Flash Flood Warning 43, NWS Billings, MT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
922 PM MDT SAT SEP 7 2013

.UPDATE...
HAVE CANCELED THE SEVERE THUNDERSTORM WATCH FOR SOUTHEASTERN
MONTANA WITH THIS UPDATE WITH THE MAJORITY OF THE STRONG STORM
ACTIVITY NOW SHIFTED INTO THE DAKOTAS. SCATTERED THUNDERSTORMS
WILL CONTINUE OVERNIGHT FOR PARTS OF SOUTHEASTERN MONTANA...SOME
OF WHICH COULD BE SEVERE...BUT LARGE SCALE SEVERE ACTIVITY IS NO
LONGER EXPECTED.

CHURCH

&&

.SHORT TERM...VALID FOR SUN AND MON...

INGREDIENTS ARE IN PLACE ACROSS THE REGION FOR A BUSY AFTERNOON
AND NIGHT. UPPER TROUGH OVER WASHINGTON STATE SLOWLY MOVING
EASTWARD. LOW LEVEL JET OVER EAST HAS BROUGHT UP AN ABUNDANT
AMOUNT OF MOISTURE ACROSS THE EASTERN SECTIONS OF MONTANA AND
NEARBY AREAS. MONSOONAL MOISTURE IS EXPECTED TO STREAM ACROSS THIS
SAME AREA. PRECIPITABLE WATER LEVELS UP AROUND 1.50 INCHES...WHICH
IS HIGHLY UNUSUAL FOR THIS TIME OF YEAR...WILL LIKELY LEAD TO
THUNDERSTORMS WITH VERY HEAVY RAINFALL. WE HAVE ALSO SEEN SOME
TRAINING INDICATED BY CELLS OVER CUSTER COUNTY ALREADY TODAY.
THUS...THE FLASH FLOOD WATCH WILL REMAIN IN PLACE THROUGH 6AM. THE
HRRR MODEL DEVELOPS TWO WAVES OF CONVECTIVE ACTIVITY...PRIMARILY
HITTING AREAS FROM BIG HORN COUNTY NORTH AND EAST.

DUE TO INSTABILITY FACTORS AND SHEAR PROFILES...WE COULD ALSO SEE
SOME HAIL AND DAMAGING WIND EPISODES...THROUGH AT THIS TIME I FEEL
TORRENTIAL RAINFALL MORE OF A THREAT. THE SHEAR PROFILE AND
OVERALL PATTERN DOES ALSO SUPPORT THE SLIGHT CHANCE OF AN ISOLATED
TORNADO IN THE EASTERN COUNTIES...THOUGH WOULD LIKE TO SEE SHEAR
JUST A BIT STRONGER AND LESS INITIAL CLOUD COVER AND GREATER
INSTABILITY. NEVERTHELESS...WE WILL BE MONITORING STORMS CLOSELY
FOR DEEP ROTATION...ESPECIALLY FROM MILES CITY TO BROADUS
EASTWARD.

AS STORMS DIMINISH IN THE EAST LATE TONIGHT...UPPER TROUGH BEGINS
TO SWING THROUGH NORTH/CENTRAL MONTANA IN THE MORNING. BEST
MOISTURE AND SHEAR PROFILES WILL BE LOCATED FURTHER EAST...BUT
LIFT WILL BE MUCH GREATER ACROSS THE REGION WITH GOOD Q VECTOR
FORCING. HEAVY RAIN IS STILL A GOOD BET TOMORROW WITH SOME
STORMS...AND MAYBE LOTS OF SMALL HAIL OR GROUPEL. BT

.LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT...

SEASONABLY WARM WEATHER IS EXPECTED NEXT WEEK...WITH AN INCREASING
CHANCE OF CONVECTION BY FRI AND SAT WHEN THE 12 UTC GUIDANCE SHOWS
ANOTHER SURGE OF MONSOONAL MOISTURE ARRIVING. AN AMPLIFIED 500-HPA
RIDGE WILL BECOME ESTABLISHED ACROSS THE REGION ONCE AGAIN BY MID-
WEEK WITH ABOVE-NORMAL HEIGHTS FOR THIS TIME OF THE YEAR. ITS AXIS
APPEARS ORIENTED MORE NORTHWEST-SOUTHEAST THAN LAST WEEK/S VERSION
OF A LATE-SEASON RIDGE THOUGH...WHICH WILL LIKELY HELP MAINTAIN AN
EASTERLY LOW-LEVEL FLOW AND A SOMEWHAT COOLER AIR MASS IN SOUTHERN
MT AND NORTHERN WY THAN WHAT WE HAVE EXPERIENCED RECENTLY. BY LATE
IN THE WEEK...GUIDANCE SUGGESTS SHORT WAVE ENERGY WILL LIFT ACROSS
THE AREA AND LOWER THE 500-HPA HEIGHTS AS PRECIPITABLE WATER AGAIN
RISES ABOVE AN INCH. THE RESULT SHOULD BE AT LEAST ISOLATED SHOWER
AND STORM ACTIVITY...AND INCREASING CLOUDS TO HOLD BACK HIGHS SOME
MORE. IF TRENDS IN THE 12 UTC GUIDANCE HOLD TRUE WITH LATER CYCLES
THEN WE MAY NEED TO LOWER HIGHS A BIT THROUGH THE PERIOD AND RAISE
POPS A BIT BY FRI AND SAT. SCHULTZ

&&

.AVIATION...

SCATTERED THUNDERSTORMS WILL CONTINUE ACROSS THE FORECAST AREA
THIS EVENING...BUT THE ACTIVITY SHOULD SLOWLY DIMINISH BY LATE
TONIGHT. VERY HEAVY RAINFALL WITH THESE STORMS WILL RESULT IN
LOCALIZED MVFR/IFR CONDITIONS WITH POSSIBLE LIFR CONDITIONS. ALSO LOW
CEILINGS MIGHT FORM BY SUNDAY MORNING. CHURCH
&&

.PRELIMINARY POINT TEMP/POPS...

    SUN     MON     TUE     WED     THU     FRI     SAT
-----------------------------------------------------------
BIL 060/081 057/079 054/084 055/085 058/088 060/088 057/088
    55/T    50/B    00/U    00/U    00/U    12/T    22/T
LVM 053/080 048/077 046/084 046/085 051/087 052/090 054/090
    34/T    31/U    00/U    00/U    02/T    23/T    32/T
HDN 059/083 055/081 052/085 053/087 057/090 058/089 059/090
    56/T    51/B    00/U    00/U    00/U    11/U    12/T
MLS 063/082 059/080 055/084 055/085 057/086 060/086 058/088
    56/T    62/W    10/U    00/U    00/U    11/U    11/U
4BQ 062/084 058/081 052/084 054/086 057/086 058/086 059/090
    55/T    52/W    00/U    00/U    00/U    12/T    22/T
BHK 061/081 057/077 053/080 054/081 054/080 056/081 055/081
    66/T    72/T    11/U    10/U    00/U    11/U    12/T
SHR 058/082 053/077 047/083 050/085 053/089 055/087 053/087
    35/T    42/W    00/U    00/U    00/U    12/T    22/T

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...FLASH FLOOD WATCH IN EFFECT UNTIL 6 AM MDT SUNDAY FOR ZONES
      29>33-35>38-57-58.
WY...FLASH FLOOD WATCH IN EFFECT UNTIL 6 AM MDT SUNDAY FOR ZONES
      98-99.

&&

WEATHER.GOV/BILLINGS

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BILLINGS MT
855 PM MDT SAT SEP 7 2013

MTZ028>042-056>058-063>068-WYZ098-099-090300-
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-
855 PM MDT SAT SEP 7 2013

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

.DAY ONE...TONIGHT

STRONG THUNDERSTORMS WITH VERY HEAVY RAINFALL...GUSTY WINDS AND
HAIL ARE POSSIBLE TONIGHT. A FEW STORMS MAY BE SEVERE. A FLASH
FLOOD WATCH IS IN EFFECT THROUGH LATE TONIGHT OVER PARTS OF SOUTH
CENTRAL AND ALL OF SOUTHEAST MONTANA...AND FOR SHERIDAN COUNTY IN
WYOMING.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

SEVERE THUNDERSTORMS ARE POSSIBLE AGAIN SUNDAY ACROSS SOUTHEAST
MONTANA. HEAVY RAINFALL IS POSSIBLE WITH STORMS OVER THE ENTIRE
AREA ON SUNDAY.

.SPOTTER INFORMATION STATEMENT...

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

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