MESOSCALE PRECIPITATION DISCUSSION 0072
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
542 AM EDT SUN MAY 10 2015
 
AREAS AFFECTED...EDWARDS PLATEAU INTO N-CNTRL TEXAS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 100941Z - 101541Z
 
SUMMARY...AS LOW LEVEL FLOW INTERCEPTS THE TAIL END OF AN OUTFLOW
BOUNDARY MOVING ACROSS CNTRL TEXAS LATER THIS MORNING...TRAINING
CONVECTION IS EXPECTED TO DEVELOP WHICH MAY LEAD TO FLASH FLOODING
AFTER 12Z.

DISCUSSION...A LARGELY FORWARD PROPAGATING MCS WAS OBSERVED TO BE
TRACKING ENEWD ACROSS THE I-20 CORRIDOR AS OF 09Z AT ABOUT 30 TO
40 KTS. THIS FORWARD PROPAGATION IS DUE IN PART TO DRY AIR IN THE
MID-UPPER LEVELS AS SEEN IN THE CIRA LAYERED TPW PRODUCT WHICH IS
ALLOWING DRY AIR ENTRAINMENT AND A QUICK 1 TO 2 INCHES OF RAIN AS
THE MCS MOVES THROUGH THE REGION. AT 09Z...AN OUTFLOW BOUNDARY
EXTENDED AHEAD OF THE MCS FROM JUST PAST BWD...SWWD TO JUST SOUTH
OF 6R6. LOW LEVEL MOISTURE RETURN VIA A ROBUST LOW LEVEL JET AS
SAMPLED BY AREA VAD WIND PLOTS...IS EXPECTED TO INCREASE AHEAD OF
A SLOW MOVING COLD FRONT CURRENTLY ADVANCING THROUGH WEST TEXAS.

ALTHOUGH 09Z GPS PRECIPITABLE WATER VALUES FROM CNTRL TEXAS TO THE
RIO GRANDE ARE ONLY 1.25 TO 1.50 INCHES...THESE VALUES ARE
FORECAST TO INCREASE THROUGH 15Z...ACCORDING TO THE RAP...TO 1.50
TO 2.00 INCHES GIVEN 40-50 KT OF 850 MB FLOW ACROSS SRN TO CNTRL
TEXAS. THE CONCERN FOR FLASH FLOODING COMES WITH REGARDS TO THE
SRN FLANK OF THE OUTFLOW BOUNDARY...WHICH IS FORECAST TO ONLY
SLOWLY PROPAGATE EWD THROUGH 15Z...BEING OVERRUN BY THE LOW LEVEL
JET AND DEEPENING MOISTURE WITH CELL TRAILING FROM SW TO NE.
RECENT RUNS OF THE HRRR SEEM TO BE PICKING UP ON THIS IDEA WITH
OTHER 00Z HI-RES MODELS HIGHLIGHTING SIGNIFICANT FLASH FLOODING
BEYOND 15Z ACROSS N-CNTRL TEXAS. GIVEN RECENT HEAVY RAINS ACROSS
PORTIONS OF NRN TEXAS AND IN THE VICINITY OF THE RED RIVER...FLASH
FLOODING IS OF GREATER CONCERN.

OTTO

ATTN...WFO...EWX...FWD...OUN...SJT...

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

LAT...LON   33999786 33669553 31669742 30409983 30480109 
            30770127 31720034 32829931 
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