Flash Flood Warning 6, NWS Sioux Falls, SD

AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
250 PM CDT TUE JUN 22 1999

WEAK THUNDERSTORMS DEVELOPED IN FAR WESTERN CWA...IN AND JUST EAST
OF SFC DEWPT/THETAE AXIS AHEAD OF APCHG CDFNT.  THIS ACTIVITY AIDED
A BIT BY WEAK WAVE APPARENT IN 500MB PROFILER LOOP.  ALSO A FEW TSRA
JUST SKIRTING SOUTHEAST CWA...WITH MORE ACTIVITY FARTHER SOUTHEAST
INTO IOWA...ASSOC WITH LEADING WAVE AHEAD OF MAIN TROUGH STILL OVER
EASTERN SECTIONS OF MT/WY...PER WATER VAPOR LOOP.

LATEST SFC ANALYSIS /18Z/ SHOWS SFC CDFNT EAST OF KPHP AND KBIS...
STILL WEST OF...BUT CLOSE TO...KMBG-KPIR LINE.  TNGT IS DEFINITELY
THE MAIN FOCUS FOR THIS PACKAGE...AS CDFNT/UPR TROF MOVE EAST ACRS
CWA.  BELIEVE SVR THREAT LIMITED SOMEWHAT BY PERSISTANT STRATUS DECK
WHICH ADVECTED NORTH ON 30-40KT LLJ EARLY THIS MORNING.  AIRMASS MAY
ALSO BE TOO WARM FOR SIGNIFICANT HAIL...WITH LATEST LAPS SOUNDINGS
INDICATING WET-BULB ZERO LEVELS IN THE 12-13KFT RANGE.  CANNOT RULE
OUT ISOLATED EVENTS...BUT AT THIS TIME WIDESPREAD SVR DOES NOT SEEM
LIKELY.  WITH PCPTBL WATER AOB 1.5 INCHES...AND POTENTIAL FOR SLOW
MOVING/TRAINING STORMS /700-500MB FLOW RUNNING 15-30KT FROM THE
S-SW...NEARLY PARALLEL TO FRONT...ON AREA PROFILERS/...THINK HEAVY
RAINS MAY BE MORE OF A CONCERN.  FFG REMAINS LOWEST IN MORVR AREA...
WHERE 3HR VALUES RANGE FROM 1.4 TO 1.7.  WILL NOT GO WITH ANY FLOOD
WATCHES FOR NOW...BUT MAY BE SOMETHING FOR NEXT SHIFT TO LOOK AT
ONCE DEVELOPMENT/MOVEMENT OF STORMS BECOMES MORE CLEAR.

NGM/ETA SIMILAR IN FRONT POSITION THROUGH 24HR...WITH AVN A TAD
SLOWER.  THROUGH THE FIRST 6HR...ETA SEEMED TO HANDLE MOVEMENT OF
NORTHERN END OF FRONT THE BEST...WHILE IN NEBRASKA ALL MODELS LOOKED
A BIT SLOW.  THIS WOULD FAVOR FASTER MOVING MODELS...BUT AM HESITANT
TO REMOVE ALL MENTION OF PRECIP IN SOUTHEASTERN COUNTIES FOR WED AND
WILL KEEP LOWER END CHC/SLGT CHC POPS IN NW IA COUNTIES FOR MAINLY
WED MORNING.

DRY WEATHER THEN EXPECTED INTO FRIDAY...WITH NEXT SYSTEM COMING OUT
OF ROCKIES TO PRODUCE CHANCE OF THUNDERSTORMS SATURDAY.  GUIDANCE
TEMPERATURES SEEM REASONABLE...WITH MORE SUN COUNTERACTING SLIGHTLY
COLDER AIRMASS BEHIND FRONT ON WEDNESDAY.  READINGS THU SHOULD BE
SIMILAR OR SLIGHTLY WARMER THAN WED...AS WEAK SOUTHERLY FLOW REGIME
RESUMES.

.FSD...NONE.
 HAMEN