Severe Thunderstorm Warning 27, NWS Billings, MT

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
458 PM MDT WED JUN 17 2015

.UPDATE...

THE FORECAST HAS BEEN UPDATED TO INCLUDE A SEVERE THUNDERSTORM
WATCH FOR PARTS OF SOUTH CENTRAL AND ALL OF SOUTHEAST MT UNTIL 11
PM MDT. SCATTERED STORMS ARE SLOWLY INTENSIFYING AS OF 5 PM MDT
AND THE DOWNSTREAM ENVIRONMENT IS CHARACTERIZED BY 500 TO 1000
J/KG OF MLCAPE AND 40-50 KT OF 0-6-KM BULK WIND SHEAR...SO A FEW
SEVERE STORMS ARE POSSIBLE. THE LIMITING FACTOR FOR A MORE ROBUST
EVENT COULD BE SURFACE DEWPOINTS WHICH ARE ONLY IN THE MID 40S TO
LOWER 50S F. SCHULTZ

&&

.SHORT TERM...VALID FOR THU AND FRI...

WEAK RIDGING AND RISING HEIGHTS HAVE BUILT ACROSS OUR FORECAST
AREA THIS AFTERNOON. THIS HAS RESULTED IN WARMER TEMPERATURES AT
THE SURFACE AND ALOFT. SATELLITE SHOWING MOSTLY SUNNY SKIES ACROSS
OUR CENTRAL AND EASTERN AREAS AS A WEAK CAP IS IN PLACE DUE TO
WARM AIR ALOFT. HOWEVER...SOME WEAK CONVECTION HAS DEVELOPED
ACROSS WHEATLAND COUNTY WITH SLIGHTLY STRONGER CONVECTION ACROSS
THE NORTH CENTRAL PORTIONS OF THE STATE. THIS STRONGER ACTIVITY IS
ASSOCIATED WITH A WEAK SURFACE FRONT THAT HAS SHIFTED SOUTH OUT OF
CANADA ALONG WITH AN AREA OF MOISTURE CONVERGENCE FROM FERGUS
COUNTY NORTH TO THE CANADIAN BORDER. ENSEMBLE MODELS CONTINUE TO
DEVELOP THUNDERSTORMS ACROSS OUR NORTHWEST AREAS AND MOVE THEM
SOUTHEAST ACROSS YELLOWSTONE COUNTY...AS WELL AS OUR EASTERN AREAS
WHERE THEY SHOW A CLUSTER OF THUNDERSTORMS FORMING ACROSS OUR
SOUTHEAST COUNTIES DURING THE EVENING. AS A RESULT...HAVE
INCREASED PRECIP CHANCES ACROSS OUR EASTERN AREAS. CAN'T RULE OUT
AN ISOLATED STRONG TO SEVERE THUNDERSTORM AGAIN THIS AFTERNOON AND
EVENING...ALTHOUGH CHANCES LOOK A BIT LESS THAN YESTERDAY. THE
ACTIVITY WILL SHIFT EAST INTO THE DAKOTAS AFTER MIDNIGHT LEAVING
JUST A 20-30 PERCENT CHANCE FOR A SHOWER/THUNDERSTORM ACROSS OUR
FAR EASTERN COUNTIES ADJACENT TO THE DAKOTA BORDERS.

THURSDAY WILL BRING BETTER CHANCES FOR SHOWERS AND THUNDERSTORMS
AS A SURFACE LOW DEVELOPS ACROSS NORTHERN WYOMING SHIFTING A COOL
FRONT THROUGH THE AREA DURING THE EVENING. A DISTURBANCE WILL MOVE
ACROSS THE AREA WITH THUNDERSTORMS EXPECTED TO DEVELOP BY EARLY
AFTERNOON OVER THE HIGHER TERRAIN. A STRONG SOUTHEAST SURFACE FLOW
WILL ADVECT HIGHER DEWPOINTS INTO THE AREA. TEMPERATURES WILL WARM
INTO THE 80S...AND THIS COMBINED WITH STEEP LAPSE RATES AND
FAVORABLE WIND SHEAR WILL ALLOW FOR THE LIKELIHOOD OF SEVERE
THUNDERSTORMS ACROSS THE ENTIRE FORECAST AREA DURING THE AFTERNOON
AND EARLY EVENING WITH THE ACTIVITY CONTINUING LATE INTO THE
EVENING TOWARD THE DAKOTA BORDERS.

FOR FRIDAY...SOUTHWEST FLOW ALOFT RETURNS AS AN UPPER LEVEL
TROUGH APPROACHES THE PACIFIC NORTHWEST COAST. ANOTHER DISTURBANCE
WITHIN THE FLOW WILL MOVE ACROSS THE FORECAST AREA BRINGING
CONTINUED CHANCES FOR THUNDERSTORMS. BETTER DYNAMICS WILL HAVE
SHIFTED ACROSS EASTERN MONTANA INTO THE DAKOTAS AND THIS IS WHERE
THE MAIN FOCUS WILL BE FOR SEVERE ACTIVITY ALTHOUGH A STRONG STORM
WILL BE POSSIBLE ANYWHERE ACROSS THE FORECAST AREA. HOOLEY

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

EXTENDED FORECAST WILL BE A BATTLE BETWEEN A BUILDING RIDGE
ACROSS THE ROCKIES AND UPPER LEVEL IMPULSES RIDING THE TOP OF THE
RIDGE ACROSS MONTANA. FOR THE MOST PART...THE WEEKEND DOES FEATURE
BUILDING UPPER HEIGHTS WHICH WILL TEND TO SUPPRESS CONVECTION.
MID LEVEL TEMPERATURES CONTINUE TO WARM AS WELL WHICH WILL HELP
CAP THE ATMOSPHERE...ESPECIALLY THE FURTHER SOUTH YOU GO.
HOWEVER...SHORT WAVE ENERGY RIDING OVER THE TOP OF THE RIDGE WILL
BE A FACTOR AND WILL LIKELY PRODUCE WAVES OF STORMS THAT SOUTHERN
MONTANA WILL BE ON THE SOUTHERN EDGE OF. TIMING AND HOW DEEP THESE
WAVES PENETRATE IS TOO HARD TO PINPOINT NOW. HAVE LEFT IN SOME LOW
STORM CHANCES FOR MAINLY THE NORTHEAST PARTS OF THE REGION...WITH
SOUTHERN AREAS REMAINING DRY...BUT WILL HAVE TO BE WATCHED. FOR
TUESDAY INTO WEDNESDAY...STORM CHANCES WILL EXPAND ACROSS MOST
AREAS AS RIDGE SHIFTS EAST AND WE GET UNDER A SOUTHWEST FLOW.
TEMPERATURES WILL MOSTLY BE NEAR SEASONAL VALUES. THE HOTTEST DAY
UNDER THE RIDGE WILL LIKELY BE MONDAY..WHEN TEMPS COULD APPROACH
90 IN MANY AREAS. FRIEDERS

&&

.AVIATION...

VFR CONDITIONS WILL PREVAIL. THERE IS A RISK OF THUNDERSTORMS
INTO TONIGHT WHICH COULD RESULT IN SOME LOCAL MVFR CONDITIONS IN
HEAVY RAINFALL. STRONG WINDS AND HAIL ARE ALSO POSSIBLE WITH THE
MOST INTENSE CELLS THIS EVENING. FRIEDERS/SCHULTZ

&&

.PRELIMINARY POINT TEMP/POPS...

    THU     FRI     SAT     SUN     MON     TUE     WED
-----------------------------------------------------------
BIL 056/085 061/083 055/080 055/080 057/085 058/083 059/080
    34/T    33/T    32/T    21/B    11/B    11/B    32/T
LVM 050/085 052/080 047/079 049/080 050/084 051/082 050/079
    34/T    23/T    31/B    11/B    11/B    11/B    22/T
HDN 056/088 060/085 056/081 055/082 056/087 058/085 058/081
    33/T    33/T    32/T    21/B    11/B    12/T    33/T
MLS 057/083 063/085 055/080 055/080 057/083 059/082 059/078
    43/T    43/T    32/T    21/B    22/T    22/T    33/T
4BQ 057/085 062/085 055/079 055/080 057/084 058/084 056/078
    43/T    33/T    43/T    21/B    22/T    22/T    33/T
BHK 054/078 059/081 054/078 053/077 054/079 057/079 057/075
    32/T    44/T    43/T    21/B    22/T    22/T    44/T
SHR 054/085 057/083 053/077 052/079 053/083 054/080 054/077
    33/T    33/T    32/T    31/B    11/U    11/B    33/T

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...SEVERE THUNDERSTORM WATCH 307 IN EFFECT UNTIL 11 PM MDT THIS
      EVENING FOR ZONES 30>33-36>38-57-58.
WY...SEVERE THUNDERSTORM WATCH 307 IN EFFECT UNTIL 11 PM MDT THIS
      EVENING FOR ZONES 98-99.

&&

WEATHER.GOV/BILLINGS

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BILLINGS MT
459 PM MDT WED JUN 17 2015

MTZ028>042-056>058-063>068-WYZ098-099-182300-
SOUTHERN WHEATLAND-MUSSELSHELL-TREASURE-NORTHERN ROSEBUD-CUSTER-
FALLON-NORTHERN STILLWATER-YELLOWSTONE-POWDER RIVER-CARTER-
SOUTHERN BIG HORN-EASTERN CARBON-NORTHERN PARK-
NORTHERN SWEET GRASS-GOLDEN VALLEY-RED LODGE FOOTHILLS-
NORTHERN BIG HORN-SOUTHERN ROSEBUD-JUDITH GAP-PARADISE VALLEY-
LIVINGSTON AREA-BEARTOOTH FOOTHILLS-ABSAROKA/BEARTOOTH MOUNTAINS-
CRAZY MOUNTAINS-NORTHEAST BIGHORN MOUNTAINS-SHERIDAN FOOTHILLS-
459 PM MDT WED JUN 17 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL
MONTANA...SOUTH CENTRAL MONTANA...SOUTHEAST MONTANA AND NORTH
CENTRAL WYOMING.

.DAY ONE...TONIGHT

A FEW SEVERE THUNDERSTORMS WITH LARGE HAIL...DAMAGING WINDS AND
HEAVY RAINFALL ARE POSSIBLE THROUGH THIS EVENING. THE GREATEST
RISK OF SEVERE THUNDERSTORMS IS OVER SOUTHEAST MONTANA AND NORTH
CENTRAL WYOMING.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

CONDITIONS ON THURSDAY APPEAR FAVORABLE FOR SCATTERED STRONG TO
SEVERE THUNDERSTORMS ACROSS THE REGION. LARGE HAIL...DAMAGING
WINDS AND HEAVY RAINFALL ARE THREATS WITH THESE STORMS. THERE IS
ALSO ANOTHER CHANCE OF STRONG TO SEVERE THUNDERSTORMS OVER PARTS
OF THE AREA ON FRIDAY AFTERNOON AND EVENING.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

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