weather.gov     
National Weather Service

Area Forecast Discussion
NWS Homepage
This page is being discontinued on March 12, 2014.
The same data is available at this site. Please update your bookmarks.
Thank you, and we apologize for the inconvenience.
Please send an email to SR-SRH.Webmaster@noaa.gov with any concerns.


Current Version
Previous Version:    01  02  03  04  05  06  07  08  09  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  
[Printable]
067
FXUS65 KBYZ 211630
AFDBYZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
930 AM MST FRI NOV 21 2014

.UPDATE...
ZONAL FLOW OVER THE AREA WITH WEAK ENERGY SLIDING THROUGH.
MOISTURE PRETTY LIMITED WITH THESE WAVES AND SO THERE IS NOT MUCH
HAPPENING ON AREA RADARS. LOWERED POPS A LITTLE MORE FOR TODAY.
RAISED TEMPERATURES FOR THE WEST AS STARTING OUT PRETTY WARM AND
OUTSIDE OF A FEW MORE CLOUDS TODAY...SHOULD APPROACH HIGHS OF
YESTERDAY. WINDS WILL BE STRONG OVER THE WEST TODAY AND THIS
HANDLED WELL. WINDS WILL GET EVEN STRONGER TONIGHT AT LIVINGSTON
AND BIG TIMBER AND WILL ADDRESS THAT ON THE AFTERNOON PACKAGE AS
THE MODELS CONTIUE TO FLOW IN. TWH

&&

.SHORT TERM...VALID FOR TDY AND SAT...

MINIMAL CHANGE TO THE SHORT TERM PERIOD THIS MORNING. GREATEST
CONCERN THROUGH THE PERIOD CONTINUES TO BE POTENTIAL FOR STRONG
AND GUSTY WINDS DEVELOPING ACROSS THE WEST...INCLUDING
LIVINGSTON...NYE...BIG TIMBER...AND HARLOWTON. MOST RECENT
GUIDANCE HAS PULLED BACK ON WINDS SIGNIFICANTLY...SHRINKING WINDOW
FOR STRONG WINDS...AND LOWERING PEAK FORECAST WINDS. BEST
CONDITIONS APPEAR TO BE LATE TONIGHT/EARLY SATURDAY...AROUND 12Z...AS
GRADIENT TIGHTENS JUST AHEAD OF UPPER LEVEL PACIFIC WAVE. DID
PARE BACK WINDS SLIGHTLY FROM 03-09Z TONIGHT AND AFTER 15Z AS
WELL. OTHERWISE PEAK WIND FORECASTS OF GUSTS NEAR 70 MPH IN
LIVINGSTON AND NYE...AND UP TO 50 MPH FROM BIG TIMBER TO
HARLOWTON STILL APPEAR IN THE BALLPARK. CHOSE NOT TO ISSUE A WIND
ADVISORY AT THIS TIME BASED ON MARGINAL GUIDANCE. CONTINUED
ATTENTION WILL BE NEEDED IN LATER SHIFTS.

THE PACIFIC TROF WILL BEGIN TO CROSS THE REGION TONIGHT...BRINGING
SNOW SHOWERS TO AREA MOUNTAINS...AND SOME POTENTIAL FOR SCATTERED
SHOWERS ACROSS THE PLAINS. WESTERN MOUNTAIN FACES COULD SEE SOME
BETTER ACCUMULATIONS OF SNOW...WHILE DOWNSLOPE FLOW SHOULD LIMIT
EASTERN SLOPE ACCUMULATIONS...AS WELL AS ANY STRONG SHOWER
POTENTIAL INTO THE PLAINS. HAVE CONTINUED WITH INHERITED POPS
ACROSS THE PLAINS...AS DOWNSLOPE SHOULD BE MAJOR LIMITING FACTOR
OVER MUCH OF THE AREA...BUT STILL CANNOT DISCOUNT POTENTIAL FOR
MIX OF PRECIP. DID RAISE POPS IN WESTERN MOUNTAINS SLIGHTLY...AS
WELL AS SNOW AMOUNTS HOWEVER.

AS FOR TEMPS...EXPECT TO SEE HIGHS IN THE 40S TODAY AND SATURDAY
AHEAD OF THE APPROACHING WEATHER SYSTEM...AND RELATIVELY WARM
PACIFIC SYSTEM WILL NOT BRING MUCH IN THE WAY OF COOLER AIR INTO
THE REGION. THEREFORE...ANY PRECIP IN THE PLAINS WILL LIKELY
START AS RAIN AND TURN TO SNOW LATER ON. AAG

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

BIG COOL DOWN ON SUNDAY AS A COLD FRONT MOVES THROUGH THE REGION
DRIVEN BY AN INTENSE UPPER LEVEL DISTURBANCE OVER THE DAKOTAS.
FRONT DOES WASH OUT AS IT MOVES WESTWARD THROUGH CENTRAL MONTANA
AS DOWNSLOPE PLAYS A ROLE. OTHER FACTOR IS THAT THE COLD AIR
BEHIND THIS FRONT IS NOT REAL DEEP AND ITS MORE DRIVEN BY THE
STRENGTH OF THE UPPER LEVEL FEATURE VERSUS A TAP OF ARCTIC AIR.
THIS IS REFLECTED ON MONDAY WHERE TEMPERATURES ARE ONLY 3 TO 5
DEGREES BELOW NORMAL IN THE POST FRONTAL ENVIRONMENT. SHOWER
ACTIVITY LOOKS LIMITED BOTH DAYS AND FAVORS EITHER THE FRONTAL
BOUNDARY OR OROGRAPHIC MECHANISMS.

TUESDAY AN UPPER LEVEL RIDGE BEGINS TO MAKE A PUSH INTO THE
PACIFIC WEST BUT MODELS IN DISAGREEMENT IN HOW FAR EAST AND HOW
STRONG THIS RIDGE WILL BECOME. THE PATTERN HINTS AT AN ALIGNMENT
FOR A SNOW MAKER AS THE PATTERN ALLOWS NORTHWESTERLY FLOW ALOFT
ALONG THE CANADIAN FRONT RANGE PUSHES COLDER AIR INTO THE REGION
WHILE DEEP MOISTURE FLOWS OVER THE RIDGE AXIS INTO MONTANA AND
WYOMING. THIS IS THE CURRENT GFS SOLUTION AND WAS THE 11/20 00Z
ECMWF SOLUTION FOR THE EC HAS BROUGHT A STRONGER RIDGE INTO THE
REGION THE PAST TWO RUNS. THIS IS A DRIER AND WARMER SOLUTION. A
COUPLE OF BIG PICTURE FEATURES BEAR WATCHING. OVER THE ATLANTIC A
MASSIVE UPPER LEVEL RIDGE IS CONSISTENTLY PROJECTED SO THIS WILL
TREND TOWARDS A HIGHER AMPLITUDE PATTERN OVER THE CONUS. BUT THE
MODELS ARE VERY UNCERTAIN ABOUT ITS IMPACTS OVER THE NORTHERN
INTERMOUNTAIN REGION AS EVIDENCED BY SIGNIFICANT NOISE IN THE GFS
ENSEMBLES. WILL REINFORCE THE MESSAGE DAY SHIFT STATED THAT
UNCERTAINTY IS VERY SIGNIFICANT FOR THESE LATER PERIODS.

BOTTOM LINE IS WATCHING WEATHER PATTERN WEDNESDAY TO SEE IF IT
COULD PRODUCE A LOT OF SNOW ON A BUSY TRAVEL DAY BUT FOR NOW HAVE
CONSENSUS TEMPERATURES AROUND 30 AND SCATTERED SHOWERS AS A
COMPROMISE. BORSUM


&&

.AVIATION...

LINGERING LOW LEVEL WIND SHEAR AT KMLS WILL DIMINISH BY MIDDAY.
GUSTIEST WINDS OVER THE NEXT 24 HOURS WILL BE ALONG THE
WESTERN FOOTHILLS. EXPECT SW GUSTS TO 35 KTS AT KLVM TODAY
INCREASING TO NEAR 50 KTS LATE TONIGHT INTO SATURDAY MORNING.
OTHERWISE...VFR WILL PREVAIL AT LOWER ELEVATIONS WITH AREAS OF
MID AND HIGH CLOUD. THE BEARTOOTH ABSAROKAS WILL BEGIN TO PICK UP
SOME SNOW AND WILL BE FREQUENTLY OBSCURED LATE TONIGHT. JKL

&&

.PRELIMINARY POINT TEMP/POPS...

    TDY SAT     SUN     MON     TUE     WED     THU
-------------------------------------------------------
BIL 046 029/048 030/040 025/038 024/038 021/031 010/025
    0/B 12/W    21/N    22/J    23/J    45/J    32/J
LVM 048 030/045 024/035 021/033 019/034 023/032 009/024
    0/N 14/W    22/J    32/J    24/J    44/W    32/J
HDN 046 022/049 026/041 020/038 019/038 018/031 007/025
    0/B 02/W    21/N    22/J    23/J    34/J    31/B
MLS 043 021/041 025/033 015/030 015/034 015/025 003/022
    0/U 02/W    32/W    11/B    22/W    23/J    21/B
4BQ 045 021/044 026/035 018/031 015/035 017/028 007/021
    0/B 02/W    22/J    11/B    23/J    24/J    31/B
BHK 042 020/040 024/029 011/023 013/031 012/021 000/019
    0/B 02/W    23/J    21/N    12/J    23/J    21/B
SHR 045 021/045 022/037 017/034 015/035 018/033 008/025
    0/U 03/W    31/N    22/J    23/J    44/W    32/J

&&

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

&&

$$
WEATHER.GOV/BILLINGS




U.S. Dept. of Commerce
NOAA National Weather Service
1325 East West Highway
Silver Spring, MD 20910
E-mail: w-nws.webmaster@noaa.gov
Page last modified: May 16, 2007
NATIONAL WEATHER SERVICE: for Safety, for Work, for Fun - FOR LIFE