991
FXUS65 KBYZ 210639
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
1239 AM MDT TUE APR 21 2026
KEY MESSAGES
- HOT AND DRY INTO WEDNESDAY. ELEVATED FIRE WEATHER CONCERNS.
EXPECT RISES ON STREAMS AND RIVERS DUE TO MOUNTAIN SNOWMELT.
- IMPACTFUL WEATHER SYSTEM LIKELY LATE WEDNESDAY INTO FRIDAY. IMPACTS
INCLUDE STRONG WINDS, PRECIPITATION (RAIN AND SNOW), AND COOLER
TEMPERATURES.
- LATE WEEK WEATHER SYSTEM COULD IMPACT TRAVEL AND RECREATION.
HAZARDOUS COOL AND WET CONDITIONS COULD ALSO IMPACT YOUNG
LIVESTOCK.
DISCUSSION
TODAY THROUGH MONDAY...
ELEVATED FIRE CONCERNS CONTINUE INTO WEDNESDAY AS WARM AND MOSTLY
DRY CONDITIONS CONTINUE UNDER UPPER LEVEL RIDGING. HIGHS WILL BE
IN THE 70S TO UPPER 80S AND MINIMUM RELATIVE HUMIDITY IN THE TEENS
FOR MANY LOCATIONS TODAY AND WEDNESDAY. WINDS TODAY WILL BE BREEZY
AT TIMES WEST OF BILLINGS, WITH GUSTS OUT OF THE SOUTH TO
SOUTHWEST OF 25 TO 35 MPH. WEDNESDAY WILL SEE STRONGER, MORE
WIDESPREAD GUSTS AHEAD OF A SYSTEM MOVING IN LATE WEDNESDAY/EARLY
THURSDAY, WITH GUSTS OF 35 TO 50 MPH FROM BILLINGS WEST AND 25 TO
35 MPH ACROSS THE REST OF THE REGION. ONE LIMITING FACTOR FOR
GRASS FIRE CONCERNS IS THAT GREEN UP IS WELL UNDERWAY FOR SOME
LOCATIONS. REGARDLESS, TAKE CARE NOT TO CAUSE A SPARK!
ADDITIONALLY, WITH THESE ABOVE NORMAL TEMPERATURES, MOUNTAIN
SNOWMELT WILL INCREASE AND LEAD TO RISES ON STREAMS AND RIVERS,
ALTHOUGH NO FLOODING IS EXPECTED.
BEFORE THE NEXT SYSTEM, A SUBTLE WAVE ROUNDING THE RIDGE WILL
BRING SOME ELEVATED MOISTURE (PWATS 150-180% OF NORMAL OVER THE
WEST) INTO THE AREA LATE THIS AFTERNOON AND EVENING. WITH THIS, AN
ISOLATED SHOWER OR TWO IS POSSIBLE (10 TO 20 PERCENT CHANCE),
PARTICULARLY OVER THE MOUNTAINS, BUT VERY DRY AIR NEAR THE
SURFACE WILL LIMIT THE AMOUNT OF PRECIPITATION THAT MAKES IT TO
THE GROUND.
LATE WEDNESDAY THROUGH FRIDAY, A SPRING STORM SYSTEM WILL MOVE
THROUGH THE REGION, DROPPING HIGHS INTO THE 40S BY FRIDAY. MODELS
CONTINUE TO DISAGREE ON THE EXACT TRACK AND SPEED OF THIS SYSTEM,
BUT CONFIDENCE IS HIGH IN A CHANGE TO COOLER AND WETTER WEATHER.
THE FIRST OPTION FOR HOW THIS SYSTEM DEVELOPS IS A SLOWER TRACK
ACROSS THE REGION BEFORE THE UPPER LOW STALLS OVER NORTH DAKOTA,
WITH ENERGY WRAPPING AROUND AND CONTINUING PRECIP OVER THE CENTRAL
AND EASTERN PORTIONS OF THE REGION. THE RESULT OF THIS OPTION
WOULD BE THE HIGHEST PRECIP TOTALS FALLING NEAR THE DAKOTA BORDER
AND A LONGER PERIOD OF STRONG WINDS ON THURSDAY FROM BILLINGS
EAST. A SECOND OPTION IS A FASTER TRACK THAT LIFTS THE UPPER LOW
NORTHEAST INTO CANADA, WHICH WOULD BRING MORE PRECIP TO WESTERN
PORTIONS OF THE REGION (AND MUCH LESS TO EASTERN PORTIONS) AND
FAVOR THE MOUNTAINS AND FOOTHILLS AS ENERGY WRAPS AROUND THURSDAY
INTO FRIDAY. WINDS WOULD STILL BE STRONG WITH THE SECOND OPTION,
BUT DURING A SHORTER WINDOW. ONE AREA OF CONCERN IS EASTERN
MONTANA, WHERE DYNAMIC COOLING FROM THE LOW PRESSURE SYSTEM MAY
ALLOW RAIN TO SWITCH OVER TO SNOW MORE QUICKLY, AND WITH THE
STRONGER WINDS, MAY RESULT IN BLOWING SNOW IMPACTS.
CONSIDERING THE ABOVE OPTIONS, THERE IS CURRENTLY A 30-60% CHANCE
FOR A GUST GREATER THAN 60 MPH THURSDAY, HIGHEST OVER FAR EASTERN
MONTANA AND NORTH-CENTRAL WYOMING. FOR PRECIP, THERE IS A A
50-80% CHANCE OF AT LEAST 0.5" OVER THE MOUNTAINS, FOOTHILLS, AND
HIGHER HILLS, AND A 25-50% CHANCE OF THE SAME OVER THE PLAINS.
PRECIP WILL FALL AS ALL SNOW OVER THE MOUNTAINS, WITH A 60-80%
CHANCE OF AT LEAST 8". OVER THE PLAINS, PRECIP WILL BEGIN AS RAIN,
GRADUALLY SWITCHING TO SNOW. GIVEN DAYTIME HIGH TEMPS REMAINING
ABOVE FREEZING, LITTLE TO NO ACCUMULATING SNOW IS EXPECTED,
OUTSIDE OF THE HIGHER HILLS AND FOOTHILLS, AND WILL MOSTLY BE ON
GRASSY SURFACES.
INTO EARLY NEXT WEEK, CONDITIONS LOOK TO REMAIN COOLER AND
UNSETTLED, WITH HIGHS GENERALLY IN THE 40S AND 50S. ARCHER
AVIATION
WILDFIRE SMOKE FROM THE EAST FIRE (JUST SOUTH OF RED LODGE) IS
SPREADING EASTWARD WITH THE PREVAILING WINDS. OCCASIONAL
REDUCTIONS OF SLANT RANGE VISIBILITY ARE POSSIBLE NEAR SHERIDAN AS
A RESULT. OTHERWISE, VFR WILL PREVAIL ACROSS THE REGION UNDER
STRONG HIGH PRESSURE ALOFT. MIXED SW WINDS WILL GUST 25-35 KNOTS
AT KLVM TUESDAY AFTERNOON.
ISOLATED HIGH BASED CONVECTION IS BEGINNING TO SHOW UP THIS
EVENING, DEVELOPING OVER THE SOUTHERN MOUNTAINS AND MOVING NORTH
ACROSS THE WESTERN HALF OF THE FORECAST AREA THROUGH 07Z. MAIN
IMPACT FROM THIS ACTIVITY WILL BE THE POTENTIAL FOR ERRATIC
STRONGER WIND GUSTS OF 35 TO 45KTS NEAR ANY CELLS. THIS COULD
IMPACT KBIL/KSHR FROM 00Z-07Z THIS EVENING. AT THIS TIME THE
POTENTIAL IS TOO LOW TO MENTION IN THE TAFS, BUT WILL RECONSIDER
WITH SUBSEQUENT TAF ISSUANCE IF THIS ACTIVITY CONTINUES TO SHOW IN
THE MODELS. CHAMBERS/JKL
PRELIMINARY POINT TEMP/POPS
TDY WED THU FRI SAT SUN MON
-------------------------------------------------------
BIL 086 053/079 041/049 030/045 027/049 028/050 030/055
0/U 14/W 87/W 34/J 11/B 12/W 22/W
LVM 080 047/068 035/045 025/040 020/046 023/048 027/053
0/B 14/W 98/W 66/J 21/B 12/J 22/W
HDN 086 050/083 039/049 029/046 026/049 025/051 028/056
0/B 14/W 88/W 35/J 22/J 12/W 22/W
MLS 085 054/086 038/048 029/042 025/044 025/048 027/052
0/U 12/W 78/W 23/J 11/B 12/W 11/B
4BQ 084 055/084 039/049 029/042 026/046 025/048 029/052
0/U 01/N 58/W 23/J 11/B 12/W 22/W
BHK 084 050/086 038/049 026/041 022/041 022/045 025/049
0/U 01/B 38/W 32/J 11/B 12/J 22/J
SHR 082 048/078 036/049 024/042 020/046 021/047 026/052
0/B 12/W 68/W 56/J 32/J 23/W 22/W
BYZ WATCHES/WARNINGS/ADVISORIES
MT...NONE.
WY...NONE.
WEATHER.GOV/BILLINGS
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