655  
FXUS65 KBYZ 272104  
AFDBYZ  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BILLINGS MT  
304 PM MDT THU APR 27 2017  
   
SHORT TERM...VALID FOR FRI AND SAT
 
 
LOTS OF ENERGY DROPPING INTO THE CENTRAL ROCKIES CUTTING OUT A  
POWERFUL UPPER TROUGH ACROSS OUR REGION. THIS PATTERN HAS CREATED  
AN INVERTED SURFACE TROUGH FROM SE WYOMING TO NORTH CENTRAL  
MONTANA CUTTING RIGHT THROUGH OUR CWA. THIS WILL CONTINUE TO BE  
THE FOCUS FOR PRECIPITATION, AND OVER THE BIG HORNS REGION WILL  
BE AIDED BY DEEP NORTHEASTERLY UPSLOPE FLOW IN THE 825-400 MB  
LAYER.  
 
CURRENTLY, ACCUMULATIONS ARE BEING MUTED BY THE WARMTH OF THE  
DAY, BUT ONCE THE SUN SETS AND DYNAMIC COOLING KICKS IN EVEN  
STRONGER WE SHOULD SEE THE SNOWFALL PILE UP MUCH MORE EFFICIENTLY.  
WE ARE STILL LOOKING FOR AROUND A FOOT OR MORE OF SNOWFALL IN THE  
BIG HORNS WITH GENERALLY LESSER AMOUNTS IN THE FOOTHILLS AND  
ABOUT 4-6 INCHES AROUND THE CITY OF SHERIDAN. THE PRECIPITATION  
WILL LIKELY CONTINUE THROUGH FRIDAY MORNING BEFORE IT BEGINS TO  
TAPER SLOWLY DOWN. MUCH OF THE PRECIPITATION WILL BE OVER BY  
FRIDAY EVENING AS WIND FIELDS IN THE LOWER LEVELS TURN MORE  
SOUTHEASTERLY  
 
OTHER AREAS MAY SEE A COUPLE OF INCHES OF WET SNOW OVERNIGHT INTO  
FRIDAY...MAINLY OVER HIGHER HILLS SOUTH OF BILLINGS AND POSSIBLY  
OVER N/NE FACING SLOPES IN THE FOOTHILLS OF THE BEARTOOTHS,  
CRAZIES AND BELTS...AND POSSIBLY IN THE BULL MOUNTAINS. ROADS ARE  
EXPECTED TO GENERALLY REMAIN JUST WET AT LOWER ELEVATIONS, SO WE  
DO NOT PLAN TO ISSUE ANY ADVISORIES AT THIS TIME.  
 
FOR SATURDAY, THE UPPER LOW WILL DIVE FURTHER SOUTH. HOWEVER, ITS  
QUASI-AXIS WILL STILL NEED TO DRIFT OVER OUR AREA AND COULD LEAD  
TO A FEW RAIN OR SNOW SHOWERS. THE HIGHER TERRAIN HAS THE BEST  
SHOT OF ANYTHING MEASURABLE. WE CERTAINLY DO NOT EXPECT MUCH IF  
ANY IMPACTS ON SATURDAY AS TEMPS TRY TO WARM UP TO THE 55 DEGREE  
MARK IN MANY LOCATIONS. BT  
 
   
LONG TERM...VALID FOR SUN...MON...TUE...WED...THU
 
 
NOT MUCH CHANGE NEEDED TO THE EXTENDED PERIOD WHICH WILL FEATURE A  
NNW FLOW ALOFT WITH ENERGY IN THE FLOW, UNTIL THE END OF THE  
PERIOD WHEN AN UPPER RIDGE WILL BUILD INTO THE AREA.  
 
JET ENERGY WILL DIVE SE THROUGH THE REGION FOR MOST OF THE PERIOD.  
ON SUNDAY, MODELS SHOWED A SURFACE LOW MOVING SE FROM S. CANADA  
AND IT'S ATTENDANT COLD FRONT MOVING THROUGH THE AREA. THE FRONT  
WILL SPREAD ISOLATED TO SCATTERED SHOWERS ACROSS THE AREA THROUGH  
SUN. NIGHT, AS WELL AS WINDY CONDITIONS. SHOWERS WITH AFTERNOON  
THUNDERSTORMS WILL CONTINUE ON MONDAY DUE TO THE ENERGY ALOFT.  
WINDY CONDITIONS WILL CONTINUE AS WELL BEHIND THE COLD FRONT. MORE  
SHOWERS WILL CONTINUE MON. NIGHT AND TUESDAY WITH THE ENERGY  
ALOFT. THUNDERSTORMS ARE POSSIBLE TUE. AFTERNOON. THE SHOWERS  
WILL DECREASE TUE. NIGHT.  
 
ANTICYCLONIC FLOW AHEAD OF THE RIDGE WILL MOVE IN ON WEDNESDAY  
WITH DRIER CONDITIONS, AND THURSDAY LOOKED DRY UNDER THE RIDGE.  
TEMPERATURES WILL BE AROUND NORMAL FOR MUCH OF THE PERIOD, EXCEPT  
FOR THURSDAY, WHEN HIGHS WILL APPROACH 70 IN MANY AREAS. ARTHUR  
 

 
   
AVIATION
 
 
RAIN AND SNOW WILL AFFECT AREAS FROM ROUNDUP TO KBIL TO KSHR  
TONIGHT, WITH THE HEAVIEST PRECIPITATION EXPECTED S OF KBIL.  
SCATTERED RAIN/SNOW SHOWERS WILL AFFECT MUCH OF THE REMAINDER OF  
THE AREA. EXPECT MVFR/IFR CONDITIONS IN THE RAIN AND SNOW WITH IFR  
TO LIFR CONDITIONS AROUND KSHR. THE NE BIGHORNS WILL BE OBSCURED,  
WHILE AREAS OF OBSCURATION WILL AFFECT THE OTHER MOUNTAINS. THESE  
CONDITIONS WILL PERSIST FRIDAY MORNING, THEN SLIGHTLY DECREASE  
FRI. AFTERNOON. ARTHUR  
 

 
   
PRELIMINARY POINT TEMP/POPS
 
 
FRI SAT SUN MON TUE WED THU  
-----------------------------------------------------------  
BIL 037/047 035/055 037/060 041/057 039/056 039/063 042/068  
96/O 32/W 22/W 32/W 34/T 32/W 11/B  
LVM 031/046 027/053 033/056 036/055 035/055 034/062 038/065  
66/O 22/W 23/W 33/W 33/T 32/W 21/B  
HDN 038/050 034/056 035/062 040/058 038/058 038/063 040/069  
85/O 22/W 22/W 33/W 34/W 32/W 11/B  
MLS 035/054 035/058 036/062 042/058 039/058 039/062 041/068  
22/O 11/B 01/B 23/T 23/W 22/W 11/B  
4BQ 034/051 031/056 032/061 040/057 037/055 037/060 039/066  
32/O 11/E 01/U 33/T 24/W 22/W 11/B  
BHK 029/052 029/057 032/060 037/056 035/055 034/057 036/062  
11/B 01/B 01/U 33/T 23/W 21/B 11/B  
SHR 033/041 028/049 029/055 037/052 035/052 035/057 036/063  
+7/O 32/W 11/B 33/W 34/W 32/W 11/B  
 

 
   
BYZ WATCHES/WARNINGS/ADVISORIES
 
 
MT...WINTER STORM WARNING IN EFFECT UNTIL MIDNIGHT MDT FRIDAY  
NIGHT FOR ZONE 38.  
WY...WINTER STORM WARNING IN EFFECT UNTIL MIDNIGHT MDT FRIDAY  
NIGHT FOR ZONES 98-99.  
 

 
 

 
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