696  
FXUS64 KBRO 172323 AAA  
AFDBRO  
 
AREA FORECAST DISCUSSION...UPDATED  
NATIONAL WEATHER SERVICE BROWNSVILLE TX  
523 PM CST FRI JAN 17 2025  
   
..NEW AVIATION  
 
   
SHORT TERM  
 
(TONIGHT THROUGH SATURDAY NIGHT)  
ISSUED AT 310 PM CST FRI JAN 17 2025  
 
KEY MESSAGES:  
 
- PATCHY TO WIDESPREAD FOG WILL DEVELOP TONIGHT AFTER MIDNIGHT  
ACROSS MUCH OF DEEP SOUTH TEXAS.  
 
- ONE FINAL WARM DAY IS EXPECTED ON SATURDAY, BUT THE ARRIVAL OF AN  
ARCTIC AIRMASS WILL BRING WELL BELOW NORMAL TEMPERATURES SUNDAY  
THROUGH NEXT WEEK.  
 
- LOW TEMPERATURES SATURDAY NIGHT WILL FALL INTO THE 30S AND 40S.  
 
PERSISTENT LOW LEVEL SOUTHERLY FLOW WILL MAINTAIN GENERALLY MILD AND  
HUMID CONDITIONS, ESPECIALLY IN COMPARISON TO EARLIER THIS WEEK.  
TONIGHT WILL BE THE WARMEST NIGHT FOR AT LEAST THE NEXT 5-6 DAYS,  
WITH LOWS RANGING FROM THE MID 50S ACROSS THE NORTHERN RANCHLANDS TO  
MID 60S. THIS IS NEAR OR SLIGHTLY ABOVE NORMAL FOR LOW TEMPERATURES  
MID JANUARY. HIGH RES AND PROBABILISTIC GUIDANCE INDICATE THERE IS A  
MEDIUM CHANCE (40-60%) OF VISIBILITY FALLING BELOW 3 SM AND A LOW  
TO MEDIUM CHANCE (20-40%) OF VISIBILITY FALLING BELOW 1/2 SM AFTER  
MIDNIGHT TONIGHT INTO EARLY SATURDAY MORNING ACROSS MOST OF DEEP  
SOUTH TEXAS.  
 
ANY MORNING FOG SHOULD QUICKLY DISSIPATE BY MID SATURDAY MORNING,  
AND OUR ATTENTION WILL TURN TO THE ARRIVAL OF A COLD FRONT. WE'LL  
START TO SEE SOUTHERLY WINDS SHIFT TO THE NORTH LATE SATURDAY  
MORNING INTO SATURDAY AFTERNOON, BUT WE'LL STILL WARM UP INTO THE  
LOW TO MID 70S ACROSS THE NORTHERN RANCHLANDS TO THE UPPER 70S  
ACROSS THE RIO GRANDE VALLEY. ENJOY THE WARMTH WHILE IT LASTS, AS  
THE ARRIVAL OF THE NOTABLY COLDER AIRMASS IS EXPECTED SATURDAY  
NIGHT. LOW TEMPERATURES WILL FALL INTO THE MID TO UPPER 30S ACROSS  
THE NORTHERN RANCHLANDS TO MID AND UPPER 40S ACROSS THE RIO GRANDE  
VALLEY. IN COMBINATION WITH NORTHERLY WINDS AROUND 10-15 MPH, THE  
"FEELS LIKE" TEMPERATURES WILL BE IN THE MID 20S ACROSS THE NORTHERN  
RANCHLANDS TO THE UPPER 30S ACROSS THE RIO GRANDE VALLEY. THIS IS  
JUST THE START OF ANOTHER PERIOD OF UNSEASONABLY COLD WEATHER.  
 
 
   
LONG TERM  
 
(SUNDAY THROUGH NEXT FRIDAY)  
ISSUED AT 310 PM CST FRI JAN 17 2025  
 
THE PRIMARY CONCERN FOR THE LONG TERM FORECAST REMAINS THE  
POTENTIAL FOR FREEZING TEMPERATURES AND WINTER PRECIPITATION EARLY  
NEXT WEEK. MUCH UNCERTAINTY STILL REMAINS IN THE FORECAST, AS  
MODELS VARY WITH THE EVOLUTION OF THE SYNOPTIC PATTERN, AND IT’S  
IMPACTS ON DEEP SOUTH TEXAS.  
 
A DEEP UPPER-LEVEL TROUGH CENTERED OVER THE CENTRAL US AT THE  
START OF THE PERIOD WILL SLOWLY SHIFT EAST AS AN EMBEDDED  
SHORTWAVE TRAVERSES THE WESTERN PERIPHERY OF THE TROUGH EARLY NEXT  
WEEK. THIS WILL ENHANCE NORTHERLY LOW-LEVEL FLOW, DRIVING AN  
ADDITIONAL SURGE OF ARCTIC AIR ACROSS THE PLAINS. HERE MODELS  
BEGIN TO DIFFER, WITH RECENT GFS AND GEFS RUNS MOVING THE BULK OF  
THE COLDER AIRMASS TOWARDS THE MISSISSIPPI RIVER VALLEY, WHILE  
RECENT RUNS OF THE CANADIAN MODELS DRIVE THE AIRMASS FURTHER SOUTH  
TOWARDS TEXAS. RECENT ECMWF RUNS ARE THIS VARIATION BETWEEN THE  
MODELS LEADS TO A SIGNIFICANT DIFFERENCE IN THE TEMPERATURE AND  
PRECIP TYPE ACROSS DEEP SOUTH TEXAS.  
 
STARTING WITH MONDAY MORNING, THE WARMER GUIDANCE IS KEEPING  
TEMPERATURES ABOVE FREEZING ACROSS THE CWA, WHILE THE MORE EXTREME  
OF THE COLDER GUIDANCE IS DRIVING FREEZING TEMPERATURES INTO THE  
RIO GRANDE VALLEY. CONFIDENCE IS HIGHEST IN REACHING FREEZING  
TEMPERATURES ACROSS PORTIONS OF JIM HOGG AND ZAPATA COUNTIES  
MONDAY MORNING, WITH THE REMAINDER OF THE CWA MORE LIKELY TO STAY  
ABOVE FREEZING. HOWEVER, GIVEN THE UNCERTAINTY IN THE MODELS, THIS  
MAY CHANGE AS THE EVENT APPROACHES.  
 
TUESDAY MORNING LOOKS TO BE THE BEST CHANCE OF RECEIVING ANY  
WINTER PRECIP. MODELS STILL VARY WILDLY, HOWEVER CONFIDENCE IS  
HIGHER FOR COLDER TEMPERATURES EXTENDING FURTHER SOUTH, WITH  
FREEZING TEMPERATURES LIKELY ACROSS THE NORTHERN COUNTIES. THERE  
IS A LOW TO MEDIUM CHANCE FOR FREEZING DRIZZLE ACROSS ACROSS  
PORTIONS OF THE NORTHERN COUNTIES. PRECIPITATION IS MORE LIKELY TO  
REMAIN A COLD RAIN OR DRIZZLE ACROSS THE RIO GRANDE VALLEY,  
THOUGH WINTRY PRECIP CAN’T BE RULED OUT.  
 
AS ANOTHER SHORTWAVE MOVES ACROSS THE SOUTHERN PLAINS TUESDAY,  
RAIN CHANCES AND CLOUD COVER WILL LIKELY DECREASE AS THE LOW LEVEL  
MOISTURE MOVES OUT OF THE REGION. THIS WILL LIKELY ALLOW FOR  
BETTER COOLING TUESDAY NIGHT INTO WEDNESDAY, WHICH WILL RESULT IN  
THE BEST CHANCES FOR A FREEZE ACROSS MOST OF THE CWA, AND A DEEP  
FREEZE FOR NORTHERN PORTIONS OF THE CWA.  
 
TEMPERATURES LOOK TO WARM SLIGHTLY THROUGH THE REMAINDER OF THE  
PERIOD, WITH HIGH TEMPERATURES RETURNING TO THE MID 50S TO LOW  
60S, AND LOW TEMPERATURES LIKELY REMAINING ABOVE FREEZING.  
 
 
   
AVIATION  
 
(00Z TAFS)  
ISSUED AT 517 PM CST FRI JAN 17 2025  
 
VFR CONDITIONS ARE EXPECTED TO GIVE WAY TO MVFR AND IFR CONDITIONS  
TONIGHT AS PATCHY FOG DEVELOPS LATE. BEST CHANCE OF ANY DENSE FOG  
WOULD LIKELY BE NEAR HRL AROUND DAYBREAK. VFR CEILINGS RETURN BY  
MID MORNING SATURDAY. BREEZY SOUTHERLY WINDS THIS EVENING DIMINISH  
OVERNIGHT AND A WEAK FRONTAL BOUNDARY ARRIVES BY LATE SUNDAY  
MORNING, TURNING LIGHT WINDS NORTHERLY.  
 
 
   
MARINE  
 
ISSUED AT 310 PM CST FRI JAN 17 2025  
 
TONIGHT THROUGH SATURDAY NIGHT...SOUTH TO SOUTHWEST WINDS PREVAIL  
THROUGH SATURDAY MORNING. SOME PATCHY FOG WILL BE POSSIBLE ALONG THE  
LAGUNA MADRE LATE TONIGHT INTO EARLY TOMORROW MORNING. WINDS WILL  
SHIFT TO THE NORTH WITH THE PASSAGE OF A COLD FRONT. NORTHERLY WINDS  
WILL STRENGTHEN LATE SATURDAY NIGHT AS THE COLD AIRMASS SPILLS  
SOUTHWARD. WINDS WILL LIKELY APPROACH SMALL CRAFT ADVISORY TO GALE  
WARNING CRITERIA AFTER MIDNIGHT SATURDAY NIGHT AND INTO SUNDAY  
MORNING.  
 
SUNDAY THROUGH NEXT FRIDAY...ADVERSE MARINE CONDITIONS LOOK TO  
PERSIST THROUGH THE FIRST HALF OF THE WEEK. A SMALL CRAFT ADVISORY  
WILL LIKELY CARRY OVER INTO THE BEGINNING OF THE LONG TERM PERIOD,  
AS STRONG NORTHERLY WINDS AND HIGH SEAS CONTINUE IN THE WAKE OF  
THE COLD FRONT. PRESSURE GRADIENTS LOOK TO FURTHER TIGHTEN TUESDAY  
AS A PASSING MID-LEVEL SHORTWAVE REINFORCES THE NORTHERLY FLOW.  
THIS WILL LIKELY INCREASE WINDS TO AROUND 30KTS AND GUSTS ABOVE  
GALE FORCE TUESDAY INTO WEDNESDAY. WINDS AND SEAS LOOK TO DECREASE  
WEDNESDAY, WITH FAVORABLE MARINE CONDITIONS RETURNING BY WEDNESDAY  
NIGHT.  
 
 
   
PRELIMINARY POINT TEMPS/POPS  
 
BROWNSVILLE 64 77 47 54 / 0 0 0 0  
HARLINGEN 59 77 41 53 / 0 0 0 0  
MCALLEN 60 79 43 55 / 0 0 0 0  
RIO GRANDE CITY 54 78 41 54 / 0 0 0 0  
SOUTH PADRE ISLAND 64 70 49 56 / 0 0 0 0  
BAYVIEW/PORT ISABEL 61 73 44 54 / 0 0 0 0  
 
 
   
BRO WATCHES/WARNINGS/ADVISORIES  
 
TX...NONE.  
GM...NONE.  
 
 
 
 
SHORT TERM...22  
LONG TERM....60  
AVIATION...56-HALLMAN  
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