156  
FXUS64 KHGX 201536  
AFDHGX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX  
1036 AM CDT WED JUN 20 2018  
   
DISCUSSION
 
 
RAINS TO THE NORTH MOVING OUT QUICKLY AND THE SWATH OUT TO OUR  
WEST REMAINING IN PLACE. LATEST VISIBLE SATELLITE LOOPS INDIC-  
ATING SOME BREAKS IN THE CLOUDS OVER OUR E/SE COUNTIES, AND IF  
THIS TREND CONTINUES TO SPREAD INTO OTHER PARTS OF THE CWA, WE  
COULD SEE DEVELOPMENT OF SCATTERED ACTIVITY LATER IN THE DAY.  
HOWEVER, ON THE PLUS SIDE, NOT REALLY SEEING ANY BOUNDARIES TO  
FOCUS THESE STORMS. CURRENT FORECAST GRIDS SEEM TO HAVE THINGS  
COVERED AND NOT PLANNING ON ANY SIGNIFICANT CHANGES AT PRESENT.  
41  
 

 
   
PREV DISCUSSION
 
/ISSUED 442 AM CDT WED JUN 20 2018/  
 
THE BULK OF THE RAIN THIS MORNING IS FOCUSED WEST OF THE  
INTERSTATE 45 CORRIDOR, WITH A LINE OF SHOWERS ASSOCIATED WITH A  
LEADING EDGE OF HIGHER 850 MB MOISTURE/SPEED CONVERGENCE ZONE  
CROSSING THE INTERSTATE 10 CORRIDOR AS OF THIS WRITING. WILL HAVE  
TO KEEP AN EYE ON THIS INITIAL ROUND FOR A MINOR OR STREET  
FLOODING THREAT THROUGH THE MORNING COMMUTE AS IT MOVES ACROSS AN  
AREA THAT EXPERIENCED ANYWHERE FROM 2 TO NEARLY 5 INCHES OF RAIN  
YESTERDAY. INFRARED SATELLITE IMAGERY TRENDS HAVE SHOWN CLOUD TOPS  
WARMING SINCE 4 AM CDT AND EXPECT RAIN RATES TO BEGIN TAPERING  
OFF WITHIN THIS ACTIVITY... BUT HAVE NOTED BACKBUILDING ON THE  
KHGX RADAR AND THIS SECOND ROUND WILL BRING ADDITIONAL RAINFALL TO  
THIS AREA AND AGGRAVATE MINOR FLOODING CONCERNS.  
 
FARTHER DOWN THE COAST TOWARDS CORPUS CHRISTI, AN EXPANSIVE RAIN  
SHIELD CONTINUES TO BRING PERIODS OF HEAVY RAINFALL TO THE MIDDLE  
TEXAS COAST. THIS SECOND AREA OF RAIN HAS ALREADY BEGUN SPREADING  
INTO JACKSON COUNTY EARLY THIS MORNING AS THE PARENT MID-LEVEL LOW  
OVER THE LOWER TEXAS COAST WOBBLES EARLY THIS MORNING. THIS WILL  
RAISE CONCERNS FOR A SECONDARY MINOR OR POTENTIALLY FLASH FLOOD  
THREAT TODAY AS SEVERAL ROUNDS OF RAINFALL WRAP AROUND THE PARENT  
SYSTEM AND HAVE ISSUED A FLASH FLOOD WATCH FOR JACKSON, WHARTON,  
MATAGORDA, AND COLORADO COUNTIES FOR THIS POTENTIAL. WIDESPREAD  
1-2 INCH RAIN AMOUNTS ARE EXPECTED IN THE WATCH AREA, BUT BASED ON  
TRENDS FOR THIS ACTIVITY OVER THE GULF RAINFALL TOTALS MAY  
APPROACH OR EXCEED 3-4 INCHES IN A SHORT PERIOD OF TIME. DEPENDING  
ON TRENDS WITH BOTH THE EARLY MORNING ACTIVITY ALONG INTERSTATE  
10 AND THE RAINFALL EXPECTED TO SPREAD ACROSS THE MATAGORDA BAY  
AREA, THE FLASH FLOOD WATCH MAY NEED TO BE EXPANDED EASTWARD TO  
CAPTURE ANY SHIFTS IN THE FLOODING THREAT.  
 
AS AN APPROACHING MID/UPPER LEVEL TROUGH CROSSES THE SOUTHERN  
PLAINS LATER TODAY, IT IS EXPECTED TO BEGIN TO SHEAR OUT THE SOUTH  
TEXAS LOW AND STRETCH IT TOWARDS THE NORTHEAST. WHILE DAYTIME  
HEATING WILL AGAIN CONTRIBUTE TO SCATTERED DEVELOPMENT THROUGH  
THE DAY, THIS SHEARING OF THE LOW MAY RESULT IN A SOUTHWEST TO  
NORTHEAST ORIENTED LINE OF SHOWERS AND THUNDERSTORMS TO DEVELOP  
ACROSS THE REGION AND ATTEMPT TO TRANSLATE EAST AS THE NORTHERN  
STREAM SYSTEM SHIFTS TOWARDS THE MID-MISSISSIPPI VALLEY. SPC HREF  
MEMBERS, THE HRRR, AND TTU-WRF SEEMS TO BE FAIRLY CONSISTENT WITH  
AT LEAST SOME DEVELOPMENT CONSISTENT WITH THE 500 MB SHEAR AXIS,  
THEY DIFFER IN HOW QUICKLY THIS BAND EITHER MOVES OUT OF THE  
REGION OR DISSIPATES. LOSS OF FORCING IS EXPECTED TO RESULT IN AT  
LEAST WEAKENING OF ACTIVITY OVERNIGHT TONIGHT, BUT RAIN MAY EXIT  
OR END SOONER DEPENDING ON THE AMPLIFICATION OF THE SOUTHERN  
PLAINS TROUGH LATER THIS AFTERNOON AND EVENING AS IT MAY BE ABLE  
TO SWEEP THIS ACTIVITY EAST. SIMILAR TO THE WATCH AREA, FORECAST  
RAIN TOTALS THROUGH THE DAY ARE UNDER 2 INCHES BUT LOCALLY HIGHER  
TOTALS NEARING OR EXCEEDING 4 INCHES WILL BE POSSIBLE IN HEAVIER  
SHOWERS OR THUNDERSTORMS.  
 
A FEW SHOWERS OR THUNDERSTORMS MAY LINGER INTO THE MORNING HOURS  
ON THURSDAY WITH RAIN CHANCES THURSDAY AFTERNOON THROUGH THE END  
OF THE WEEK CENTERING AROUND THE POTENTIAL FOR ISOLATED SHOWERS  
AND POSSIBLY A THUNDERSTORM ALONG THE SEA BREEZE. AFTER A FEW DAYS  
WITH HIGHS IN THE 80S, TEMPERATURES ARE EXPECTED TO REBOUND BACK  
INTO THE LOWER 90S BY THIS WEEKEND.  
 
HUFFMAN  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
COLLEGE STATION (CLL) 87 74 91 75 96 / 70 50 50 10 10  
HOUSTON (IAH) 83 76 90 76 94 / 70 60 60 20 20  
GALVESTON (GLS) 84 81 86 81 88 / 60 60 60 20 20  
 

 
   
HGX WATCHES/WARNINGS/ADVISORIES
 
 
TX...FLASH FLOOD WATCH UNTIL 7 PM CDT THIS EVENING FOR THE FOLLOWING  
ZONES: COASTAL JACKSON...COASTAL MATAGORDA...COLORADO...  
INLAND JACKSON...INLAND MATAGORDA...MATAGORDA ISLANDS...  
WHARTON.  
 
GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 7 PM CDT THIS EVENING  
FOR THE FOLLOWING ZONES: COASTAL WATERS FROM FREEPORT TO  
MATAGORDA SHIP CHANNEL TX OUT 20 NM...COASTAL WATERS FROM  
HIGH ISLAND TO FREEPORT TX OUT 20 NM.  
 
SMALL CRAFT ADVISORY UNTIL 4 PM CDT THIS AFTERNOON FOR THE  
FOLLOWING ZONES: WATERS FROM FREEPORT TO MATAGORDA SHIP  
CHANNEL TX FROM 20 TO 60 NM...WATERS FROM HIGH ISLAND TO  
FREEPORT TX FROM 20 TO 60 NM.  
 

 
 

 
 
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