020
FXUS65 KBYZ 060120
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
720 PM MDT MON MAY 5 2025
KEY MESSAGES
- COOL AND WET CONDITIONS CONTINUE ACROSS THE AREA THROUGH
TUESDAY. SEVERAL INCHES OF SNOW CAN BE EXPECTED IN THE
MOUNTAINS, WITH WET SNOWFALL ACCUMULATIONS ON GRASSY SURFACES
ALONG THE FOOTHILLS.
- DRIER AND WARMER CONDITIONS WILL RETURN FOR THE SECOND HALF OF
THE WEEK. ISOLATED SHOWERS AND THUNDERSTORMS EXPECTED THURSDAY
AND FRIDAY.
UPDATE
SATELLITE IMAGERY SHOWS WEAK TROF DROPPING FROM WESTERN MT INTO
CENTRAL ID (ASSOCIATED WITH A MODEST 70KT H3 NORTHERLY JET) WHILE
AN EXTENDED SOUTHERLY FLOW REMAINS FROM NM TO SOUTHEAST MT.
DIFFLUENCE W/ UPSLOPE WINDS CONTINUES TO PRODUCE WIDESPREAD PRECIP
OVER THE WEST HALF OF OUR FORECAST AREA, IN THE FORM OF LOWER
ELEVATION RAIN AND MOUNTAINS/FOOTHILLS SNOW (SNOW LEVEL IS NEAR
4500FT). IN THE EAST, THERE IS ENERGY LIFTING OUT OF EASTERN WY
THAT IS SPREADING RAIN INTO SHERIDAN/BIG HORN COUNTIES AND FAR
SOUTHEAST MT. IN FACT, AN ENHANCED AREA OF RAIN IS APPROACHING
BILLINGS FROM THE SOUTHEAST AS OF 01Z. RAIN IS FALLING AT
SHERIDAN, WITH A TEMP OF 38F, BUT WEB CAMERAS SHOW SOME SNOW AT
BURGESS JUNCTION. ALL WINTER HIGHLIGHTS LOOK GOOD AND WILL MAKE NO
CHANGES AT THIS TIME. SNOW LEVELS DEFINITELY FELL FARTHER/QUICKER
THAN PREVIOUSLY THOUGHT, BUT ALL HIGHWAYS ACROSS OUR WEST ARE WET.
THE EXCEPTION IS BOZEMAN PASS WHICH LOOKS VERY SNOWY AND HAS
RECENTLY BEEN CLOSED BY MT-DOT. MONITOR THEIR WEBSITE OR CALL 511
FOR ROAD CONDITIONS IF YOU ARE PLANNING TO TRAVEL WEST ON I-90.
FORECAST IS IN GOOD SHAPE, BUT HAVE RAISED POPS AND LOWERED SNOW
LEVELS A BIT PER CURRENT TRENDS. WE ARE STARTING TO SEE PRECIP
BECOME LIGHTER IN OUR NORTH, AS EXPECTED, BUT THE REMAINING AREAS
WILL SEE PRECIP CONTINUE FOR MUCH OF THE NIGHT INTO TUESDAY
MORNING PER THE AFOREMENTIONED ENERGY FROM THE SOUTH AND CONTINUED
UPSLOPING.
OBSERVED 24-HR PRECIP HAS ALREADY EXCEEDED AN INCH AT FISHTAIL,
BIG TIMBER, MELVILLE AND JUST EAST OF HARLOWTON. PLACER BASIN
SNOTEL HAS PICKED UP 0.70" OF SWE, WITH 0.50" AT COLE CREEK. A
GOOD DRINK OF WATER.
JKL
DISCUSSION
REST OF TODAY THROUGH WEDNESDAY NIGHT...
UPPER SHORTWAVE AND TROUGH IS SLOWLY DROPPING THROUGH THE REGION
TODAY. SHOWERS AND MOUNTAIN/FOOTHILL SNOW WILL CONTINUE TO
SPREAD SOUTH AND EASTWARD INTO THIS EVENING. THE WINTER STORM
WARNING FOR THE ABSAROKA/BEARTOOTHS REMAINS IN EFFECT UNTIL NOON
TUESDAY. WITH UPSLOPE FLOW FAVORING NORTH-NORTHEAST FACING
SLOPES, MUCH LESS SNOWFALL IS FORECAST AROUND COOKE CITY (UP TO 3
INCHES POSSIBLE). THE CURRENT FORECAST HAS ADDITIONAL SNOWFALL OF
8-14 INCHES FOR FAVORED SLOPES.
COOLER TEMPERATURES (OVERNIGHT LOWS IN THE 20S AND 30S) AND
DECREASING SNOW LEVELS WILL BRING ACCUMULATING SNOW TO THE
BEARTOOTH/RED LODGE FOOTHILLS THIS EVENING. AS A RESULT, WINTER
WEATHER ADVISORIES WILL GO INTO EFFECT AT 6 PM, WITH 2-5 INCHES OF
SNOWFALL EXPECTED. A WINTER WEATHER ADVISORY WILL ALSO GO INTO
EFFECT AT 3 PM TODAY FOR THE BIGHORN MOUNTAINS. TOTAL SNOW AMOUNTS
OF 5-10 INCHES ARE FORECAST. THOSE TRAVELING ON HIGHWAY 14 SHOULD
EXPECT ADVERSE CONDITIONS WITH FALLING AND ACCUMULATING SNOW.
THE AFOREMENTIONED TROUGH WILL BEGIN TO FORM A LOW AND BEGIN
PHASING WITH ANOTHER LOW NEAR THE FOUR CORNERS REGION TONIGHT. AS
THIS OCCURS, ANOTHER PUSH OF PRECIPITATION WILL COME UP FROM THE
SOUTHEAST LATE TONIGHT. THIS PUSH WILL BRING A MODERATE TO HIGH
CHANCE (50-80%) FOR PRECIPITATION IN THE FAR EAST WHERE POPS ARE
FORECAST TO BE LOWEST THIS EVENING. TOTAL LIQUID PRECIPITATION
AMOUNTS ACROSS THE FORECAST AREA THROUGH TUESDAY RANGE FROM 0.1"
IN THE NORTH AND EAST, TO OVER AN INCH IN THE MOUNTAINS AND
FOOTHILLS.
SPLIT FLOW PATTERN TAKES PLACE AS THE PHASING LOW MOVES THROUGH
THE SOUTHERN PLAINS. UPPER LEVEL RIDGING BEGINS TO BUILD INTO THE
NORTHERN ROCKIES ON WEDNESDAY, BRINGING WARM AND DRY CONDITIONS.
HIGHS ON TUESDAY WILL BE IN THE 40S AND 50S WHILE WEDNESDAY WILL
SEE TEMPS CLIMB BACK INTO THE 70SF.
MATOS
THURSDAY THROUGH MONDAY...
EXTENDED FORECAST REMAINS SPRING-LIKE WITH ONLY FRIDAY AND
SATURDAY LOOKING MAINLY DRY. FOR THE REST OF THE EXTENDED THERE
ARE DECENT (30 TO 50%) CHANCES FOR SHOWERS AND THUNDERSTORM EACH
DAY, MAINLY OF THE AFTERNOON AND EVENING VARIETY, ESPECIALLY FOR
THE WESTERN MOUNTAINS AND FOOTHILLS. THE DIFFERENCE BETWEEN THIS
EXTENDED PERIOD AND THE PAST WEEK OR SO WILL BE LESS OF A ROLLER
COASTER OF TEMPERATURES AND WARMER TEMPERATURES OVERALL.
SYNOPTIC PATTERN STARTS OUT ZONAL ON THURSDAY WITH A SHORTWAVE
TROF QUICKLY MOVING OFF THE WEST COAST AND INTO THE AREA. THIS
SHOULD BRING A CHANCE FOR SHOWERS AND THUNDERSTORMS THURSDAY
AFTERNOON THROUGH MUCH OF THURSDAY NIGHT. HIGHS WILL BE NEAR 80 THURSDAY
AHEAD OF THE SHORTWAVE.
RIDGING BUILDS IN BEHIND THE SHORTWAVE FOR FRIDAY AND SATURDAY FOR
DRY CONDITIONS WITH PLENTY OF SUN. HIGHS IN THE MID 70S FRIDAY
CLIMB TO THE MID 80S FOR SATURDAY.
BACK SIDE OF THE RIDGE BRINGS UNSTABLE SOUTHWEST FLOW TO THE AREA
SUNDAY. TEMPERATURE FORECASTS ARE WELL INTO THE MID TO EVEN UPPER
80S SUNDAY AFTERNOON. THIS WILL HELP FUEL SCATTERED SHOWERS AND
THUNDERSTORMS IN THE AFTERNOON AND EVENING AS A SHORTWAVE
DISTURBANCE RIDES THAT SOUTHWEST FLOW OVER THE WESTERN MOUNTAINS
AND INTO THE PLAINS. THIS IS A PATTERN FOR STRONGER THUNDERSTORMS
THIS TIME OF YEAR, BUT WILL DEPEND ON WHETHER GULF MOISTURE CAN
MAKE IT INTO THE AREA. RIGHT NOW MODELS SEEM TO BE LIMITING THE
LOW LEVEL MOISTURE AND LEANING ON MID-LEVELS TO GENERATE
CONVECTION. WILL KEEP AN EYE ON THIS PERIOD GOING FORWARD.
MONDAY SEES FALLING HEIGHTS ALOFT AND UNSETTLED CONDITIONS TAKING
HOLD AS A BROAD WEST COAST TROF DIGS INTO THE GREAT BASIN AND
DESERT SOUTHWEST. BROAD DIFFLUENT SOUTHERLY FLOW OVER THE AREA
WILL BE A GOOD SETUP FOR WIDESPREAD SHOWER AND THUNDERSTORM
ACTIVITY. TEMPERATURES TREND 5 TO 10 DEGREES COOLER THAN SUNDAY
FOR MONDAY AFTERNOON. CHAMBERS
AVIATION
STORM SYSTEM WILL SPREAD MVFR CONDITIONS EASTWARD THIS AFTERNOON
INTO THIS EVENING WITH OCCASIONAL IFR CONDITIONS NEAR MORE
PERSISTENT PRECIPITATION. AS THE EVENING PROGRESSES WILL SEE MORE
FREQUENT IFR OR LOWER CONDITIONS, ESPECIALLY ALONG AND WEST OF A
KSHR TO KBIL LINE. AREA FOOTHILLS INCLUDING KSHR AND KLVM WILL GET
SOCKED IN WITH LOW STRATUS/RAIN AND SNOW/AND DEVELOPING UPSLOPE
FOG. EXPECT CEILINGS UNDER 1000 FEET AGL TO BECOME PREDOMINANT BY
SUNSET, WITH CEILINGS UNDER 500 FEET AGL TO DEVELOP BY LATE
EVENING INTO THE OVERNIGHT HOURS. MOUNTAINS AND PASSES WILL BE
OBSCURED THROUGH THE PERIOD. THE HOURS AROUND SUNRISE TOMORROW ARE
LOOKING LIFR IN MANY AREAS AS AN ADDITIONAL AREA OF PRECIPITATION
ARRIVES AND UPSLOPE WINDS GENERATE INCREASED FOG POTENTIAL.
CHAMBERS
PRELIMINARY POINT TEMP/POPS
TUE WED THU FRI SAT SUN MON
-----------------------------------------------------------
BIL 037/049 036/072 050/079 050/076 050/085 055/085 054/079
+5/R 00/U 02/T 51/U 01/U 13/T 44/T
LVM 032/047 034/069 045/075 045/076 046/083 051/079 047/072
+4/O 01/U 03/T 41/U 01/B 25/T 55/T
HDN 037/051 035/074 044/080 049/077 049/086 052/086 052/081
+7/R 11/U 02/W 51/U 01/U 13/T 44/T
MLS 041/055 041/075 051/080 052/076 049/086 056/087 055/082
85/R 10/B 01/U 51/U 00/U 12/W 43/T
4BQ 040/052 040/071 050/076 051/074 049/083 057/085 055/082
97/R 11/B 00/U 31/U 00/U 01/U 32/T
BHK 040/056 040/072 047/079 048/076 046/083 052/086 052/084
84/R 00/B 00/U 41/U 00/U 11/U 31/B
SHR 032/046 035/069 039/075 045/075 046/084 049/085 049/081
+8/R 21/B 02/W 32/T 11/U 13/T 44/T
BYZ WATCHES/WARNINGS/ADVISORIES
MT...WINTER WEATHER ADVISORY IN EFFECT UNTIL NOON MDT TUESDAY FOR
ZONES 56-66-171.
WINTER STORM WARNING IN EFFECT UNTIL NOON MDT TUESDAY FOR
ZONE 67.
WY...WINTER WEATHER ADVISORY IN EFFECT UNTIL NOON MDT TUESDAY FOR
ZONE 198.
WEATHER.GOV/BILLINGS
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