Tornado Warning 15, NWS Billings, MT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
248 PM MDT SAT AUG 3 2013

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

HIGH CONFIDENCE EXISTS IN SEVERE WEATHER THIS AFTERNOON AND
EVENING...PARTICULARLY IN OUR NW AND FROM ROUNDUP TO BILLINGS TO
LODGE GRASS EAST. SHEAR AND INSTABILITY ARE QUITE FAVORABLE...AND
THERE IS MODEST LARGE SCALE ASCENT ASSOCIATED WITH SHORTWAVE
CURRENTLY MOVING SLOWLY THROUGH CENTRAL MT. LARGE HAIL AND STRONG
WINDS ARE THE PRIMARY THREATS...BUT THERE IS A RISK OF A TORNADO
ESPECIALLY IN OUR SE WHERE DEWPTS ARE FLIRTING WITH 60F...LCL
HEIGHTS ARE QUITE LOW AND LOW LEVEL SHEAR IS GREATEST. LATEST PWAT
ANALYSIS SHOWS VALUES IN EXCESS OF AN INCH FROM ROSEBUD COUNTY
EAST...SO HEAVY RAIN IS AN OBVIOUS THREAT AS WELL. DRIER GREAT
BASIN AIR HAS REDUCED CONVECTIVE CHANCES OVER OUR SW MTNS AND
FOOTHILLS...SEE DEWPT TO 24F AT YELLOWSTONE LAKE...AND STRONGER
FORCING ASSOCIATED WITH SHORTWAVE IN CENTRAL MT WILL BE ACROSS OUR
NORTH AND EAST. RECENT RADAR SHOWS INTENSE TSTMS FROM A LITTLE NW
OF LEWISTOWN TO NEAR HAVRE. WOULD EXPECT CONVECTION TO FIRE VERY
SOON IN THE WHEATLAND TO MUSSELSHELL AREA...BUT STORMS ARE LIKELY
A FEW HOURS OFF YET IN OUR FAR EAST. ONSET OF SOUTHEASTERLY LOW
LEVEL WILL HELP THE CONVECTION IN OUR EAST BY EVENING...AND WITH
THIS IN MIND WE MAY SEE ADDITIONAL ROUNDS OF ACTIVITY LATE IN THE
EVENING OR INTO THE OVERNIGHT HOURS CLOSER TO THE DAKOTAS BORDER.

CONVECTIVE CHANCES WILL BE REDUCED THE NEXT COUPLE OF DAYS AS THE
AIRMASS WILL BE NOT QUITE AS MOIST AND MID LEVEL TEMPS WILL TURN
WARMER. THAT BEING SAID...MOISTURE WILL NOT BE SCOURED OUT
COMPLETELY WITH TONIGHTS SHORTWAVE...AND LINGERING HIGHER THETA-E
AXIS IN OUR SOUTHEAST MAY BE A FOCUS OF ANY STRONGER TSTMS
ESPECIALLY AS AN ADDITIONAL SHORTWAVE MOVES THROUGH THE AREA LATE
SUNDAY. WILL KEEP HIGHEST POPS IN THIS AREA. OTHERWISE GREATER
SEVERE THREAT WILL SHIFT TO OUR EAST AND WILL KEEP ONLY ISOLD
MAINLY DIURNAL POPS THROUGH THE REMAINDER OF THE SHORT TERM
PERIOD. HEIGHTS WILL BEGIN TO FALL AS SHORTWAVE BEGINS TO APPROACH
FROM THE NORTH BY LATE MONDAY...SO COULD SEE SOME SHOWERS OR WEAK
STORMS THROUGH THE NIGHT MONDAY NIGHT PER THIS WAVE AND SFC
FRONTAL PASSAGE.

AS FOR TEMPERATURES...SUNDAY WILL BEGIN TURN WARMER PER HEIGHT
RISES AND WEAKER SFC WINDS. MONDAY SHOULD BE THE WARMEST OF THE
NEXT SEVERAL DAYS WITH PREFRONTAL CONDITIONS/WNW WINDS AHEAD OF
MONDAY NIGHT CLIPPER. BELIEVE WE WILL SEE TEMPS NEAR OR SLIGHTLY
ABOVE 90 FOR THE FIRST TIME IN SEVERAL DAYS ON MONDAY...BUT THIS
WARMING WILL BE SHORT-LIVED AS COOLER AIR ARRIVES FROM THE NORTH
MONDAY NIGHT.

JKL

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

DUE TO A LARGE UPPER LOW OVER THE HUDSON BAY REGION...OUR
FORECAST AREA WILL BE UNDER THE INFLUENCE OF CYCLONIC FLOW
TUESDAY. THE LONG RANGE MODEL PROGGS ARE NOT ENTIRELY IN SYNC
AFTER TUESDAY...WITH THE ECMWF MOVING THAT UPPER LOW A LITTLE
CLOSER TO THE GREAT LAKES AND PLACING SOME WEAK RIDGING OVER
SOUTHERN MONTANA. THE GFS ON THE OTHER HAND KEEPS THE CYCLONIC
FLOW OVER US DEEP INTO NEXT WEEK. ITS VERY DIFFICULT THIS FAR OUT
TO DETERMINE WHICH SOLUTION IS THE MOST LIKELY. HOWEVER EACH
SOLUTION KEEPS TEMPERATURES BELOW NORMAL...THE ECMWF IS SIMPLY
DRIER. WILL BLEND POPS AND TEMPS WHICH SHOULD KEEP US IN THE BALL
PARK EITHER WAY. MAIN CHANGE WAS TO PULL POPS BACK FROM EAST AT
MID WEEK WHERE SURFACE HIGH SHOULD SETTLE AND STABILIZE ATMOSPHERE.
BT
&&

.AVIATION...

SCATTERED THUNDERSTORMS WILL DEVELOP ACROSS THE FORECAST AREA
BY EVENING...MOST NUMEROUS FROM KBIL TO KBHK BETWEEN 00Z AND 04Z.
LOCAL MVFR TO LIFR CEILINGS ARE LIKELY IN THE STRONGER
THUNDERSTORMS...A FEW OF WHICH MAY PRODUCE LARGE HAIL AND DAMAGING
WINDS. VFR CONDITIONS ARE EXPECTED TO INCREASE FROM WEST TO EAST
AFTER MIDNIGHT. BT

&&

.PRELIMINARY POINT TEMP/POPS...

    SUN     MON     TUE     WED     THU     FRI     SAT
-----------------------------------------------------------
BIL 057/085 059/090 059/080 057/082 058/083 058/082 059/086
    42/T    22/T    22/T    22/T    32/T    22/T    22/T
LVM 049/086 052/088 051/084 051/084 052/085 051/079 050/087
    22/T    22/T    23/T    23/T    43/T    33/T    22/T
HDN 056/087 059/091 058/084 056/084 058/085 058/083 059/087
    42/T    22/T    22/T    22/T    32/T    22/T    22/T
MLS 058/086 060/091 060/081 057/083 058/083 058/081 058/087
    62/T    22/T    22/T    12/T    21/B    11/B    22/T
4BQ 057/086 056/089 058/081 052/082 055/082 055/080 059/086
    62/T    22/T    22/T    12/T    21/B    11/B    22/T
BHK 056/081 055/086 059/077 051/077 052/076 052/077 054/081
    62/T    22/T    22/T    12/T    21/B    11/B    22/T
SHR 055/086 055/090 055/083 053/083 054/085 054/078 055/087
    42/T    22/T    22/T    32/T    32/T    32/T    22/T

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...SEVERE THUNDERSTORM WATCH 463 IN EFFECT UNTIL 9 PM MDT THIS
      EVENING FOR ZONES 28>33-35>38-42-57-58-63-68.
WY...NONE.

&&

WEATHER.GOV/BILLINGS

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BILLINGS MT
156 PM MDT SAT AUG 3 2013

MTZ028>042-056>058-063>068-WYZ098-099-042000-
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-
156 PM MDT SAT AUG 3 2013

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

SCATTERED THUNDERSTORMS WILL AFFECT MUCH OF EASTERN MONTANA THIS
AFTERNOON AND INTO THIS EVENING. SOME OF THESE STORMS WILL LIKELY
BE SEVERE WITH LARGE HAIL THE PRIMARY THREAT. DAMAGING WIND IS ALSO
POSSIBLE ALONG WITH VERY HEAVY RAIN. THE THREAT OF SEVERE STORMS
INCLUDES BILLINGS...THOUGH THE BEST CHANCE WILL BE ACROSS AREAS
TO THE NORTH AND EAST OF BILLINGS. ANYONE WITH OUTDOOR PLANS
SHOULD BE PREPARED FOR HAZARDOUS WEATHER.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

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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