Severe Thunderstorm Warning 74, NWS Aberdeen, SD

AREA FORECAST DISCUSSION FOR CENTRAL/N-EAST SD AND W-CENTRAL MN
NATIONAL WEATHER SERVICE ABERDEEN SD
305 PM CDT SAT JUN 29 2002

MAJOR ISSUES WITH THIS AFTN PACKAGE REVOLVE AROUND PCPN CHCS TONIGHT
FOR THE WEST...AND PCPN CHANCES MONDAY FOR THE EAST. CURRENTLY TEMPS
ACROSS FAR WRN CWA HAVE WARMED ENOUGH TO ERODE CAP. SOME ISOLD CU
STARTING TO FORM...BUT NOTHING ORGANIZED YET. MODELS DIFFER SLIGHTLY
ON THE FINER DETAILS...WITH THE AVN SEEMING TO DO A BETTER JOB IN
THE NEAR TERM. DRYLINE CONTS TO PUSH E...WITH DWPTS FALLING NICELY
ON THE WRN SIDE OF BOUNDARY. WITH LARGE DWPT SPREAD OUT WEST...FEEL
THAT IF ANY TSRA DEVELOP...WILL BE WIND MAKERS WITH VERY LITTLE PCPN
TOUCHING GROUND. DRY LIGHTNING COULD ALSO BE REAL THREAT. ALSO
HELPING PSBL TSRA FORMATION WILL BE GOOD 85H-7H FRONTOGENESIS TAKING
PLACE BETWEEN 00Z-06Z SUNDAY. BOTH AVN AND ETA AGREE ON THIS
FEATURE...WITH DECENT 7H Q-VECTOR CONVERGENCE. BEST THETA-E FORCING
TAKES PLACE ALONG THE ERN CWA...BUT WITH 7H TEMPS PROGGED TO BE +13
TO +15 AT 7H...CAP MAY WEAKEN...BUT NOT BREAK. PROBABLY WILL SEE
SOMETHING SIMILAR TO LAST NIGHT...WHERE ENOUGH SPRINKLES LANDED ON
ASOS TO REGISTER A TRACE. WILL MENTION SMALL POPS FOR KMBG
AREA...AND LEAVE EVERYBODY ELSE DRY. TROF/FRONT PUSHES THROUGH ON
SUNDAY...WITH LOWER DWPTS AND SLIGHTLY COOLER(RELATIVE TO TDY)
TEMPS. SUNDAY SHOULD ACTUALLY BE A NICE DAY WITH LIGHTER WNDS AND
COOLER TEMPS.

NEXT CONCERN SHOWS UP LATE SUNDAY NIGHT INTO MONDAY. AVN/ETA BOTH
SHOW GOOD 7H WAVE PUSHING THROUGH DURING THE DAY ON MONDAY...WITH
THE AVN A BIT SLOWER. GOOD 7H THETA-E FORCING SEEN WITH MODERATE
AMOUNTS OF 85H-7H FRONTOGENESIS TAKING PLACE. HOWEVER...THERMAL
RIDGES AT 8H AND 7H RETURN...AND NOT SURE THAT WE WILL WARM UP
ENOUGH TO REACH CONVECTIVE TEMPS. DWPTS REBOUND QUICKLY ON
MONDAY...WITH LOWER 70S EXPECTED ALONG I-29 CORRIDOR. ETA SEEMS TO
LATCH ONTO CAPPING IDEA...WHILE AVN IS REAL BULLISH WITH PCPN ON
MONDAY. FOR NOW WILL CONT HOT AND DRY FCST FOR MONDAY.

GUIDANCE TEMPS SEEMED BALLPARKISH...WITH EXCEPTION OF TUESDAY.
APPEARS THAT GUIDANCE MAY BE A BIT TOO LOW. WENT A CATEGORY ABOVE
GUIDANCE FOR TUESDAY.

.EXTENDED DISCUSSION...

EXTENDED REMAINS A QUANDARY. THIS TIME THE EXT AVN WANTS TO LATCH ON
TO A TROUGH/COOL FRONT AND DRAG IT DOWN INTO NEBRASKA AND IOWA AND
KEEP IT THERE UNTIL THURSDAY. THIS WOULD MEAN A SIGNIFICANT CHANGE
IN MAX TEMPS WED AND THUR OF EXTENDED. THIS DRASTIC SLOW DOWN IN THE
AVN MAY BE ANOMALOUS SINCE LAST FEW RUNS HAVE SHOWCASED A BIT OF A
FASTER WARM FRONT RETURN SCENARIO. MAJORITY OF OTHER EXTENDED MODELS
STILL HAVE A SOLUTION THAT BRINGS RETURN OF WARM FRONTAL BOUNDARY TO
NORTH OF CWA BY WEDNESDAY...SIMILAR TO EXT AVN EXCEPT THAT THEY ARE
ALL A BIT FASTER. AVN EXTENDED PRECIP FORECAST CONTINUES TO PEG A
LARGE AREA OF > .25 INCH PRECIP OVER CWA THROUGHOUT DAYS 5 THROUGH
7. FOR NOW...WILL LEAVE PRECIP OUT OF EXTENDED AS GUIDANCE NUMBERS
ARE NOT VERY HELPFUL OR SIGNIFICANT.

.ABR...NONE.
HINTZ/DORN