Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 110954
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
354 AM MDT FRI APR 11 2014

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

A DRY NORTHWEST FLOW ALOFT WILL BE OVER THE FORECAST AREA TODAY.
SATELLITE SHOWING SOME MID AND HIGH LEVEL CLOUDS CURRENTLY MOVING
SOUTHEAST OUT OF CANADA AND THESE WILL MOVE ACROSS OUR FORECAST
AREA TODAY BUT STILL SHOULD SEE A PARTLY SUNNY DAY. A 90-100KT JET
MAX MOVES ACROSS OUR AREA THIS AFTERNOON. MODELS SHOW 700MB WINDS
AROUND 30KTS AND SOME OF THESE WINDS WILL MIX DOWN TO THE SURFACE
THIS AFTERNOON RESULTING IN A BREEZY DAY FROM BILLINGS WESTWARD
WITH WINDY CONDITIONS FROM BIG TIMBER TO LIVINGSTON. MIXING
COMBINED WITH SUNSHINE WILL ALLOW TEMPERATURES TO WARM WELL ABOVE
NORMAL INTO THE MIDDLE 60S TO LOWER 70S FOR MOST LOCATIONS ACROSS
THE PLAINS.

THE WEATHER PATTERN TAKES A BIG CHANGE STARTING LATE TONIGHT INTO
THE WEEKEND. A STORM SYSTEM DROPS SOUTH OUT OF CANADA LATE TONIGHT
INTO SATURDAY MORNING SWEEPING A COLD FRONT THROUGH THE AREA BY
EARLY SATURDAY MORNING. WINDS WILL BECOME NORTHEAST SATURDAY
AFTERNOON PROVIDING FOR A DEEP UPSLOPE FLOW THROUGH ABOUT 700MB
SATURDAY NIGHT. MODELS ARE IN BETTER AGREEMENT WITH THE LOCATION
FOR THE HEAVIEST PRECIP...MAINLY ALONG AND WEST OF A SHERIDAN-
BILLINGS-ROUNDUP LINE WITH THE HIGHER AMOUNTS ALONG THE EAST
SLOPES OF THE BEARTOOTH/ABSAROKA AND BIG HORN MOUNTAINS. PRECIP IS
EXPECTED TO BE IN THE FORM OF RAIN THROUGH MOST OF THE DAY
SATURDAY WITH A RAIN/SNOW MIX DURING THE AFTERNOON WEST OF
BILLINGS. 850MB TEMPERATURES DROP BELOW FREEZING EARLY SATURDAY
EVENING RESULTING IN A CHANGE OVER TO ALL SNOW. GROUND
TEMPERATURES LOOK TO BE WARM ENOUGH TO LIMIT ACCUMULATIONS EAST OF
THE FOOTHILLS AREAS BUT SEVERAL INCHES OF SNOW WILL BE POSSIBLE
FOR THE FOOTHILLS LOCATIONS FROM LIVINGSTON TO RED LODGE TO
SHERIDAN. HOWEVER...CAN`T RULE OUT AN INCH OR TWO ON GRASSY
SURFACES FURTHER EAST TOWARD BILLINGS SATURDAY NIGHT. CONFIDENCE
IS INCREASING FOR SOME TYPE OF SNOW ADVISORY FOR THE FOOTHILLS
LOCATIONS FOR THE SATURDAY NIGHT TIMEFRAME. HOOLEY

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

MEDIUM RANGE PROGS FROM OUR MODELS AGREE ON SOME LINGERING
PRECIPITATION ACROSS MUCH OF THE AREA SUNDAY AS THE BEST FORCING
WILL BE TRACKING SOUTH OF THE AREA. THEREFORE...RELATIVELY VERY
LITTLE ADDITIONAL ACCUMULATION IS EXPECTED EITHER IN THE MOUNTAINS
NOR IN THE LOWER ELEVATIONS THROUGH THE DAY. WINDS WILL TRANSITION
FROM UPSLOPE TO DOWNSLOPE IN THE FOOTHILLS SUNDAY EVENING WITH AN
ENSUING DRYING TREND. THE PROGS CONTINUE TO BE IN DECENT AGREEMENT
FOR OUR REGION ON MONDAY WITH CYCLONIC FLOW OVER THE MIDWEST AND
EASTERN UNITED STATES WITH AN AMPLIFIED RIDGE ON THE WEST COAST.
ECMWF AND GFS THEN DIVERGE ON THEIR SOLUTIONS FOR THE REST OF THE
WEEK. THE ECMWF BREAKS DOWN THE WEST COAST RIDGE AS A SHORT WAVE
TROUGH TRAVERSES OVER IT...AS SUCH THE FLOW OVER OUR REGION
BECOMES ZONAL WITH WEAK PACIFIC WAVES BRINING US A CHANCE OF
SHOWERS AROUND THE MID WEEK TIME FRAME. HOWEVER...THE GFS TAKES
THAT SHORT WAVE TROUGH THROUGH THE RIDGE AND INTO THE DESERT SW AT
MIDWEEK CREATING A SPLIT FLOW AND KEEPING OUR FORECAST DRIER THAN
THE ECMWF. THE LATTER PART OF THE WEEK IS EVEN MORE INCONSISTENT
BETWEEN THE TWO LONGER RANGE MODELS. WE DECIDED TO USE A BLEND DUE
TO THE UNCERTAINTY...BUT I LEANED JUST A LITTLE BIT HEAVIER ON THE
ECMWF AS ITS PATTERN OF PROGRESSIVE WAVES OVER THE REGION IS WHAT
WE HAVE OFTEN SEEN OVER THE LAST MONTH OR TWO. BT

&&

.AVIATION...

NO SIGNIFICANT THREATS TO AVIATION ARE EXPECTED THROUGH FRIDAY
WITH ONLY HIGH CLOUDINESS OVER THE REGION. SURFACE WINDS WILL BE
GUSTY AT TIMES AFTER 17Z ALONG MOST ROUTES IN THE FORECAST AREA.
BT

&&

.PRELIMINARY POINT TEMP/POPS...

    TDY SAT     SUN     MON     TUE     WED     THU
-------------------------------------------------------
BIL 070 040/048 027/039 028/055 034/060 036/057 034/050
    0/N 27/R    73/O    10/U    00/B    22/W    32/W
LVM 068 036/046 025/041 024/057 033/059 035/057 033/051
    1/N 37/O    83/O    10/U    01/B    23/W    32/W
HDN 072 039/050 028/042 026/057 031/061 034/059 033/051
    0/B 27/R    63/O    10/U    00/B    22/W    33/W
MLS 071 038/051 026/041 026/054 029/055 032/054 030/048
    0/B 23/R    22/O    10/U    00/B    22/W    22/W
4BQ 072 040/053 027/041 024/053 028/059 032/056 031/047
    0/B 13/R    42/O    10/U    00/B    22/W    33/W
BHK 067 037/049 025/037 023/048 024/049 027/050 026/044
    1/B 22/R    12/O    00/B    00/B    22/W    22/W
SHR 070 039/050 029/037 020/051 029/059 033/057 034/050
    0/B 27/R    85/O    20/U    00/B    21/B    33/W

&&

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

&&

$$
WEATHER.GOV/BILLINGS



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