MESOSCALE PRECIPITATION DISCUSSION 0217
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
339 PM EDT MON MAY 28 2018

AREAS AFFECTED...NORTHWEST/NORTH-CENTRAL KS...SOUTH-CENTRAL NE

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 281935Z - 290135Z

SUMMARY...A VERY SLOW-MOVING AND TRAINING BAND OF CONVECTION HAS
BEEN SETTING UP OVER PORTIONS OF NORTH-CENTRAL KS AND ADJACENT
AREAS OF SOUTH-CENTRAL NE. FLASH FLOODING IS LIKELY AND COULD BE
LOCALLY SIGNIFICANT THROUGH THE AFTERNOON HOURS.

DISCUSSION...THE LATEST GOES-16 VISIBLE SATELLITE IMAGERY SHOWS AN
IMPRESSIVELY FOCUSED AREA OF CONVECTION THAT IS IMPACTING GRAHAM
AND PHILLIPS COUNTIES OF NORTHWEST TO NORTH-CENTRAL KS...AND THE
CONVECTION EXTENDS NORTHEAST UP ACROSS SOUTH-CENTRAL NE IN A
SOMEWHAT MORE BROKEN NATURE. CLOUD TOPS HAVE BEEN COOLING OVER THE
LAST HOUR AS STRONG SURFACE CONVERGENCE VIA COLLIDING OUTFLOW
BOUNDARIES AND PROXIMITY OF A SYNOPTIC FRONT ALL INTERACT WITH A
STRONGLY UNSTABLE BOUNDARY LAYER...WITH THE LATEST RAP ANALYSIS
DEPICTING MLCAPE VALUES OF 2500 TO 3000+ J/KG. SURFACE CLOUD
STREETS ARE NOTED IN VISIBLE IMAGERY THAT ARE ALIGNED WITH THE
NOSE OF THIS INSTABILITY AND ITS ENTRAINMENT INTO THE SOUTHWEST
FLANK OF THE CONVECTIVE AXIS.

ON THE LARGER SCALE...THE ACTIVITY IS AGAIN BEING FACILITATED 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.

GIVEN THE SET-UP WITH EXTREMELY FAVORABLE THERMODYNAMICS IN
PLACE...EXPECT VERY HEAVY RAINFALL POTENTIAL...AND ESPECIALLY WITH
PWATS OF NEAR 1.5 INCHES WHICH IS ABOUT 1 TO 2 SIGMAS ABOVE NORMAL
FOR THIS TIME OF THE YEAR. THERE WILL BE MULTIPLE LOW LEVEL
FORCING BOUNDARIES REMAINING PLACE...AND AS UPSTREAM HEIGHT
FALLS/TROUGHING APPROACHES THIS AFTERNOON...EXPECT ADDITIONAL
CONVECTIVE POTENTIAL EXPANDING ALONG THE NOSE OF BEST INSTABILITY
AND THE QUASI-STATIONARY FRONTAL ZONE OVER THE REGION WHICH WILL
INCLUDE NORTHWEST KS.

RAINFALL RATES OF 2 TO 3 INCHES/HR ARE EXPECTED WITH ADDITIONAL
STORM TOTAL POTENTIAL OF AS MUCH AS 4 TO 6 INCHES THROUGH 00Z.
FLASH FLOODING IS LIKELY.

ORRISON

ATTN...WFO...DDC...GID...GLD...ICT...OAX...

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

LAT...LON   41679801 41209765 40439784 39839822 39369867
            38749942 38559952 38119979 37740007 37670053
            37960131 38260159 38820186 39170194 39360208
            39760198 39970074 40369989 40819932 41549872