MESOSCALE PRECIPITATION DISCUSSION 0242
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
322 PM EDT THU JUN 18 2015
 
AREAS AFFECTED...CENTRAL AND NORTHEAST TEXAS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 181922Z - 190022Z
 
SUMMARY...CONVECTION DEVELOPING ALONG TRAILING TROF/FEEDER BAND
ACROSS NORTH CENTRAL TEXAS WITH POSSIBILITY OF SLOW CELL MOTION
AND TRAINING FOR POTENTIAL FLASH FLOODING.

DISCUSSION...VISIBLE LOOP/RADAR AND SURFACE OBSERVATIONS SHOW A
WELL DEFINED TRAILING FEEDER BAND ON THE SOUTHERN PERIPHERY OF
T.D. BILL IN NORTH CENTRAL TEXAS TOWARD SOUTHWEST ARKANSAS.  WITH
STRONG CONFLUENT FLOW FROM THE SURFACE THROUGH THE MID-LEVELS...
LEADING TO VERY GOOD  MOISTURE CONVERGENCE FOR CONVECTIVE
INITIATION.  ADDiTIONALLY...INSTABILITIES ARE MAXIMIZED ALONG THIS
BOUNDARY AS WELL... WITH MLCAPES RANGING FROM 2500 J/KG IN THE
WEST NEAR GDJ LESSENING TOWARD THE EAST.  LOW LEVEL MOISTURE IS
ALSO POOLED ALONG THE BOUNDARY WITH 850MB DEWPOINTS IN THE 16-18 C
RANGE WITH TOTAL PWATS IN THE 1.75-1.9" RANGE PER GPS NETWORK.  SO
THERE IS A BIT OF DRY AIR ALOFT...CELLS SHOULD BE CAPABLE OF
1.5-2"/HR.

WITH SOME THE DRY AIR ALOFT...CELLS POTENTIALLY COULD BE OUTFLOW
DOMINANT AT FIRST BUT WITH AVAILABLE MOISTURE AND SLOW CELL
MOTIONS...SHOULD MOISTEN LEADING TO THE POTENTIAL FOR SCATTERED
LOCALIZED BUT HIGH RAIN TOTALS...THIS IS MORE TRUE FURTHER WEST
WITH SLOWER CELL MOTIONS AND UPWIND PROPAGATION VECTORS NEARLY
ZERO OR EVEN SUPPORTIVE OF BACKBUILDING. BILL WILL BE MOVING
NEARLY PARALLEL TO THE ORIENTATION OF THE BAND AND CELL MOTION
VECTORS WILL BE PARALLEL TO THE BAND FPR THE POTENTIAL FOR
TRAINING.  THIS SHOULD BE A HIGHER PROBABILITY FURTHER EAST WHERE
CELL MOTIONS ARE FASTER.     

GALLINA

ATTN...WFO...EWX...FWD...SHV...SJT...

ATTN...RFC...ABRFC...LMRFC...WGRFC...

LAT...LON   33499457 33469417 32939412 32069492 31059724 
            30749929 31389939 31959809 33169565