026  
FXUS65 KBYZ 160300  
AFDBYZ  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BILLINGS MT  
800 PM MST SUN DEC 15 2024  
   
KEY MESSAGES  
 
- BREEZY CONDITIONS (GUSTS 20-35 MPH) CONTINUE TONIGHT. WINDS ON  
MONDAY WILL BE MUCH LIGHTER.  
 
- ANOTHER PERIOD OF LIGHT SNOW CAN BE EXPECTED MONDAY NIGHT AND  
TUESDAY, WITH LIGHT ACCUMULATIONS POSSIBLE OVER THE LOWER  
ELEVATIONS AND SEVERAL INCHES OF SNOW IN THE MOUNTAINS.  
 
 
   
UPDATE  
 
DRIER AIR CONTINUES TO ADVECT FROM THE WEST, AND PRECIP HAS ALL  
BUT TAPERED OFF. THUS, HAVE CANCELLED THE WINTER WEATHER ADVISORY.  
AS TEMPERATURES FALL BELOW FREEZING TONIGHT, WET ROADS WILL TURN  
ICY, SO PLEASE STAY ALERT IF YOU WILL BE TRAVELING.  
 
THERE REMAIN A FEW SNOW SHOWERS OVER THE MOUNTAINS, COURTESY OF  
COLD POOL ALOFT ALONG TROF AXIS, ANALYZED TO BE -34C AT 500MB AS  
OF 03Z. SHOWERS WILL END OVER THE NEXT FEW HOURS AS THE TROF  
CONTINUES TO MOVE EAST AND WE BEGIN TO UNDERGO HEIGHT RISES FROM  
THE WEST.  
 
PERSISTENT DOWNSLOPE WINDS WILL RULE OUT ANY CHANCE OF FOG  
TONIGHT, DESPITE THE COOL/WET DAY WE JUST EXPERIENCED. LOOK FOR  
LOW TEMPS MOSTLY IN THE 20S TO LOWER 30S. JKL  
 
 
   
DISCUSSION  
 
TONIGHT THROUGH MONDAY NIGHT...  
 
TONIGHT WILL SEE PRECIPITATION EXIT THE REGION TO THE EAST. WINDS  
WILL STILL BE GUSTING INTO THE 30S MPH IN FALLON AND CARTER  
COUNTIES LEADING TO THE POTENTIAL FOR BLOWING SNOW. WINDS WILL  
DECREASE THROUGHOUT THE OVERNIGHT. MINIMUM TEMPERATURES TONIGHT  
WILL BE IN THE HIGH TEENS TO MID 20S F ACROSS THE REGION.  
 
TOMORROW WILL BE A TRANSITION DAY BETWEEN THE WEATHER SYSTEM  
EXITING AND THE ONE THAT WILL MOVE INTO THE REGION LATE TUESDAY.  
TEMPERATURES WILL BE SIMILAR TO TODAY WITH HIGHS IN THE 30S F.  
SHORTWAVE RIDGING WILL GIVE WAY TO UPPER LEVEL TROUGHING LATE  
TUESDAY. PRECIPITATION CHANCES WILL BEGIN TO ENTER THE WESTERN  
MOUNTAINS LATE TOMORROW MORNING AND SPREAD ACROSS THE LOWER  
ELEVATIONS (40-60%) IN THE AFTERNOON THROUGH THE OVERNIGHT. AS  
OPPOSED TO THIS WEEKENDS SYSTEM, THIS ONE APPEARS TO BE ALL SNOW.  
FURTHER DETAILS ON THIS SYSTEM WILL BE IN THE LONG TERM  
DISCUSSION. TORGERSON  
 
TUESDAY THROUGH SUNDAY...  
 
A BACK AND FORTH PERIOD FROM LIGHT RAIN/SNOW TO SLIGHT WARMING IS  
THE NAME OF THE GAME THROUGH THE REST OF THE WEEK.  
 
STARTING THE GAME OFF IS A WAVE PASSING THROUGH AND ALLOWING A  
BACKDOOR COLD FRONT TO SET UP LATE MONDAY INTO TUESDAY MORNING.  
THIS PERIOD WILL BE COOL ENOUGH TO SEE ITS PRECIP TYPE OF SNOW,  
THOUGH AMOUNTS WITH GENERALLY BE LIGHT, WITH ONLY A 20-30% CHANCE  
FOR LOWER ELEVATIONS OF SOUTH-CENTRAL MT TO GET AT LEAST AN INCH  
OF SNOW (90% IN THE MOUNTAINS, MAINLY ON WEST FACING SLOPES). ONLY  
MINOR WINTER IMPACTS EXPECTED FROM THIS SYSTEM.  
 
MOVING INTO THE MIDWEEK WE SEE A RIDGE BUILD OVER THE STATE AND A  
STRONG PRESSURE GRADIENT SET UP OVER SOUTH-CENTRAL MT, INCREASING  
STRONG WIND POTENTIAL FROM LIVINGSTON AND NORTH THROUGH  
HARLOWTON. CURRENTLY THERE IS A 50-70% CHANCE FOR WIND GUSTS TO  
REACH AT LEAST 50 MPH TUESDAY NIGHT THROUGH WEDNESDAY NIGHT. A  
COLD FRONT IS THEN PROGGED TO CRASH OVER THE AREA, EXTENDING  
BREEZY WINDS OUT OVER THE PLAINS THROUGH SOUTHEAST MONTANA (GUSTS  
30-40 MPH). THIS FRONTAL PASSAGE HAS A VERY SMALL CHANCE TO  
PRODUCE LIGHT RAIN/SNOW SHOWERS AS WELL.  
 
THE WEEKEND SEE A MORE PROMINENT RIDGE SET UP OVER THE WESTERN  
CONUS. THAT SAID, UNCERTAINLY LIES WITH HOW FAR EAST THIS RIDGE  
WILL GET TO THROUGH THE WEEKEND. THE TWO EASILY SEEN OUTCOMES ARE  
THE RIDGE MOVING FAR ENOUGH EAST THAT ALL OF SOUTH-CENTRAL AND  
SOUTHEAST MT SEES WARM AND DRY CONDITIONS. THE OTHER OUTCOME IS  
THE RIDGE STAYING FURTHER WEST, WHICH WOULD KEEP FAR EASTERN  
MONTANA UNDER MORE CYCLONIC FLOW, ALLOWING A PUSH OF COOLER  
TEMPERATURES AND AT LEAST SMALL CHANCES OF RAIN/SNOW TO OCCUR  
THROUGH THE WEEKEND. REGARDLESS OF EITHER OUTCOME, NO HUGE WINTER  
STORMS ARE EXPECTED DURING THIS PERIOD.  
 
VERTZ  
 
 
   
AVIATION  
 
OVERNIGHT TONIGHT WE ARE EXPECTING THE PRECIPITATION TO EXIT TO  
THE EAST. THE MAIN CONCERN IN THE SHORT TERM WILL BE SPORADIC  
GUSTY WINDS INTO THE 30'S KT RANGE ACROSS THE AREA, WITH EXTRA  
EMPHASIS AROUND KSHR AND KMLS. KSHR HAD A OBSERVATION OF A 49KT  
GUST AT 2150Z BUT WE DO NOT EXPECT THIS TO BE THE NORMAL. ALL  
PRECIP SHOULD BE CLEAR OF OUR AREA BY 6Z WITH THE WINDS DYING DOWN  
SHORTLY AFTER. VFR CONDITIONS SHOULD PREVAIL WITH A CHANCE (50%)  
OF A DIP DOWN TO MVFR AT SITES LIKE KSHR, KMLS, AND KBHK FOR VIS  
REDUCTIONS.  
 
TOMORROW WE EXPECT WIDESPREAD VFR CONDITIONS AND LIGHTER WINDS.  
WMR  
 
 
   
PRELIMINARY POINT TEMP/POPS  
 
MON TUE WED THU FRI SAT SUN  
-----------------------------------------------------------  
BIL 025/038 023/038 023/046 030/046 028/049 029/050 031/052  
01/B 42/S 10/B 10/U 00/B 00/B 00/B  
LVM 022/039 026/041 028/049 033/049 031/053 033/054 033/051  
04/J 73/S 11/N 10/N 00/B 00/B 11/B  
HDN 024/039 023/037 020/046 027/044 021/047 023/047 025/050  
20/B 53/S 10/B 10/U 00/B 00/U 00/B  
MLS 024/033 020/029 014/036 021/034 015/037 016/037 021/042  
20/U 32/S 11/E 10/B 00/B 00/B 00/B  
4BQ 025/035 022/034 018/042 025/039 020/043 021/043 025/046  
40/U 21/B 10/B 10/B 00/B 00/B 00/B  
BHK 021/030 013/027 010/033 017/032 008/033 011/032 015/037  
20/U 12/S 10/E 10/N 00/B 00/B 00/B  
SHR 019/040 018/040 018/050 026/047 023/053 027/055 028/053  
20/U 22/S 10/B 10/U 00/B 00/U 00/B  
 
 
   
BYZ WATCHES/WARNINGS/ADVISORIES  
 
MT...NONE.  
WY...NONE.  
 
 
 
 
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