[MCD] SWOMCD

[MCD at goshenarc.org]

ACUS11 KWNS 240054
SWOMCD
SPC MCD 240053 
SDZ000-NEZ000-240230-

MESOSCALE DISCUSSION 2091
NWS STORM PREDICTION CENTER NORMAN OK
0753 PM CDT MON AUG 23 2004

AREAS AFFECTED...CNTRL AND SRN SD THROUGH WRN AND CNTRL
NEB...EXTREME NE CO AND NW KS

CONCERNING...SEVERE THUNDERSTORM WATCH 776...

VALID 240053Z - 240230Z

THREAT FOR MAINLY LARGE HAIL AND ISOLATED DAMAGING WIND EXPECTED TO
PERSIST FROM S CNTRL SD SWD THOUGH CNTRL AND SW NEB NEXT 2-3 HOURS.
AREAS E OF WW 776 ACROSS E CNTRL NEB ARE ALSO BEING MONITORED FOR
ADDITIONAL THUNDERSTORM DEVELOPMENT. 

THIS EVENING A DRYLINE EXTENDS FROM CNTRL NEB SWWD TO A WEAK SURFACE
LOW IN SWRN NEB. E OF THIS BOUNDARY...THE ATMOSPHERE REMAINS VERY
UNSTABLE WITH MLCAPE FROM 2500 TO 3000 J/KG. GIVEN THE DEGREE OF
INSTABILITY...SHEAR PROFILES REMAIN SUFFICIENT FOR SUPERCELLS ALONG
AND E OF THE DRYLINE WITH AROUND 30 KT OF 0-6 KM SHEAR. STRONGEST
STORMS REMAIN OVER TRIPP COUNTY IN SRN SD AND CUSTER COUNTY IN NEB
AS OF 0035Z. HOWEVER...WEAK MID LEVEL FLOW IS RESULTING IN VERY SLOW
STORM MOTIONS WITH SOME SWD PROPAGATION WHICH IS ALSO ENHANCING LOW
LEVEL STORM RELATIVE HELICITY.

OTHER STORMS ARE DEVELOPING A LITTLE FARTHER WEST IN W CNTRL NEB
WHERE NUMEROUS OUTFLOW MERGERS ARE OCCURRING. SEVERE THREAT IS MORE
MARGINAL IN THIS AREA DUE TO MORE LIMITED LOW LEVEL MOISTURE.
HOWEVER...STORMS MAY INTENSIFY BRIEFLY AS THEY DEVELOP IN THE
ENHANCED CONVERGENCE ZONE ASSOCIATED WITH MERGING OUTFLOWS. 

OUTFLOW BOUNDARY OVER CNTRL NEB IS SURGING RAPIDLY EWD. THIS MIGHT
PROMOTE ADDITIONAL STORMS DEVELOPING E OF WW 776 THIS EVENING AS IT
INTERCEPTS THE STRONGER INSTABILITY E OF THE DRYLINE.

..DIAL.. 08/24/2004

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

ATTN...WFO...FSD...ABR...GID...LBF...UNR...GLD...

41999971 40310029 40030144 41230159 44210030 44529878 

WWWW