MESOSCALE PRECIPITATION DISCUSSION 0213
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
846 AM EDT MON MAY 28 2018

AREAS AFFECTED...NORTHWEST KS...SOUTHWEST TO CENTRAL NE

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

VALID 281245Z - 281745Z

SUMMARY...HEAVY PERSISTENT RAINS WILL RESULT IN SOME FLASH
FLOODING POTENTIAL OVER THE NEXT FEW HOURS.

DISCUSSION...LATEST GOES-16 CLEAN IR SATELLITE IMAGERY CONTINUES
TO SHOW AN IMPRESSIVE COLD-TOPPED CONVECTIVE CANOPY ACROSS
PORTIONS OF NORTHWEST KS AND UP ACROSS A LARGE AREA OF CENTRAL
NEBRASKA.

THE ACTIVITY IS BEING SUSTAINED BY A PERSISTENT DEEP LAYER WARM
ADVECTION PATTERN ACROSS THE CENTRAL PLAINS AND IS COUPLING WITH
NOTABLY DIVERGENT FLOW ALOFT COURTESY OF A MODEST 250 MB JET
COUPLET AROUND THE EASTERN FLANK OF A LARGE SCALE TROUGH ACROSS
THE INTERMOUNTAIN WEST WHICH IS FAVORING RELATIVELY FOCUSED LARGE
SCALE ASCENT.

ADDITIONALLY...THE DEEP LAYER WARM ADVECTION REGIME...NOTED IN THE
850/500 MB LAYER IN PARTICULAR...HAS ALLOWED FOR A NOSE OF
MODERATE INSTABILITY TO SURGE NORTH UP ACROSS THE PLAINS...WITH
MUCAPE VALUES OF 1500 TO 2000 J/KG NOTED AS PER THE LATEST RAP
ANALYSIS. MUCH OF THE MORE ORGANIZED CONVECTION IS CURRENTLY
ALIGNED WITH THIS NOSE OF INSTABILITY.

GIVEN THE LATEST SATELLITE AND RADAR TRENDS AND WITH MULTIPLE
INGREDIENTS FOR HEAVY RAINFALL CURRENTLY ANCHORED IN PLACE...THE
THREAT FOR EXCESSIVE TOTALS APPEARS TO BE INCREASING AT LEAST FOR
THE NEXT FEW HOURS.

ALREADY THE PWATS ACROSS THE REGION ARE AS HIGH AS 1.4 TO 1.5
INCHES...WHICH IS PROMOTING RAINFALL RATES UPWARDS OF 2 INCHES/HR.
THE LATEST MRMS FLASH DATA IS ALREADY INDICATING QPE/FFG RATIOS OF
ABOUT 1.3 TO 1.4 LOCALLY ACROSS CENTRAL NEBRASKA...AND WITH THESE
RATIO TRENDS INCREASING ACROSS PORTIONS OF NORTHWEST KS.

EXPECT AN ADDITIONAL 3 TO 4 INCHES OF RAIN GOING THROUGH
MIDDAY...WITH SOME ISOLATED HEAVIER AMOUNTS NOT OUT OF THE
QUESTION. THIS IS CONSISTENT WITH THE LATEST HRRR/HRRRX GUIDANCE.
FLASH FLOODING WILL BE POSSIBLE GIVEN THESE ADDITIONAL TOTALS OF
WHICH SOME WILL BE FALLING ON INCREASINGLY MOIST/SATURATED SOIL
CONDITIONS.

ORRISON

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

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

LAT...LON   41680055 41389974 40619965 39609993 39170032
            39150117 39790164 40460184 41110169 41490126