MESOSCALE PRECIPITATION DISCUSSION 0691
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
505 PM EDT MON AUG 14 2017

AREAS AFFECTED...SOUTHEAST NEB...NORTHWEST MO...NORTHEAST KS

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 142105Z - 150100Z

SUMMARY...SMALL CLUSTER OF THUNDERSTORMS LIKELY TO BE STATIONARY
INITIALLY AND WITH RAIN RATES TO 2"/HR MAY POSE LOCALIZED FLASH
FLOODING CONCERN.

DISCUSSION...SURFACE ANALYSIS DEPICTS THE SOUTHERN EXTENT OF A
SURFACE FRONT DRAPED ACROSS E AND S NEB.  VWP/RAP ANALYSIS AND
GOES-16 VISIBLE CU STREAMERS SUGGEST WEAK SLY FLOW ACROSS E KS
THAT VEERS SLIGHTLY TOWARD SW IA AT THIS SE BULGE IN THE COLD
FRONT.  ADDITIONALLY...STREAMERS SUGGEST SOME DEFORMATION OR SELY
TURN ACROSS NE KS INTO S CENTRAL NEB UNDER RESPONSE TO FALLING SFC
PRESSURES ACROSS THE CENTRAL NEB/KS BORDER.  EVEN THOUGH 850MB
FLOW IS WEAK THERE IS SUFFICIENT MST CONVERGENCE WITHIN A UNSTABLE
ENVIRONMENT (MLCAPES TO 3000 J/KG AND GREATER UPSTREAM) AND
POOLING ALONG CONFLUENT FLOW AT 7H DURING THE ASCENT TO SUPPORT
TPWS TO REACH 1.75". 

GOES-16 WV LOOP ALSO SUPPORTS THE IDEA OF GOOD PLACEMENT BETWEEN
THE WAVE OVER AR...TRAILING MID-LEVEL TROF (JET ENTRANCE ACROSS NE
MO/SE IA)AND UPSTREAM RIDGING THAT WOULD SUGGEST VERY WEAK
PROPAGATION VECTORS IN THE VICINITY OF THE DEVELOPING CONVECTION
PERHAPS SLIGHTLY ESE WHICH APPEARS TO BE PARALLEL TO THE BEST
CONVERGENCE AXIS AS WELL SUGGESTIVE OF MINOR TRAINING/REPEATING
(GIVEN WEAK FLOW).
WITH AMPLE MOISTURE AND INFLOW/UPPER LEVEL OUTFLOW...RAIN RATES
ARE LIKELY TO REACH 2"/HR FOR A FEW HOURS POTENTIALLY LEADING TO
2-4" TOTALS AND POSSIBLE LOCALIZED FLASH FLOODING CONCERNS.  THIS
IS SUPPORTED BY THE 12Z WRF NMMB/ARW.

LIMITING FACTORS ARE LIKELY RELATED TO MID-LEVEL DRY
AIR...SUPPORTED BY 12Z RAOBS AT OAX/TOP AND RECENT RAP FORECAST
SOUNDINGS.  THIS POTENTIALLY WILL ALLOW FOR COLD POOL DEVELOPMENT
AND ALLOW FOR OUTFLOW TO PROPAGATE CELLS SOUTH AND WEST WITH
TIME...THIS PROPAGATION TOWARD BETTER INSTABILITY WILL LIKELY
SPELL THE END FOR FLASH FLOOD THREAT GIVEN TOTALS ARE DRIVEN
MAINLY ON STATIONARY NATURE OF DOWNDRAFTS. 

GALLINA

ATTN...WFO...EAX...OAX...TOP...

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

LAT...LON   40759630 40289511 39679467 39289557 39669655
            40279676 40559664