12HR - SEVERE WEATHER OUTLOOK

SEVERE WEATHER OUTLOOK

ISSUED: 251621Z

VALID:  251600Z - 260000Z

DEFINITIONS...

NOTICE LEVEL...THIS REPRESENTS A GREATER THAN 5 % CHANCE OF SEVERE WEATHER OCCURING WITHIN THE GREEN REGION ON THE MAP.

CAUTION LEVEL...THIS REPRESENTS A GREATER THAN 10%  CHANCE OF SEVERE WEATHER OCCURING WITHIN THE YELLOW REGION ON THE MAP.

ALERT LEVEL...THIS REPRESENTS A GREATER THAN 30% CHANCE OF SEVERE WEATHER OCCURING WITHIN THE RED REGION ON THE MAP.

SYNOPSIS...

STRONG MID AN UPPER LEVEL JET CONTINUES OVER NORTH 1/2 OF US.  EMBEDDED WITHIN THIS JET ARE UPR AIR DISTURBANCES THAT CONTINUE THE RECYCLING OF SEVERE WEATHER WITHIN THIS REGION.

ONE SUCH LOW PRESSURE SYSTEM IS BEING ENHANCED BY A MOD LOW LEVEL JET OF 30+KTS UP THE FRONT RANGE OF THE ROCKIES.  THIS COULPLED WITH BACKING WINDS SUGGESTS AN ALERT REGION TO BE SET UP FOR MOST OF NE SOUTH DAKOTA, SE NORTH DAKOTA AND EXTREME SW MINNESOTA.

THE THINKING IS CURRENT THUNDERSTORM ACTIVITY WILL BEGIN TO WANE OVER WESTERN MN, BUT BEHIND THIS WEAKENING COMPLEX NEW STORMS WILL RAPIDLY DEVELOP AS THE MID LVL JET NOSES INTO A DEEP LAYER OF MOISTURE.

THE ONLY INHIBITING FACTOR IS THERE IS QUITE A BIT OF CINH OVER MOST OF SD AND NE.  CAPE VALUES OF +3000 ARE LIKELY OVER EASTERN SD BY MID TO LATE AFTERNOON.  SO IF STORMS DEVELOP THEY WILL TURN SEVERE QUITE RAPIDLY.

SURROUNDING THE ALERT AREA IS A LARGE CAUTION AREA IN WHICH WE EXPECT SCT STRONG TO SVR THUNDERSTORMS TO DEVELOP, BUT MOST OF THE ACTIVITY WILL DEVELOP INTO ONE OR TW LARGE COMPLEXES OF STORMS AND RAPIDLY MOVE ESE.

RISK LEVEL IN ALERT REGION...

...TORNADOES...< 10%

...DAMANGING WINDS...<40 %

...DAMAGING HAIL...<50 %

RISK LEVER IN CAUTION REGION...

...TORNADOES...<5%
...DAMAGING WINDS...20 >%
...DAMAGING HAIL...20 >%

RS...