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000
FXUS65 KBYZ 131027
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
427 AM MDT THU JUN 13 2013

.SHORT TERM...VALID FOR TDY AND FRI...

OVERVIEW...CONVECTIVE INIHIBITION ON WEDNESDAY REALLY LIMITED
THUNDERSTORM ACTIVITY YESTERDAY. THIS WAS MAINLY DUE TO LOW LEVEL
STRATUS THAT DEVELOPED IN THE MORNING FOLLOWING HEAVY RAINS ON
TUESDAY. LACK OF BOUNDARY LAYER WINDS IN THE MORNING ALLOWED THIS
CLOUD COVER TO PERSIST INTO MID DAY BY WHICH TIME CONVECTIVELY
INDUCED CLOUD COVER WAS ALREADY IN PLACE. AS A RESULT TEMPERATURES
WERE HELD A GOOD 10 DEGREES BELOW FORECAST EXPECTATIONS WHICH TOOK
AWAY ENERGY FOR STORMS. MID LEVEL INSTABILITY WAS THERE AND
THUNDERSTORMS DID OCCUR...BUT OUTSIDE OF A COUPLE AROUND SHERIDAN
THE STRENGTH OF STORMS WAS BELOW EXPECTATIONS. SO WHY IS TODAY
DIFFERENT...FIRST STRATUS DEVELOPMENT THIS MORNING IS EXPECTED TO
BE MINIMAL AND CONFINED TO AREAS AROUND SHERIDAN AND NEAR
HARLOWTON...WHICH SHOULD BE EASILY BURNED OFF BY THE SUN BY MID
MORNING. THIS WILL ALLOW GOOD SOLAR INSOLATION AND COMBINED WITH
PREFRONTAL WARMING AND WARM ADVECTION FROM THE SOUTH PUSH
TEMPERATURES INTO THE 75 TO 85 DEGREE RANGE. WITH DEW POINTS
REMAINING NEAR 50 DEGREES ACROSS THE AREA FORECAST CAPE VALUES OF
1500 TO 2500 JOULES SEEM REASONABLY ATTAINABLE TODAY. SHEAR VALUES
OF 40 TO 50KTS WILL SUPPORT SUSTAINED STRONG UPDRAFTS AND ENERGY
WRAPPING AROUND THE UPPER LOW TO THE WEST WILL PROVIDE LIFT ALONG
WITH A PREFRONTAL TROF AND THE COLD FRONT ITSELF. THE COLD FRONT
WILL MOVE EAST OF THE AREA BY SUNRISE WITH THE UPPER LOW MOVING
THROUGH DURING THE MORNING FRIDAY. BY FRIDAY AFTERNOON WESTERLY
WINDS WILL DRY THINGS OUT ALLOWING FOR A COOL AND DRY AFTERNOON
AND A NICE WEEKEND ACROSS THE AREA.

TODAY...AS MENTIONED ABOVE CONDITIONS LOOK FAVORABLE FOR STRONG TO
SEVERE THUNDERSTORMS TODAY INTO TONIGHT. AREAS WEST OF ROSEBUD
COUNTY WILL BE FAVORED FOR STRONGER STORMS THIS AFTERNOON AS THE
COLD FRONT MOVES INTO THIS AREA LATE IN THE DAY. AREAS TO THE
EAST WILL BE STRONGLY CAPPED DURING THE AFTERNOON BUT SHOULD AN
ISOLATED STORM MANAGE TO BREAK THE CAP THERE LATE AFTERNOON IT
WOULD LIKELY TURN SEVERE FAIRLY QUICKLY WITH CAPE VALUES OVER 2500
JOULES PROGGED THERE ALONG WITH FAVORABLE SHEAR. COLD FRONT SHOULD
MOVE THROUGH THE REST OF THE FORECAST AREA DURING THE EVENING
HOURS PUSHING THE SEVERE THREAT ALONG AND AHEAD OF IT.
PRECIPITABLE WATER VALUES OVER AN INCH WILL PERSIST AHEAD OF AND
SLIGHTLY BEHIND THE COLD FRONT LEADING TO THE POTENTIAL FOR HEAVY
RAINFALL WITH STORM TODAY INTO TONIGHT. AS A RESULT FLASH FLOOD
WATCHES REMAIN IN EFFECT TIL MIDNIGHT TONIGHT FOR AREAS BURNED BY
2012 WILDFIRES AS WELL AS SHERIDAN...GOLDEN VALLEY AND NORTHERN
STILLWATER COUNTIES WHERE HEAVY RAIN OCCURRED DURING THE PAST FEW
DAYS. BEHIND THE FRONT EXPECT WIDESPREAD SHOWER ACTIVITY WITH A
FEW EMBEDDED THUNDERSTORMS AS STRONG QG FORCING AND MID LEVEL
FRONTOGENESIS BUILDS IN FROM THE WEST. 700MB TEMPERATURES WILL
FALL BELOW 0C EARLY FRIDAY MORNING ALLOWING FOR SOME LIGHT SNOW
ACCUMULATION IN THE WESTERN MOUNTAINS ABOVE 8000 FEET.

FRIDAY...UPPER LOW WILL MOVE ACROSS WESTERN ZONES BEFORE TURNING
MORE NORTHWARD MID TO LATE MORNING. AS A RESULT BEST CHANCES FOR
PRECIPITATION WILL BE WEST WHILE EASTERN AREAS WILL LIKELY DRY OUT
EARLY IN THE DAY. WEST TO NORTHWEST WINDS WILL BE GUSTY FRIDAY
AFTERNOON AND THIS DOWNSLOPE FLOW WILL HELP DRY OUT THE LOWER
LEVELS OF THE ATMOSPHERE. TEMPERATURES WILL STILL BE COOL FOR THIS
TIME OF YEAR WITH HIGHS MAINLY IN THE 60S TO LOW 70S...AND THAT
NORTHWEST WIND WILL MAKE IT FEEL COOLER THAN THAT. THE THREAT FOR
FLASH FLOODING AND SEVERE THUNDERSTORMS SHOULD BE OVER FOR THE
NEXT SEVERAL DAYS AT LEAST ONCE WE GET PAST THURSDAY NIGHT.
CHAMBERS

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

THE EXTENDED FORECAST BEGINS ON SATURDAY WITH A PERIOD OF QUIET
WEATHER THROUGH THE WEEKEND AS ZONAL FLOW ALOFT TRANSITIONS TO
RIDGING ALOFT BY EARLY NEXT WEEK. TEMPERATURES WILL SEE A SLOW
WARMING TREND FROM THE MID 70S TO THE MID 80S THROUGH THIS PERIOD
AS HEIGHTS RISE OVER THE FORECAST AREA WITH THE RIDGE BUILDING IN.
WESTERLY WINDS ON SATURDAY WILL KEEP THE FORECAST AREA DRY. A WEAK
COLD FRONT BACKS INTO THE FORECAST AREA SATURDAY NIGHT...BUT WITH
LIMITED MOISTURE TO WORK WITH THIS WILL REMAIN A DRY FRONT. WINDS
WILL TURN TO THE EAST AND SOUTHEAST UNDER THE RIDGING ALOFT BY
EARLY NEXT WEEK. THIS WILL HELP TO INCREASE DEW POINTS AND BRING A
SLOWLY INCREASING CHANCE FOR SHOWER AND THUNDERSTORMS BY MID TO
LATE NEXT WEEK. THE INCREASING CHANCES OF PRECIPITATION WILL COME
TO A HEAD BY WEDNESDAY INTO THURSDAY AS THE NEXT PACIFIC WAVE
IS SET TO MOVE ACROSS THE FORECAST AREA. CHURCH
&&

.AVIATION...

WIDELY SCATTERED SHOWERS...AND A FEW THUNDERSTORMS...WILL
CONTINUE ACROSS THE AREA THIS MORNING BEFORE CLEARING OUT BY LATE
MORNING. EXPECT MVFR TO LIFR CONDITIONS IN ANY THUNDERSTORM.
ANOTHER ROUND OF THUNDERSTORMS...SOME WITH HAIL AND GUSTY
WINDS...WILL BE POSSIBLE FROM A KMLS TO KSHR LINE WEST BY LATE
THURSDAY AFTERNOON...AHEAD OF A SURFACE COLD FRONT. GUSTY WINDS 25
TO 35 KTS OUT OF THE NORTHWEST ARE EXPECTED BEHIND THE FRONT AFTER
00Z. CHURCH

&&

.PRELIMINARY POINT TEMP/POPS...

    TDY FRI     SAT     SUN     MON     TUE     WED
-------------------------------------------------------
BIL 083 050/067 047/078 051/079 052/080 055/085 052/077
    4/T 64/T    10/U    01/U    12/T    22/T    22/T
LVM 076 042/062 042/078 043/079 045/081 046/084 049/075
    5/T 65/T    10/U    01/U    12/T    22/T    22/T
HDN 085 051/069 046/078 050/080 051/080 056/088 052/081
    4/T 64/T    10/U    11/U    12/T    22/T    22/T
MLS 085 054/071 050/078 053/079 053/078 055/084 057/082
    2/T 64/T    10/U    11/U    12/T    22/T    22/T
4BQ 086 053/071 046/078 050/080 051/079 055/087 055/087
    2/T 53/T    10/U    11/U    12/T    22/T    21/U
BHK 080 053/070 047/076 050/075 050/075 054/080 058/079
    1/N 63/T    10/U    11/U    12/T    22/T    21/U
SHR 085 049/067 043/078 047/078 049/079 053/086 050/085
    3/T 62/T    10/U    11/U    12/T    22/T    22/T

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...FLASH FLOOD WATCH IN EFFECT THROUGH THIS EVENING FOR ZONES
      29-31-34-36>38-42-57-58-64-65-67.
WY...FLASH FLOOD WATCH IN EFFECT THROUGH THIS EVENING FOR ZONE 99.

&&

$$
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