MESOSCALE PRECIPITATION DISCUSSION 0086
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
354 PM EDT FRI MAY 15 2015
 
AREAS AFFECTED...SOUTHEAST TX 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 151953Z - 152253Z
 
SUMMARY...SEA BREEZE ACTIVITY AND CONTINUATION OF AN ORGANIZED MCS
WILL PRODUCE WIDESPREAD RAIN IN SE TX THROUGH 23Z. THE AREA IS
VERY PRONE TO RUNOFF AND FLASH FLOODING GIVEN THE RECENT WET
WEATHER PATTERN.


DISCUSSION...JUDGING BY OBSERVATIONS AND RAP FORECASTS OF LOW
LEVEL WIND SPEEDS...THE MCS TRACKING SLOWLY EAST ALONG THE TX GULF
COAST SHOULD CONTINUE TO PRODUCE HEAVY RAIN AT LEAST THROUGH 22 OR
23Z. THIS IS NOT REFLECTED IN THE MODELS...ALTHOUGH THE 12Z
WRF-ARW AT LEAST HAD SOME SIGNAL. THE HRRR APPEARS TO EAGER TO
DISSIPATE THE SYSTEM. SUCH A RAPID LOSS OF INTENSITY DOES NOT
APPEAR LIKELY...GIVEN BOTH MID AND LOWER LEVEL SUPPORT...WITH THE
RAP 700 WIND FIELDS SHOWING A WELL DEFINED SHORTWAVE...AND 850 MB
SOUTHERLY INFLOW FORECAST TO REMAIN AT OR ABOVE 15-20 KNOTS. 

MID LEVEL STEERING FLOW WOULD TAKE THE MCS EAST TO ENE AT ABOUT 20
KNOTS. ADDITIONAL THUNDERSTORMS ACROSS SE TX AND WRN LA...INDUCED
BY THE MOIST ONSHORE FLOW / SEA BREEZE...MAY BECOME LOCALLY
ANCHORED AND BRIEFLY PROPAGATE TOWARD THE INFLOW. THE COMBINATION
OF THE MCS AND SEA BREEZE ACTIVITY SHOULD PRODUCE A RELATIVELY
WIDESPREAD RAINFALL FOOTPRINT OVER THIS REGION THROUGH LATE
AFTERNOON. 

LOCAL RAIN AMOUNTS ARE LIKELY TO EXCEED 1.5 INCHES...AS ALREADY
OBSERVED TODAY. WFO HGX HAD NOTED FLASH FLOODING YESTERDAY WITH
ONLY 1 INCH PER HOUR RATES...OWING TO THE LONG TERM RAINFALL
SURPLUS IN THIS REGION...WITH SOME SPOTS HAVING SEEN 3 TO 6 TIMES
THE CLIMATOLOGICAL RAINFALL FOR THE PAST 14 DAY PERIOD.

BURKE

ATTN...WFO...BRO...CRP...EWX...HGX...LCH...SHV...

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

LAT...LON   32629364 31939281 31039284 28219477 27039640 
            26579727 26569801 26879807 27869747 29279721 
            30489591 32429460