Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 010435
AFDBYZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
935 PM MST SAT FEB 28 2015

.UPDATE...
FORECAST AREA WAS DEVOID OF PRECIPITATION THIS EVENING PER
WEBCAMS AND RADAR IMAGERY. LOWERED POPS THROUGH 06Z. NEXT
VORTICITY MAXIMUM WAS MOVING S INTO E MT PER WATER VAPOR IMAGERY.
RADAR SHOWED SOME SNOW OVER NE MT WITH THIS FEATURE. THE VORTICITY
WILL PUSH S THROUGH 18Z SUN...AND THEN EXIT THE AREA. BASED ON RH
AND QPF GUIDANCE...HAVE SPREAD SLIGHT CHANCE POPS S THROUGH KSHR
AND OVER SE MT OVERNIGHT...THEN EXPANDED THEM OVER THE SE SUN
MORNING.

TEMPERATURES WERE IN THE TEENS OVER W MT...AND GIVEN CURRENT DEW
POINTS...MAY NOT REACH FORECAST LOWS. THUS RAISED THEM A FEW
DEGREES OVER PORTIONS OF THE AREA W OF KBIL.

OTHERWISE...MODELS CONTINUED TO ROTATE A SHARP TROUGH SE INTO THE
REGION MON NIGHT PUSHING A STRONG COLD FRONT S THROUGH THE AREA.
BY 12Z TUE...850 MB TEMPERATURES WERE FORECAST TO BE -16 TO -20
DEGREES C. MODEL TIME-HEIGHT CROSS SECTIONS CONTINUED TO SHOW DEEP
INSTABILITY AND GOOD LIFT WITH THIS SYSTEM...WHICH SHOULD BRING AN
INTENSE PERIOD OF SNOW FROM AREAS W OF A ROUNDUP TO KSHR LINE MON
NIGHT. GUSTY WINDS WILL ACCOMPANY THE SNOW. JUDITH GAP WILL LIKELY
SEE BLIZZARD-LIKE CONDITIONS BEGINNING MON AFTERNOON. REMAINDER OF
FORECAST WAS IN GOOD SHAPE. ARTHUR

&&

.SHORT TERM...VALID FOR SUN AND MON...

QUIET REMAINDER OF THE WEEKEND EXPECTED BEFORE ANOTHER BLAST OF
ARCTIC AIR AND SNOW ARRIVE MONDAY AFTERNOON INTO TUESDAY.
AFTERNOON SATELLITE SHOWING MOSTLY CLOUDY SKIES ACROSS THE EAST
WITH PARTLY SUNNY SKIES ELSEWHERE. SUN BEGAN TO BREAK THROUGH LATE
THIS MORNING ACROSS THE CENTRAL AND WESTERN AREAS AND THIS HAS
ALREADY GENERATED A GOOD AMOUNT OF CU AND A LOWER CLOUD DECK FOR
MANY AREAS. EXPECT THIS TO CONTINUE THIS AFTERNOON WITH SOME
LINGERING FLURRIES OR LIGHT SNOW SHOWERS BUT THESE WILL MAINLY BE
CONFINED TO THE MOUNTAINS AND FOOTHILLS LOCATIONS. SKIES WILL
BEGIN TO PARTIALLY CLEAR AFTER SUNSET ALLOWING TEMPERATURES TO
QUICKLY DROP THIS EVENING. ANOTHER DISTURBANCE WILL DROP SOUTH OUT
OF CANADA LATE TONIGHT INTO SUNDAY MORNING...MAINLY ACROSS THE FAR
EASTERN PORTIONS OF MONTANA SO HAVE ADDED A SLIGHT SNOW SHOWER
CHANCE FOR THESE LOCATIONS LATE TONIGHT INTO SUNDAY MORNING.

DRY NORTHWEST THEN ZONAL FLOW ALOFT WILL PREVAIL ACROSS THE
FORECAST AREA FOR SUNDAY. SURFACE FLOW WILL BECOME SOUTHERLY
SUNDAY AFTERNOON WITH WEAK LEE-SIDE TROUGHING DEVELOPING SUNDAY
EVENING. THIS COMBINED WITH PARTLY TO MOSTLY SUNNY SKIES WILL
ALLOW TEMPERATURES TO MODERATE A FEW MORE DEGREES FROM TODAY WITH
OVERNIGHT LOWS SUNDAY NIGHT SLIGHTLY MILDER AS WELL.

MAIN FOCUS IN THE SHORT TERM WILL BE MONDAY AFTERNOON AND NIGHT
AS A POTENT BUT QUICK ARCTIC BLAST ARRIVES. MODELS BRING THE FRONT
THROUGH THE JUDITH GAP AREA BY NOON AND THE FAR SOUTHEAST AREAS
LATE AFTERNOON. DYNAMICS WITH THIS SYSTEM ARE VERY STRONG BUT ONLY
FOR ABOUT A 6-12 HOUR PERIOD. GFS REMAINS ROBUST IN QPF AMOUNTS
BUT THE ECMWF CAME IN WITH MUCH LESS QPF. BELIEVE HARDEST IMPACTED
AREAS WILL BE JUDITH GAP AND THE FOOTHILLS LOCATIONS. ALTHOUGH
JUDITH GAP DOES NOT LOOK TO RECEIVE A LOT OF SNOW...STRONG WINDS
WILL LIKELY BRING SIGNIFICANTLY REDUCED VISIBILITIES. CONFIDENCE
FOR SIGNIFICANT SNOW AMOUNTS IS HIGH FOR THE RED LODGE FOOTHILLS
BUT LOWER FURTHER ONTO THE PLAINS AND MOUNTAIN LOCATIONS. AREAS
FURTHER OUT ON THE PLAINS LIKE BILLINGS MAY ONLY SEE 2-3 INCHES
AND MAYBE NOT EVEN THAT MUCH DUE TO A POSSIBLE STRONG NORTHWEST
WIND AND AT 700MB WHICH MAY RESULT IN SOME DOWNSLOPING OFF THE
SNOWIES AND BULL MOUNTAINS. HOWEVER...DYNAMICS MAY BE STRONG
ENOUGH TO OVERCOME THIS. CONTEMPLATED A WINTER STORM WATCH FOR THE
JUDITH GAP AREA...AS WELL AS THE BEARTOOTH/ABSAROKA/BIG HORN
MOUNTAINS AND ADJACENT FOOTHILLS BUT HAVE DECIDED TO HOLD OFF A
BIT LONGER. CONFIDENCE IS MUCH BETTER FOR POSSIBLE ADVISORIES FOR
THE LOWER ELEVATIONS BUT SNOW AMOUNTS REMAIN A BIT UNCERTAIN.
ALSO...THIS IS STILL 48-54 HOURS OUT. THIS MAY ALSO BE A CASE
WHERE THE FOOTHILLS AGAIN RECEIVE MORE SNOW THAN THE MOUNTAINS.
EXPECT THE HIGH TEMPERATURE TO BE REACHED EARLY IN THE DAY WITH
TEMPERATURES QUICKLY FALLING THROUGH THE AFTERNOON AND EVENING.
HOOLEY

.LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT...

TUESDAY WILL SEE DRYING CONDITIONS BEHIND THE COLD FRONT WITH SNOW
SHOWER ACTIVITY IN THE MORNING DISSIPATING DURING THE AFTERNOON
HOURS. MODELS PROG DRIER AIR QUICKLY MOVING INTO THE AREA SO
REALLY EXPECT MINIMAL ACCUMULATIONS TUESDAY WITH FOOTHILLS AND
MOUNTAINS SEEING AN INCH OR TWO. COLDEST AIR AND THE SURFACE HIGH
WILL BE SLIDING ACROSS THE AREA SO TEMPERATURES WILL BE ANCHORED
IN THE TEENS AND SINGLE DIGITS. THIS SETS THE STAGE FOR A VERY
COLD TUESDAY NIGHT AND ONGOING WINDS OVER SOUTHEAST MONTANA MAY
SETUP 20 BELOW ZERO WINDCHILLS.

REMAINDER OF THE FORECAST PERIOD IS GOVERNED BY AN UPPER LEVEL
RIDGE AXIS MOVING FROM THE EASTERN PACIFIC WEDNESDAY TO THE
CENTRAL GREAT BASIN BY THE WEEKEND. THIS SLOWLY BUILDS HEIGHTS AND
CAUSES FLOW ALOFT TO TRANSITION FROM NORTHERLY TO WEST
NORTHWESTERLY DRIVING MODERATING TEMPERATURES. PATTERN LOOKS DRY
WITH WINDS BECOMING THE PRIMARY FORECAST ISSUE WITH A KLONDIKE
CHINOOK PATTERN WEDNESDAY NIGHT BECOMING A MORE TRADITIONAL
FOOTHILLS GAPFLOW PATTERN ON THURSDAY CONTINUING THROUGH FRIDAY.
HAVE ELEVATED WIND SPEEDS FOR HARLOWTON AREA WEDNESDAY NIGHT AND
THEN THE GAP FLOW AREAS AND THE YELLOWSTONE RIVER BASIN THURSDAY
AND FRIDAY. BORSUM
&&

.AVIATION...

VFR CONDITIONS ARE EXPECTED THE REST OF THE NIGHT. A FEW MID
LEVEL CLOUDS WILL MOVE THROUGH THE AREA AND PRODUCE A FEW
FLURRIES...BUT NOTHING SIGNIFICANT ENOUGH TO RESTRICT VISIBILITY.
WINDS WILL BE LIGHT. TWH
&&

.PRELIMINARY POINT TEMP/POPS...

    SUN     MON     TUE     WED     THU     FRI     SAT
-----------------------------------------------------------
BIL 008/029 016/036 007/011 901/025 015/043 027/049 029/051
    10/U    02/O    85/J    10/U    00/N    00/N    10/N
LVM 007/030 012/036 004/010 908/028 013/042 025/048 028/051
    10/U    03/O    96/J    10/U    00/N    00/N    10/N
HDN 005/032 011/039 008/014 903/024 011/044 023/050 026/052
    21/B    00/B    75/J    10/U    00/B    00/B    00/B
MLS 007/027 010/036 005/010 903/019 009/043 024/047 026/048
    22/J    00/B    42/J    10/N    00/B    01/B    11/B
4BQ 003/029 010/037 006/011 903/020 006/042 020/048 023/050
    21/B    00/U    64/J    10/B    00/U    00/B    10/B
BHK 004/025 006/033 003/010 905/015 004/040 021/044 022/046
    22/J    00/U    31/N    11/N    00/B    01/B    10/B
SHR 003/026 007/037 008/008 912/015 004/040 019/046 023/049
    20/U    00/U    97/J    10/U    00/U    00/U    00/U

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.

&&

$$
WEATHER.GOV/BILLINGS


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