455  
FXUS64 KHGX 272345  
AFDHGX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX  
645 PM CDT TUE JUN 27 2017  
   
AVIATION
 
 
FORECAST PERIOD OPENS WITH A FAIRLY STRAIGHTFORWARD BIG PICTURE -  
SLOWLY DIMINISHING STORMS FOR THE NORTHERN SITES, WHILE THE WORKED  
OVER SOUTH STAYS DRIER. HOWEVER, TIMING THE SPECIFICS FOR CLL,  
UTS, AND CXO INTO THIS EVENING AND HOW QUICKLY THINGS WIND DOWN  
WILL BE TRICKY, AND MAY (BUT HOPEFULLY WILL NOT) REQUIRE  
AMENDMENTS.  
 
OTHERWISE, THE NEXT CHALLENGE WILL BE THE POSITION OF A POTENTIAL  
COASTAL TROUGH LATE TONIGHT INTO TOMORROW FOR DEVELOPMENT OF  
SHOWERS AND STORMS TOMORROW. KEPT CONTINUITY WITH THE PREVIOUS  
FORECAST AND BROUGHT VCSH AS FAR NORTH AS IAH, BUT LATEST HRRR AND  
RAP HAVE BEEN PLAYING COY ABOUT PENETRATION OF RAIN THAT FAR  
INLAND. ANY FURTHER OFFSHORE, AND IAH AND PERHAPS EVEN SGR AND  
HOU WILL BE DRIER. OTHERWISE, TRIED TO HIGHLIGHT A SHORT WINDOW  
FOR BEST CHANCES OF STORMS BEFORE THIS TROUGH GETS DRAGGED EAST  
AND ACTIVITY WINDS DOWN FOR THE DAY.  
 
LUCHS  
 

 
   
PREV DISCUSSION
 
/ISSUED 346 PM CDT TUE JUN 27 2017/  
 
DISCUSSION...  
SCATTERED SHOWERS AND THUNDERSTORMS CONTINUE TO SPREAD ACROSS THE  
REGION THIS AFTERNOON, WITH ISOLATED AMOUNTS OF NEARLY 2 TO 2.5  
INCHES HAVING FALLEN ACROSS PARTS OF THE HOUSTON METRO SO FAR  
TODAY. EXPECT THIS ACTIVITY TO LINGER THROUGH THE EVENING HOURS,  
WEAKENING BUT NOT ENTIRELY DISSIPATING AS A SHORTWAVE TROUGH OVER  
SOUTH CENTRAL TEXAS TRANSLATES ACROSS THE REGION. A COASTAL LOW  
ALONG THE MIDDLE AND LOWER TEXAS COAST IS ALSO EXPECTED TO NUDGE  
INTO THE NORTHWEST GULF AS A RESULT OF THE PASSAGE OF THIS  
FEATURE, BUT SHORT TERM GUIDANCE DIFFERS SOMEWHAT ON THE EXACT  
TRAJECTORY THIS LOW WILL TAKE... WHICH WILL HAVE A DRAMATIC IMPACT  
ON RAIN CHANCES FOR THE REGION.  
 
SPEED CONVERGENCE ALONG THE TROUGH AXIS IS EXPECTED TO RESULT IN  
NEW DEVELOPMENT ALONG THE COASTAL TROUGH OVERNIGHT (AIDED BY LIFT  
FROM THE APPROACHING SHORTWAVE), WITH MODEL SOLUTIONS RANGING FROM  
SCATTERED TO NUMEROUS THUNDERSTORMS ACROSS THE BOTTOM TWO TIERS  
OF COUNTIES WITH A MORE NORTHEAST TRAJECTORY TO A DRY OVERNIGHT  
FORECAST WITH A MORE EASTERLY TRAJECTORY. HAVE TRENDED WITH A MORE  
NORTHEAST TRAJECTORY GIVEN GREATER CONSENSUS FROM 12Z GUIDANCE  
AND HAVE MAINTAINED THE MENTION OF THUNDERSTORMS FOR AREAS SOUTH  
OF A COLUMBUS TO CLEVELAND LINE DURING THE OVERNIGHT PERIOD IN THE  
FORECAST BUT CONFIDENCE IS LOW IN JUST HOW FAR INLAND STORMS WILL  
EXTEND. WHAT IS PARTICULARLY CONCERNING ABOUT THE NORTHEAST  
TRAJECTORY IS A FEW SOLUTIONS (RAP/HRRR) HAVE SHOWN FAIRLY  
CONSISTENT RUN-TO-RUN SOLUTIONS HIGHLIGHTING A SWATH OF GREATER  
THAN 3 INCH AMOUNTS ACROSS PARTS OF GALVESTON, BRAZORIA, CHAMBERS,  
AND POSSIBLY SOUTHEASTERN HARRIS COUNTIES EARLY TO LATE MORNING  
WEDNESDAY. THESE KINDS OF AMOUNTS EXCEED FLASH FLOOD GUIDANCE, BUT  
BECAUSE OF CONCERNS ABOUT THE ACTUAL TRAJECTORY OF THE TROUGH  
HAVE HELD OFF ON A FLASH FLOOD WATCH FOR NOW. HOWEVER, RESIDENTS  
ARE ADVISED TO CHECK ROAD CONDITIONS BEFORE BEGINNING THEIR  
MORNING COMMUTE SHOULD THE MORE PESSIMISTIC RAP/HRRR SOLUTION  
MATERIALIZE.  
 
ELEVATED ATMOSPHERIC MOISTURE LEVELS (PRECIPITABLE WATER VALUES IN  
EXCESS OF 1.8-2 INCHES) AND DAYTIME HEATING WILL ALLOW  
THUNDERSTORM ACTIVITY TO DEVELOP AGAIN INLAND ON WEDNESDAY, WITH  
DAYTIME INLAND THUNDERSTORMS AND NIGHTTIME MARINE THUNDERSTORMS  
PERSISTING ON THURSDAY AND FRIDAY. HIGHS THROUGH THE END OF THE  
WEEK ARE EXPECTED TO GRADUALLY WARM FROM THE MID TO UPPER 80S  
WEDNESDAY TO UPPER 80S TO LOW 90S BY FRIDAY. THUNDERSTORMS MAY  
SKIRT THE NORTHERN COUNTIES OF SOUTHEAST TEXAS FRIDAY NIGHT AS AN  
UPPER TROUGH ROTATES ACROSS THE GREAT PLAINS, BUT DRY AND HOT  
CONDITIONS ARE EXPECTED THIS WEEKEND AS UPPER RIDGING BUILDS IN  
FROM THE WEST. A PASSING UPPER LEVEL DISTURBANCE MAY WEAKEN THE  
RIDGE ENOUGH TO ALLOW FOR A FEW SHOWERS (OR MAYBE EVEN A STORM)  
TO DEVELOP EARLY NEXT WEEK... WITH HEAT INDEX VALUES IN THE  
100-105 DEGREE RANGE PERSISTING THIS WEEKEND INTO THE BEGINNING OF  
NEXT WEEK.  
 
HUFFMAN  
 
MARINE...  
A COASTAL TROUGH WILL DEVELOP TONIGHT AND EAST WINDS WILL  
STRENGTHEN. THE TROUGH WILL HELP TO FOCUS NUMEROUS SHOWERS AND  
THUNDERSTORMS OVER THE COASTAL WATERS TONIGHT AND MARINERS IN  
SMALL CRAFT SHOULD EXERCISE CAUTION TONIGHT. WINDS WILL DIMINISH  
ON WEDNESDAY AS THE COASTAL TROUGH MOVES EAST. THE PRESSURE  
GRADIENT WILL TIGHTEN WEDNESDAY NIGHT THROUGH FRIDAY AS LOW  
PRESSURE DEEPENS IN THE LEE OF THE ROCKIES AND MOVES ACROSS THE  
CENTRAL PLAINS ON THURSDAY. ONSHORE WINDS WILL PERSIST THROUGH THE  
WEEKEND BUT SPEEDS WILL DECREASE AS THE GRADIENT RELAXES.  
 
TIDES WILL REMAIN ELEVATED THROUGH WEDNESDAY AS E-SE WINDS  
PREVAIL. SOME MINOR COASTAL FLOODING WILL BE POSSIBLE ON THE  
BOLIVAR PENINSULA. RIP CURRENTS COULD STRENGTHEN DUE TO THE STRONG  
AND PERSISTENT ONSHORE FLOW.  
 
43  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
COLLEGE STATION (CLL) 72 90 74 91 77 / 40 20 10 30 10  
HOUSTON (IAH) 73 88 75 89 78 / 50 40 30 60 20  
GALVESTON (GLS) 78 85 79 87 81 / 60 60 50 70 40  
 

 
   
HGX WATCHES/WARNINGS/ADVISORIES
 
 
TX...NONE.  
GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 5 AM CDT WEDNESDAY FOR  
THE FOLLOWING ZONES: COASTAL WATERS FROM FREEPORT TO THE  
MATAGORDA SHIP CHANNEL OUT 20 NM...COASTAL WATERS FROM HIGH  
ISLAND TO FREEPORT OUT 20 NM...WATERS FROM FREEPORT TO THE  
MATAGORDA SHIP CHANNEL FROM 20 TO 60 NM...WATERS FROM HIGH  
ISLAND TO FREEPORT FROM 20 TO 60 NM.  
 

 
 

 
 
DISCUSSION...39  
AVIATION/MARINE...25  
 
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