841  
FXUS64 KBRO 220001 AAA  
AFDBRO  
 
AREA FORECAST DISCUSSION...UPDATED  
NATIONAL WEATHER SERVICE BROWNSVILLE TX  
701 PM CDT THU OCT 21 2021  
   
DISCUSSION
 
UPDATED FOR LATEST AVIATION DISCUSSION BELOW.  
 

 
   
AVIATION
 
THE AFTERNOON SEA BREEZE HAS CLEARED THE RGV AND IS  
PRODUCING ONLY SOME ISOLD CONV OVER ZAPATA COUNTY. SO EXPECT THE  
SHORT TERM TO REMAIN RAIN FREE FOR THE TIME BEING. THE SURFACE  
WINDS WILL DECREASE LATER TONIGHT WHICH WILL COMBINE WITH THE  
ELEVATED SURFACE DEWPOINTS TO ALLOW FOR SOME INCREASED POTENTIAL  
FOR FOG FORMATION ACROSS MAINLY THE NORTHERN RANCHLANDS LATER  
TONIGHT INTO FRI MORNING. SOME OF THIS MAY CREEP INTO THE RGV  
IMPACTING THE AIRPORTS FOR A COUPLE OF HOURS TOMORROW MORNING  
POSSIBLY RESULTING IN SOME MVFR/IFR VSBYS. THIS SHOULD BE PRETTY  
SHORT LIVED AFTER SUNRISE WITH INCREASING DAYTIME HEATING. THE SEA  
BREEZE TOMORROW MAY FIRE UP SOME AFTERNOON CONV IN THE BRO AREA  
AND WILL INCLUDE A PROB30 GROUP DURING THE AFTERNOON HOURS.  
 

 
   
PREV DISCUSSION
 
/ISSUED 307 PM CDT THU OCT 21 2021/  
 
SHORT TERM (TONIGHT THROUGH FRIDAY NIGHT): QUASI-ZONAL MID-LEVEL  
FLOW WILL PERSIST THROUGH MUCH OF THE SHORT-TERM PERIOD. TONIGHT  
SHOULD BE MOSTLY CLEAR TO PARTLY CLOUDY, WITH GENERALLY A DRY AND  
STABLE ATMOSPHERE IN PLACE. HOWEVER, LATEST RUN OF THE HRRR WAS  
INDICATING SHOWERS/STORMS DEVELOPING JUST SOUTH OF THE RIVER LATE  
THIS AFTERNOON OR EARLY THIS EVENING, THEN DISSIPATING BEFORE  
CROSSING OVER INTO THE RGV. CURRENTLY KEPT POPS OUT OF THE  
FORECAST TONIGHT, BUT WILL CONTINUE TO MONITOR TRENDS. OTHERWISE,  
A FAIRLY INACTIVE NIGHT IS IN STORE WITH LOW TEMPERATURES DROPPING  
INTO THE UPPER 60S OR LOWER 70S. PATCHY TO AREAS OF FOG MAY  
DEVELOP AGAIN AFTER MIDNIGHT TONIGHT, MAINLY ACROSS THE NORTHERN  
RANCHLANDS AND WESTERN PORTIONS OF THE CWA. AT THIS TIME, A DENSE  
FOG ADVISORY IS NOT ANTICIPATED.  
 
AS SURFACE RIDGING OVER THE PLAINS CONTINUES TO SLIDE SOUTHEAST OVER  
THE LOWER MISSISSIPPI VALLEY OVER THE NEXT 24 HOURS, WINDS WILL  
BEGIN TO VEER FROM EAST TO SOUTHEAST BY FRIDAY EVENING, BUT WILL  
REMAIN GENERALLY LIGHT. CONDITIONS LOOK FAVORABLE FOR SEABREEZE  
ACTIVITY TO GET GOING IN THE AFTERNOON, THOUGH STILL SOME  
QUESTIONS REMAIN ON JUST HOW CONVECTIVELY ACTIVE THE SEABREEZE  
WILL BE AS LOW TO MID-LEVEL DRY AIR BEGINS TO ERODE BY THE  
AFTERNOON. WEAK SHORTWAVE TROUGHS EMBEDDED IN THE MID-LEVEL FLOW  
MAY HELP TO ASSIST IN SHOWER DEVELOPMENT, MAINLY IN THE AFTERNOON.  
SO, DECIDED TO KEEP IN 20-30% POPS FOR MOST INLAND LOCATIONS  
TOMORROW IN THE FORM OF SPOTTY SHOWERS AND THUNDERSTORMS. SLIGHTLY  
BETTER RAIN CHANCES WILL OCCUR FRIDAY NIGHT INTO SATURDAY  
MORNING, ESPECIALLY NEAR THE COAST, AS A SHORTWAVE TROUGH SLIDES  
CLOSER TO THE CWA. THERE IS STILL SOME UNCERTAINTY ON HOW FRIDAY  
NIGHT WILL PLAY OUT, BUT WILL KEEP POPS GENERALLY 20-30% FRIDAY  
NIGHT.  
 
A COASTAL FLOOD ADVISORY REMAIN IN EFFECT BETWEEN 3 PM TODAY AND 4  
AM FRIDAY MORNING. HIGH TIDE IS SCHEDULED TO OCCUR AT 6:17 PM CDT THIS  
EVENING. AS OF THIS WRITING, WATER LEVELS AT SPI BRAZOS SANTIAGO  
ARE STILL ABOUT 0.8 FEET ABOVE PREDICTED LEVELS (OBSERVED AT 0.68  
FEET MHHW). MINOR FLOODING WILL BE POSSIBLE, ESPECIALLY ALONG  
NARROW PARTS OF SPI AND BOCA CHICA BEACHES THIS EVENING AND  
OVERNIGHT TONIGHT. ANOTHER COASTAL FLOOD ADVISORY MAY BE NEEDED  
FOR FRIDAY AFTERNOON/EVENING.  
 
LONG TERM (SATURDAY THROUGH THURSDAY): A NEARLY ZONAL FLOW WILL  
PREVAIL OVER DEEP SOUTH TEXAS WITH THE WEEKEND AS A PAIR OF MODEST  
SHORT WAVES TRANSVERSE OVER THE CWA IN THE MID TO UPPER LEVEL FLOW.  
HOWEVER, RAIN CHANCES SHOULD REMAIN FAIRLY LIMITED AS PWATS BETWEEN  
1.5 TO 1.7 INCHES WITH ISOLATED CONVECTION POSSIBLE OVER THE COASTAL  
WATERS. RAIN CHANCES ARE EXPECTED TO INCREASE MONDAY INTO TUESDAY AS  
DEEP TROPICAL MOISTURE SURGES INTO THE REGION. THE LATEST GFS  
SUGGEST PWATS QUICKLY JUMP TO NEAR 2.4 INCHES, ESPECIALLY ALONG THE  
COAST, BY MONDAY NIGHT. THE DEEP MOISTURE THEN SHIFTS NORTHEAST LATE  
TUESDAY AS DRIER AIR FILTERS INTO THE AREA. A LARGE 500MB TROUGH  
WILL SWING OVER THE PLAINS MID TO LATE WEEK PUSHING THE ASSOCIATED  
COLD FRONT INTO DEEP SOUTH TEXAS BY LATE WEEK. ABOVE NORMAL  
TEMPERATURES ARE EXPECTED THROUGH MUCH OF THE PERIOD, EXCEPT  
TEMPERATURE MAY BE LOWER ON TUESDAY DUE TO INCREASE CLOUD COVER AND  
RAIN CHANCES.  
 
MARINE (NOW THROUGH FRIDAY NIGHT): BROAD SURFACE RIDGING OVER THE  
GULF WILL KEEP MARINE CONDITIONS MOSTLY FAVORABLE THROUGH THE  
SHORT TERM PERIOD. LIGHT TO MODERATE EAST/NORTHEAST WINDS WILL  
GRADUALLY SHIFT SOUTHEASTERLY BY FRIDAY NIGHT. GULF SEAS WILL  
LIKEWISE REMAIN TAME, WITH SIGNIFICANT WAVE HEIGHTS RANGING  
BETWEEN 2 AND 3 FEET. SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE  
BEGINNING ON FRIDAY AS WEAK SURFACE & MIDLEVEL TROUGHING  
APPROACHES THE WATERS.  
 
SATURDAY THROUGH TUESDAY...MODERATE ONSHORE FLOW AND LOW TO MODERATE  
SEAS WILL PREVAIL ALONG THE LOWER TEXAS COAST THROUGH THE PERIOD.  
HOWEVER, BRIEF PERIODS OF SMALL CRAFT EXERCISE CAUTION CONDITIONS  
MAY BE POSSIBLE AT TIMES THIS WEEKEND.  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
BAYVIEW/PORT ISABEL 71 85 73 87 / 10 30 20 20  
BROWNSVILLE 71 89 73 89 / 10 30 20 20  
HARLINGEN 68 89 71 89 / 10 20 20 20  
MCALLEN 71 91 73 91 / 10 20 20 20  
RIO GRANDE CITY 70 92 71 94 / 10 20 20 10  
SOUTH PADRE ISLAND 77 82 78 83 / 10 30 20 20  
 

 
   
BRO WATCHES/WARNINGS/ADVISORIES
 
 
TX...COASTAL FLOOD ADVISORY UNTIL 4 AM CDT FRIDAY FOR TXZ256-257-351.  
 
GM...NONE.  

 
 

 
 
THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT:  
HTTPS://WEATHER.GOV/RGV  
 
60-SPEECE/69-FARRIS  
 
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