MESOSCALE PRECIPITATION DISCUSSION 0768
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1057 PM EST SUN NOV 06 2016
 
AREAS AFFECTED...SOUTHEAST TX 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 070355Z - 070930Z
 
SUMMARY...HEAVY RAINS TO CONTINUE OVER THE NEXT SEVERAL HOURS. THE
SLOW MOVEMENT OF STRONGER CONVECTIVE CELLS WILL FOSTER SOME
POTENTIAL FOR FLASH FLOODING.

DISCUSSION...A SLOW-MOVING MCS CONTINUES TO ADVANCE THROUGH
SOUTHEAST TX THIS EVENING WITH HEAVY RAINFALL RATES THAT HAVE BEEN
AS HIGH AS 2 TO 2.5 INCHES/HR. THE CONVECTION IS BEING SUSTAINED
BY THE ADVANCE OF SHORTWAVE TROUGH ACROSS THE SOUTHERN
PLAINS...WITH MUCH OF SOUTHEAST TX LOCATED UNDERNEATH A FAVORABLE
AREA OF UPPER LEVEL DIFFLUENCE. MEANWHILE...A BROAD AREA OF
CONFLUENT LOW LEVEL FLOW IS NOTED NEAR AND JUST AHEAD OF THE
CONVECTIVE MASS ALONG WITH A RELATIVELY ANOMALOUS POOL OF MOISTURE
ADVECTING NORTH FROM THE WESTERN GULF OF MEXICO. PWATS OF 1.5 TO
1.75 INCHES ARE SEEN OVER THE SOUTHEAST TX COASTAL PLAIN WHICH IS
A SOLID 2 STANDARD DEVIATIONS ABOVE NORMAL.

RECENT RUNS OF THE HRRR AND HRRR_EXP ARE FORECASTING A PERSISTENCE
OF THE MCS OVER THE NEXT SEVERAL HOURS AS IT MOVES SLOWLY
EASTWARD. THERE HAVE BEEN SOME LOCALLY WETTER TRENDS NOTED TO WITH
THE HRRR GUIDANCE...ALONG WITH SUGGESTION THAT THE MAIN MCS
FOCUSED CURRENTLY WEST OF THE HOUSTON METRO AREA WILL EVENTUALLY
MERGE LATER IN THE NIGHT WITH ACTIVITY FOCUSING NEAR THE UPPER TX
COAST.

GIVEN THE HIGH PWATS AND A WELL-DEFINED INSTABILITY GRADIENT NEAR
THE TX COAST...THE RAINFALL RATES WHICH ARE ALREADY OVER 2
INCHES/HR...MAY ACTUALLY INCREASE A BIT MORE AS CONVECTION FOCUSES
FARTHER EAST NEAR HOUSTON AND ESPECIALLY NORTH OF GALVESTON BAY.
EXPECT RAINFALL AMOUNTS OF AS MUCH AS 3 TO 6 INCHES WITH LOCALLY
HEAVIER AMOUNTS NOT OUT OF THE QUESTION THROUGH 09Z. DESPITE THE
DRY ANTECEDENT CONDITIONS...THE INTENSE RAINFALL RATES OVER A
SHORT PERIOD OF TIME WILL FOSTER SOME FLASH FLOODING CONCERNS AND
ESPECIALLY WITHIN THE URBANIZED AREAS.

ORRISON

ATTN...WFO...HGX...LCH...SHV...

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

LAT...LON   31259512 31209454 30809404 30439376 29979381 
            29729395 29449453 29159513 29339582 29909617 
            30669596 31099558