SWOMCD
SPC MCD 150703
MOZ000-IAZ000-KSZ000-NEZ000-150830-
MESOSCALE DISCUSSION 0828
NWS STORM PREDICTION CENTER NORMAN OK
0203 AM CDT FRI MAY 15 2009
AREAS AFFECTED...NERN KS...SERN NE...SRN IA...NRN MO
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 150703Z - 150830Z
DEEP CONVECTION SHOULD CONTINUE TO INCREASE IN BOTH COVERAGE AND
INTENSITY ACROSS THE MIDDLE MISSOURI RIVER VALLEY THROUGH EARLY
TODAY. WITH AN ATTENDANT INCREASE IN THE POTENTIAL FOR LARGE HAIL
WITH SOME OF THESE STORMS...A WATCH IS POSSIBLE.
ESSENTIALLY AS FORECAST...STORMS ARE INCREASING ON THE NOSE OF
40-50KT LLJ FROM NERN KS ACROSS THE MO RIVER VALLEY ATTM. IN
ADDITION TO THE NOCTURNAL STRENGTHENING OF THE LLJ...SLOPED ASCENT
ACROSS THIS CORRIDOR IS LIKELY ENHANCED BY AGEOSTROPHIC ADJUSTMENTS
BENEATH/WITHIN ENTRANCE REGION OF MID/UPPER LEVEL JET STREAK
SPREADING ACROSS THE UPPER MS VALLEY EARLY TODAY. EML PLUME
CHARACTERIZED BY 8-9 C/KM LAPSE RATES IN THE 700-500MB LAYER...AND
HIGH MOISTURE CONTENT OF LOW LEVEL AIR MASS STREAMING INTO THE
REGION OF ISENTROPIC ASCENT...WERE CONTRIBUTING TO UPSTREAM MUCAPE
OF 2000-2500 J/KG. MODEST EFFECTIVE WLY SHEAR OF 30-40KT SHOULD
SUPPORT ORGANIZED/PERSISTENT UPDRAFTS AND PERHAPS SOME UPSCALE
DEVELOPMENT INTO AN MCS ACROSS NERN KS/NRN MO AREA OVER THE NEXT
SEVERAL HOURS. GREATEST THREAT FROM THIS INCREASE IN THUNDERSTORM
DEVELOPMENT IS EXPECTED TO BE LARGE HAIL. A VARIETY OF HAIL MODEL
OUTPUT THROUGH 12 UTC SUGGESTS THAT HAIL SIZE COULD EXCEED 1 INCH
GIVEN INSTABILITY/LAPSE RATES...SHEAR...AND PERSISTENT LIFT ACROSS
THE REGION.
..CARBIN.. 05/15/2009
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...LSX...DVN...SGF...DMX...EAX...OAX...TOP...ICT...
GID...
LAT...LON 38549373 38629484 38739602 38709721 38999807 39409825
40279797 40749688 40869490 40459256 39819165 39059140
38579209 38549373
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