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000
FXUS65 KBYZ 050438
AFDBYZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
938 PM MST WED DEC 4 2013

.UPDATE...
ANOTHER QUICK UPDATE TO THE FORECAST TO ADJUST WEATHER GRIDS TO
SHOW FLURRIES THROUGH MIDNIGHT AND THEN PRECIPITATION ENDING
THEREAFTER. ALSO RAISED LOW TEMPERATURES A COUPLE DEGREES FOR
BILLINGS...BUT STILL SHOWING A LOW OF 10 BELOW ZERO.

PREVIOUS UPDATE...
QUICK UPDATE TO THE FORECAST TO CANCEL THE WIND
CHILL ADVISORY FOR JUDITH GAP. WINDS HAVE TRENDED DOWN THERE THIS
EVENING AND ARE EXPECTED TO REMAIN BELOW 10 MPH FOR THE REST OF
THE NIGHT AS SURFACE HIGH PRESSURE SETTLES IN.

CHURCH

&&

.SHORT TERM...VALID FOR THU AND FRI...

VERY COLD WEATHER IN STORE FOR THE NEXT FEW DAYS...WITH COLDEST
AIR YET TO COME.

AREAS OF VERY LIGHT SNOW/FLURRIES CONTINUE THIS AFTERNOON BUT WITH
COVERAGE AND INTENSITY DIMINISHING AS ASCENT WANES. THIS PCPN
SHOULD END OR TAPER TO NO MORE THAN FLURRIES THIS EVENING. SFC
HIGH REMAINS TO OUR NW SO GUSTY WINDS CONTINUE AT JUDITH GAP AND
ACROSS OUR EAST. SOME AREAS OF BLOWING SNOW EXIST...BUT BIGGER
IMPACT WILL EVOLVE INTO WIND CHILLS AS TEMPS FALL TONIGHT BUT
WINDS REMAIN IN THE TEENS. THIS WILL YIELD WIND CHILLS ON THE
ORDER OF 2O TO 30 BELOW ACROSS OUR EAST TONIGHT AND PROBABLY INTO
THE DAYTIME HOURS ON THURSDAY. ALSO...JUDITH GAP WINDS ARE STILL
GUSTING INTO THE 30S AND WINDS IN THIS FAVORED SPOT WILL STAY UP
INTO THE EVENING IF NOT A BIT LONGER. WILL MAKE NO CHANGE TO THE
BLSN/WIND CHILL HIGHLIGHTS FOR THESE AREAS.

BRUTALLY COLD AIRMASS WILL SETTLE OVER THE AREA THE NEXT FEW DAYS.
THOUGH WE WILL STILL BE COLD ADVECTING TONIGHT...COLDEST AIR WILL
SURGE INTO OUR AREA THURSDAY NIGHT INTO FRIDAY AS ENERGY FROM
CENTRAL CANADA PUSHES TO THE SW OVER THE NEXT 24-36 HOURS...WITH
INCREASINGLY CONFLUENT FLOW ALOFT RESULTING IN A STRENGTHENING
SFC HIGH EAST OF THE MTNS. SO EXPECT A SHIFT TO EAST WINDS AS THE
COLD AIR IS SHOVED ALL THE WAY TO THE FOOTHILLS. MODELS IN VERY
GOOD AGREEMENT IN SHOWING 850MB TEMPS WELL INTO THE -20S BY
FRIDAY. THIS WILL YIELD EASILY THE COLDEST TEMPS IN A COUPLE
YEARS...PERHAPS LONGER...THOUGH IT REMAINS TO BE SEEN WHETHER WE
REACH THE AIRMASS/S POTENTIAL DUE TO CLOUD COVER. ALSO...MODELS
CONTINUE TO BE TOO COLD WITH OUR CURRENT WX...WE HAVE ACTUALLY
DIURNALLED OUR WAY UP INTO THE SINGLE DIGITS ABOVE ZERO MOST
PLACES TODAY...SO MUST KEEP THAT IN MIND FOR OUR TEMP FORECAST
OVER THE NEXT COUPLE DAYS.

BEST POTENTIAL FOR A COLD NIGHT TONIGHT WILL BE OVER OUR WEST AS
SFC HIGH PUSHES IN AND WINDS TURN LIGHTER...AND THIS IS ALSO
WHERE WE ARE MOST LIKELY TO SEE SOME CLEARING. RECORD LOW OF -20
AT LIVINGSTON WILL BE CHALLENGED. PROBABLY TOO MUCH WIND FOR A
VERY COLD NIGHT IN OUR EAST...OF COURSE THE WIND CHILLS WILL NOT
FEEL GOOD. AS PREVIOUSLY MENTIONED...COLDEST AIR WE WILL SEE COMES
INTO OUR AREA THURSDAY NIGHT-FRIDAY. EXPECT HIGHS TO STAY BELOW
ZERO ACROSS THE AREA ON FRIDAY. FRIDAY NIGHT WILL BE A VERY COLD
NIGHT BUT WITH ONGOING MOIST ISENTROPIC ASCENT THERE WILL BE CLOUD
COVER TO KEEP TEMPS A BIT MODERATED...ESPECIALLY IN OUR WEST.
COULD SEE 25 TO 30 BELOW IN OUR FAR EAST THOUGH IF CLOUD COVER IS
LESS OF A FACTOR FRIDAY NIGHT.

IF YOU ARE CURIOUS WHEN OUR CWA LAST SAW MINUS 30...LOOK NO
FURTHER THAN 2011 AS MILES CITY HIT 31 BELOW IN LATE FEBRUARY. IF
BILLINGS REACHES 20 BELOW...AND THIS IS DEBATABLE...IT WOULD BE
THE FIRST TIME SINCE 1997. INTERESTINGLY...DAILY RECORDS WILL BE
TOUGH TO REACH AS WE WILL BE COMPETING WITH A BRUTAL COLD SNAP AT
THIS TIME IN 1972.

ENERGY FROM NW CANADA WILL DROP ALONG THE WEST COAST OVER THE NEXT
24-36 HOURS...PICKING UP SOME PACIFIC MOISTURE...AND PERIOD OF
FAIRLY MOIST ISENTROPIC ASCENT AHEAD OF THIS ENERGY SHOULD BE
ENOUGH TO PROVIDE SOME OVERRUNNING LIGHT SNOWFALL FOR OUR WEST
HALF THURSDAY NIGHT THROUGH FRIDAY NIGHT. THERE WILL BE NO
DENDRITIC LAYER GIVEN THE VERY COLD AIR WHICH WILL BE IN
PLACE...SO SNOWFALL WILL BE VERY FINE THUS LIMITING ACCUMULATIONS
TO AN INCH OR LESS.

JKL

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

NOT MANY CHANGES TO THE EXTENDED FORECAST FROM THE PREVIOUS
VERSION. MODELS REMAIN IN DECENT AGREEMENT IN BRINGING ANOTHER
SHOT OF ARCTIC AIR INTO THE REGION FRIDAY NIGHT INTO SATURDAY AND
AGAIN SUNDAY NIGHT INTO MONDAY. AT THIS TIME...EACH OF THESE
SYSTEMS DO NOT SHOW MUCH MOISTURE WITH THEM SO MAINLY SOME LIGHT
SNOW SHOWERS OR FLURRIES CAN BE EXPECTED SATURDAY AND SUNDAY. AT
THE SAME TIME SATURDAY NIGHT INTO SUNDAY...MODELS DEVELOP A
SURFACE LOW OVER THE FOUR CORNERS REGION AND SHIFT IT EAST INTO
COLORADO AND KANSAS LATE SUNDAY. THE NORTHERN FRINGE OF THE PRECIP
MOVES ACROSS CENTRAL WYOMING SO WILL NEED TO WATCH THIS FOR ANY
NORTHWARD TRENDS. IN ANY CASE...EXPECT BITTERLY COLD TEMPERATURES
TO CONTINUE SATURDAY AND SUNDAY.

BY MONDAY INTO WEDNESDAY...MODELS ARE IN GOOD AGREEMENT IN TRYING
TO BRING MORE OF A PACIFIC FLOW ALOFT ACROSS OUR FORECAST AREA AS
OPPOSED TO THE CURRENT ARCTIC AIRMASS. BOTH THE GFS AND ECMWF TRY
TO BRING SOME WEAK RIDGING OVER THE STATE...AS WELL AS A LEE- SIDE
TROUGH ACROSS OUR FORECAST AREA. THIS WOULD BRING IN THE
LIKELIHOOD OF A TIGHTENING PRESSURE GRADIENT AND WINDY CONDITIONS
FROM MAINLY BILLINGS TO LIVINGSTON. AS A RESULT...MODELS WARM
TEMPERATURES UP NEAR FREEZING BY TUESDAY. HOWEVER...GIVEN THE
EXTENSIVE SNOW COVER ACROSS OUR AREA ALONG WITH VERY COLD AIR
ACROSS THE BIG HORN BASIN...THESE NUMBERS MAY BE A BIT
CONSERVATIVE. AT THIS TIME...HAVE TWEAKED TEMPERATURES UPWARD A
DEGREE OR TWO BUT NOT NEARLY AS MUCH AS GUIDANCE FOR THE MONDAY
THROUGH WEDNESDAY TIMEFRAME. HOOLEY
&&

.AVIATION...

AREAS OF LIGHT SNOW AND MVFR CONDITIONS WILL OCCUR OVER THE AREA
TONIGHT. THERE WILL ALSO BE LOCALIZED MOUNTAIN OBSCURATION. EXPECT
VFR CONDITIONS ON THU. ARTHUR
&&

.PRELIMINARY POINT TEMP/POPS...

    THU     FRI     SAT     SUN     MON     TUE     WED
-----------------------------------------------------------
BIL 910/901 915/907 917/906 915/010 905/010 001/020 016/027
    10/I    13/S    32/J    12/J    33/J    32/J    11/B
LVM 920/001 917/907 918/001 911/008 906/011 902/019 014/023
    11/B    25/S    52/J    12/J    33/J    32/J    22/J
HDN 913/902 917/907 919/906 916/007 907/007 001/018 012/025
    10/I    12/S    22/J    12/J    22/J    22/J    11/B
MLS 913/904 921/909 926/908 918/004 911/003 906/013 006/022
    10/I    00/I    11/I    11/B    22/J    21/B    11/B
4BQ 913/903 921/907 922/906 916/005 910/005 906/014 008/024
    10/I    01/I    11/I    11/B    22/J    21/B    11/B
BHK 912/905 921/909 925/907 916/001 910/002 910/009 901/020
    10/I    00/I    01/I    11/B    12/J    21/B    11/B
SHR 912/901 917/904 918/000 913/010 904/003 901/021 009/025
    10/I    02/S    22/J    22/J    33/J    22/J    11/B

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WINTER WEATHER ADVISORY IN EFFECT UNTIL 5 AM MST THURSDAY FOR
      ZONES 30>33-36>38-57-58.
WY...WINTER WEATHER ADVISORY IN EFFECT UNTIL 5 AM MST THURSDAY FOR
      ZONES 98-99.

&&

$$
WEATHER.GOV/BILLINGS