Severe Thunderstorm Warning 178, NWS Des Moines, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
330 PM CDT MON JUN 11 2001

FORECAST CONCERNS TONIGHT DEAL WITH SEVERE POTENTIAL AND TIMING. I
WOULD HAVE THOUGHT WE WOULD GET SOMETHING GOING IN NW IA BY THIS
TIME BUT THE MAIN GENESIS AREA REMAINS IN MN.  STRONG CAP IN PLACE
OVER WESTERN IA AND THIS WILL LIKELY REMAIN IN PLACE UNTIL THE COLD
FRONT PUSHES THROUGH.  WATER VAPOR IMAGERY SHOWING THE REMNANTS OF A
SHEARED OUT SHORT WAVE MOVING THROUGH NEBRASKA.  THE FEELING IS THAT
THIS SHORT WAVE WILL ACT TO WEAKEN THE CAP ENOUGH SO THAT THE FRONT
WILL OVERCOME IT WHEN IT MOVES THROUGH LATER THIS EVENING.  ANY
SEVERE CHANCES SHOULD BE CONFINED TO THE NORTHERN THIRD OF THE
STATE...CLOSE TO THE WARM FRONT AND TRIPLE POINT ALTHOUGH I LEFT THE
CHANCE FOR SEVERE WORDING IN THE SOUTHWEST PART OF THE CWA AS WELL
BECAUSE IF THE SHORTWAVE DOES BREAK THE CAP AND SOME STORMS DEVELOP
IT WILL STILL BE IN A FAVORABLE PART OF THE DAY FOR SEVERE WEATHER.

MY MODEL OF PREFERENCE IS THE ETA/MESOETA AS THE TRACK RECORD HAS
BEEN PRETTY GOOD WITH THEM AND THEY INITIALIZED WELL WITH THE
CONVECTION THIS MORNING.  KEEPING THIS IN MIND...THE MODEL PUSHES THE
BOUNDARY SOUTH OVERNIGHT CONTINUING THUNDERSTORM CHANCES OVER THE
CWA THEN BRINGS IN ANOTHER SHORTWAVE TUESDAY MORNING FOR ADDITIONAL
CONVECTION MAINLY ACROSS THE NORTH ONCE AGAIN.  HOWEVER...EVERYTHING
WILL BE HINGANT UPON WHAT HAPPENS TONIGHT AND WHERE THE BOUNDARIES
FINALLY SET UP.  AS THIS IS KEY AND YET UNCLEAR...I HAVE KEPT POPS
LOW IN THE SECOND PERIOD AND BEYOND AND REFRAINED FROM MENTIONING
SEVERE WORDING.  THE MID SHIFT WILL BE BETTER SUITED TO DEFINE THESE
AREAS HAVING HAD TIME TO SEE WHERE THE BOUNDARIES ARE SETTING UP.

MY THOUGHT FOR NOW IS THAT TUESDAY AFTERNOON SHOULD BE PRETTY WORKED
OVER SO THUNDERSTORMS SHOULD NOT OCCUR BUT IF WE GET LITTLE
CONVECTION OVER US TONIGHT THEN WE WILL BE PRIMED FOR AN ACTIVE DAY
TOMORROW.  THE NEXT BEST CHANCE WILL COME LATE WEDNESDAY INTO
THURSDAY AS A STRONG SHORTWAVE LIFTS OUT OF THE WEST.

ALTHOUGH WE SETTLE DOWN IN THE LATER IN THE EXTENDED WE STILL HAVE
WEAK WAVES MOVING ACROSS SO I PUT SOME MENTION OF LATE DAY OR
OVERNIGHT THUNDERSTORMS IN THE EXTENDED.

.DSM...NONE.

FAB