MESOSCALE PRECIPITATION DISCUSSION 0121
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1007 AM EDT SUN MAY 24 2015
 
AREAS AFFECTED...NORTHEAST TEXAS...WESTERN ARKANSAS...SOUTHEAST
OKLAHOMA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 241407Z - 242007Z
 
SUMMARY...INCREASING RAIN RATES ALONG OUTFLOW BOUNDARY AHEAD OF
LIFTING MCV TO EXACERBATE ONGOING FLOODING CONDITIONS.    

DISCUSSION...WELL DEFINED SHORTWAVE ADVANCING EASTWARD ACROSS
NORTH CENTRAL TEXAS HAS A NEGATIVE TILTED TROF CONNECTING UP TO
SHEARED MCV ACROSS EASTERN TX. THIS MCV IS LIFTING NORTH FOCUSING
SOUTHEASTERLY INFLOW AND MOISTURE TRANSPORT NOSING INTO TEXARKANA
REGION.  TPWS OF 1.75-1.9" ALONG WITH INCREASING SBCAPES OF
1000-1500 J/KG SHOULD SUPPORT STRONG UPDRAFTS AND HIGH RAINFALL
EFFICIENCY OF 1.5-2"/HR RATES. 
 
THIS WARM AND UNSTABLE ENVIRONMENTAL AIR WILL FOCUS WITHIN
INCREASING MOISTURE CONVERGENCE ALONG A DRAPED OUTFLOW BOUNDARY
FROM LAST NIGHTS CONVECTIVE COMPLEX ANALYZED NORTH-SOUTH ALONG THE
OK/AR BORDER THEN BENDING BACK ALONG THE RED RIVER. IT IS THIS
CONVECTION THAT WILL ORIENT ALONG THE OUTFLOW BOUNDARY SOUTHWEST
TO NORTHEAST FROM DAL TO FSM TO FYV.  A SECONDARY FOCUS NEARER THE
UPPER SHORTWAVE ACROSS NORTH CENTRAL TEXAS WILL BE VERY SLOW
MOVING AS IT IS STUCK IN THE COL OF THE FLOW. INSTABILITY IS
SUFFICIENT FOR DEEP CONVECTION CAPABLE OF SIMILAR HIGH RATES BUT
ON A SMALLER AREAL SCALE. 

AS THE MCV IN EAST TEXAS LIFTS NORTH...TRAINING OF THESE CELLS
ALONG THE NORTHEAST TEXAS/EASTERN OKLAHOMA AXIS WILL LEAD TO AN
ADDITIONAL 2-4" TOTAL WITH THE POSSIBILITY OF HIGHER LOCAL AMOUNTS
COMPOUNDING THE FLOODING CONDITIONS ALREADY IN PLACE. 

THE ORIENTATION OF THE SOLUTION IS IN LINE WITH 06Z NAM-CONEST AND
RECENT FEW RUNS OF THE HRRR. 

GALLINA

ATTN...WFO...FWD...LZK...OUN...SGF...SHV...TSA...

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

LAT...LON   36679420 36569243 35209246 33959315 32099523 
            32169572 32629648 32779839 32959860 33469781 
            34159641 34729583 34819572