MESOSCALE PRECIPITATION DISCUSSION 0431
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1113 PM EDT SAT AUG 08 2015
 
AREAS AFFECTED...NORTHERN KS...SOUTHEAST NEB...SOUTHERN
IA...NORTHERN MO 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 090300Z - 090900Z
 
SUMMARY...HIGHLY EFFICIENT MCS TO DEVELOP AT NOSE OF STRENGTHENING
LOW LEVEL JET OVERNIGHT. CELL MERGERS AND BACKBUILDING/TRAINING
CONVECTION IS EXPECTED TO PRODUCE FLASH FLOODING.

DISCUSSION...PLEASE SEE RECENT 0119Z SPENES DESCRIBING THE
DETAILED SYNOPTIC SETUP FOR THIS EVENT. COLD-TOPPED CONVECTION IS
ALREADY DEVELOPING ACROSS PORTIONS OF WEST-CENTRAL KS AND ALSO
NEAR THE BORDER AREAS OF SOUTHEAST NEB/NORTHWEST MO AND SOUTHWEST
IA...AND THIS CONVECTION WILL GRADUALLY EXPAND IN COVERAGE OVER
THE NEXT FEW HOURS WITH MERGING CLUSTERS LEADING UP TO A MORE
ORGANIZED MCS.

AREA VWPS ACROSS KS/MO ALREADY SHOWING AN INCREASING SOUTHWEST LOW
LEVEL JET AND CORRIDOR OF SPEED CONVERGENCE THAT IS OVERRUNNING A
STATIONARY FRONT SITUATED OVER KS AND ALONG A NORTHEASTWARD
EXTENDING 850 MB FRONT AHEAD OF A WAVE OF LOW PRESSURE.
MEANWHILE...A SUBTLE VORT MAX APPEARS TO BE OVER SOUTHEAST NEB
WHICH IN CONJUNCTION WITH INCREASING WARM ADVECTION IS LIKELY
RESPONSIBLE FOR THE CURRENT ELEVATED ACTIVITY OVER THE NEB/IA/MO
BORDER REGION. SOME MID LEVEL CAPPING IS NOTED IN REGIONAL 00Z
RAOB DATA...BUT THIS SHOULD BE OVERCOME TONIGHT AS THE LOW LEVEL
JET INCREASES TO NEAR 40 KTS OR HIGHER WHILE ALSO GRADUALLY
VEERING AHEAD OF AN 850 MB TROUGH/FRONT. HEIGHT FALLS/SHORTWAVE
ENERGY EJECTING OUT INTO THE HIGH PLAINS WILL ALSO TEND TO PROVIDE
AT LEAST SOME MODEST LARGER SCALE ASCENT IN TIME WHICH WILL
FURTHER ERODE ANY RESIDUAL MID LEVEL CAPPING.

THE MOISTURE PROFILES ARE QUITE IMPRESSIVE...WITH PWATS CLOSE TO 2
INCHES OVER NORTHERN KS/NORTHERN MO AND INTO SOUTHWEST IA. THE 00Z
CIRA LAYERED PWAT PLOT SHOWS A CORE OF ENHANCED MOISTURE
ESPECIALLY IN THE 700MB TO 500MB LAYER OVER SOUTHERN NEB/NORTHERN
KS WHICH IS MOVING EAST INTO NORTHERN MO AND IA. CONVECTION SHOULD
BE QUITE EFFICIENT WITH RAINFALL PRODUCTION AND RATES AS A
RESULT...WITH RATES LIKELY EXCEEDING 2 INCHES/HR.

THE 12Z NSSL-WRF AND 01Z HRRR APPEAR TO HAVE A REASONABLY GOOD
HANDLE ON THE CURRENT ACTIVITY...AND BOTH OF THESE MODELS SUGGEST
AN EXCELLENT SET-UP FOR MERGING CELLS...BACKBUILDING/TRAINING
CONVECTION AND ULTIMATELY A LARGER SCALE MCS IN TIME...ESPECIALLY
AFTER 06Z THAT WILL IMPACT SOUTHERN IA AND NORTHERN MO. PORTIONS
OF NORTHERN KS AND NORTHERN MO IN PARTICULAR HAVE SEEN HEAVY RAINS
OVER THE LAST WEEK...AND ADDITIONAL HEAVY/CONCENTRATED RAINS WILL
LIKELY RESULT IN FLASH FLOODING. WILL CONTINUE TO MONITOR.

ORRISON

ATTN...WFO...DDC...DMX...DVN...EAX...GID...ICT...LSX...OAX...
TOP...

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

LAT...LON   41759306 41609159 40909103 40189151 39869392 
            39509519 38759712 38389875 38859958 39249938 
            40289778 41319532