Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 260345 AAB
AFDBYZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
845 PM MST TUE NOV 25 2014

.UPDATE...

THE FORECAST IS GENERALLY ON TRACK THIS EVENING...ALTHOUGH SNOW IS
TAKING A BIT LONGER TO MOVE EASTWARD TOWARD BILLINGS THAN THOUGHT.
LIGHT SNOW WILL FINALLY REACH BILLINGS AFTER MIDNIGHT WITH AN INCH
OF ACCUMULATION STILL VERY POSSIBLE BY DAYBREAK. THE HEAVIEST SNOW
IN BILLINGS PROPER WILL THEN BE WEDNESDAY MORNING WITH TOTALS NEAR
3 INCHES A DISTINCT POSSIBILITY. WE REDUCED POPS OVER SOUTHEASTERN
MT TONIGHT AND WEDNESDAY MORNING BASED ON THE SLOWER MOVEMENT EAST
TO THE SNOWFALL SUGGESTED BY RADAR TRENDS AND RECENT HRRR RUNS. WE
ONLY MADE MINOR TWEAKS TO THE REST OF THE FORECAST AS THE SNOWFALL
WEST AND SOUTH OF BILLINGS WILL CONTINUE MAKING ITS WAY NORTHEAST.
OUR WINTER STORM WARNINGS AND WINTER WEATHER ADVISORIES LOOK TO BE
WELL ON TRACK. SCHULTZ

&&

.SHORT TERM...VALID FOR WED AND THU...

CLIPPER ENERGY HAS EXITED THE AREA TO THE SOUTHEAST WITH SNOW
FOR THE MOST PART ENDING OVER THE EASTERN HALF OF THE FORECAST
AREA. COLD FRONT ASSOCIATED WITH THIS SYSTEM HAS BANKED UP AGAINST
THE WESTERN FOOTHILLS AT THIS TIME WITH NORTHERLY WINDS NOW IN
PLACE FROM LIVINGSTON TO RED LODGE. SNOW IS INCREASING ALONG THIS
FRONTAL BAND FROM SOUTHERN ROSEBUD AND SHERIDAN COUNTY WEST TO
RED LODGE...BIG TIMBER AND LIVINGSTON. DOWNSLOPE DRY SLOT HAS
DEVELOPED FROM BILLINGS AND HARDIN TO ROUNDUP AND HARLOWTON AND
THIS SHOULD PERSIST FOR A FEW MORE HOURS. ONCE TEMPERATURES START
TO COOL AT THE SURFACE AND DOWNSLOPE WINDS DECOUPLE SOME SHOULD
SEE THIS AREA FILL IN WITH SNOW. MODELS IN GOOD AGREEMENT WITH
ISENTROPIC SNOW FROM TONIGHT THROUGH WEDNESDAY OVER WESTERN AND
CENTRAL ZONES...SHIFTING NORTHEAST AS A WARM FRONT LATE WEDNESDAY
INTO THURSDAY. AS WARM ADVECTION SHALLOWS OUT THE COLD LOW LEVEL
AIR WILL SEE A TRANSITION TO MIXED PRECIPITATION WITH THE
POTENTIAL FOR SOME FREEZING RAIN MIXED IN ESPECIALLY WEDNESDAY
NIGHT INTO THURSDAY FROM BILLINGS EAST. TEMPERATURES WILL REALLY
WARM UP ON THURSDAY AS ZONAL FLOW ALOFT PRODUCES A STRONG
DOWNSLOPE GRADIENT WHICH WILL PUSH TEMPERATURES WELL INTO THE 40S
WEST AND CENTRAL...WITH ABOVE FREEZING TEMPERATURES EXPECTED OVER
EASTERN AREAS IN THE AFTERNOON. EXPECT A PERIOD OF STRONG GAP
WINDS FOR WESTERN FOOTHILLS LOCATIONS STARTING WEDNESDAY NIGHT AND
CONTINUING THROUGH FRIDAY AHEAD OF NEXT COLD FRONT...AND BUMPED
WIND SPEEDS UP TO ADVISORY CRITERIA FOR THIS. WILL HOLD OFF
ISSUING HIGHLITES UNTIL WE ARE FURTHER ALONG WITH CURRENT WINTER
HIGHLITES.

WINTER HIGHLITES...MADE SOME ADJUSTMENTS TO THE GOING HIGHLITES.
ALREADY SEEING 6 TO 10 INCHES OF SNOW IN THE BIGHORN MOUNTAINS AND
WITH SNOW EXPECTED TO CONTINUE INTO TOMORROW BUMPED THAT AREA TO A
WARNING. STARTED ADVISORY FOR CARBON...SOUTHERN BIG
HORN...SOUTHERN ROSEBUD AND SHERIDAN COUNTY EARLY TO ACCOUNT FOR
CURRENT RADAR AND ROAD CONDITION TRENDS. SNOW LOOKS TO BE SLOWER
TO SHIFT EAST TONIGHT THAN PREVIOUS FORECAST EXPECTED. IT IS
POSSIBLE THAT AREAS FROM ROUNDUP TO BILLINGS COULD BE JUST EAST OF
THE PRECIPITATION UNTIL LATE THIS EVENING WITH SNOW NOT GETTING
INTO TREASURE AND NORTHERN ROSEBUD COUNTY UNTIL SUNRISE. AS A
RESULT PUSHED BACK THE START TIME FOR TREASURE AND ROSEBUD COUNTY
UNTIL 3AM. LEFT BILLINGS...MUSSELSHELL AND NORTHERN BIG HORN
TIMING ALONE FOR NOW AS SNOW WILL BE CLOSE ENOUGH THAT ONLY A
SLIGHT DEVIATION IN CURRENT MODEL TIMING WILL BRING SNOW IN BY MID
EVENING.

IMPACTS...DOT WEBCAMS SHOWING A MIXED BAG OF SNOWY AND WET ROADS
WITH A FEW AREAS THAT ARE STILL DRY. WITH SUNSET MOST ROADWAYS
WILL QUICKLY ICE UP...ESPECIALLY BRIDGES AND OVERPASSES. THOSE
TRAVELING TONIGHT SHOULD SLOW DOWN AND BE ALERT FOR BLACK ICE.
CHAMBERS

.LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE...

MAIN THEME WITH THE EXTENDED FORECAST IS A ROLLER COASTER RIDE
WITH TEMPERATURES. MODELS SEEM TO BE IN DECENT AGREEMENT WITH THE
SYNOPTIC FEATURES BUT DIFFER QUITE A BIT WITH TIMING AND EVOLUTION
OF SYSTEMS. AFTER A SOMEWHAT MILD THANKSGIVING DAY...THE MAJORITY
OF FRIDAY LOOKS TO BE MILD AS WELL BUT ANOTHER ARCTIC FRONT WILL
BE POISED TO MOVE ACROSS THE FORECAST AREA. VARIOUS MODEL
SOLUTIONS BRING THE FRONT THROUGH DURING THE AFTERNOON OR NOT
UNTIL FRIDAY NIGHT. WE WILL KEEP FRIDAY TEMPERATURES MILD BUT THIS
MAY GET CHANGED DURING THE NEXT DAY OR TWO. BY SATURDAY...MODELS
SHOW THE FORECAST AREA ENTRENCHED IN ARCTIC AIR SO MOST LIKELY
OVERNIGHT LOWS FRIDAY NIGHT WILL NOT RISE MUCH IF ANY FOR THE DAY
SATURDAY. SNOW WILL ACCOMPANY THE FRONT FRIDAY NIGHT AND LINGER
INTO SATURDAY BUT AMOUNTS AT THIS TIME ARE UNCERTAIN.

GIVEN THE WARM DAY ON FRIDAY FOLLOWED BY SNOW WITH OVERNIGHT LOWS
IN THE TEENS...EXPECT THE POSSIBILITY OF SLICK ROADS FRIDAY NIGHT
THROUGH SATURDAY. CONDITIONS LOOK TO BE DRY FOR SUNDAY BUT THE
COLD AIR WILL REMAIN IN PLACE. LEE-SIDE TROUGHING AND DOWNSLOPE
WINDS RETURN FOR MONDAY AND DEPENDING ON SNOW COVER...TEMPERATURES
COULD WARM BACK INTO THE 30S. THIS WILL BE SHORT-LIVED AS ANOTHER
ARCTIC FRONT MOVES THROUGH MONDAY NIGHT BUT MODELS AGAIN DIFFER IN
THE TIMING. HOOLEY

&&

.AVIATION...

A BAND OF LIGHT TO MODERATE SNOW WILL REMAIN ANCHORED ALONG THE
FOOTHILLS FROM LIVINGSTON TO RED LODGE TO SHERIDAN MOST OF THE
NIGHT. THE SNOW WILL BE LOCALLY HEAVY AROUND RED LODGE. THIS WILL
CAUSE LIFR TO VLIFR CONDITIONS IN THESE LOCATIONS. MOUNTAINS WILL
BE OBSCURED IN SNOW. THE SNOW BAND WILL SHIFT EAST OVERNIGHT AND
IMPACT BILLINGS WITH IFR TO LIFR CONDITIONS. SNOW WILL BE HEAVIEST
IN BILLINGS TOWARD MORNING. THE SNOW WILL MOVE INTO MILES CITY
WEDNESDAY MORNING. TWH

&&

.PRELIMINARY POINT TEMP/POPS...

    WED     THU     FRI     SAT     SUN     MON     TUE
-----------------------------------------------------------
BIL 024/032 027/048 036/048 016/018 001/015 007/030 018/032
    99/O    31/B    01/B    36/S    32/J    11/B    13/S
LVM 025/040 037/049 039/046 023/025 006/023 017/034 023/034
    +6/O    31/N    12/W    36/S    42/J    21/B    23/S
HDN 023/032 023/047 032/048 014/016 002/018 005/028 014/034
    99/O    41/B    01/B    23/S    32/J    11/B    12/S
MLS 019/027 021/043 030/044 011/013 903/012 002/024 012/026
    28/S    73/O    11/B    34/S    31/B    11/B    12/S
4BQ 020/030 020/047 031/047 015/017 003/020 007/030 015/031
    27/S    61/E    11/B    23/S    31/B    11/B    12/S
BHK 014/022 016/037 028/042 012/014 902/011 001/024 012/029
    25/S    63/O    11/B    23/S    31/B    11/B    12/S
SHR 022/032 023/048 033/049 019/021 006/024 010/034 018/033
    99/S    21/B    00/B    12/S    22/J    10/B    12/S

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WINTER WEATHER ADVISORY IN EFFECT UNTIL NOON MST WEDNESDAY
      FOR ZONES 28-40-41-63>65.
     WINTER WEATHER ADVISORY IN EFFECT UNTIL 6 PM MST WEDNESDAY
      FOR ZONES 29-34-35-38-42-57-58.
     WINTER WEATHER ADVISORY IN EFFECT FROM 3 AM TO 6 PM MST
      WEDNESDAY FOR ZONES 30-31.
     WINTER STORM WARNING IN EFFECT UNTIL 6 PM MST WEDNESDAY FOR
      ZONE 39.
     WINTER STORM WARNING IN EFFECT UNTIL NOON MST WEDNESDAY FOR
      ZONES 56-66>68.
WY...WINTER WEATHER ADVISORY IN EFFECT UNTIL 6 PM MST WEDNESDAY
      FOR ZONE 99.
     WINTER STORM WARNING IN EFFECT UNTIL 6 PM MST WEDNESDAY FOR
      ZONE 98.

&&

$$
WEATHER.GOV/BILLINGS



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