAT THE GFS SHOWS. ENSEMBLE MEMBERS FOR BOTH
MODELS ALSO SHOW A LARGE DISCREPANCY IN MOISTURE WITH THIS SYSTEM
AS WELL. WITH THE NBM 25TH TO 75TH HIGH TEMPERATURE RANGE BETWEEN
44 AND 63 FOR THE HIGH AT KBIL ON FRIDAY, P-TYPE AND SNOW LEVELS
ARE VERY MUCH A BIG QUESTION MARK AT THE MOMENT TOO.
IN SHORT; AN ACTIVE PATTERN WILL CONTINUE, HOWEVER, THERE REMAINS
HIGH UNCERTAINTY IN SPECIFICS, ESPECIALLY FURTHER OUT IN TIME.
WMR
AVIATION
FOR THE REMAINDER OF THE AFTERNOON, AN AREA OF MVFR CIGS FROM KMLS
TO KBHK SHOULD GRADUALLY DISSIPATE, BUT IT IS POSSIBLE SOME LOW
CLOUDS LINGER NEAR THE DAKOTAS BORDER INTO THE EVENING. OTHERWISE,
VFR WILL PREVAIL, WITH ISOLATED SHOWERS OVER THE WEST. MOUNTAINS
WILL BE OCCASIONALLY OBSCURED.
TONIGHT INTO SATURDAY, A WEATHER SYSTEM WILL BRING AREAS OF RAIN
AND WEST SNOW, MAINLY WEST OF KBIL TONIGHT, AND FROM KSHR ACROSS
SOUTHEAST MT LATE TONIGHT AND TOMORROW. IN ADDITION TO PRECIP, WE
EXPECT LOW CLOUDS TO INCREASE IN COVERAGE TONIGHT, WITH SOME FOG
ALSO POSSIBLE ESPECIALLY IN EAST WIND UPSLOPE AREAS (THOUGH THERE
REMAINS UNCERTAINTY HOW WIDESPREAD ALL OF THIS WILL BECOME). ALL
TAFS ARE EXPECTED TO BE IMPACTED BY MVFR/IFR BEGINNING LATE
TONIGHT. MOUNTAINS WILL BE OBSCURED.
JKL
PRELIMINARY POINT TEMP/POPS
SAT SUN MON TUE WED THU FRI
-----------------------------------------------------------
BIL 035/043 032/040 031/053 034/049 033/051 031/053 032/048
45/O 68/O 13/R 56/O 43/O 23/R 23/O
LVM 034/046 031/041 029/050 031/042 029/045 027/047 029/044
67/R 97/O 26/O 67/S 43/S 23/S 34/S
HDN 035/043 031/041 028/054 031/049 032/051 029/054 029/049
56/R 58/O 22/R 57/R 44/O 22/R 23/O
MLS 030/040 029/039 028/049 031/047 031/050 031/053 031/049
24/O 34/O 10/E 44/O 32/O 22/O 22/O
4BQ 034/039 029/037 028/046 030/046 030/046 029/051 030/049
37/O 55/S 21/E 45/O 43/O 22/O 22/O
BHK 025/039 023/038 023/045 026/044 026/046 025/051 027/048
16/S 43/S 20/B 35/O 43/O 12/S 22/O
SHR 035/042 030/038 024/051 027/046 027/045 023/050 024/046
88/R 69/O 22/R 47/O 55/S 23/O 24/O
BYZ WATCHES/WARNINGS/ADVISORIES
MT...WINTER STORM WARNING IN EFFECT UNTIL 6 PM MDT SUNDAY FOR ZONE
68.
WINTER WEATHER ADVISORY IN EFFECT UNTIL 9 AM MDT SATURDAY FOR
ZONE 172.
WY...NONE.
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