MESOSCALE PRECIPITATION DISCUSSION 0328
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
400 PM EDT WED AUG 27 2014
 
AREAS AFFECTED...CENTRAL HIGH PLAINS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 271959Z - 280159Z
 
SUMMARY...A TRIO OF SURFACE BOUNDARIES ACTING UPON AVAILABLE
MOISTURE AND INSTABILITY COULD LEAD TO HOURLY RAIN RATES OF UP TO
2" OVER AREAS WITH SATURATED SOILS.  FLASH FLOODING IS POSSIBLE.

DISCUSSION...A FEW FOCI FOR CONVECTIVE DEVELOPMENT EXIST ACROSS
THIS REGION, WITH AN INVERTED TROUGH ACROSS EASTERN WY, A ZONE OF
SIGNIFICANT BOUNDARY LAYER MOISTURE CONVERGENCE ACROSS SD AND
WESTERN NE, AND A ZONE OF THERMAL CONTRAST ACROSS KS. 
TEMPERATURES AT 700 HPA INDICATE NO LOW- TO MID-LEVEL CAPPING IS
PRESENT ACROSS THE DEFINED AREA.  CAPE VALUES NEAR AND SOUTH OF
THE BOUNDARIES ARE CURRENTLY IN THE 1000-2000 J/KG RANGE PER THE
19Z SPC MESOANALYSIS PAGE.  VAD WIND PROFILES ACROSS KS ALREADY
INDICATE 25 KTS OF 850 HPA INFLOW INTO THE FRONTAL ZONE.  ACROSS
THE REGION, 850 HPA INFLOW STRENGTH IS IN EXCESS OF THE MEAN
850-400 HPA WINDS, WHICH SHOULD LEAD TO PRECIPITATION EFFICIENCY
ACROSS THE REGION.  PRECIPITABLE WATER VALUES -- PER RECENT RAP
RUNS AND THE SPC MESOANALYSIS PAGE -- ARE BETWEEN 1.5-2" IN THIS
REGION.  THE PW VALUES ARE 2.5 SIGMAS ABOVE AVERAGE, NEAR THE 99TH
PERCENTILE FOR LATE AUGUST.  THE CRITERIA FOR THE WET MULTICELL
ENVIRONMENT HAVE BEEN MET BEST ACROSS KS AND SOUTHERN NE. 
CONVECTION ACROSS WESTERN NE AND SOUTHWEST SD HAS BEEN SLOW TO
MOVE AS OF LATE, RAMPING UP THEIR RISK FOR FLASH FLOODING.

THERE IS A MODEST SIGNAL IN THE MESOSCALE QPF GUIDANCE --
INCLUDING THE 06Z AND 12Z SSEO NEIGHBORHOOD PROBABILITIES OF
EXCEEDING THREE HOUR FLASH FLOOD GUIDANCE VALUES -- OF HEAVY
RAINFALL THAT COULD LEAD TO FLASH FLOODING WITHIN THIS REGION. 
FOR THE NORTHWEST PART OF THIS REGION, SINGLE CELLULAR/PULSE
CONVECTION DRIVEN BY CONVECTIVE OUTFLOWS IS EXPECTED DUE TO
RELATIVELY LIMITED LOW-LEVEL INFLOW.  INFLOW ACROSS WESTERN KS IS
EXPECTED TO RAMP UP TO 30-35 KTS BY THE END OF THE PERIOD PER
RECENT RAP RUNS, WHICH COULD LEAD TO MORE ORGANIZED CONVECTIVE
ACTIVITY ACROSS KS AND SOUTHERN NE.  HOURLY RAIN RATES UP TO 2",
WITH LOCAL AMOUNTS UP TO 4", ARE ANTICIPATED.  CONSIDERING THE
ABOVE, FLASH FLOODING IS POSSIBLE HERE.

ROTH

ATTN...WFO...FSD...ICT...ABR...GID...LBF...DDC...UNR...GLD...
BOU...CYS...

ATTN...RFC...ABRFC...CBRFC...MBRFC...

LAT...LON   43479966 42590030 42030015 41479944 40219807 39319807
            38839860 38779976 38760014 39210143 39670235 40420279
            41370368 42330477 43010523 43830471 44430391 44780225
            44810024 44429900 43479966