Severe Thunderstorm Warning 100, NWS Sioux Falls, SD

AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
350 PM CDT MON JUN 17 2002

GENERAL PTRN CONTS TO BE LARGELY UNSETTLED THRU MUCH OF THE WEEK...
WITH A SW FLOW ALOFT CHARACTERIZING THE FLOW. IN THE SHORT TERM
TNGT...WK SHORTWV...EVIDENCED ON THE VISIBLE SAT PICTURE IS CRNTLY
MOVG THRU THE CNTRL PTNS OF THE STATE. SOME REDEVELOPING CU HAS ALSO
FIRED IN ERN WY. IT APPEARS THAT THE SHORTWV PASSING THRU LATE THIS
PM AND EVENING IS IT...AND AM NOT CONVINCED THAT THE CU IN THE WRN
PLAINS WL SPARK ANYTHING LATE TNGT. THEREFORE WORDED THE ZONES FOR
MAINLY EVENING ACTIVITY...EXCEPT IN THE FAR EAST WHERE IT WL TAKE
SOME TIME FOR THIS WAVE TO PASS THRU. FOR LOW TEMPS...WENT ABV
GUIDANCE SLIGHTLY WITH THE INCRG DEWPTS AND SRLY FLOW.

IN THE TUE THRU WED PERIODS...TIMING IS DIFFICULT AT BEST OF ANY
SHORTWVS MOVG UP THE SW FLOW ALOFT. MDLS ARE SHOWING ONE MOVG
ACTUALLY THRU THE DAYTIME TUE...WITH PLENTY OF LIFT BUT NOTHING TO
SPEAK OF FOR FRONTOGENESIS OR LOW LVL BNDRYS. THEREFORE THOUGHTS ARE
THAT SOME SMALL POPS ARE WARRANTED...BUT TIMING AND LOCATION OF
SPECIFICS ARE HARD TO TELL RIGHT NOW. SAME PROBLEM TUE NIGHT...WITH
A COUPLE OF SLIGHT SHORTWVS MOVG UP WITH NOT MUCH FOR LOW LVL BNDRYS
OR FRONTOGENESIS. ON WED...BOTH MODELS AGREE THAT A STRONG LOW LVL
BNDRY MOVES CLOSER AND INTO THE WRN SECTION OF THE CWA. 700MB TEMPS
SUGGEST THAT LITTLE IF ANY CAPPING EXISTS ANYWHERE IN THE FSD FA.
THEREFORE FOR AFTN POPS...KEYED ON THE BNDRY MAINLY OVER THE NORTH
AND SOUTH. BUT WEDNESDAY NIGHT APPEARS TO BE THE MAIN FOCUS FOR
ACTION. THIS TIMING HAS BEEN CONSISTENT NOW SINCE LAST SATURDAY...SO
PUT LIKELY POPS IN FOR WED NIGHT...HOPEFULLY NOT GIVING IT THE KISS
OF DEATH BY DOING THIS. BUT THE SFC TO 850MB BNDRY MOVES INTO THE
MIDDLE OF THE CWA...WITH PLENTY OF HIGH DEWPTS AND A STRONG SHORTWV
MOVG OVER IT. AVN KEYS ON THE NRN AND CNTRL SECTIONS OF THE CWA WED
OVERNIGHT...WITH THE ETA OVER THE CNTRL AND SRN SECTIONS. BELIEVE
THAT BOTH MAY BE CORRECT...IN THAT EVEN IF OR WHEN THE LOW LVL BNDRY
HANGS UP JUST NORTH OF NW IA...THAT ANY DEVELOPING CONVECTION WL
PUSH THE MICROSCALE BNDRYS FUTHER SOUTH...INTIATATING CONVECTION
FURTHER SOUTH IN NW IA LATE NIGHT.

FOR THURSDAY...LINGERING TS WITH THE LOW LVL BNDRY MAY BE A GOOD BET
IN THE EAST AND SOUTH IN THE MRNG HRS...DRYING IN THE AFTN. ON
THURSDAY NIGHT...PUT SOME LOW POPS IN THE SRN PTNS OF THE FSD FA
WITH THE BNDRY JUST TO THE SOUTH...AND THE SW FLOW ALOFT PERSISTING.
IN THE EXTENDED...MODELS STILL SHOWING AN UPPER TROF MOVG THRU
SOMEWHERE IN THE FRI NIGHT TIMEFRAME. FOR TEMPS IN GENERAL...MANY
TIMES WENT ABOVE GUIDANCE FOR BOTH LOWS AND HIGHS...DUE TO THE HIGH
SFC DEWPTS AND WARM 850MB TEMPS MIXING DOWN.

.FSD...NONE
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