Tornado Warning 22, NWS Billings, MT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
215 PM MDT MON JUN 21 2010

.SHORT TERM...VALID FOR TUE AND WED...

FILLING UPPER LOW PUSHING INTO NORTH CENTRAL MONTANA EARLY THIS
AFTERNOON. JET MAX WAS PUSHING INTO CENTRAL MONTANA ON THE FRONT
SIDE OF THE LOW. THIS JET WAS ALREADY TRIGGERING THUNDERSTORMS
OVER CENTRAL MONTANA. LOW LEVEL MOISTURE FROM ALL THE RAIN OF THE
LAST WEEK WAS CAUSING DEWPOINTS TO CLIMB WELL INTO THE 50S OVER
CENTRAL AND EASTERN ZONES. CAPES HAVE ALREADY CLIMBED TO 1500J/KG
OVER THE CENTRAL AND EAST. PLENTY OF BUOYANCY FOR THE ATMOSPHERE
ONCE THE WEAK MID LEVEL CAP ERODES. CAP EROSION WILL CAUSE QUICK
DEVELOPMENT OF STORMS AGAIN. THE SPEED SHEAR LOOKS STRONGER TODAY
COMPARED TO SUNDAY...ALTHOUGH THE DIRECTIONAL SHEAR DOES NOT
LOOKS AS IMPRESSIVE. WOULD EXPECT SEVERE THUNDERSTORMS TO DEVELOP
OVER CENTRAL ZONES EARLY THIS AFTERNOON. SOME SUPER CELLS WILL BE
POSSIBLE BUT MORE THEN LIKELY THE STORMS WILL EVOLVE INTO MULTI
CELL WITH THE PRIMARY THREAT BEING LARGE HAIL. PRECIPITABLE
WATERS WERE FROM .75 NEAR COLUMBUS TO 1.10 EAST OF BILLINGS...SO
STORMS WILL HAVE HEAVY RAIN ONCE AGAIN. FLASH FLOOD WATCH LOOKS
GOOD. ONE THING THAT WILL NEED TO BE WATCHED IS DRIER AIR ALOFT
MOVING IN ON SOUTHWEST. DEWPOINTS WERE FALLING INTO THE 30S AT
WEST YELLOWSTONE AND THE PARK...INCLUDING SOME OBSERVATIONS NEAR
THE EAST SLOPES. THIS MAY SERVE TO DRY OUT THE LOW LEVELS SOME AND
COULD CAUSE TO PUSH THE MAIN DEVELOPMENT NORTH AND EAST OF
BILLINGS. WILL HAVE TO WATCH THIS EVOLVE.

A COUPLE OF DIFFERENCES FROM YESTERDAY. THE SHEAR IS A LITTLE
DIFFERENT AS DISCUSSED ABOVE. ALSO...STORM MOTION LOOKS STRONGER
AND IS IN FACT EXPECTED TO BE 1.5 TO 2 TIMES GREATER. THIS MEANS
STORMS SHOULD MOVE FASTER TODAY. THAT BEING SAID...STILL EXPECT
AN ACTIVE DAY FROM AROUND BILLINGS EASTWARD. WILL BE INTERESTING
TO SEE HOW THIS EVOLVES AS THE STRONGEST DYNAMIC FORCING IS
DIRECTED OVER NORTHERN MONTANA...BUT THE DEEPEST SHEAR RESIDES
OVER THE SOUTH. WILL RELY ON WEAKER ENERGY COMING OFF THE
MOUNTAINS FOR DEVELOPMENT. THE COLD FRONT...CURRENTLY NEAR
COLUMBUS...WILL ALSO TRIGGER CONVECTION AS THE FRONT MOVES EAST.
WILL LIKELY HAVE A COMPLEX SHIFT OVER EASTERN MONTANA THIS
EVENING.

THE UPPER LOW FILLS COMPLETELY AND MOVES INTO NORTH DAKOTA
TUESDAY WHILE A SECONDARY WAVE MOVES INTO MONTANA TUESDAY
AFTERNOON. WEAK UPSLOPE FLOW COMBINED WITH THE SHORTWAVE ENERGY
AND WEAK CAPES NEAR 600JKG SHOULD PROMOTE A FEW CELLS TUESDAY
AFTERNOON AND EVENING. THE DEEPEST CAPE WILL RESIDE OVER SHERIDAN
COUNTY AND INTO THE FAR SOUTHEAST PART OF THE FORECAST
AREA...RIGHT TO THE NORTH OF THE COLD FRONTAL BOUNDARY THAT
SETTLES OVER NORTHERN WYOMING. WILL KEEP POPS GOING FOR TUESDAY
AND HIT THESE AREAS A LITTLE HARDER.

WEDNESDAY WILL BE OUR BEST CHANCE OF GETTING A DRY DAY THIS WEEK
AS AN UPPER RIDGE BUILDS IN AND THE FLOW ALOFT TURNS WEST.
TEMPERATURES SHOULD REBOUND AS A THERMAL RIDGE FORMS UNDERNEATH
THE MID LEVEL RIDGE. ANOTHER UPPER TROUGH WILL MOVE INTO IDAHO
WEDNESDAY NIGHT AND THIS PROMPTS SOUTHWEST FLOW. THIS FLOW WILL
BRING MORE MID LEVEL MOISTURE AND ENERGY INTO THE WEST FOR AN
INTRODUCTION FOR POPS AGAIN. HUMPHREY

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

MADE ONLY MINOR CHANGES TO THE EXTENDED FORECAST WHICH WERE MAINLY
IN THE FORM OF RAISING TEMPERATURES. ENERGY SEEN OFF THE BC COAST IN
WATER VAPOR IMAGERY EARLY THIS AFTERNOON WILL INDUCE A SW FLOW ALOFT
OVER THE AREA THU THROUGH FRI. THE TROUGH WAS FORECAST TO MOVE
THROUGH THE AREA IN THE SAT TIME FRAME ALTHOUGH MODELS DIFFERED
SOMEWHAT WITH THE TIMING OF THE SYSTEM. MODELS DID PUSH A COLD FRONT
THROUGH THE REGION FRI NIGHT AHEAD OF THE TROUGH. DID RAISE
TEMPERATURES OVER THE EASTERN ZONES AHEAD OF THE FRONT ON FRI WITH
STRONG THERMAL RIDGE IN PLACE. ALSO RAISED POPS FRI NIGHT DURING THE
FRONTAL PASSAGE. AN UPPER RIDGE MAY BUILD OVER THE REGION ON SUN
AHEAD OF ANOTHER PACIFIC TROUGH. THIS NEXT TROUGH WAS FORECAST TO
APPROACH THE AREA ON MON. HAVE RAISED TEMPERATURES SUN AND MON. ALSO
RAISED SOME MINS THROUGH THE PERIOD. ARTHUR

&&

.AVIATION...

SHOWERS AND THUNDERSTORMS WILL DEVELOP AROUND KBIL AND KSHR THIS
AFTERNOON. THE PRECIPITATION WILL BECOME MORE WIDESPREAD AND
SPREAD E INTO KMLS AND KBHK LATER THIS AFTERNOON. CONDITIONS IN
THE SHOWERS AND THUNDERSTORMS WILL RANGE FROM MVFR TO LIFR. LARGE
HAIL AND WIND GUSTS IN EXCESS OF 55 KT WILL BE POSSIBLE WITH
THUNDERSTORMS FROM KBIL E THROUGH THE EVENING. THE THUNDERSTORMS
WILL MOVE E OUT OF THE AREA LATE THIS EVENING. SOME PATCHY FOG AND
STRATUS WILL BE POSSIBLE OVERNIGHT IN AREAS THAT RECEIVE RAIN.
LOCAL CONDITIONS WILL BE RESTRICTED TO MVFR/IFR IN ANY STRATUS
AND FOG. A WEAK UPPER TROUGH WILL CROSS THE AREA ON TUE BRINGING A
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS. MVFR/IFR CONDITIONS
WILL BE POSSIBLE IN THE PRECIPITATION. ARTHUR

&&

.PRELIMINARY POINT TEMP/POPS...

    TUE     WED     THU     FRI     SAT     SUN     MON
-----------------------------------------------------------
BIL 051/076 053/080 057/082 059/079 053/077 056/082 057/085
    32/T    11/U    22/T    22/T    22/T    22/T    22/T
LVM 041/074 043/080 048/079 049/071 048/074 048/080 049/081
    22/T    12/T    22/T    22/T    42/T    22/T    22/T
HDN 051/078 053/081 053/087 056/083 055/083 055/088 056/089
    33/T    21/U    22/T    22/T    22/T    22/T    22/T
MLS 054/078 056/081 058/086 060/086 057/080 057/083 058/084
    62/T    21/U    22/T    32/T    32/T    22/T    22/T
4BQ 055/077 055/079 055/086 059/085 057/081 056/084 057/086
    63/T    31/U    22/T    22/T    32/T    22/T    22/T
BHK 056/076 054/079 055/084 058/085 057/081 055/085 059/088
    72/T    21/B    22/T    33/T    32/T    22/T    22/T
SHR 049/076 047/078 050/086 053/081 050/079 053/083 051/085
    34/T    31/U    22/T    22/T    32/T    22/T    22/T

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...FLASH FLOOD WATCH IN EFFECT UNTIL MIDNIGHT MDT TONIGHT FOR
      ZONES 29>33-35>38-57-58.
     TORNADO WATCH 367 IN EFFECT UNTIL 9 PM MDT THIS EVENING FOR
      ZONES 30>33-36>38-57-58.
WY...FLASH FLOOD WATCH IN EFFECT UNTIL MIDNIGHT MDT TONIGHT FOR
      ZONE 99.
     TORNADO WATCH 367 IN EFFECT UNTIL 9 PM MDT THIS EVENING FOR
      ZONES 98-99.

&&

WEATHER.GOV/BILLINGS

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BILLINGS MT
225 PM MDT MON JUN 21 2010

MTZ028>042-056>058-063>068-WYZ098-099-222030-
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 BIG HORN MOUNTAINS-SHERIDAN FOOTHILLS-
225 PM MDT MON JUN 21 2010

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

.DAY ONE...THIS AFTERNOON AND TONIGHT

A COLD FRONT WILL PUSH THROUGH THE FORECAST AREA THIS AFTERNOON
THROUGH THIS EVENING. THUNDERSTORMS WILL DEVELOP ALONG THIS
FRONT. SOME OF THESE STORMS MAY BECOME SEVERE FROM BILLINGS EAST
AND SOUTHEAST. LARGE HAIL...DAMAGING WINDS AND VERY HEAVY RAIN WILL
BE THE PRIMARY THREATS THROUGH THIS EVENING. MUCH OF THE AREA HAS
RECENTLY RECEIVED SIGNIFICANT RAINFALL. ADDITIONAL RAINFALL WILL
QUICKLY RUN OFF AND MAY LEAD TO FLASH FLOODING.

STAY TUNED TO LOCAL MEDIA FOR ANY SEVERE WEATHER WARNINGS OR FLASH
FLOOD WARNINGS INTO TONIGHT.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

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

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