MESOSCALE PRECIPITATION DISCUSSION 0116
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
817 PM EDT FRI APR 14 2017

AREAS AFFECTED...CENTRAL NEB

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

VALID 150016Z - 150501Z

SUMMARY...INCREASING CONVECTION WITH POSSIBILITY OF TRAINING AND
BACKBUILDING LEADING TO POSSIBLE FLASH FLOODING CONDITIONS.

DISCUSSION...SURFACE ANALYSIS SHOWS A VERY SHARP TROF/EFFECTIVE
FRONT EXTENDING FROM EAST CENTRAL CO N OF MCK AND LXN TO BVN TO
OFK. STRONG 20-25KTS CONVERGING WITH WEAK ENE FLOW NORTH OF THE
BOUNDARY APPEARS SUFFICIENT FOR CONVECTION TO BREAK OUT PER
RADAR/GOES-16 MESO WINDOW IMAGERY.  THIS CONVECTION WILL BE STRONG
WITH SEVERE WX (SEE SPEC MCD 490) WITH MLCAPE AOA 3000 J/KG. 
ADDITIONALLY MOISTURE CONVERGENCE IS STRONGER AT THE APEX OF
DRYLINE BULGE THAT APPEARS TO BE NORTH AND E OF MCK ATTM PER
RADAR/SFC OBS...EAST OF WHICH UPPER 50S TDS ENRICH TO LOWER 60S BY
ODX/GRI/HSI...THOUGH THE DEPTH OF THE MST IS LIMITED TO AROUND
1.06" PER GPS NETWORK AND RAP ANALYSIS ESTIMATES. 

RAP FORECAST SUGGESTS STRENGTHENING LOW LEVEL JET AFTER 00Z OVER
40KTS BY 00Z AND 50KTS THOUGH MAIN AXIS WILL BACK AND REMAIN SOUTH
ACROSS SE NEB THIS INCREASE SHOULD ALLOW FOR A MORE FAVORABLE
BACKBUILDING ENVIRONMENT...PARTICULARITY GIVEN THE INCREASED
DIFFLUENCE EXPECTED OVER N CENTRAL NEB (LEAVING AREA IN RGT.
ENTRANCE TO 50-60 KT NNE ORIENTED JET STREAK) LEADING TO GOOD
EVACUATION AND BROAD SCALE ASCENT TO MAINTAIN THE CONVECTIVE LINE.
 THIS MST FLUX AND RELATIVE STATIONARY LOCATION TO THE ENE
ORIENTED BOUNDARY WILL ALLOW FOR MOISTURE TO INCREASE TOWARD 1.25"
TPWS INCREASING RAINFALL EFFICIENCY AS WELL.

ADDITIONALLY MEAN CLOUD BARING WIND PROFILES WHILE QUICK AROUND
20-25KT TOWARD THE NE ARE FAIRLY PARALLEL TO THE BOUNDARY LEADING
TO THE POSSIBILITY OF A FEW TRAINING TRACKS.  ONE LIMITING FACTOR
WOULD BE SOME SELY FORWARD PROPAGATION PARTICULARLY IF/WHEN COLD
POOL GENERATION WOULD OCCUR...PERHAPS AROUND THE 02Z TIME FRAME.  
UPPER LEVEL FORCING AXIS/HEIGHT FALLS ARE EXPECTED TO OVERWASH THE
REGION TOWARD 04-05Z...LEADING TO EVENTUAL EASTWARD PROGRESSION OF
THE COMPLEX AROUND THAT TIME PERIOD.  WITH RAIN RATES OF
1.25-1.5"/HR EXPECTED (POSSIBLY HIGHER AFTER DOWNDRAFT PROFILES
MOISTEN/SATURATE) AND BACKBUILDING IT IS NOT OUT OF THE REALM OF
POSSIBILITY OF RAINFALL TOTALS OF 2-3" WITH LOCALIZED 4" OR
HIGHER...IF COLD POOL GENERATION DOES NOT MATERIALIZE AS GREAT AS
EXPECTED.  THE BEST CORRIDOR FOR THESE RATES IS A FEW MILES NORTH
OF THE BOUNDARY AND SOUTH...LIKELY OUT OF THE SAND HILLS AND OVER
AREAS WHERE 1HR FFG IS 1.5" AND 3HR IS 2-2.5"... SO AREAL COVERAGE
OF FF IS FAIRLY LOW AS WELL LEADING TO THE FLASH FLOODING
EXPECTATION TO BE POSSIBLE.

GALLINA

ATTN...WFO...GID...LBF...OAX...

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

LAT...LON   42159743 41429671 40939716 40489866 40379977
            40370017 40660043 41000002 41609901 41929828