Tornado Warning 6, NWS Rapid City, SD

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
325 PM MDT TUE JUL 13 2004

.DISCUSSION...20Z SFC ANALYSIS SHOWS SURFACE HIGH OVER WESTERN
DAKOTAS.  UPPER RIDGE AXIS CENTERED OVER COLORADO AND EASTERN
MONTANA WITH NORTHWEST FLOW OVER CWA. WATER VAPOR SHOWS SHORTWAVE
MOVING INTO SW WYOMING.

.TODAY AND TONIGHT...MOISTURE IS ROTATING AROUND UPPER LEVEL RIDGE
ALONG WITH SHORT WAVE ENERGY...BRINGING A POSSIBILITY FOR CONVECTION
ACROSS NE WYOMING AND SOUTHWESTERN SOUTH DAKOTA THIS EVENING AND
OVERNIGHT. THE BEST OPPORTUNITY FOR STORMS WILL BE OVER THE SOUTHERN
CWA. A STRONG INVERSION CAP IS INHIBITING CONVECTION THIS AFTERNOON.

.SHORT TERM...WEDNESDAY AFTERNOON AND EVENING THE BLACK HILLS AND
SOUTHERN CWA WILL HAVE CAPE LEVELS BETWEEN 1500 AND 2000 AND LIS
AROUND -6. GOOD SHEAR AND HELICITY SHOULD ALLOW FOR THE DEVELOPMENT
OF SUPERCELLS IN THOSE AREAS. THE CAP MAY BE AN ISSUE...ESPECIALLY
OVER THE PLAINS BUT SHOULD BE WEAK ENOUGH FOR CONVECTION OVER THE
HILLS AND NEARBY PLAINS.

.THURSDAY AND FRIDAY...THE UPPER RIDGE AXIS WILL PERSIST OVER THE
ROCKIES WITH SHORTWAVES ROTATING INTO THE AREA. THERE WILL BE A
SLIGHT CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS ON BOTH DAYS.

.SATURDAY THROUGH TUESDAY...MODELS HAVE BEEN CONSISTENT IN KEEPING
UPPER RIDGE OVER THE AREA BUT SHOW RUN TO RUN DIFFERENCES IN THE
EXACT PLACEMENT OF THE RIDGE AXIS...VARYING BETWEEN DIRECTLY OVER
OUR CWA AND SLIGHTLY TO THE WEST. A MORE WESTWARD LOCATION OF THE
RIDGE AXIS WOULD LEAD TO MORE ACTIVE WEATHER WITH NORTHWEST FLOW
ALOFT...WITH QUIETER WEATHER IF THE RIDGE AXIS DIRECTLY OVERHEAD.
GFS STARTING TO SHOW A CHANGE IN THE LARGE SCALE PATTERN FOR EARLY
NEXT WEEK...WITH AN UPPER TROUGH APPROACHING ON MONDAY...THEN MOST
OF THE ENERGY STAYING NORTH ON TUESDAY. DUE TO THESE CONTINUED
DIFFERENCES AND THE LOCALIZED NATURE OF ANY CONVECTION THAT MIGHT
DEVELOP IN THE LATTER DAYS OF THE FORECAST...WILL KEEP THE FORECAST
MAINLY DRY FOR NOW. GUIDANCE TEMPERATURES LOOK REASONABLE THROUGH
THE PERIOD SO HAVEN/T STRAYED VERY FAR.

&&

UNR WATCHES/WARNINGS/ADVISORIES...
.SD...NONE.
.WY...NONE.

EK/GR

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE RAPID CITY SD
600 AM MDT TUE JUL 13 2004

SDZ001-002-012>014-024>032-041>044-046-047-049-072>074-WYZ054>058-
071-141300-
BENNETT-BUTTE-CENTRAL BLACK HILLS-CUSTER CO PLAINS-FALL RIVER-HAAKON-
HARDING-HERMOSA FOOT HILLS-JACKSON-MELLETTE-NORTHEASTERN CROOK-
NORTHERN BLACK HILLS-NORTHERN CAMPBELL-NORTHERN FOOT HILLS-
NORTHERN MEADE CO PLAINS-PENNINGTON CO PLAINS-PERKINS-RAPID CITY-
SHANNON-SOUTHERN BLACK HILLS-SOUTHERN CAMPBELL-SOUTHERN FOOT HILLS-
SOUTHERN MEADE CO PLAINS-STURGIS/PIEDMONT FOOT HILLS-TODD-TRIPP-
WESTERN CROOK-WESTON-WYOMING BLACK HILLS-ZIEBACH-
600 AM MDT (700 AM CDT) TUE JUL 13 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN SOUTH DAKOTA AND
NORTHEASTERN WYOMING.

.DAY ONE...TODAY AND TONIGHT
THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER NORTHEAST
WYOMING...THE BLACK HILLS...AND SOUTHWEST SOUTH DAKOTA LATE THIS
AFTERNOON AND TONIGHT. THE MAIN THREAT FROM THE SEVERE THUNDERSTORMS
WILL BE HAIL LARGER THAN 3/4 INCH AND WIND GUSTS GREATER THAN 60 MPH.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY
SOME THUNDERSTORMS ARE POSSIBLE WEDNESDAY THROUGH FRIDAY ACROSS THE
REGION...PRIMARILY DURING THE AFTERNOON AND EVENING HOURS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY.

JOHNSON