Wind Chill Advisory 4, NWS Billings, MT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
326 AM MST SUN JAN 26 2014

.SHORT TERM...VALID FOR TDY AND MON...

THE SHORT TERM FOCUS IS ON THE ARCTIC FRONTAL PASSAGE TODAY...AND
ITS RELATED IMPACTS TO TRAVEL...WHICH WILL BE SIGNIFICANT IN SOME
AREAS. AS OF 10 UTC...THE SURFACE FRONT IS PICKING UP STEAM...BUT
IS STILL NORTH OF THE MONTANA-CANADIAN LINE. SURFACE WINDS IN ITS
WAKE HAVE BEEN GUSTING TO 40 KT...AND SOME OBSERVATIONS HAVE BEEN
SHOWING BRIEF 3/4SM VISIBILITY IN SNOW...BOTH OF WHICH ARE LIKELY
A GOOD PROXY FOR THE CONDITIONS PARTS OF OUR AREA WILL SEE TODAY.

TODAY...THE 00 UTC GUIDANCE SLOWED A BIT WITH THE ARRIVAL OF REAL
LOW- AND MID-LEVEL COLD AIR ADVECTION. THAT MAY ALLOW THE SURFACE
TEMPERATURES TO STAY A BIT WARMER INITIALLY...AND THAT COULD KEEP
ROADS FROM COOLING BELOW 32 F BEFORE SNOW STARTS...INCREASING THE
ODDS OF SLICK SURFACES ONCE SNOW DOES BEGIN. SPEAKING OF THAT...A
QUICK-HITTING BATCH OF FORCING VIA FRONTOGENESIS TOPPED BY A 130+
KT 300-HPA JET STREAK FAVORS A PERIOD OF POST-FRONTAL SNOW ACROSS
MOST OF THE AREA TODAY. WE LEANED A BIT MORE ON THE 00 UTC GFS TO
BUILD THE POP/SNOW FORECAST TODAY SINCE IT OFFERS A MIDDLE-OF-THE
ROAD TIMING TO THE SURFACE FRONT AND THE LOCATION OF ITS GREATEST
QPF MATCHES WELL WITH OUR CONCEPTUAL MODEL OF WHERE THE MOST SNOW
WILL FALL IN RELATION TO THE JET STREAK AND THE CLIMATOLOGICALLY-
FAVORED SPOTS FOR UPSLOPE ENHANCEMENT IN THIS PATTERN. THE 00 UTC
GFS AND A BLEND OF SNOW RATIO METHODS SUPPORTS SNOW TOTALS FROM 1
TO 3 INCHES IN MANY PLACES...WITH 2 TO 4 INCHES OVER BIG HORN AND
SOUTHERN ROSEBUD COUNTIES DOWN TO SHERIDAN...AND SOMEWHAT GREATER
AMOUNTS IN THE IMMEDIATE FOOTHILLS. FORECAST SOUNDINGS DON/T HAVE
MUCH DEPTH TO THEIR SIMULATED SATURATION...ESPECIALLY AT BILLINGS
AND MILES CITY...SO THIS WILL BE A QUICK SHOT OF SNOW ACROSS MOST
OF THE AREA. WE ARE ONLY EXPECTING ABOUT AN INCH IN BILLINGS.

THE OTHER ISSUE TODAY WILL BE WINDS OWING TO VERY STRONG PRESSURE
RISES /5-10 HPA PER 3 HOURS IN SOUTHEASTERN MT/ BEHIND THE ARCTIC
FRONT. STRONG COLD AIR ADVECTION WILL HAVE ACCESS TO 850-HPA WIND
SPEEDS OF 45 KT...ALL OF WHICH SHOULD PRODUCE 55 MPH GUSTS ACROSS
MANY OPEN AREAS TODAY. WE WOULD BE MORE CONCERNED ABOUT GETTING A
WIDESPREAD AREA OF 60+ MPH GUSTS IN SOUTHEASTERN MT IF THE MODELS
HAD 850-HPA WIND SPEEDS JUST A BIT HIGHER...AS ONLY 30 PERCENT OR
SO OF HIGH WIND EVENTS SINCE 1999 IN THAT AREA HAVE OCCURRED WHEN
WINDS AT THAT LEVEL ARE LESS THAN 50 KT. REGARDLESS...WE FEEL THE
COMBINATION OF NEAR-HIGH-WIND CRITERIA SPEEDS AND FALLING/BLOWING
SNOW IS WELL-HANDLED WITH OUR WINTER WEATHER ADVISORY. CONDITIONS
WILL BE PARTICULARLY NASTY IN SHERIDAN COUNTY...AND NEAR-BLIZZARD
WORDING WILL BE EMPHASIZED IN OUR MESSAGING THERE TODAY. IF THERE
WAS A BIT MORE SATURATION TO SOUNDINGS TO IMPLY A LONGER DURATION
OF FALLING SNOW THERE...WE WOULD HAVE CONSIDERED GOING FULL SPEED
AHEAD WITH A BLIZZARD WARNING FOR SHERIDAN COUNTY GIVEN POTENTIAL
IMPACTS ALONG INTERSTATE 90. SOMETHING TO KEEP AN EYE ON TODAY.

AS FOR THE WINTER WEATHER ADVISORY...WE ADDED TREASURE...NORTHERN
ROSEBUD...AND CUSTER COUNTIES INTO IT SINCE THAT AREA WILL LIKELY
GET SOLID 50+ MPH WIND GUSTS...CAUSING TRAVEL ISSUES EVEN IF THEY
ONLY GET AN INCH OR TWO OF SNOW. THE REST OF THEA ADVISORY WASN/T
CHANGED FROM ITS ORIGINAL ISSUANCE.

STARTING TONIGHT...THINGS SETTLE DOWN AND WE ARE LEFT WITH A COLD
AIR MASS ALL THE WAY THROUGH MON NIGHT. OUR FORECAST TEMPERATURES
ARE WEIGHTED SOMEWHAT TOWARD MODEL 2 METER GUIDANCE...NOT THE MOS
NUMBERS...WHICH ARE COLDER BUT PERHAPS TOO COLD WITHOUT TRUE DEEP
OR FRESH SNOW PACK /EXEMPLIFIED BY THE FACT THAT MOS WAS TOO COLD
WITH THE OTHER TWO COLDER PERIODS IN JANUARY/. FORECAST SOUNDINGS
SUGGEST BOUNDARY LAYER WINDS WILL STAY NEAR 10 KT IN SOUTHEASTERN
MT ALL THE WAY THROUGH TUE NIGHT...CAUSING WIND CHILL PROBLEMS. A
WIND CHILL ADVISORY HAS THUS BEEN ISSUED FOR SOUTHEASTERN MT FROM
01 UTC TONIGHT /THE END OF TODAY/S WINTER WEATHER ADVISORY/ UNTIL
19 UTC MON. NOTE THAT THE WIND CHILL HEADLINE START TIME COULD BE
PUSHED AHEAD IF THE WINTER WEATHER ADVISORY IS CANCELLED EARLIER.
WE WILL ALSO PROBABLY NEED A WIND CHILL ADVISORY AGAIN OVER THOSE
SAME AREAS MON NIGHT...BUT THERE IS ENOUGH OF A BREAK IN ANY WIND
CHILLS UNDER 20 BELOW ZERO IN OUR CURRENT FORECAST TO HOLD OFF ON
CARRYING THE ADVISORY FOR ALL OF THE NEXT 48 HOURS NOW...ALTHOUGH
WE COULD END UP DOING THAT LATER. SCHULTZ

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

UNSETTLED WEATHER PATTERN CAN BE EXPECTED FOR TUESDAY THROUGH
NEXT SUNDAY ACROSS SC/SE MT. WINDS WILL BE A CONCERN TUESDAY AS
WEAK RIDGING OVER MONTANA WILL BE KNOCKED DOWN BY A STRONG SHORT
WAVE MOVING IN FROM THE PACIFIC NORTHWEST. THE WAVE WILL CAUSE A
LEE SIDE TROUGH TO DEEPEN AND A FAST 700 MB FLOW TO DEVELOP. THIS
WILL RESULT IN GAP FLOW WINDS DEVELOPING NEAR NYE AND LIVINGSTON
WITH STRONG WINDS POSSIBLE IN THE BIG TIMBER AREA. WINDS WILL
WEAKEN BY WEDNESDAY MORNING AS BROAD UPPER LEVEL TROUGH MOVES IN
OVER THE NORTHERN PLAINS. THE TROUGH WILL BRING A NORTHERLY FLOW
ALONG WITH A PUSH OF ARCTIC AIR INTO THE AREA...BRINGING BELOW
NORMAL TEMPERATURES FOR THE REMAINDER OF THE WEEK ALONG WITH
PERIODS OF SNOW. BEST CHANCE FOR SIGNIFICANT SNOWFALL WILL BE
WEDNESDAY/WEDNESDAY NIGHT WITH STRONG BAROCLINIC ZONES SETTING UP
NEAR BILLINGS. STILL SOME UNCERTAINTY ON WHERE THIS ZONE WILL SET
UP EXACTLY BUT WILL KEEP LIKELY POPS GOING FOR BILLINGS WEST.
COLD TEMPERATURES WILL CONTINUE FOR THURSDAY THROUGH SUNDAY AS
REINFORCING SHOTS OF ARCTIC AIR WILL MOVE INTO THE AREA BEHIND A
SERIES OF UPPER LEVEL SHORT WAVES. RICHMOND

&&

.AVIATION...

AN ARCTIC COLD FRONT WILL BRING A WIND SHIFT TO THE NORTH-
NORTHWEST BETWEEN 15 AND 18Z TODAY. WIND GUSTS OF 35-45 KTS ARE
EXPECTED FROM KSHR-KMLS TO KBHK WITH THE FRONTAL PASSAGE. THE
ARCTIC FRONT WILL ALSO BRING A PERIOD OF SNOW SHOWERS WHICH WILL
PRODUCE MVFR TO IFR CONDITIONS. AREAS OF BLOWING SNOW WILL ALSO
BRING AREAS OF LOW VISIBILITY. THE SNOW WILL TAPER OFF FROM NORTH
TO SOUTH DURING THE AFTERNOON. RICHMOND

&&

.PRELIMINARY POINT TEMP/POPS...

    TDY MON     TUE     WED     THU     FRI     SAT
-------------------------------------------------------
BIL 039 004/018 004/030 021/037 018/030 016/027 012/027
    8/O 10/B    00/B    17/S    62/S    23/S    23/S
LVM 039 002/019 001/032 020/036 020/032 017/030 012/032
    7/S 30/U    01/N    27/S    62/S    23/S    33/S
HDN 037 003/016 003/026 016/036 015/028 013/026 011/025
    +/O 10/B    00/U    17/S    52/S    33/S    23/S
MLS 034 913/005 907/021 011/029 008/021 008/020 006/019
    8/O 00/B    00/B    13/S    31/B    12/S    22/S
4BQ 037 905/010 904/024 013/034 013/026 010/026 008/025
    9/O 10/U    00/U    14/S    42/S    23/S    22/S
BHK 032 914/901 918/016 007/026 004/018 004/018 005/018
    8/O 00/I    00/U    12/S    21/B    12/S    12/S
SHR 043 905/011 905/025 014/037 015/030 012/028 009/029
    +/O 30/B    00/U    27/S    43/S    24/S    33/S

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WINTER WEATHER ADVISORY IN EFFECT UNTIL 6 PM MST THIS EVENING
      FOR ZONES 30>33-36>38-57-58-63.
     WIND CHILL ADVISORY IN EFFECT FROM 6 PM THIS EVENING TO NOON
      MST MONDAY FOR ZONES 32-33-36-37.
     WINTER WEATHER ADVISORY IN EFFECT UNTIL 9 PM MST THIS EVENING
      FOR ZONES 39-56-66.
WY...WINTER WEATHER ADVISORY IN EFFECT UNTIL 6 PM MST THIS EVENING
      FOR ZONES 98-99.

&&

WEATHER.GOV/BILLINGS

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