EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
835 PM EDT TUE SEP 27 2016

...VALID 01Z WED SEP 28 2016 - 12Z WED SEP 28 2016...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
45 SE MMMA 45 SW MMMA 30 ESE BKS NGP 15 W KMZG.


0100 UTC UPDATE

NO CHANGES MADE TO THE PREVIOUS EXCESSIVE RAINFALL POTENTIAL
OUTLOOK.  FEEL HEAVY RAIN THREAT IS MARGINAL ACRS S TX WITH LOW
LEVEL SFC FLOW REMAINING SLIGHTLY OFFSHORE..WITH BETTER SFC/MIXED
LAYER CAPE ALSO JUST OFFSHORE AND EXPECTED TO REMAIN SO OVERNIGHT.
 HOWEVER MSTR REMAINS QUITE HIGH AND SEVERAL HRRR RUNS SHOW SCTD
TSTMS DVLPG ACRS S TX..SO COULD NOT COMPLETELY REMOVE THE HEAVY
RAIN THREAT.  THUS MAINTAINED MARGINAL RISK AREA ACRS SOUTH TX OUT
OF RESPECT FOR HI NUMBER OF HI RES MODELS THAT HAVE ISOLD AMOUNTS
RANGING FROM 2 TO 6 INCHES FOR THE REMAINDER OF THE NIGHT. 

SULLIVAN

PREVIOUS DISCUSSION

...SOUTH TEXAS...

A SURFACE FRONTAL BOUNDARY WILL REMAIN NEARLY STATIONARY ALONG THE
LOWER TX COAST TODAY. DEEP-LAYER INSTABILITY (AT LEAST 500-1000
J/KG) AND DEEP MOISTURE (PWS 2-2.25 INCHES) WILL REMAIN SUFFICIENT
FOR ADDITIONAL HEAVY RAINFALL ALONG THE IMMEDIATE LOWER TX
COAST...ALTHOUGH THE LACK OF LOW-LEVEL INFLOW (AROUND 10 KTS) AS
WELL AS BULK SHEAR (<20 KTS BETWEEN 0-6 KM) WILL KEEP THE ACTIVITY
FROM BECOMING ORGANIZED (I.E. A MARGINAL RISK FOR FLASH FLOODING).
GIVEN THE PERSISTENT FAVORABLE THERMODYNAMICAL SETUP (INSTABILITY
ADVECTING IN OFF THE GOMEX)...EVEN WITH PULSE TYPE ACTIVITY EXPECT
AREAL-AVERAGE TOTALS OF 1-2" PER A MULTI-MODEL CONSENSUS(HIGHEST
AROUND BROWNSVILLE-PORT MANSFIELD EAST TO SOUTH PADRE
ISLAND)...WHILE PER THE HIGH-RES CAMS EXPECT ISOLATED AMOUNTS OF
3-6" IN THIS ENVIRONMENT.

HURLEY