Area Forecast Discussion
Issued by NWS Billings, MT

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000
FXUS65 KBYZ 110939
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
339 AM MDT THU SEP 11 2014

.SHORT TERM...VALID FOR TDY AND FRI...

VIGOROUS UPPER LEVEL SYSTEM WILL CROSS THE AREA THIS MORNING
KEEPING RAIN AND SNOW GOING THROUGH MID DAY. PRECIPITATION WILL
DECREASE THIS AFTERNOON AS THE SYSTEM SHIFTS SOUTHEASTWARD.
ADDITIONAL SNOW ACCUMULATIONS POSSIBLE ABOVE 4000 FEET THROUGH MID
DAY. SOME ROADS...INCLUDING PORTIONS OF I-90 IN SHERIDAN COUNTY...MAY
SEE SOME SNOW ACCUMULATION THIS MORNING RESULTING IN A DIFFICULT
MORNING COMMUTE.

TODAY...BEST AREA OF PRECIPITATION OVERNIGHT HAS BEEN FROM ALONG
THE WESTERN FOOTHILLS AND ACROSS THE SOUTHERN HALF OF THE FORECAST
AREA...SOUTH OF A BILLINGS TO EKALAKA LINE. THIS AREA OF
PRECIPITATION HAS MAINLY BEEN ASSOCIATED WITH JET DYNAMICS ON THE
LEFT FRONT QUAD OF THE 140KT JETSTREAM SLIDING ALONG THE MT/WY
STATE LINE. NEXT UP FOR THE AREA WILL BE A VERY STRONG AREA OF QG
FORCING THAT WILL MOVE ACROSS THE AREA FROM NORTHWEST TO SOUTHEAST
THROUGH THE DAY. LIFT FROM THIS AREA OF STRONG DYNAMICS WILL
ENHANCE UPSLOPE PRECIPITATION IN THE FOOTHILLS AND MOUNTAINS AS
WELL AS ENHANCING ISENTROPIC LIFT OVER THE LOWER ELEVATIONS. GIVEN
THIS HAVE KEPT CATEGORICAL POPS ACROSS A LARGE AREA THIS
MORNING...TAPERING OFF PRECIPITATION CHANCES IN THE AFTERNOON AS
THE DYNAMICS SHIFT SOUTHEAST. THE LAST AREAS TO SEE PRECIPITATION
END WILL BE THE BEARTOOTH AND BIG HORN FOOTHILLS THIS EVENING.

PRECIPITATION TYPE CONTINUES TO BE TRICKY. RAIN IS GENERALLY
TURNING TO SNOW AT ABOUT 34 DEGREES THIS MORNING...WITH AREAS
GENERALLY SOUTH OF A HARLOWTON TO BILLINGS TO ASHLAND LINE ALREADY
BELOW THIS THRESHOLD. OBSERVATIONS AND WEB CAMS SHOWING SNOW OVER
MOST OF THESE AREAS AT 3 AM. THE HEAVIEST ACCUMULATIONS NOTED ON
WEB CAMS SO FAR HAVE BEEN ACROSS SOUTHERN SHERIDAN COUNTY WITH
A SLUSHY ACCUMULATION COVERING I-90 IN THIS AREA. HAD REPORTS LATE
LAST EVENING OF ACCUMULATIONS IN LIVINGSTON AND RED LODGE AS WELL.
WITH THE ENHANCED LIFT FROM THE STRONG QG FORCING EXPECT DYNAMIC
COOLING TO DROP TEMPERATURES A COUPLE MORE DEGREES THIS MORNING.
THIS SHOULD DROP SNOW LEVELS DOWN INTO THE VALLEYS OF SOUTH
CENTRAL MONTANA INCLUDING BILLINGS AROUND SUNRISE...THOUGH DO NOT
EXPECT MUCH IF ANY ACCUMULATION BELOW 4000 FEET. EXPECT SNOW TO
CHANGE BACK OVER TO RAIN LATE THIS MORNING AND INTO THE EARLY
AFTERNOON BEFORE PRECIPITATION REALLY TAPERS OFF LATE IN THE DAY.
TEMPERATURE THIS AFTERNOON SHOULD HOLD IN THE 40S WITH SUBSTANTIAL
CLOUD COVER IN PLACE.

AS CLOUDS CLEAR AND DRIER AIR WORKS INTO THE AREA TONIGHT...EXPECT
TEMPERATURES TO DROP QUICKLY THIS EVENING WITH THE POTENTIAL FOR
RECORD LOW TEMPERATURES. A HARD FREEZE LOOKS PROBABLE FOR MUCH OF
THE AREA FRIDAY MORNING. AREAS THAT HAVE RESIDUAL SNOW COVER COULD
SEE TEMPERATURES NEAR 20 DEGREES TO START THE DAY.

DRIER NORTHWEST FLOW WILL BE OVER THE AREA FRIDAY WITH PLENTY OF
SUN. EXPECT TEMPERATURES TO RECOVER INTO THE LOWER 60S AFTER A
COLD START TO THE DAY. CHAMBERS


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

NO SIGNIFICANT CHANGES IN THE EXTENDED FORECAST WITH THIS FORECAST
PACKAGE. THE THEME THROUGH THE MIDDLE OF NEXT WEEK WILL BE A SLOW
WARMING TREND WITH DRY CONDITIONS IN PLACE.

SATURDAY AND SUNDAY...NORTHWESTERLY FLOW WITH SHORTWAVES PASSING
EAST OF THE FORECAST AREA WILL KEEP BACKDOOR COLD FRONT IN PLACE.
THIS WILL KEEP HIGH TEMPERATURES BELOW SEASONAL AVERAGES...ALTHOUGH
WARMER THAN THE CURRENT AIRMASS. NO SOURCES OF FORCING AND DRIER
AIRMASS IN PLACE WILL KEEP THE FORECAST DRY.

RIDGING WILL SLOWLY BUILD INTO THE AREA THROUGH THE MIDDLE AND END
OF THE WEEK. TEMPERATURES WILL CONTINUE THE SLOW WARMING
TREND...WITH HIGH TEMPERATURES IN THE UPPER 70S BY WEDNESDAY.
CONSENSUS SEEMS TO BE FOR A WEAK SHORTWAVE RIDING OVER THE RIDGE
BY TUESDAY INTO WEDNESDAY. WAVE WILL HELP TO SUPPRESS THE RIDGE
SLIGHTLY AND PUSH A WEAK FRONT THROUGH THE AREA...HOWEVER MODELS
ARE ALL PASSING THE WAVE NORTH AND KEEPING US DRY WITH THE
DOWNSLOPE FLOW. EVEN IF TRACK SHIFTS SOUTH...WOULD LIKELY ONLY BE
WORTH SOME SLIGHT CHANCE POPS...AND WOULDN`T BE A VERY DYNAMIC
SYSTEM.

CHURCH

&&

.AVIATION...

IFR AND LIFR CONDITIONS ARE EXPECTED IN MOST LOCATIONS THIS
MORNING. RAIN AND SNOW WILL WILL BE MIXED NEAR KLVM...KBIL...AND
KMLS. SNOW WILL BE HEAVIEST NEAR KSHR...WHERE WE ESTIMATE A 50
PERCENT CHANCE OF SEEING AIRPORT MINIMUMS /VISIBILITY DOWN TO 1/4
MILE/ AT TIMES BEFORE 17 UTC. FLIGHT CONDITIONS WILL IMPROVE FROM
NORTH TO SOUTH THIS AFTERNOON. CHURCH
&&

.PRELIMINARY POINT TEMP/POPS...

    TDY FRI     SAT     SUN     MON     TUE     WED
-------------------------------------------------------
BIL 044 029/060 037/060 042/063 044/072 048/077 050/079
    +/O 10/U    01/U    11/U    10/U    11/U    11/U
LVM 041 022/063 031/062 035/066 038/076 044/079 045/080
    7/O 10/U    01/U    11/U    10/U    01/U    11/U
HDN 046 028/062 035/063 041/066 042/074 046/078 047/080
    +/O 10/U    01/U    11/U    11/U    11/U    11/U
MLS 049 030/061 037/061 040/065 043/072 046/076 048/078
    5/O 10/U    01/U    11/U    11/U    01/U    11/U
4BQ 044 028/059 036/061 041/065 043/073 047/077 050/079
    +/O 20/U    01/U    11/U    10/U    11/U    11/U
BHK 046 028/057 034/059 037/062 040/070 044/073 046/076
    4/O 10/U    01/U    11/U    11/U    01/U    11/U
SHR 038 021/057 031/060 036/065 039/074 044/078 046/081
    +/O 30/U    01/U    10/U    11/U    11/U    11/U

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WINTER WEATHER ADVISORY IN EFFECT UNTIL NOON MDT TODAY FOR
      ZONES 28-40-41-63>65.
     WINTER WEATHER ADVISORY IN EFFECT UNTIL 3 PM MDT THIS
      AFTERNOON FOR ZONES 38-58.
     WINTER STORM WARNING IN EFFECT UNTIL 3 PM MDT THIS AFTERNOON
      FOR ZONES 56-66>68.
WY...WINTER STORM WARNING IN EFFECT UNTIL 3 PM MDT THIS AFTERNOON
      FOR ZONES 98-99.

&&

$$
WEATHER.GOV/BILLINGS


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