MESOSCALE PRECIPITATION DISCUSSION 0133
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1128 PM EDT THU MAY 10 2018

AREAS AFFECTED...SOUTHERN & CENTRAL NE

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

VALID 110327Z - 110827Z

SUMMARY...THUNDERSTORMS ARE SHOWING MORE POTENTIAL FOR TRAINING
ACROSS SOUTHWEST NE AS OF LATE.  HOURLY RAIN TOTALS TO 1.5" WITH
LOCAL AMOUNTS TO 4" ARE POSSIBLE THROUGH 08Z.

DISCUSSION...SATELLITE IMAGERY INDICATES THAT THE BREADTH OF THE
COLD CLOUD TOPS ASSOCIATED WITH A CONVECTIVE COMPLEX ACROSS NE IS
CLOSE TO MCC CRITERIA.  AN OUTFLOW BOUNDARY/SQUALL LINE APPEARS TO
BE WEAKENING AS IT ENTERS CENTRAL NE.  BETWEEN THE WEAKENING TREND
IN CENTRAL NE AND A LOW PRESSURE SYSTEM HANGING BACK ACROSS
EASTERN CO, CONVECTION APPEARS TO BE ATTEMPTING TO TRAIN ACROSS
SOUTHWEST NE AS OF LATE AND RADAR INDICATED RAIN RATES ARE ON THE
RISE.  THE 12C ISOTHERM AT 700 HPA APPEARS TO BE ACTING AS THE
SOUTHERN LIMIT FOR CONVECTION.  INFLOW AT 850 HPA IS
SOUTH-SOUTHEAST AT 50-55 KTS PER THE GOODLAND KS VAD WIND PROFILE.
 EFFECTIVE BULK SHEAR IS 50+ KTS AND UPSTREAM MU CAPE VALUES OF
2000-3000 J/KG HAVE BEEN ANALYZED ACROSS NORTHEAST CO AND NEAR THE
WESTERN KS/NE BORDER PER SPC MESOANALYSES.  PRECIPITABLE WATER
VALUES WERE ~1" IN THE NORTH PLATTE NE SOUNDING AT 00Z, AND RECENT
RAP RUNS SUGGEST A LOCAL MAXIMUM OF 1.25"+ MAY EXIST WITHIN THE
CONVECTIVE AREA.

THE MESOSCALE GUIDANCE APPEARS TO BE HANDLING THE CONVECTIVE
EVOLUTION IN THIS AREA WELL.  THE GALVEZ-DAVISON INSTABILITY INDEX
IMPLIES CONVECTIVE COVERAGE SHOULD BE STEADY STATE THROUGH 06Z
BEFORE SLOWLY FADING THEREAFTER.  EXPECTATIONS ARE FOR THE
CONVECTION TO EVENTUALLY SHIFT EASTWARD, AROUND 08Z, ACROSS THE
REGION AS THE SURFACE LOW PULLS EASTWARD INTO KS.  INFLOW AT 850
HPA IS ALSO EXPECTED TO WEAKEN SOMEWHAT NEAR THE FRONTAL BOUNDARY
AT AND BEYOND 08Z.  AS IT DOES SO, 850 HPA INFLOW VEERS WITH TIME
WHICH SHOULD CAUSE AN EASTWARD SHIFT TO THE CONVECTION. 
CONVECTIVE PROPAGATION VECTORS INDICATE EASTWARD MOVEMENT AT 20
KTS, THOUGH RADAR IMAGERY INDICATES A MOVEMENT OF 25-30 KTS IS
MORE REPRESENTATIVE.  CELL TRAINING/MERGERS ARE EXPECTED TO LEAD
TO HOURLY RAIN TOTALS TO 1.5" WITH LOCAL AMOUNTS TO 4".  THIS
COULD EXCEED THE THREE HOURLY FLASH FLOOD GUIDANCE VALUES, BUT IN
GENERAL, THE RAIN IS EXPECTED TO HELP RELIEVE DROUGHT CONDITIONS.

ROTH

ATTN...WFO...BOU...GID...GLD...LBF...

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

LAT...LON   41819912 40779861 40340226 41330182