888  
FXUS64 KBRO 182308 AAA  
AFDBRO  
 
AREA FORECAST DISCUSSION...UPDATED  
NATIONAL WEATHER SERVICE BROWNSVILLE TX  
508 PM CST WED DEC 18 2024  
   
..NEW AVIATION
 
 
   
SHORT TERM
 
 
(TONIGHT THROUGH THURSDAY NIGHT)  
ISSUED AT 212 PM CST WED DEC 18 2024  
 
THE LATEST RADAR AND SATELLITE IMAGERY REVEAL SCATTERED SHOWERS ALONG  
AND AHEAD OF A SOUTHWARD MOVING COLD FRONT THIS AFTERNOON, MAINLY  
OVER PORTIONS OF THE MID TEXAS COAST. THE COLD FRONT SHOULD REACH  
THE NORTHERN RANCHLANDS LATE THIS AFTERNOON AND THE RIO GRANDE  
VALLEY LATER THIS EVENING. GIVEN THE PRESENCE OF MEAGER INSTABILITY  
AND SUFFICIENT MOISTURE CONTENT ACROSS DEEP SOUTH TEXAS, SCATTERED  
SHOWERS AND A FEW ISOLATED THUNDERSTORMS SHOULD DEVELOP AFTER 3 OR 4  
PM THIS AFTERNOON AS FORCING ALONG/AHEAD OF THE COLD FRONT  
INCREASES. PRECIPITATION CHANCES ARE HIGHEST (AROUND 30-40%) ALONG  
AND WEST OF THE I-69 CORRIDOR, WITH SLIGHTLY LOWER CHANCES (20% OR  
LESS) EAST OF THE INTERSTATE. THIS IS IN LINE WITH THE LATEST SUITE  
OF HIGH RES GUIDANCE AS WELL, WHICH INDICATE THE HIGHEST COVERAGE OF  
SHOWERS AND ISOLATED THUNDERSTORMS WILL LIKELY RESIDE OVER THE  
MID/UPPER RGV AND THE RIO GRANDE PLAINS.  
 
COLD AIR ADVECTION WILL FILTER IN LATE THIS EVENING AND OVERNIGHT  
AND DESPITE LINGERING POST-FRONTAL STRATUS CLOUD COVER, THERE WILL  
BE NOTICEABLY COOLER TEMPERATURES ACROSS DEEP SOUTH TEXAS TONIGHT  
THROUGH TOMORROW NIGHT. THIS WILL BE MUCH CLOSER TO SEASONAL  
NORMALS, AND EVEN SLIGHTLY BELOW FOR SOME LOCATIONS, FOR MID  
DECEMBER. AFTER A WARM WEDNESDAY AFTERNOON WITH HIGHS MOSTLY IN THE  
80S, THURSDAY AFTERNOON'S HIGH TEMPERATURES WILL BE ANYWHERE FROM 10  
TO 15 DEGREES COOLER WITH HIGHS MOSTLY IN THE UPPER 60S AND LOW 70S.  
LOW TEMPERATURES TONIGHT AND TOMORROW NIGHT WILL RANGE FROM THE  
UPPER 40S AND LOW 50S ACROSS THE NORTHERN RANCHLANDS TO THE MID TO  
UPPER 50S ACROSS THE RIO GRANDE VALLEY. HOWEVER, A FEW AREAS OVER  
THE NORTHERN RANCHLANDS MAY DIP INTO THE MID 40S IF RADIATIONAL  
COOLING PROCESSES ARE MAXIMIZED DUE TO CLEAR SKIES AND LIGHT WINDS  
THURSDAY NIGHT.  
 

 
   
LONG TERM
 
 
(FRIDAY THROUGH NEXT WEDNESDAY)  
ISSUED AT 212 PM CST WED DEC 18 2024  
 
THE LONG TERM BEGINS ON FRIDAY WITH SOUTHWESTERLY FLOW ALOFT AS DEEP  
SOUTH TEXAS REMAINS ON THE NORTHWEST SIDE OF A MID-LEVEL HIGH,  
CENTERED OVER THE WESTERN GULF OF MEXICO. OVER THE WEEKEND, THE  
HIGH WILL SLIP EASTWARD AND FLOW WILL BECOME MOSTLY ZONAL INTO  
MONDAY AS A MID-LEVEL HIGH OVER NORTHWESTERN MEXICO MOVES  
SOUTHWARD.  
 
AT THE SURFACE, HIGH PRESSURE WILL REMAIN IN CONTROL ACROSS THE AREA  
WITH NORTHEASTERLY WINDS CONTINUING THROUGH FRIDAY NIGHT, TURNING  
EASTERLY ON SATURDAY AND THEN SOUTHEASTERLY BY SUNDAY AS A HIGH  
PRESSURE OVER THE EASTERN US DOMINATES THE COUNTY WARNING AREA (CWA)  
WITH RETURN FLOW. HIGHER MOISTURE CONTENT NEAR, AND SOUTH OF, THE US-  
MEXICO BORDER AND AN OVERRIDING PATTERN IS EXPECTED TO KEEP MOSTLY  
CLOUDY SKIES OVER THE RIO GRANDE VALLEY OVER THE WEEKEND, BUT MORE  
SUNSHINE IS EXPECTED FROM THE BEGINNING TO THE MIDDLE OF NEXT WEEK.  
SOUTHEASTERLY WINDS AND DRY WEATHER ARE EXPECTED THROUGH THE REST OF  
THE PERIOD. TEMPERATURES WILL BE AVERAGE THROUGH SATURDAY WITH  
OVERNIGHT LOWS IN THE UPPER 40S TO MID 50S AND HIGHS IN THE UPPER  
60S TO MID 70S. AS SOUTHEASTERLY FLOW RETURNS BY SUNDAY, ABOVE  
NORMAL TEMPERATURES WILL RESUME WITH HIGHS IN THE 70S ON SUNDAY  
FOLLOWED BY 70S AND 80S THROUGH NEXT WEDNESDAY AND LOWS IN THE 50S  
AND 60S.  
 

 
   
AVIATION
 
 
(00Z TAFS)  
ISSUED AT 503 PM CST WED DEC 18 2024  
 
A COLD FRONT MOVING SOUTH WILL MOVE ACROSS THE AERODROMES LATER  
THIS EVENING. AS THE FRONT APPROACHES, SOME ISOLATED SHOWERS ARE  
POSSIBLE, MAINLY AT MFE WHERE MVFR CONDITIONS ARE EXPECTED LATE  
THIS EVENING AND PERIODICALLY AFTER 2 AM. VFR CONDITIONS ARE  
EXPECTED ELSEWHERE, THROUGH WITH THE FRONTAL PASSAGE BRIEF MVFR  
CONDITIONS WILL BE POSSIBLE THROUGH LATE THIS EVENING.  
 

 
   
MARINE
 
 
ISSUED AT 212 PM CST WED DEC 18 2024  
 
TONIGHT THROUGH THURSDAY NIGHT...THE PASSAGE OF A COLD FRONT WILL  
RESULT IN NORTHERLY WINDS PREVAILING THROUGH MUCH OF THE PERIOD.  
INCREASED WINDS AND GUSTS, AROUND 15 TO 20 KNOTS, WILL RESULT IN  
ELEVATED SEAS AROUND 4 TO 6 FEET TONIGHT INTO EARLY TOMORROW  
MORNING. A SMALL CRAFT ADVISORY HAS BEEN ISSUED FOR TONIGHT FOR THE  
NORTHERN GULF WATERS AS THERE IS A HIGHER POTENTIAL FOR WINDS AND  
WIND GUSTS EXCEEDING 20-25 KNOTS. SMALL CRAFT EXERCISE CAUTION  
CONDITIONS WILL PREVAIL OVER THE SOUTHERN GULF WATERS. CONDITIONS  
BECOME MORE FAVORABLE THURSDAY AND THURSDAY NIGHT AS WINDS AND SEAS  
SUBSIDE AS HIGH PRESSURE SETTLES IN.  
 
FRIDAY THROUGH NEXT WEDNESDAY...THROUGHOUT MOST OF THE PERIOD,  
CONDITIONS WILL GENERALLY CONSIST OF SLIGHT TO MODERATE SEAS (2-4  
FT), RESULTING FROM GENTLE TO MODERATE WINDS, WHICH WILL GRADUALLY  
TRANSITION FROM NORTHEASTERLY ON FRIDAY TO SOUTHEASTERLY BY SUNDAY.  
A FEW ROUNDS OF SMALL CRAFT EXERCISE CAUTION HEADLINES ARE POSSIBLE,  
PARTICULARLY ACROSS THE OFFSHORE (20-60 NM) GULF WATERS ON FRIDAY AS  
WELL AS SUNDAY INTO TUESDAY AS SLIGHT PRESSURE GRADIENTS DEVELOP.  
MOSTLY DRY CONDITIONS ARE EXPECTED THROUGHOUT THE PERIOD WITH THE  
EXCEPTION OF A LOW CHANCE (20-30%) OF SHOWERS OVER THE OFFSHORE  
WATERS MONDAY INTO TUESDAY AS A WEAK FRONTAL BOUNDARY LIFTS  
NORTHEASTWARD OVER THE COASTAL WATERS.  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
BROWNSVILLE 58 69 57 73 / 10 0 0 10  
HARLINGEN 54 70 55 71 / 20 0 0 10  
MCALLEN 57 71 57 72 / 40 0 0 10  
RIO GRANDE CITY 56 70 54 69 / 40 0 0 10  
SOUTH PADRE ISLAND 63 66 64 71 / 10 0 0 10  
BAYVIEW/PORT ISABEL 58 67 58 72 / 10 0 0 10  
 

 
   
BRO WATCHES/WARNINGS/ADVISORIES
 
 
TX...NONE.  
GM...SMALL CRAFT ADVISORY FROM 9 PM THIS EVENING TO 6 AM CST THURSDAY  
FOR GMZ135-155-175.  
 

 
 

 
 
SHORT TERM...22  
LONG TERM....65  
AVIATION...68  
 
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