MESOSCALE PRECIPITATION DISCUSSION 0233
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
809 AM EDT FRI MAY 19 2017

AREAS AFFECTED...NORTH CENTRAL TEXAS

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

VALID 191205Z - 191705Z

SUMMARY...THE THREAT OF TRAINING SHOWERS/THUNDERSTORMS ALONG A LOW
LEVEL BOUNDARY MAY RESULT IN A FLASH FLOOD THREAT THIS MORNING IN
NORTH CENTRAL TEXAS.

DISCUSSION...SHOWERS AND THUNDERSTORMS PREVIOUSLY INITIATED NEAR
THE DRY LINE ARE EXPECTED TO CONTINUE IN A CLUSTER ACROSS NORTH
CENTRAL TEXAS. THE CLUSTER OF SHOWERS/STORMS IS EXPECTED TO
PERSIST AS A COUPLED UPPER DIVERGENCE/LOWER CONVERGENCE COUPLET
OCCURS UNDER DIFLUENT FLOW ALOFT DOWNSTREAM FROM AN UPPER JET
MAXIMA OVER NEW MEXICO AND SOUTHWEST TEXAS. THE HIGH RESOLUTION
RAPID REFRESH RUNS CONTINUE SHOWING WELL DEFINED BOUNDARY LAYER
MOISTURE CONVERGENCE AND 850-700 MB MOISTURE FLUXES INTO THE
CLUSTER.  THE CLUSTER CONTINUES TO BE SUPPORTED BY
INSTABILITY...INCLUDED MIXED LAYER CAPE VALUES NEAR 2000 J/KG.

DEEP LAYER MEAN WINDS ARE FORECAST TO BE SOUTHWEST WITH
PROPAGATION TO THE SOUTHEAST....RESULTING IN A NET EAST NORTHEAST
MOTION. KDYX RADAR SHOWS 1-2 INCHES PER HOURS HAVE FALLEN WITHIN
THE BAND.  2-4 INCHES OF RAIN ARE EXPECTED WITHIN THE BAND THROUGH
18Z.  THE POTENTIAL IS THERE FOR ISOLATED HIGHER AMOUNTS WITH THE
09Z HIGH RES RAPID REFRESH (HRRR) INDICATING UP TO 5 INCHES OF
RAIN. THIS IS THE HIGHEST GUIDANCE WITH THE NEXT HIGHEST FORECAST
RAINFALL 3 INCHES IN THE NSSL WRF. ..AND LOWER AMOUNTS IN THE WRF
ARW/NMMB/CANADIAN REGIONAL GEM/NAM CONUS NEST. THE 6 HOUR HIGH
RESOLUTION ENSEMBLE FORECAST NEIGHBORHOOD PROBABILITY OF EXCEEDING
2 INCHES OF RAIN IS 30-40 PERCENT. BASED ON THESE SIGNALS...FLASH
FLOODING WILL CONTINUE TO BE POSSIBLE THIS MORNING.

PETERSEN

ATTN...WFO...FWD...MAF...SJT...

ATTN...RFC...WGRFC...

LAT...LON   33459719 32529768 31749928 31250044 31090158
            31960130 32600005 33099925 33419823