Issued by NWS Brownsville, TX
000 FXUS64 KBRO 212017 AFDBRO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BROWNSVILLE TX 217 PM CST SAT NOV 21 2009 .DISCUSSION...A FAIRLY PROGRESSIVE PATTERN WILL PREVAIL ACROSS THE LOWER 48 STATES FOR THE UPCOMING FORECAST PERIOD AS A STEADY SERIES OF 500 MB SHORT WAVES CONTINUE TO DIG ACROSS THE CONUS REGION FROM THE WEST AND NORTHWEST. A FAIRLY ZONAL PATTERN WILL PREVAIL OVER DEEP SOUTH TEXAS FOR THE SHORT TERM ALLOWING FAIRLY DRY AND BENIGN CONDITIONS TO PREVAIL OVER THE NEXT COUPLE OF DAYS. THE CURRENT COOL AND DRY SURFACE HIGH OVER THE AREA WILL BE STEADILY MOVING EAST ALLOWING THE LOW LEVEL FLOW TO BECOME MORE E-SE RESULTING IN AN INCREASE IN SURFACE DEWPOINTS AND WARMING TEMPS. THE NEXT MAJOR MID LEVEL TROUGH TO AFFECT THE RIO GRANDE VALLEY AREA WILL DIG INTO THE CENTRAL PLAINS STATES LATE MON CUTTING OFF TUES AND WED. THIS WILL PUSH THE NEXT MIDWEST COLD FRONT THROUGH DEEP SOUTH TX ON TUES RESULTING IN THE NEXT GOOD RAIN CHC FOR THE REGION. AFTER THIS FRONT CLEARS THE REGION AN EASTERN PACIFIC CLOSED MID LEVEL BAJA LOW WILL FORM UP AND WILL MOVE OVER THE NORTHERN PORTIONS OF MEXICO DURING THE LATTER HALF OF THE UPCOMING WORK WEEK. MEANWHILE AT THE LOW LEVELS AN E/NE FLOW WILL PERSIST THROUGH THE END OF THE WEEK DUE TO THE SURFACE RIDGING DOMINATING THE EASTERN HALF OF THE NATION. THIS COMBINATION OF W-SW FLOW ALOFT AND THE E-NE FLOW AT THE SURFACE WILL LIKELY MAINTAIN GENEROUS CLD COVER DURING THE LATTER HALF OF THIS WEEK. THIS BAJA LOW WILL EVENTUALLY OPEN UP AND WILL MOVE OVER NORTHEAST MEX AND SOUTHERN TEX FRI AND SAT WITH YET ANOTHER BROAD 500 MB TROUGH AXIS DIGGING INTO THE SOUTH CENTRAL PLAINS EARLY NEXT WEEK. WILL MAINTAIN A MENTION OF SOME SLGT CHC/CHC POPS AFTER TUES TO ACCOUNT FOR THIS POTENTIAL OVERRUNNING SITUATION. SHORT TERM COMPARISONS BETWEEN THE MAV AND MET TEMPS/POPS LOOK PRETTY CLOSE AND WILL NOT STRAY TOO FAR FROM THIS OVERALL TREND. RUN TO RUN AND MODEL TO MODEL CONSISTENCY WITH LONG RANGE GUIDANCE LOOKS ABOVE AVERAGE AND WILL GO CLOSE TO MEX POPS FROM DAYS 3 TO 7 AND NEAR TO A LITTLE BELOW GUIDANCE FOR MAX AND MIN TEMPS IN THE LONGER RANGE. && .AVIATION...MOSTLY CLEAR SKIES AND LIGHT TO MODERATE NORTHERLY WINDS ARE PREVAILING TDA ACROSS DEEP SOUTH TX. SOME HIGHER CIRRUS CLDS ARE ADVECTING NWD FROM MEXICO AND WILL DRIFT OVERHEAD THRU THIS AFTN WITH NO IMPACTS TO AVIATION INTERESTS. FAIRLY LIGHT NORTH TO NORTHEAST WINDS ARE EXPECTED TO PREVAIL THRU THE OVRNGT AS HIGH PRESSURE TAKES CONTROL. ANTICIPATE VFR CONDITIONS TO PERSIST THRU THE NEXT 24 HRS. && .MARINE...THE 1 PM OBSERVATION FROM BUOY020 INDICATES WINDS WERE WEST NORTHWEST AROUND 16 KTS GUSTING TO AROUND 19 KTS AND SEAS WERE AROUND 6 FT WITH A PERIOD OF 8 SECONDS. MARINE CONDITIONS WILL CONTINUE TO GRADUALLY IMPROVE THRU THIS AFTN ACROSS THE OFFSHORE WATERS. THE DAY BEGAN WITH SCA CONDITIONS DUE TO ELEVATED WINDS AND SEAS. HIGH PRESSURE WILL GRADUALLY TAKE HOLD THE REST OF TDA THRU MON. MARINE SC CLDS WILL GRADUALLY ERODE TO THE ESE THRU THIS AFTN/EVE. THE LIGHT TO MODERATE NORTHERLY FLOW WILL PREVAIL INTO TNGT. WINDS WILL VEER NE TO E OVRNGT THRU SUN NGT AND REMAIN LIGHT TO MODERATE. SE FLOW WILL RETURN ON MON AS HIGH PRESSURE SHIFTS FARTHER EAST. SEAS WILL CONTINUE TO SUBSIDE THIS AFTN AND ARE EXPECTED TO REMAIN RELATIVELY LOW SUN INTO MON. THE ONSHORE SE FLOW WILL BEGIN TO STRENGTHEN BY LATE MON INTO TUE IN RESPONSE TO A COLD FRONT WORKING THRU NORTH AND CENTRAL TX. SEAS WILL GRADUALLY BUILD POSSIBLY RESULTING IN SCEC TO POSSIBLY MARGINAL SCA CONDITIONS. THE FRONT IS PROGGED TO PUSH THRU THE COASTAL WATERS ON TUE. SCA CONDITIONS WILL BE POSSIBLE IN CONJUNCTION WITH THE FROPA AND POSSIBLY PERSIST THRU WED. && .PRELIMINARY POINT TEMPS/POPS... BAYVIEW/PORT ISABEL 57 77 65 80 / 0 0 10 20 BROWNSVILLE 53 79 64 80 / 0 0 10 20 HARLINGEN 52 78 63 82 / 0 0 10 20 MCALLEN 53 81 62 83 / 0 0 10 20 RIO GRANDE CITY 53 81 60 82 / 0 0 10 20 SOUTH PADRE ISLAND 59 76 64 79 / 0 0 10 20 && .BRO WATCHES/WARNINGS/ADVISORIES...NONE. && $$ THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT: HTTP://WWW.WEATHER.GOV/BROWNSVILLE SYNOPTIC/GRIDS...60 MARINE/AVIATION...57 MESO...MARTINEZ
