375
FXUS65 KBYZ 182020
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
120 PM MST TUE NOV 18 2025
KEY MESSAGES
- SCATTERED LIGHT SHOWERS TONIGHT AND WEDNESDAY.
- ABOVE NORMAL TEMPERATURES CONTINUE THROUGH THE WEEKEND.
- BREEZY WINDS ALONG THE WESTERN FOOTHILLS THIS WEEKEND; A PERIOD
OF STRONGER WINDS POSSIBLE SUNDAY NIGHT AND MONDAY.
- CONFIDENCE INCREASING FOR COLDER TEMPS AND POTENTIAL LIGHT SNOW
BY NEXT TUESDAY.
- WINTRY TRAVEL IMPACTS POSSIBLE FOR THANKSGIVING AND THE HOLIDAY
WEEKEND...MONITOR THE FORECAST!
DISCUSSION
SATELLITE IMAGERY SHOWS A SW FLOW OVER THE REGION, WITH A CUT OFF
LOW OVER SOUTHERN CA (A NON-FACTOR FOR US) AND AN UPSTREAM WEAK
PACIFIC WAVE NEAR THE WA/BC COAST. THERE IS ALSO WEAK ENERGY
LIFTING OUT OF NORTHERN WY WHICH CONTINUES TO PRODUCE LIGHT
SHOWERS IN AN AREA FROM ROUGHLY LODGE GRASS TO FORSYTH. THERE IS
A STRONGER WAVE IN CENTRAL WY THAT, AS IT TRACKS NE, WILL PRODUCE
AN AREA OF SHOWERS OVER OUR EASTERN ZONES TONIGHT. FREEZING LEVELS
REMAIN HIGH AND NONE OF THE PRECIP WILL BE SIGNIFICANT, BUT
OVERALL THE FORECAST IS WETTER THAN IT LOOKED PREVIOUSLY. EASTERN
AREAS COULD SEE 0.05-0.20" OF RAIN TONIGHT (30% CHANCE OF 0.10" OR
MORE FROM ASHLAND TO BAKER/EKALAKA). ON WEDNESDAY WE WILL SEE
IMPACTS FROM THE PACIFIC WAVE, WITH A PERIOD OF ISOLATED TO
SCATTERED SHOWERS OVER THE ENTIRE REGION, AND A POSSIBLE SHORT
PERIOD OF UPSLOPE ENHANCEMENT OVER OUR WESTERN FOOTHILLS IN THE
AFTERNOON AND EARLY EVENING, AFTER WHICH SUBSIDENCE AND DRYING
ARRIVE. THERE WILL BE A MODEST CANADIAN FRONT/PRESSURE RISES FROM
THE NORTH BEGINNING TOMORROW MORNING, THUS WE WILL SEE COOLER
TEMPS AND LOWER SNOW LEVELS TOMORROW. IN FACT, IT IS POSSIBLE THAT
A MIX WITH WET SNOW COULD OCCUR AT SUCH PLACES AS JUDITH GAP AND
MELVILLE, AND EVENTUALLY RED LODGE BY LATER IN THE DAY. THE CHANCE
OF MEASURABLE SNOW AT THESE LOCATIONS IS LOW (20% OR LESS) BUT IT
IS SOMETHING TO KEEP AN EYE ON AS THERE IS A GOOD DEAL OF MODEL
SPREAD STILL. THERE COULD BE A BIT OF WET SNOW OVER BOZEMAN PASS
AS WELL.
AFTER TOMORROW EVENING WE WILL SEE SEVERAL DAYS OF DRY WEATHER,
WITH CONTINUED WARMER THAN NORMAL TEMPS, THROUGH SUNDAY AND
POSSIBLY MONDAY. LOOK FOR HIGHS MOSTLY IN THE 50S TO NEAR 60F. THE
LONGWAVE PATTERN WILL CONSISTENT OF A CUT OFF LOW OVER THE SW
CONUS AND DRY ZONAL FLOW THROUGH THE NORTHERN ROCKIES AND UPPER
HIGH PLAINS. DOWNSLOPE PRESSURE GRADIENTS INCREASE BUT THE LOW TO
OUR SOUTH SHOULD HELP TO KEEP PRESSURES OVER YNP A BIT LOWER, SO
IT CURRENTLY LOOKS AS IF BREEZY WINDS WILL BE KEPT SOMEWHAT IN
CHECK THROUGH THE WEEKEND. EVENTUALLY WE ARE LOOKING AT A PRE-
FRONTAL WINDIER PERIOD AS A TROF APPROACHES FROM THE NW. AS IT
LOOKS NOW, THIS LOOKS TO OCCUR SUNDAY NIGHT & MONDAY, WITH 700MB
WINDS NEAR 50 KNOTS POSSIBLY SUPPORTING ADVISORY LEVEL GUSTS AT
THE GAP AREAS, AND 50+ MPH GUSTS ALONG THE US-191 CORRIDOR.
ENSEMBLES ARE STARTING TO HINT AT INCREASED WIND HERE, BUT AGAIN
WITH PLENTY OF SPREAD AMONG THE MEMBERS. SOMETHING TO MONITOR.
CHANGES ARE IN STORE BY MONDAY NIGHT OR TUESDAY (FINALLY!) AS A
SHARPER TROF AND CANADIAN COLD FRONT ARRIVE. WITH CONFIDENCE WE
ARE LOOKING AT COLDER THAN NORMAL TEMPS BY TUESDAY AND AT LEAST A
LOW CHANCE OF LIGHT SNOW (20-30%). IT ALSO LOOKS AS IF TEMPS
SHOULD STAY BELOW NORMAL AS WE MOVE THROUGH THANKSGIVING AND TO
THE FOLLOWING WEEKEND. CPC HAS THIS HIGHLIGHTED IN THEIR 8-14 DAY
OUTLOOK. SPECIFICS ARE IMPOSSIBLE AT THIS TIME BUT HOLIDAY TRAVEL
IMPACTS ARE A DEFINITE POSSIBILITY, SO WE URGE PEOPLE TO WATCH THE
FORECAST OVER THE COMING DAYS. FOR THOSE OF YOU LONGING FOR A
DOSE OF WINTER, YOU MAY FINALLY GET YOUR WISH.
JKL
AVIATION
ISOLATED TO SCATTERED SHOWERS WILL CONTINUE INTO WEDNESDAY, AND
WILL CAUSE MOUNTAIN OBSCURATION AT TIMES. BRIEF, LOCALIZED
CEILING REDUCTIONS TO MVFR ARE POSSIBLE WITH THE SHOWERS,
OTHERWISE, VFR CONDITIONS WILL PREVAIL. TONIGHT INTO WEDNESDAY
MORNING, PATCHY FOG IS POSSIBLE (10-20% CHANCE) OVER THE EAST,
INCLUDING NEAR KMLS AND KBHK. ARCHER
PRELIMINARY POINT TEMP/POPS
WED THU FRI SAT SUN MON TUE
-----------------------------------------------------------
BIL 039/049 030/052 032/057 034/055 036/056 036/054 028/037
12/W 20/U 00/U 00/B 11/B 13/W 32/J
LVM 035/050 028/053 029/055 032/053 034/054 036/053 025/037
14/W 10/U 00/U 00/B 11/B 23/W 43/J
HDN 036/049 026/051 027/057 030/056 031/057 031/055 025/039
22/W 20/U 00/U 00/B 11/B 13/W 33/W
MLS 036/048 026/047 028/054 031/052 032/054 031/052 025/035
22/W 00/U 00/U 00/B 01/B 11/B 21/B
4BQ 039/049 028/051 030/055 033/053 033/054 032/053 028/037
51/B 20/U 00/U 00/U 00/B 11/B 21/B
BHK 037/049 023/046 027/053 029/051 030/053 028/050 022/037
52/W 00/U 00/U 00/B 00/B 11/B 21/B
SHR 034/050 025/052 027/057 027/053 028/056 028/056 022/037
21/B 20/U 00/U 00/U 11/B 12/W 34/W
BYZ WATCHES/WARNINGS/ADVISORIES
MT...NONE.
WY...NONE.
WEATHER.GOV/BILLINGS
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