MESOSCALE PRECIPITATION DISCUSSION 0109
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1029 PM EDT MON APR 10 2017

AREAS AFFECTED...CENTRAL TO NORTHEASTERN TX...

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

VALID 110228Z - 110643Z

SUMMARY...SLOW-MOVING CONVECTION CONTINUES TO FOCUS ON A FRONTAL
ZONE DRIFTING TOWARD THE SOUTH AND EAST. LOCALLY HEAVY RAINFALL
MAY PRODUCE FLASH FLOODING WHERE CELLS TRAIN...PARTICULARLY OVER
AREAS AFFECTED EARLIER IN THE EVENING. RAINFALL RATES APPROACHING
1.50 INCHES ARE LIKELY WITHIN THE MORE ROBUST CONVECTION.

DISCUSSION...THE 02Z SURFACE ANALYSIS INDICATED A SLOW-MOVING
FRONT STRETCHING SOUTHWEST-TO-NORTHEAST ACROSS MUCH OF CENTRAL TX.
SEMI-ORGANIZED CONVECTION HAS CONTINUED TO FIRE ALONG AND AHEAD OF
THIS BOUNDARY WITHIN A HIGHLY BUOYANT THERMODYNAMIC ENVIRONMENT.
RECENT 00Z SOUNDINGS SHOW IMPRESSIVE LEVELS OF INSTABILITY
REMAINING. IN PARTICULAR...WITHIN THE UNPERTURBED ENVIRONMENT
AROUND DEL RIO TX...THE DRT SOUNDING CONTAINED ALMOST 3000 J/KG OF
MIXED-LAYER CAPE...ALTHOUGH SOME CAPPING ISSUES WERE NOTED BETWEEN
800-700 MB. THE 01Z RAP OBJECTIVE ANALYSIS INDICATES MUCH OF THE
WARM SECTOR IS GENERALLY UNCAPPED WITHIN THE REGION OF MOIST
INFLOW. RECENT RUNS OF THE RAP DO SHOW AN UPTICK IN THE 850-MB
FLOW TO AROUND 25 KNOTS BY ROUGHLY 06Z. THE CURRENT CONVECTION
SHOULD REMAIN RELATIVELY WELL ORGANIZED AND EVENTUALLY DEVELOP A
COLD POOL TO BECOME MORE FORWARD-PROPAGATING OVERNIGHT. THIS HAS
BEEN DELAYED RELATIVE TO THE 12Z CAM SOLUTIONS. PERHAPS AN
UPSTREAM IMPULSE NOTED IN WATER VAPOR IMAGERY MAY ENCOURAGE THIS
TRANSITION TO OCCUR DURING THE NEXT FEW HOURS OR SO.

AS ALLUDED TO EARLIER...MODEL SOLUTIONS HAVE DONE A POOR JOB
HANDLING THE AFTERNOON/EVENING CONVECTIVE ACTIVITY. ALL OF THE 12Z
CAMS DEPICTED AN MCS MOVING TOWARD THE TX GULF COAST BY 06-08Z
WHICH IS NOT LIKELY GIVEN CURRENT RADAR/SATELLITE TRENDS.
INTERESTINGLY...THE 17Z EXPERIMENTAL-HRRR WAS THE ONLY SOLUTION
KEEPING CONVECTION WELL TO THE NORTH WHICH APPEARS TO BE CLOSER TO
THE TRUTH THAN INITIALLY BELIEVED. THE LAST COUPLE OF RUNS OF THE
OPERATIONAL HRRR FOLLOW THIS EVOLUTION AS WELL. BOTH SIGNAL A
HEFTY AXIS OF CONVECTION THROUGH 08Z JUST SOUTH OF THE FRONT FROM
EAST OF JUNCTION TX TO SOUTHWEST OF TYLER TX. CONFIDENCE DOES
REMAIN BELOW AVERAGE BUT IT APPEARS THE FLASH FLOOD THREAT DOES
REMAIN INTO THE OVERNIGHT HOURS.

RUBIN-OSTER

ATTN...WFO...EWX...FWD...HGX...MAF...SHV...SJT...

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

LAT...LON   32809530 32439466 31619483 30579592 29839771
            29609897 29740081 29670174 29890225 30370213
            30540146 30929978 31259896 31469846 31929731