423  
FXUS64 KBRO 232300  
AFDBRO  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BROWNSVILLE TX  
600 PM CDT MON APR 23 2018  
   
DISCUSSION
 
UPDATED FOR LATEST AVIATION DISCUSSION BELOW.  
 

 
   
AVIATION
 
VFR CEILINGS EXPECTED TO CONTINUE THROUGH TUESDAY  
AFTERNOON WITH HIGH PRESSURE IN PLACE AND SOME THINNING OF MID-  
LEVEL CLOUDS EXPECTED OVERNIGHT. CHANCE OF FOG REMAINS TOO LOW TO  
INCLUDE INTO THE TAFS AT THIS TIME AND WILL BE MONITORED FOR  
MAINLY BRO AND HRL EARLY TUESDAY MORNING.  
 

 
   
PREV DISCUSSION
 
/ISSUED 239 PM CDT MON APR 23 2018/  
 
SHORT TERM (NOW THROUGH TUESDAY NIGHT): QUIET WEATHER WILL  
PREVAIL WITH SURFACE HIGH PRESSURE IN PLACE OVER THE NW GULF OF  
MEXICO AND FLAT RIDGING/ZONAL FLOW ALOFT. MID-LEVEL CLOUD IS  
PROGGED TO CONTINUE THINNING INTO THE EVENING WITH SOME HIGH  
CIRRUS CONTINUING TO STREAM BY OVERNIGHT. GFS AND HRRR HINTING  
THAT A SHORTWAVE TROUGH ALOFT MAY SPEED BY IN THE MODERATELY FAST  
ZONAL FLOW AND INITIATE SOME CONVECTION OVER THE MEXICAN PLATEAU  
THIS EVENING. GUIDANCE KEEPS ANY QPF SOUTH OF THE RIO GRANDE SO  
WILL JUST INSERT SOME SILENT 10% POP'S.  
 
THE COMBINATION OF NEAR-SURFACE MOISTURE AND LIGHT WINDS MAY  
ALLOW SOME PATCHY, SHALLOW FOG TO DEVELOP ACROSS MAINLY EASTERN  
PORTIONS OF THE RIO GRANDE VALLEY AND NORTHERN RANCHLANDS DURING  
THE WEE HOURS OF TUESDAY MORNING. SIGNALS IN THE MODEL GUIDANCE  
ARE MIXED ON THIS, THOUGH. WILL RETAIN THE INHERITED AREAS AND  
EXPAND NORTHWARD TO MATCH UP WITH WFO/CRP. NOT REALLY EXPECTING  
VISIBILITIES TO FALL BELOW ABOUT 3SM ANYWHERE, THOUGH. OVERNIGHT  
LOWS WILL RANGE FROM THE MID-UPPER 60S ALONG THE RIO GRANDE TO  
AROUND 60 NEAR FALFURRIAS AND SARITA.  
 
MODERATE SOUTHEAST SURFACE FLOW RETURNS BY MID-DAY TUESDAY AS  
SURFACE HIGH CENTER MOVES OFFSHORE. MOISTURE IN THE ATMOSPHERIC  
COLUMN THINS OUT SOMEWHAT, SO SKIES SHOULD BE SUNNIER THAN TODAY.  
THIS SHOULD IN TURN ALLOW AFTERNOON TEMPS TO NUDGE UP FROM TODAY'S  
READINGS, WITH MID-UPPER 80S ALONG THE HWY. 77/I-69E CORRIDOR AND  
LOW-MID 90S FAR WEST. PARTLY CLOUDY AND MILD ON TUESDAY NIGHT, AS  
DEWPOINTS CREEP UP INTO THE MID-UPPER 60S ON CONTINUED SE FLOW.  
NO PRECIPITATION IS EXPECTED, THOUGH.  
 
LONG TERM (WEDNESDAY THROUGH MONDAY): QUIET WEATHER WILL CONTINUE  
WEDNESDAY, WITH A SHORT WAVE TROUGH DIGGING SOUTH OVER THE  
CENTRAL HIGH PLAINS AND AN UNDERLYING COLD FRONT MOVING SOUTH OVER  
CENTRAL AND SOUTH TEXAS. A MID LEVEL RIDGE WILL BE POSITIONED  
OVER THE SOUTHWEST UNITED STATES WITH SURFACE HIGH PRESSURE OVER  
THE NORTHWEST GULF. THE WEAK COLD FRONT WILL PUSH ACROSS THE AREA  
LATE WEDNESDAY NIGHT TO THURSDAY MORNING, WITH JUST ENOUGH  
MOISTURE, INSTABILITY, AND LIFT TO POTENTIALLY GENERATE A FEW NON-  
SEVERE THUNDERSTORMS LATE WEDNESDAY NIGHT THROUGH THURSDAY  
MORNING. THE ECMWF APPEARS A LITTLE MORE AGGRESSIVE WITH RAINFALL  
FOR THE UPPER VALLEY WEDNESDAY NIGHT AS THE FRONT PUSHES TOWARD  
THE COAST AROUND DAWN THURSDAY MORNING.  
 
ONCE THE FRONT CLEARS THE AREA THURSDAY, HIGH PRESSURE WILL BUILD  
IN, WITH LIGHT ONSHORE FLOW INTO FRIDAY. AS HIGH PRESSURE SHIFTS  
EAST, WINDS WILL RETURN TO SOUTHEAST. THE RICH LOW LEVEL RETURN  
MOISTURE COMBINED WITH WESTERLY MID LEVEL FLOW WITH EMBEDDED  
MINOR PERTURBATIONS OVER NORTHERN MEXICO MAY KEEP THE THREAT OF  
ISOLATED CONVECTION IN THE PICTURE THROUGH THE WEEKEND. DAYTIME  
HIGH TEMPS WILL BE NEAR NORMAL THURSDAY THROUGH THE WEEKEND AS  
INCREASED CLOUD COVER AND ONSHORE FLOW TEMPER THE HEAT.  
 
MARINE:  
NOW THROUGH TUESDAY NIGHT: FAVORABLE BOATING CONDITIONS ARE  
EXPECTED THROUGH THE SHORT-TERM. BUOY 42020 REPORTED NORTHEAST  
WINDS OF 10-12 KNOTS WITH SEAS OF 2-3 FEET AND A PERIOD OF 5  
SECONDS AS 1:50 PM CDT. SURFACE HIGH PRESSURE WILL PREVAIL ACROSS  
THE WESTERN GULF OF MEXICO THROUGH TUESDAY NIGHT. A WEAK PRESSURE  
GRADIENT WILL SUPPORT LIGHT EAST TO SOUTHEAST WINDS, BECOMING MORE  
MODERATE TUESDAY NIGHT, AND LOW SEAS AROUND 2 FEET THROUGH THE  
PERIOD.  
 
WEDNESDAY THROUGH SATURDAY NIGHT: LIGHT TO MODERATE EAST TO  
SOUTHEAST WINDS AND LOW TO MODERATE SEAS WILL PREVAIL WEDNESDAY  
THROUGH WEDNESDAY NIGHT. WINDS WILL TURN TO LIGHT NORTHEAST OR  
EAST LATE WEDNESDAY NIGHT OR THURSDAY MORNING AS A WEAK COLD  
FRONT PASSES ACROSS THE AREA, BRINGING THE POSSIBILITY OF A FEW  
SHOWERS TO THE MARINE AREAS. WINDS WILL THEN REMAIN LIGHT TO  
MODERATE NORTHEAST TO EAST WITH LOW TO MODERATE SEAS THROUGH  
SATURDAY NIGHT AS HIGH PRESSURE SPREADS OVER THE NORTHWEST GULF.  
ADVISORY CONDITION CHANCES WILL BE LOW DURING THIS PERIOD.  
 

 
   
BRO WATCHES/WARNINGS/ADVISORIES
 
 
TX...NONE.  
GM...NONE.  

 
 

 
 
THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT:  
HTTP://WEATHER.GOV/RGV  
 
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