MESOSCALE PRECIPITATION DISCUSSION 0401
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
206 PM EDT WED JUL 04 2018

AREAS AFFECTED...SOUTH-CENTRAL & SOUTHEAST TX

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 041806Z - 050006Z

SUMMARY...A CONVECTIVE LOW IS RETROGRADING INTO SOUTH-CENTRAL TX
FROM SOUTHEAST TX.  HOURLY RAIN TOTALS TO 3" WITH LOCAL AMOUNTS TO
5" ARE POSSIBLE.

DISCUSSION...A WARM CORE, DEEP LAYER LOW IS CENTERED JUST EAST OF
COLLEGE STATION TX AS OF 17Z, WHICH IS EXPERIENCING SOME
NORTHEASTERLY WIND SHEAR PER SATELLITE IMAGERY.  THE SYSTEM HAS
BEEN RETROGRADING INTO SOUTH-CENTRAL TX, AND HAS A HISTORY OF
PRODUCING 4-8" OF RAIN LOCALLY IN AND NEAR HOUSTON AND BEAUMONT
THIS MORNING.  PRECIPITABLE WATER VALUES OF 2-2.5" RESIDE WITH
THIS LOW.  INFLOW AT 850 HPA IS CYCLONIC AND 15-25 KTS PER VAD
WIND PROFILES.  ML CAPE VALUES ARE HIGHEST TO ITS WEST AND SOUTH,
IN THE 1000-2000 J/KG RANGE NEAR THE MIDDLE TX COAST AND ACROSS
CENTRAL TX.  EFFECTIVE BULK SHEAR OF 25 KTS LIES TO THE WEST OF
THIS SYSTEM, WHICH HAS OCCASIONALLY CAUSED CONVECTION TO ORGANIZE
INTO INFLOW BANDS IN ITS WESTERN AND SOUTHWESTERN QUADRANTS.

THE EXPECTATIONS ARE FOR THE CYCLONE TO CONTINUE MOVING WESTWARD
WITH ACTIVE CONVECTION, SOMETIMES BANDED, WITHIN ITS WESTERN AND
SOUTHERN QUADRANTS IN THE DIRECTION OF THE BEST INSTABILITY.  THE
MESOSCALE GUIDANCE IS NOT AS AGGRESSIVE WITH AMOUNTS THIS
AFTERNOON, WITH A GOOD SIGNAL FOR 3-5" THROUGH 00Z.  THE 12Z HREF
PROBABILITIES OF 1"+ OF RAIN AN HOUR SUGGEST 00Z SHOULD BE WITHIN
THE WANING HOURS OF THE EVENT AS THE 850 HPA AND SURFACE
REFLECTIONS OF THE SYSTEM ARE EXPECTED TO WEAKEN/DEGENERATE INTO
AN INVERTED TROUGH SOMEWHAT INLAND OF THE MIDDLE TX COAST.  IN THE
MEANTIME, HOURLY RAIN TOTALS TO 3" AND LOCAL AMOUNTS TO 5" REMAIN
POSSIBLE, WHICH WOULD BE MOST PROBLEMATIC IN URBAN AREAS.

ROTH

ATTN...WFO...CRP...EWX...FWD...HGX...

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

LAT...LON   31299707 30879650 30689630 30249577 29879514
            29659495 29389488 29149492 29039508 28279630
            27659732 27969782 28749845 29519873 30399850
            31039801