[MCD] SWOMCD

[Mesoscale Convective Discussions]

ACUS11 KWNS 121828
SWOMCD
SPC MCD 121827 
SDZ000-NEZ000-COZ000-122000-

MESOSCALE DISCUSSION 1804
NWS STORM PREDICTION CENTER NORMAN OK
0127 PM CDT SAT AUG 12 2006

AREAS AFFECTED...PARTS OF WRN/CNTRL NEB INTO CNTRL/ERN SD

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 121827Z - 122000Z

SEVERE THREAT IS LIKELY TO INCREASE LATE THIS AFTERNOON.  A WW WILL
BE ISSUED SHORTLY.

INITIATION OF CONVECTIVE DEVELOPMENT...BASED IN INCREASINGLY
UNSTABLE BOUNDARY LAYER...APPEARS UNDERWAY IN ALONG PRE-FRONTAL
THERMAL RIDGE AXIS ACROSS WESTERN NEBRASKA.  THIS APPEARS MOSTLY IN
RESPONSE TO WEAKENING INHIBITION IN RESPONSE TO STRONG SURFACE
HEATING AS TEMPERATURES ARE NOW RISING THROUGH THE 90S.  WITH
CONTINUED STEEPENING OF LOW-LEVEL LAPSE RATES THROUGH PEAK HEATING
...UPDRAFTS SHOULD CONTINUE TO INTENSIFY...AND THERMODYNAMIC
PROFILES WILL BECOME MORE FAVORABLE FOR DOWNBURSTS AS EVAPORATIVE
COOLING INCREASES NEAR HEAVY PRECIPITATION CORES.  SHEAR IS NOT
STRONG...BUT DOWNWARD TRANSFER OF MOMENTUM ASSOCIATED WITH 20-30 KT
LOWER/MID TROPOSPHERIC FLOW WILL ENHANCE RISK OF DAMAGING SURFACE
GUSTS. ACTIVITY IS EXPECTED TO INCREASE IN COVERAGE ALONG A LINE
EAST OF SYDNEY NE INTO AREAS OF SOUTH DAKOTA TO THE SOUTH/EAST OF
PIERRE NEXT FEW HOURS. MOST NOTABLE EXPANSION OF CONVECTIVE
DEVELOPMENT APPEARS LIKELY AFTER 21Z...AS ANOTHER WEAK IMPULSE
EMBEDDED WITHIN SUBTROPICAL STREAM LIFTS NORTHEAST OF THE COLORADO
ROCKIES.

..KERR.. 08/12/2006

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

ATTN...WFO...FSD...ABR...LBF...UNR...BOU...CYS...

41310268 42250193 43490114 44350070 45150049 45459912
44839819 43919824 42249939 41060047 40560195 40950264 

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