398
FXUS65 KBYZ 130656
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
1256 AM MDT TUE OCT 13 2026
KEY MESSAGES
- OCCASIONAL PRECIPITATION (LIGHT RAIN/SNOW AND DRIZZLE) OVER
SOUTHERN MONTANA INTO WYOMING INTO THIS AFTERNOON.
- LOW TEMPERATURES NEAR TO BELOW FREEZING CONTINUE THIS WEEK,
COLDEST WHERE SNOW REMAINS ON THE GROUND.
- SLIGHT CHANCE OF PRECIPITATION IN FAR SOUTHEAST MONTANA LATE
WEDNESDAY INTO EARLY THURSDAY.
- CONDITIONS TREND WARMER AND DRIER FRIDAY INTO THE WEEKEND.
DISCUSSION
THROUGH MONDAY...
UPPER TROUGHING OVER THE WESTERN US AND AN ASSOCIATED LOW CENTERED
OVER NORTHERN NEVADA WAS KEEPING DIFFLUENT FLOW OVER THE REGION.
A WEAK WAVE MOVING NORTH INTO THE AREA FROM THE SOUTH WILL BRING
RAIN/SNOW SHOWERS (20-50% CHANCE) AND SOME DRIZZLE/FLURRIES
OVERNIGHT INTO THE MORNING HOURS, LINGERING OVER SOUTHEAST MT INTO
THE AFTERNOON. WHILE THE CHANCE REMAINS LOW (LESS THAN 20%),
POCKETS OF FREEZING DRIZZLE CANNOT BE RULED OUT AROUND THE BIGHORN
AND PRYOR MOUNTAINS INTO THE MORNING HOURS, BUT WARMER GROUNDS
SHOULD LIMIT THIS THREAT. THIS COULD (LOW CHANCE) IMPACT TRAVEL
ALONG HIGHWAY 14 THROUGH THE BIGHORN MOUNTAINS. ANY RAIN OR SNOW
AMOUNTS WILL BE LIGHT. WITH THE RECENT MOISTURE, PATCHY TO AREAS
OF FOG CAN BE EXPECTED INTO THE MORNING HOURS, WITH LOCALLY DENSE
FOG POSSIBLE IN SPOTS. OTHERWISE, EXPECT HIGHS IN THE 50S TODAY
WITH CLOUDS CLEARING FROM THE NORTHWEST TO SOUTHEAST. FOG IS
POSSIBLE OVER PORTIONS OF THE AREA YET AGAIN TONIGHT INTO
WEDNESDAY MORNING. LOWS TONIGHT IN THE 20S TO LOWER 30S ARE
FORECAST.
AS THE AFOREMENTIONED LOW TRACKS EAST INTO THE CENTRAL ROCKIES, AN
ASSOCIATED WAVE LIFTING NORTH AND EAST THROUGH WYOMING LOOKS TO
BRING SHOWERS TO THE FAR SOUTHEAST WEDNESDAY AFTERNOON AND
EVENING. BEHIND THE WAVE, A DRY COLD FRONT ASSOCIATED WITH A LOW
NEAR HUDSON BAY LOOKS TO MOVE THROUGH THE AREA ON THURSDAY,
BRINGING BREEZY NORTHWEST WINDS INTO THE 20S MPH FOR MOST AREAS,
WITH POTENTIAL FOR GUSTS INTO THE 30S MPH OVER THE EAST. HIGH
PRESSURE BUILDING OVER THE REGION WILL BRING GENERALLY WARMER
CONDITIONS FOR THE WEEKEND INTO EARLY NEXT WEEK WITH HIGHS
INCREASING INTO THE 60S TO LOWER 70S. PRESSURE GRADIENTS LOOK TO
TIGHTEN ALONG THE WESTERN FOOTHILLS FRIDAY NIGHT INTO SATURDAY
MORNING, BRINGING THE POTENTIAL FOR INCREASED WINDS FROM
LIVINGSTON TO NYE. A WEAK FRONT CROSSES THE AREA BY SUNDAY
BRINGING AN END TO THE GAP WINDS. WARM CONDITIONS CONTINUE FOR
MONDAY. STP
AVIATION
06Z TAF/AVIATION DISCUSSION...MODELS ARE STRUGGLING A BIT WITH THE
STRATUS/FOG SITUATION TONIGHT, WHICH IS FURTHER COMPLICATED BY
RECENT SNOWFALL AND NEAR FREEZING TEMPERATURES WHICH MAY TURN FOG
FORMATION INTO FROST FORMATION TONIGHT. IN GENERAL EXPECT AREAS OF
FOG (IFR OR LOWER) AWAY FROM THE FOOTHILLS AND CONCENTRATED IN
RIVER VALLEYS, AND WIDESPREAD MVFR TO IFR CEILINGS ACROSS THE
AREA TONIGHT.
THAT SAID, THE RRFS AND AVNFPS CLIMATE TRENDS ARE SHOWING A
STRONG SIGNAL FOR KBIL TO GO LIFR OR LOWER WITH FOG THIS MORNING,
SO HAVE A TEMPO IN FOR HALF A MILE AND 300FT CEILING 10Z-14Z IN
THE LATEST TAFS THERE. RESEARCH SHOWS A HIGH CORRELATION BETWEEN
SIGNIFICANT PRECIPITATION IN THE PAST 24 HOURS, 5KFT OF LIGHT
WINDS ALOFT, AND TEMPERATURES NEAR FREEZING FOR KBIL FOG
DEVELOPMENT, AND ALL OF THESE ARE PRESENT TONIGHT.
ELSEWHERE, THE SIGNALS ARE LESS WELL DEFINED FOR FOG AND IN KLVM
AND KMLS MUCH OF THE GUIDANCE WANTS TO DISSIPATE THE MVFR/IFR
STRATUS DECK OVERNIGHT. THAT SEEMS UNLIKELY FOR MOST LOCATIONS
GIVEN THE LACK OF WINDS ALOFT AND WITH THE MID LEVEL DECK
INSULATING A GOOD PORTION OF THE FORECAST AREA.
KEPT THE STRATUS IN PLACE FOR KMLS ALONG WITH A VCFG MENTION, AND
IF FOG DOES DEVELOP IT WILL LIKELY GO LIFR OR LOWER QUICKLY. FOR
KLVM SCATTERED OUT THE STRATUS BUT DIDN'T COMPLETELY REMOVE IT AS
DRAINAGE WINDS OFF THE SURROUNDING MOUNTAIN SNOWPACK IS DRYING OUT
THE VALLEY THERE, HOWEVER DID KEEP A VCFG AND A 300FT DECK IN THE
FORECAST IN CASE THE WINDS DIE OFF FOR A TIME OVERNIGHT. AT KSHR
THERE IS A CHANCE FOR LIGHT PRECIPITATION OVERNIGHT AND INTO EARLY
AFTERNOON AS MID LEVEL ENERGY MOVES INTO THAT AREA FROM THE
SOUTH. THIS SHOULD KEEP FOG FROM DEVELOPING, BUT A STRATUS DECK
BETWEEN 800-1200FT AGL LOOKS TO STICK AROUND THROUGH MID MORNING
BEFORE SLOWLY RISING DURING THE REST OF THE DAY TUESDAY.
OUTSIDE OF THE TAF LOCATIONS, ANY FOG SHOULD LIFT/DISSIPATE 16-18Z
TOMORROW MORNING WITH STRATUS LIFTING/BREAKING UP MID DAY INTO THE
AFTERNOON HOURS ACROSS THE NORTHERN TIER OF THE FORECAST AREA. ISOLATED
LIGHT SHOWERS AND STRATUS WILL CONTINUE ALONG THE SOUTHERN BORDER
AREAS TOMORROW UNTIL 22Z OR SO, WITH IMPROVEMENT INTO THE EVENING
HOURS. WITH MORE CLEARING TOMORROW EVENING, EXPECT STRATUS/FOG
DEVELOPMENT TO BE POSSIBLE ONCE AGAIN GOING INTO WEDNESDAY
MORNING OVER CENTRAL AND EASTERN AREAS. CHAMBERS
PRELIMINARY POINT TEMP/POPS
TDY WED THU FRI SAT SUN MON
-------------------------------------------------------
BIL 053 030/059 039/060 036/069 046/074 045/069 044/073
0/B 00/U 00/U 00/U 00/U 00/B 00/U
LVM 049 022/054 028/061 029/072 036/074 037/071 037/074
0/B 00/U 00/U 00/U 00/N 00/U 00/U
HDN 054 028/060 034/062 032/071 035/076 038/071 037/075
2/W 00/B 00/U 00/U 00/U 00/U 00/U
MLS 053 029/058 036/058 030/068 038/074 042/069 041/073
0/B 00/B 00/U 00/U 00/U 00/U 00/U
4BQ 052 032/059 041/060 031/070 042/076 045/071 044/075
2/W 00/B 10/U 00/U 00/U 00/U 00/U
BHK 053 027/059 033/059 025/067 038/077 041/071 038/075
0/B 00/B 00/N 00/U 00/U 00/U 00/U
SHR 052 028/058 034/060 028/070 034/076 037/071 036/075
3/W 10/B 20/U 00/U 00/U 00/U 00/U
BYZ WATCHES/WARNINGS/ADVISORIES
MT...NONE.
WY...NONE.
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