[MCD] SWOMCD

[MCD at goshenarc.org]

ACUS11 KWNS 011849
SWOMCD
SPC MCD 011848 
MNZ000-IAZ000-NEZ000-SDZ000-012045-

MESOSCALE DISCUSSION 1817
NWS STORM PREDICTION CENTER NORMAN OK
0148 PM CDT SUN AUG 01 2004

AREAS AFFECTED...ERN SD/SWRN MN/NERN NEB/NWRN IA

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 011848Z - 012045Z

TORNADO WATCH LIKELY WILL BE ISSUED FOR PORTIONS OF ERN SD...SWRN MN
...NERN NEB AND NWRN IA WITHIN THE NEXT 1 TO 2 HOURS.

OUTFLOW BOUNDARY FROM EARLIER CONVECTION EXTENDS FROM DSM TO SOUTH
OF SUX...AND THEN NWWD INTO CENTRAL SD TO A LOW PRESSURE SYSTEM NEAR
PIR. A WEAK COLD FRONT ALSO WAS PUSHING SLOWLY SWD AND EXTENDED FROM
THE SURFACE LOW IN CENTRAL SD NEWD INTO NRN MN. THE AIR MASS BETWEEN
THESE TWO BOUNDARIES HAS BECOME STRONGLY UNSTABLE WITH MLCAPES
APPROACHING 3000 J/KG...AND WILL CONTINUE DESTABILIZING WITH
ADDITIONAL HEATING.

SATELLITE IMAGERY SUGGESTS A SHORTWAVE TROUGH IS MOVING EWD INTO THE
CENTRAL DAKOTAS. THE ABR 18Z SOUNDING SHOWS THE CAP HAS WEAKENED
CONSIDERABLY SINCE THE 12 RUN. THE CAPPING INVERSION SHOULD CONTINUE
ERODING DURING THE NEXT COUPLE OF HOURS AS THE UPPER TROUGH NEARS
THE AREA. GIVEN THE STRONG INSTABILITY AND DEEP LAYER SHEAR AT 45
KT...ONCE STORMS DEVELOP...THEY SHOULD EVOLVE QUICKLY INTO
SUPERCELLS. HAIL 3 INCHES OR LARGER WILL BE THE MAIN THREAT...BUT
THE BACKED BOUNDARY LAYER WINDS NORTH OF THE OUTFLOW BOUNDARY SHOULD
PROVIDE SUFFICIENT LOW LEVEL SHEAR FOR A FEW TORNADOES.

..IMY.. 08/01/2004

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...MPX...DMX...FGF...FSD...OAX...ABR...

43829844 45739847 45789742 45719448 44829424 43349404
41659424 42349817 

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