MESOSCALE PRECIPITATION DISCUSSION 0177
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1023 AM EDT SAT JUN 06 2015
 
AREAS AFFECTED...LOWER MO VALLEY 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 061423Z - 062023Z
 
SUMMARY...THUNDERSTORMS HAVE BEGUN TO FORM ACROSS EASTERN NE. 
WITH INCREASING LOW-LEVEL INFLOW AND INSTABILITY EXPECTED WITH
TIME, HOURLY RAIN RATES UP TO 2" AN HOUR ARE POSSIBLE WHICH COULD
LEAD TO FLASH FLOODING.

DISCUSSION...A SMALL CLUSTER OF THUNDERSTORMS WITH COOLING CLOUD
TOPS AND RAIN RATES PASSING 1.5" AN HOUR HAS FORMED ACROSS EASTERN
NE IN THE VICINITY OF A STATIONARY FRONT -- THE 00Z ARW HAS PICKED
UP VERY WELL ON THIS ACTIVITY.  RAINFALL AMOUNTS OF 0.75" IN 25
MINUTES HAVE BEEN OBSERVED TO THE NORTHWEST OF COLUMBUS NE PER THE
OAX/VALLEY NE FORECAST OFFICE.  LOW-LEVEL INFLOW AND INSTABILITY
INCREASES WITH TIME (EXCEEDING THE MEAN 850-400 WINDS BY ~10 KTS)
NEAR AND SOUTH OF THE BOUNDARY, WHICH SHOULD ACT TO INCREASE THE
SCOPE OF THUNDERSTORM ACTIVITY ALONG THE FRONT.  PRECIPITABLE
WATER VALUES OF CLOSE TO 1.75" PER GPS INFORMATION COULD LEAD TO
HOURLY RAIN RATES OF 2".

THERE IS A SIGNAL IN THE MESOSCALE QPF GUIDANCE OF LOCAL 2-3"
AMOUNTS ANYWHERE BETWEEN SOUTHEAST SD, EASTERN NE, AND WESTERNMOST
IA.  CONVECTION SHOULD BE FORWARD PROPAGATING ONCE IT ORGANIZES
PER THE AVAILABLE DIRECTIONAL WIND SHEAR AND CAPES EXCEEDING 3000
J/KG THIS AFTERNOON, WITH A NET MOTION OF 25 KTS TO THE
EAST-SOUTHEAST.  INCREASING INFLOW COULD LEAD TO SOME
BACKBUILDING, BUT THE MAIN THREAT IS EXPECTED TO BE CELL TRAINING.
 ACROSS SOUTHEAST SD, NORTHWEST IA, SOUTHEAST NE, AND NORTHWEST
MO, FLASH FLOOD GUIDANCE VALUES ARE UNDER 2" IN THREE HOURS. 
FLASH FLOODING IS CONSIDERED POSSIBLE WITHIN THIS REGION.

ROTH

ATTN...WFO...DMX...EAX...FSD...GID...LBF...OAX...TOP...

ATTN...RFC...MBRFC...NCRFC...

LAT...LON   43959792 43519590 42319428 41049369 39759380 
            39399475 39749596 41039753 43049888