090
FXUS65 KBYZ 141929
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
129 PM MDT TUE OCT 14 2025
KEY MESSAGES
- AREAS OF LOW CLOUDS AND FOG CONTINUE INTO WEDNESDAY.
- PRECIPITATION CHANCES INCREASE LATE TONIGHT AND WEDNESDAY;
WIDESPREAD LOWER ELEVATION RAIN AND MOUNTAIN SNOW WEDNESDAY
NIGHT TO THURSDAY EVENING; SNOW LEVELS AROUND 6500 FEET.
- BREEZY WITH SCATTERED SHOWERS FRIDAY AND SATURDAY.
- DRY AND WARMER SUNDAY, BUT ANOTHER PACIFIC SYSTEM ARRIVES NEXT
MONDAY/TUESDAY.
DISCUSSION
FOG & STRATUS WILL CONTINUE TO BE AN ISSUE (ESPECIALLY ALONG
WESTERN UPSLOPE AREAS) THROUGH TONIGHT AND MUCH OF WEDNESDAY,
THOUGH THE INCREASING POTENTIAL FOR SHOWERS WILL HELP TO MIX THE
BOUNDARY LAYER AND THUS FOG/STRATUS COVERAGE SHOULD LESSEN OVER
TIME. THAT SAID, THE DEPTH OF MOISTURE MAY SUPPORT PERIODS OF
DRIZZLE IN WESTERN UPSLOPE AREAS AGAIN TONIGHT. IT LOOKS AS IF
SURFACE TEMPS SHOULD STAY WARM ENOUGH TO AVOID ANY FREEZING
PRECIP, BUT THIS WILL OBVIOUSLY NEED TO BE MONITORED.
SATELLITE IMAGERY SHOWS A DEEP LOW OVER CENTRAL CA, WITH SOUTHERLY
FLOW EXTENDING INTO OUR REGION. THIS LOW WILL MOVE INTO THE GREAT
BASIN TONIGHT/TOMORROW. ONE SHORTWAVE IS LIFTING NORTH OF US
CURRENTLY AND ANOTHER IS EXPECTED TO ARRIVE TONIGHT. MODELS SHOW
ANOTHER PERIOD OF WARM FRONTAL PRECIP LATE TONIGHT INTO EARLY
WEDNESDAY, BUT THE GREATER POTENTIAL ARRIVES LATER WEDNESDAY AS
THE AFOREMENTIONED LOW LIFTS TO NEAR THE ID/WY BORDER. THERE MAY
EVEN BE ENOUGH ELEVATED INSTABILITY FOR EMBEDDED T-STORMS
WEDNESDAY EVENING. TEMPS TOMORROW WILL AGAIN STRUGGLE TO REACH
MOST GUIDANCE PER THE PERSISTENT UPSLOPE WINDS AND LOW CLOUD
COVER. LOOK FOR LOWS TONIGHT IN THE 30S AND HIGHS WEDNESDAY FROM
40F TO 60F, COOLEST ALONG THE WESTERN FOOTHILLS.
LATE WEDNESDAY THROUGH THURSDAY NIGHT IS THE MAIN PERIOD TO WATCH
FOR PRECIP WITH THIS UPCOMING SYSTEM, BUT MUST CONTINUE TO STRESS
UNCERTAINTIES WITH THE EVOLUTION OF THE MID LEVEL LOW, AND
RESULTANT PRECIP COVERAGE/MAGNITUDE. THE GFS AND ITS ENSEMBLES
CONTINUE TO BE DRIER OVERALL, A RESULT OF THE LOW SPLITTING WITH
ENERGY LIFTING TO OUR NORTH WEDNESDAY NIGHT ALLOWING FOR DRY
SLOTTING IN OUR EAST, AND LESS PRECIP ON THE BACK SIDE OF THE
SYSTEM THURSDAY. THE EC/GEM AND ENSEMBLES ARE SUGGESTIVE OF A MORE
CONSOLIDATED LOW, AND PRECIP OF HIGHER AMOUNTS AND LONGER
DURATION (TROWAL PERHAPS LINGERING INTO EARLY FRIDAY). THESE
DETAILS NEED TO BE WORKED OUT YET, BUT HERE'S WHAT WE CAN SAY WITH
CONFIDENCE: (1) THIS IS A SEASONABLY WARM SYSTEM AND SNOW ACCUMS
WILL REMAIN IN THE MOUNTAINS; (2) ALL LOWER ELEVATIONS WILL SEE
SOME RAIN...A 75-85% CHANCE OF AT LEAST 0.25". (3) COOL TEMPS
LINGER THROUGH THURSDAY. AS FOR THE PRECIP UNCERTAINTY, IF WE ARE
IMPACTED BY A MORE ORGANIZED LOW (WHICH IS IMPOSSIBLE TO SAY AT
THIS TIME) AN INCH OR MORE IS NOT OUT OF THE QUESTION. CURRENT NBM
PROBABILITIES SHOW A 15-40% CHANCE OF 1+ INCHES OF PRECIP,
GREATEST IN NORTH CENTRAL AND NORTHEAST PARTS, WHICH IS WHERE
TROWAL-INDUCED PRECIP COULD LAST INTO FRIDAY. REGARDING MOUNTAIN
SNOWFALL, THIS LOOKS LIKE A 5-10" EVENT FOR THE BEARTOOTH-ABSAROKA
AND CRAZY MOUNTAINS, AND MUCH LESS FOR THE BIGHORNS. THE CHANCES
OF 12+ INCHES IN THE BEARTOOTHS IS ABOUT 25%. NEEDLESS TO SAY,
ANYONE CONSIDERING VENTURING INTO THE HIGH COUNTRY WED/THU SHOULD
TAKE HEED.
AS THIS LOW EXITS WE WILL SEE ANOTHER PACIFIC SHORTWAVE OR TWO
EMERGE FROM A DEVELOPING NW FLOW ALOFT. THIS SHOULD BRING
SCATTERED SHOWERS FRIDAY INTO SATURDAY, AND A BREEZY W-NW WINDS
EACH OF THESE DAYS. THESE WILL BE MIXED WINDS AND STRONGEST OVER
OUR EAST. GUSTS IN EXCESS OF 40 MPH ARE LIKELY (>60% CHANCE).
WITH CONFIDENCE, SATURDAY NIGHT AND SUNDAY WILL BE DRY DAYS WITH
LESS WIND, AS WE SEE A PERIOD OF UPPER LEVEL RIDGING. LOOK FOR
TEMPS BACK TO THE 60S TO NEAR 70F ON SUNDAY.
MONDAY & TUESDAY: THOUGH DETAILS ARE SKETCHY SO FAR OUT,
OVERWHELMING ENSEMBLE CONSENSUS SHOWS ANOTHER PACIFIC TROF MOVING
THROUGH THE INTERMOUNTAIN WEST IN SOME FASHION EARLY NEXT WEEK.
THIS SHOULD BRING ANOTHER COOL DOWN AND INCREASING CHANCES OF MORE
PRECIPITATION, INCLUDING SNOW ACCUMULATIONS FOR THE MOUNTAINS.
P-TYPE AT LOWER ELEVATIONS IS IN QUESTION BUT THE PACIFIC FLOW
WILL NOT ALLOW ANY CANADIAN COLD, WHICH BECOMES CLIMATOLOGICALLY
MORE LIKELY AS WE MOVE THRU THE SECOND HALF OF OCTOBER.
JKL
AVIATION
A COMBINATION OF LOW STRATUS AND FOG WILL CONTINUE TO IMPACT
LOCATIONS WEST OF ROSEBUD COUNTY, ESPECIALLY ALONG THE EASTERN
SLOPES OF THE MOUNTAINS WHERE THERE COULD BE PATCHY DRIZZLE,
TONIGHT INTO WEDNESDAY. EXPECT MVFR TO LIFR FLIGHT CONDITIONS.
POTENTIAL FOR FOG & STRATUS WILL EXPAND TO EASTERN AREAS BEGINNING
LATE TONIGHT. EASTERN SLOPES OF THE MOUNTAINS WILL REMAIN
OBSCURED THROUGH THE PERIOD, WHILE TOPS ARE PERIODICALLY OBSCURED
IN LIGHT RAIN/SNOW SHOWERS. REGARDING PRECIPITATION, SCATTERED
LIGHT SHOWERS TONIGHT WILL BECOME MORE NUMEROUS TOMORROW. JKL
PRELIMINARY POINT TEMP/POPS
WED THU FRI SAT SUN MON TUE
-----------------------------------------------------------
BIL 036/047 042/050 041/060 038/056 040/066 042/056 035/051
54/W 79/R 51/B 31/U 11/B 44/W 42/W
LVM 032/045 034/049 031/057 031/057 035/065 034/055 028/048
65/W 88/R 42/W 31/B 12/W 56/W 42/W
HDN 033/049 040/049 039/060 036/056 034/068 039/058 033/052
56/W 89/R 72/W 32/W 11/B 44/W 52/W
MLS 038/057 044/053 040/058 036/056 033/066 039/059 034/053
46/W 99/R 73/W 21/U 00/U 22/W 32/W
4BQ 039/060 044/051 040/057 036/053 035/066 039/061 035/052
35/W 88/R 52/W 21/U 00/U 22/W 32/W
BHK 038/054 041/053 037/056 031/055 028/063 034/060 032/054
24/W 98/R 64/W 20/N 00/U 21/B 22/W
SHR 034/049 038/049 033/059 031/054 030/069 034/059 028/050
35/T 89/R 62/W 42/W 01/U 34/W 53/W
BYZ WATCHES/WARNINGS/ADVISORIES
MT...NONE.
WY...NONE.
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