Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 212332
AFDBYZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
532 PM MDT TUE OCT 21 2014

.UPDATE...
QUICK UPDATE TO POPS THIS EVENING. DOWNSLOPE FLOW LIMITING UVV
FIELDS FROM BILLINGS TO FOOTHILLS. LOWERED EVENING POPS HERE AND
RAISED THEM TO OUR EAST WHERE DOWNSLOPE LOSES INFLUENCE. CURRENT
RADAR RETURNS SUPPORT THIS CHANGE AS WELL. ALSO EXPANDED EVENING
POPS FURTHER EAST AS SOME ISOLATED SHOWERS DEVELOPING IN WARM
SECTOR IN POWDER RIVER/CARTER COUNTIES. BT

&&

.SHORT TERM...VALID FOR WED AND THU...

SURFACE OBS SHOWING THE COLD HAEV MOVED THROUGH LIVINGSTON WITHIN
THE PAST HOUR AS PRESSURE RISES ARE OBSERVED JUST WEST OF
BILLINGS. HOWEVER...THE MAIN THRUST OF THE FRONT IS IN THE VICNITY
OF BOZEMAN. A FEW THUNDERSTORMS HAVE DEVELOPE ALONG AND JUST AHEAD
OF THE FRONT ACROSS GALLATIN COUNTY AND NORTHERN PARK COUNTY AND
ARE QUICKLY MOVING TO THE NORTH AND NORTHEAST. CLOUDS WILL
CONTINUE TO INCREASE SLOWLY EASTWARD THROUGH THIS AFTERNOON AND
EVENING. WILL CONTINUE WITH JUST A SLIGHT SHOWER CHANCE AND AN
ISOLATED THUNDERSTORM ALONG AND WEST OF A SHERIDAN-BILLINGS-
ROUNDUP LINE THIS AFTERNOON WITH INCREASING CHANCES THIS EVENING
AS BETTER DYNAMICS ARE JUST BEHIND THE FRONT. PRECIP CHANCES WILL
SHIFT EAST DURING THE OVERNIGHT HOURS BUT THE STRONGEST DYNAMICS
LOOK TO MOVE TO THE NORTH OF OUR FORECAST AREA ACROSS NORTHEAST
MONTANA. MAIN IMPACT WITH THIS SYSTEM WILL BE GUSTY WINDS ALONG
AND ESPECIALLY BEHIND THE FRONT. HOWEVER...THE SYSTEM DOES NOT
LOOK AS WINDY AS LAST WEEKS FRONTAL PASSAGE. 700MB WINDS ARE ONLY
25 TO 35 KTS TONIGHT THROUGHW WEDNESAY WITH 850MB WINDS 25 TO 35
KTS TONIGHT AND 20 TO 25 KTS WEDNESDAY. AS A RESULT...GUSTS ACROSS
THE AREA ARE EXPECTED TO BE 30 TO 40 MPH WITH A FEW POSSIBLY CLOSE
TO 50 MPH.

THE SYSTEM WILL QUICKLY EXIT INTO NORTH DAKOTA BY EARLY AFTERNOON
WEDNESDAY BUT STIL ENOUGH INSTABILITY AND TROUGHINESS TO WARRANT A
SLIGHT SHOWER CHANCE DURING THE MORNING ACROS THE EAST. NEXT
SYSTEM APPROACHING THE PACIFIC NORTHWEST WEDNESDAY AFTERNOON WILL
ALLOWING RIDGING TO QUICKLY BUILD ACROSS MONTANA DURING THE
AFTERNOON AND OVERNIGHT HOURS. ALTHOUGH RIDGING BEGINS TO BUILD
DURING THE AFTERNOON....HIGH TEMPERATURES WILL BE ABOUT 10 TO 15
DEGREES COOLER TODAY BUT STILL SLIGHTLY ABOVE NORMAL FOR THIS TIME
OF YEAR. BY THURSDAY...A SURFACE LOW WILL MOVE ACROSS SOUTHERN
CANADA RESULTING IN LEE-SIDE TROUGHING AND A DOWNSLOPE SURFACE
FLOW ACROSS OUR AREA. MOSTLY SUNNY SKIES COMBINED WITH A DOWNSLOPE
FLOW WILL ALLOW TEMPERATURES TO WARM BACK ABOVE NORMAL WITH
READINGS IN THE UPPER 60S TO LOWER 70S. HOOLEY

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

MODELS ARE IN VERY GOOD AGREEMENT THROUGH THE EXTENDED PERIOD
LENDING GOOD CONFIDENCE TO THE FORECAST. CHANGES TO THE GOING
FORECAST ARE OF A MINOR NATURE. OVERALL A MORE PROGRESSIVE FALL
PATTERN IS STARTING TO DEVELOP PUSHING SYSTEMS THROUGH THE AREA
EVERY FEW DAYS...THOUGH STILL NO STRONG LOW PRESSURE SYSTEMS ON
THE HORIZON THAT COULD BRING SIGNIFICANT PRECIPITATION.

ZONAL FLOW ON FRIDAY HAS A DECENT MOISTURE FEED ASSOCIATED WITH
IT FOR POSSIBLY A FEW MOUNTAIN SHOWERS AND EXTENSIVE CLOUD
COVER...BUT DOWNSLOPE SHOULD KEEP LOWER ELEVATIONS MAINLY DRY.
RIDGING DEVELOPS ALOFT SATURDAY AHEAD OF A STRENGTHENING WEST
COAST TROF. THIS WILL BRING DRY AND WARMER CONDITIONS FOR
SATURDAY BUT AS THE UPPER TROF SLOWLY APPROACHES WILL SEE
PRECIPITATION CHANCES INCREASE SUNDAY AND MONDAY. HOWEVER A
SIGNIFICANT DOWNSLOPE GRADIENT AND THE PROGRESSIVE NATURE OF THIS
SYSTEM WILL PREVENT MORE THAN A 20 TO 30 PERCENT CHANCE FOR
PRECIPITATION FOR THE LOWER ELEVATIONS...THOUGH IT COULD BE
SIGNIFICANTLY HIGHER FOR MOUNTAIN LOCATIONS WHERE STRONG PULSE OF
PACIFIC MOISTURE MOVES OVER THE AREA. TEMPERATURES WILL DROP FROM
THE 70S SATURDAY TOWARD MORE SEASONAL LEVELS AS THE UPPER TROF
KICKS THROUGH THE REGION SUNDAY AND MONDAY. BRIEF RIDGING DEVELOPS
ON TUESDAY FOR SLIGHTLY WARMER TEMPERATURES BEFORE ANOTHER SHOT OF
PACIFIC MOISTURE PUSHES OVER THE AREA MID WEEK. CHAMBERS
&&

.AVIATION...

VFR CONDITIONS WILL PREVAIL TONIGHT. A COLD FRONT WILL MOVE
THROUGH THE AREA THIS EVENING WITH WEST TO NORTHWEST WINDS GUSTING
30 TO 40KTS AT TIMES. ISOLATED SHOWER AND THUNDERSTORM ACTIVITY IS
POSSIBLE ALONG AND JUST BEHIND THE FRONT...WITH LOCAL MVFR
CONDITIONS AND WIND GUSTS TO 45KTS ASSOCIATED WITH THE STRONGER
CELLS. OCCASIONAL MOUNTAIN OBSCURATION CAN BE EXPECTED TONIGHT.
WINDS WILL WEAKEN DURING THE EARLY MORNING HOURS. CHAMBERS
&&

.PRELIMINARY POINT TEMP/POPS...

    WED     THU     FRI     SAT     SUN     MON     TUE
-----------------------------------------------------------
BIL 045/065 042/070 047/066 041/073 044/057 036/055 035/058
    21/B    00/U    00/B    00/U    12/W    21/B    11/B
LVM 040/061 039/067 043/065 041/072 041/055 031/053 032/055
    31/B    00/N    01/B    10/U    13/W    21/B    11/B
HDN 043/067 038/073 043/070 038/074 040/060 034/057 032/059
    31/B    00/U    00/B    00/U    11/B    21/B    11/B
MLS 045/065 037/072 043/069 041/070 042/062 033/054 031/056
    31/B    00/U    00/B    00/U    01/B    21/B    11/B
4BQ 044/065 037/071 042/069 040/073 042/061 034/054 031/056
    21/B    00/U    00/B    00/U    01/B    21/B    11/U
BHK 044/062 035/070 040/067 038/067 041/059 032/050 029/052
    21/B    00/U    00/B    00/U    01/U    21/B    11/U
SHR 041/065 034/072 040/071 037/076 038/060 030/055 027/057
    21/B    00/B    00/B    00/U    11/B    22/W    11/B

&&

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

&&

$$
WEATHER.GOV/BILLINGS



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