[MCD] SWOMCD

[MCD at goshenarc.org]

ACUS11 KWNS 121904
SWOMCD
SPC MCD 121904 
SDZ000-NEZ000-122100-

MESOSCALE DISCUSSION 1633
NWS STORM PREDICTION CENTER NORMAN OK
0204 PM CDT MON JUL 12 2004

AREAS AFFECTED...EXTREME NRN NEB... SCNTRL SD

CONCERNING...SEVERE THUNDERSTORM WATCH 611...

VALID 121904Z - 122100Z

ENVIRONMENTAL CONDITIONS ACROSS PARTS OF THE NRN PLAINS ARE BECOMING
MORE FAVORABLE FOR SUPERCELL DEVELOPMENT THIS AFTERNOON. ADDITIONAL
WATCHES MAY BE NEEDED OVER PORTIONS OF SD AND PERHAPS NRN NEB IN THE
NEXT FEW HOURS.

A WELL-DEFINED OUTFLOW BOUNDARY ACROSS SERN SD INTERSECTS A STRONG
THERMALLY INDUCED SURFACE PRESSURE TROUGH OVER SCNTRL SD EARLY THIS
AFTERNOON. STRONG CONVERGENCE AND INTENSE HEATING INVOF THIS
INTERSECTION CONTINUES TO PROMOTE ISOLD TSTM DEVELOPMENT NORTH OF
9V9. ADDITIONAL STRONG AND OCCASIONALLY SEVERE STORMS HAVE BEEN
OCCURRING ACROSS PARTS OF NRN AND ERN SD OVER THE PAST SEVERAL HOURS
WITHIN STRONGLY SHEARED ENVIRONMENT. STRONG CAP/CONVECTIVE
INHIBITION TO THE SOUTH OF WW 611 IS CONTINUING TO SUPPRESS MORE
VIGOROUS DEVELOPMENT WITHIN HIGHLY UNSTABLE AND STRONGLY SHEARED
ENVIRONMENT. UNCERTAINTY REMAINS AS TO WHETHER THE CAP ACROSS MUCH
OF THE AREA CAN BE OVERCOME THROUGH HEATING AND WEAK BACKGROUND
FORCING ASSOCIATED WITH UPPER WAVE PASSING BY TO THE NORTH. NEW
STORM INITIATION CONTINUES TO BE MOST LIKELY FROM THE TROUGH/LOW
ACROSS EXTREME NCNTRL NEB ENEWD ACROSS THE OUTFLOW BOUNDARY IN SERN
SD OVER THE NEXT 1-2 HOURS. PERSISTENT MESOSCALE FORCING NEAR THESE
FEATURES SHOULD CONTINUE TO OVERCOME STRONG INHIBITION. CELLS
TRACKING ALONG OR NEAR THE OUTFLOW BOUNDARY SHOULD ACQUIRE ROTATION
GIVEN HIGH VALUES OF SRH AND DEEP LAYER SHEAR. IN ADDITION TO VERY
LARGE HAIL...A TORNADO AND HIGH WIND THREAT MAY ALSO DEVELOP GIVEN
VOLATILE ENVIRONMENT.

..CARBIN.. 07/12/2004

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

ATTN...WFO...FSD...OAX...ABR...LBF...UNR...

42819809 42830022 43340079 44149969 44099651 

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