Tornado Warning 22, NWS Rapid City, SD

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
200 PM MDT SAT JUL 28 2001

CURRENT SURFACE MAP HAS TROF ACROSS CENTRAL MONTANA INTO NORTHEAST
WYOMING...WITH HIGH PRESSURE OVER EASTERN DAKOTAS. STRONG SHORTWAVE
TROF MOVING THROUGH NORTHWESTERN U.S. WITH CONVECTION DEVELOPING
OVER THE HIGHER TERRAIN OF MONTANA AND WYOMING.

SHORTWAVE WILL BECOME NEGATIVELY TILTED AS IT MOVES ACROSS MONTANA
TONIGHT. ENOUGH SUPPORT FOR SCATTERED THUNDERSTORMS ACROSS THE FAR
NORTHWEST. FURTHER SOUTH...EVENING THUNDERSTORMS EXPECTED OVER
NORTHEAST WYOMING AND AROUND THE BLACK HILLS IN SOUTH DAKOTA. COLD
FRONT WILL MOVE THROUGH MOST OF THE CWA BY MORNING.

FOR SUNDAY...COLD FRONT STALLS ALONG THE SD/NE BORDER...AND EXTENDS
INTO NORTHEAST SOUTH DAKOTA. WEAK CONVERGENCE ALONG THE FRONT IN THE
AFTERNOON WILL BRING A ISOLATED AFTERNOON THUNDERSTORMS ACROSS
SOUTHWEST SOUTH DAKOTA. OTHER THUNDERSTORMS EXPECTED TO DEVELOP
ACROSS HIGHER TERRAIN OF NORTHEAST WYOMING AND THE BLACK HILLS.

SUNDAY NIGHT...LOW PRESSURE DEVELOPS OVER EAST CENTRAL WYOMING AND
TRACKS EAST THROUGH SOUTH CENTRAL SOUTH DAKOTA. LOW LEVEL JET
INCREASES TO 30-45 KNOTS ACROSS NEBRASKA INTO SOUTH CENTRAL SOUTH
DAKOTA. 850-700MB THREAT-E ADVECTION OF 3-5C/HR FORECAST OVER THE
EASTERN PART OF CWA. WILL GO WITH HIGHER POPS ACROSS THE EASTERN CWA
SUNDAY NIGHT.

MONDAY INTO MONDAY NIGHT...THETA-E AXIS SETS UP OVER NORTHEAST
WYOMING AND SOUTHWEST SOUTH DAKOTA MONDAY AFTERNOON WITH
SOUTHEASTERLY UPSLOPE FLOW...ALLOWING FOR MORE AFTERNOON
THUNDERSTORMS. WEAK SHORTWAVE TO MOVE THROUGH MONDAY NIGHT WITH
THETA-E ADVECTION ACROSS NORTHEAST WYOMING/WESTERN SOUTH DAKOTA.

IN THE EXTENDED...UPPER LEVEL TROF TO MOVE THROUGH THE AREA
TUESDAY/WEDNESDAY WITH A CONTINUED CHANCE OF THUNDERSTORMS. FLOW
BECOME MORE ZONAL THURSDAY THROUGH SATURDAY WITH THE JET STREAM IN
SOUTHEERN CANADA. WILL CONTINUE THE DRY AND WARM WEATHER FOR THE END
OF THE WEEK.

.UNR...NONE.

KC