MESOSCALE PRECIPITATION DISCUSSION 0221
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
936 PM EDT MON MAY 28 2018

AREAS AFFECTED...NORTHEAST CO...WEST AND SOUTHWEST NEB...EXT
SOUTHEAST WY...EXT NORTHEAST KS

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

VALID 290135Z - 290700Z

SUMMARY...STRONG DYNAMICS WITH INITIAL MERGERS/SLOW CELLS IN
TROWAL SHIFTING TO NEW DEVELOPMENT AROUND 04Z OVER E CO...BOTH
OVER LOWERED FFG VALUED SUGGESTING FLASH FLOODING POSSIBLE THROUGH
THE OVERNIGHT HOURS.

DISCUSSION...GOES-16 WV SUITE SHOWS A HIGHLY DYNAMIC SETUP ACROSS
THE CENTRAL HIGH PLAINS...WITH A STRONG 80-90 KT JET STREAK
UNDERCUTTING THE DEEP UPPER LOW WITH A SHORTWAVE ALONG THE
SOUTHEAST PERIPHERY AND A SHARP TROF EXTENDING SOUTHEAST ACROSS
THE LAKE/PALMER DIVIDE.  UPPER LEVEL WINDS ARE RESPONDING BY
ROUNDING THE TROF AND INCREASING OUTFLOW ACROSS THE DISCUSSION
AREA WITH EXCELLENT DIFFLUENCE.  UVVS ARE ALSO DRIVEN BY STRONG
DPVA ASCENT AND STRENGTHENING LLJ TO ACCELERATE FROM THE THE WARM
SECTOR AND THROUGH THE LINEAR MCS ACROSS W KS.  RECENT SURFACE
ANALYSIS ALSO SUGGESTS DUE TO SURFACE PRESSURE FALLS TO RETROGRADE
THE SURFACE DRYLINE BACK INTO EASTERN CO...WHILE THE SURFACE FRONT
BECOME STATIONARY OVER NE CO TO NW KS.  AS SUCH A NARROW WINDOW
EXISTS FROM EXTREME E WY NEAR THE MCV/SHORTWAVE PIVOT POINT
SOUTHEASTWARD INTO NE CO/SW NEB ALONG THE TROWAL AXIS...WILL ALLOW
FOR MASS CONVERGENCE OF THUNDERSTORMS SUPPORTING MERGERS AND
SLOWING OF CELLS.  WHILE BEST INSTABILITY IS SE INTO
KS...1500-2000 J/KG MUCAPES RESIDE TO SUPPORT STRONG INSTABILITY
FOR FURTHER UPDRAFT STRENGTH AND MST CONVERGENCE.  RECENT GPS
NETWORK AND GOES-W SOUNDER SUGGEST INCREASED OVERALL MOISTURE
VALUES WITH TPWS AT 1.1".  WITH STRONG ASCENT AND FLUX...RAIN
RATES UP TO 1.5"/HR ARE POSSIBLE AND POTENTIALLY HIGHER WITH
MERGING UPDRAFTS.  THE TROWAL/AXIS OF THESE MERGERS WILL BE ALSO
COLLOCATED WITH THE LOWER REGIONAL FFG VALUES IN THE I-80 AND
NORTHEAST I-76 CORRIDORS SUGGESTING CONTINUED POSSIBILITY FOR
FLASH FLOODING IN THE NEXT 1-3 HOURS. 

TOWARD 04Z...AS THE LINEAR MCS BEGINS TO FURTHER OUTRUN THE LOW
LEVEL BOUNDARIES AND OUTFLOW BOUNDARY ASCENT WEAKENS SLIGHTLY AND
THE CORE OF THE JET STREAK REACHES THE APEX OF THE TROF PROVIDING
GREATEST ASCENT...THE DRY LINE COLD FRONT/DRY LINE INTERSECTION
WILL START TO DROP SOUTH WITH THE TRAILING EDGE OF THE CONVECTIVE
LINE RE-ACTIVATING IN A NE TO SW MANNER. CELLS MAY INITIALLY LIFT
NORTHEAST SUPPORTING SOME TRAINING ACROSS NE CO BEFORE BECOMING
COLD POOL/OUTFLOW DOMINANT AND MARCHING EAST...THROUGH AREAS THAT
HAVE LOWERED FFG FROM LAST EVENING AND THIS EVENING'S BOUTS OF
HEAVY RAIN PROVIDING ANOTHER OPPORTUNITY FOR FLASH FLOODING TO
OCCUR.  THIS IS IN LINE WITH RECENT HRRR/HRRRV3 AND RAP MULTIPLE
CONSECUTIVE RUNS AS WELL AS THE 12Z NMMB/NAM CONEST AND MODEST
HREFMEAN PROBABILITY.  

GALLINA

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

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

LAT...LON   42980419 42930346 42790305 42380293 41820290
            41490253 41300200 41160165 41080062 40970023
            40720010 40270019 39670069 39160149 38830263
            39060345 39500379 39850375 40200345 40680332
            41080370 41540412 41940466 42460495 42810476