AFDBRO AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BROWNSVILLE TX 1222 AM CDT THU MAY 12 2011 .DISCUSSION...SEE UPDATED AVIATION SECTION BELOW FOR DISCUSSION ON THE 06Z TAF PACKAGE. && .AVIATION...MVFR CIGS HAVE AGAIN DEVELOPED OVER AREA TERMINALS EARLY THIS MORNING. THE EXCEPTION WILL AGAIN BE MFE...WHERE THIS CLOUD COVER IS MORE PATCHY. HOWEVER...THIS SITE SHOULD BE ABLE TO SEE MORE FREQUENT PERIODS OF MVFR CIGS AS WELL. CIGS SHOULD AVERAGE BETWEEN 1 AND 2 KFT THROUGH THE NIGHT...BUT WILL NOT RULE OUT PERIODS WHERE CIGS DROP DOWN INTO THE IFR RANGE. CLOUD COVER IS EXPECTED TO BEGIN TO SCATTER AND LIFT AFTER SUNRISE...ALLOWING FOR VFR CONDITIONS TO RETURN FOR MUCH OF THE DAY. HOWEVER...LOW CLOUDS WILL AGAIN DEVELOP LATE THIS EVENING INTO THE OVERNIGHT HOURS. OTHERWISE...EXPECT SOUTHEAST WINDS TO PERSIST THROUGH THE FORECAST PERIOD. WINDS BETWEEN 10-15 KNOTS EARLY THIS MORNING WILL INCREASE SLIGHTLY AND BECOME GUSTY AFTER SUNRISE. HOWEVER...WINDS WILL LET UP AGAIN THIS EVENING TO DROP BACK DOWN TO AROUND OR SLIGHTLY BELOW 10 KNOTS. && .PREV DISCUSSION... /ISSUED 616 PM CDT WED MAY 11 2011/ DISCUSSION...SEE UPDATED AVIATION SECTION BELOW FOR DISCUSSION ON THE 00Z TAF PACKAGE. AVIATION...VFR CONDITIONS THIS EVENING WILL GRADUALLY GIVE WAY TO MVFR CONDITIONS OVERNIGHT...AS STRATUS AROUND 1000 FEET DEVELOPS OVER DEEP SOUTH TEXAS. SURFACE WINDS WILL GENERALLY REMAIN MODERATE ..BUT WINDS A FEW THOUSAND FEET ABOVE THE SURFACE MAY INCREASE TO THE POINT THAT A NON-CONVECTIVE WIND SHEAR COMPONENT WILL NEED TO BE ADDED IN THE NEXT TAF FORECAST LATE TONIGHT. ATMOSPHERIC MIXING COURTESY OF INCREASING SURFACE WINDS WILL RETURN THE RIO GRANDE VALLEY TO VFR LEVELS SHORTLY AFTER SUNRISE TOMORROW MORNING. PREV DISCUSSION... /ISSUED 409 PM CDT WED MAY 11 2011/ UPDATE...MADE A MINOR ADJUSTMENT TO FRIDAY/S FORECAST. WITH THE MENTION OF A COLD FRONT MOVING THROUGH THE REGION FRIDAY IN THE PREVIOUS DISCUSSION. THE COMBINATION OF LOW LEVEL CONVERGENCE ALONG THE FRONT AND THE SEA BREEZE (LIGHT EAST WINDS SEEN ON FORECAST SOUNDINGS) SHOULD AID IN LIFT OF A MODESTLY MOIST ATMOSPHERE. ALTHOUGH UPPER DIVERGENCE IS LACKING LITTLE TO NO CAP IN THE AFTERNOON AND INCREASING INSTABILITY WITH CAPES AT 4300 J/KG MIGHT BE ENOUGH TO WARRANT THUNDERSTORM DEVELOPMENT ALONG THE FRONT. BEST CHANCES LOOK TO BE ACROSS THE LOWER VALLEY BETWEEN 1 PM AND 6 PM. WITHOUT SIGNIFICANT UPPER DIVERGENCE SEVERE CONVECTION IS NOT ANTICIPATED AT THIS TIME...BUT LATER SHIFTS WILL HAVE TO MONITOR FOR ANY FURTHER CHANGES. THE AFTERNOON OR EARLY EVENING PASSAGE OF THE FRONT WILL KEEP SOUTHEAST TO EAST WINDS ACROSS THE REGION MOST OF FRIDAY WITH NORTH TO NORTHEAST WINDS BECOMING MORE PREVALENT SATURDAY. MARINE...TONIGHT THROUGH THURSDAY NIGHT...BUOY 42020 INDICATES THAT ROUGH SWELLS FROM THE SOUTHEAST ARE APPROACHING THE LOWER TEXAS COAST AT THIS TIME...WITH OCEANOGRAPHIC MODELING SUGGESTING THAT THESE SWELLS WILL PERSIST THROUGH THE OVERNIGHT HOURS. THEREFORE...A SMALL CRAFT ADVISORY HAS BEEN ISSUED FOR THE GULF OF MEXICO WATERS EAST OF PADRE ISLAND FROM 0 TO 60 NAUTICAL MILES OFFSHORE UNTIL 7 AM CDT THURSDAY MORNING. NO OTHER MARINE FORECAST ADJUSTMENTS MADE. PREV DISCUSSION... /ISSUED 204 PM CDT WED MAY 11 2011/ SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...THE BROAD AND STRONG 500 MB AND ASSOCIATED SURFACE LOW PRESSURE SYSTEM NOW CENTERED NEAR THE TX/OK PANHANDLE REGION WILL CONTINUE TO PUSH EAST THROUGH THURS NIGHT. SOME SPORADIC 5H VORTICES WILL ADVECT OVER NORTHERN MEXICO AND SOUTHERN TX PROVIDING DECENT UVV OVER THE REGION. THE MAIN PROBLEM FOR POTENTIAL CONV WILL BE THE CONTINUED LIMITED DEEP MOISTURE LEVELS EVIDENT OVER THE REGION. THE 12Z BRO SOUNDING HAS PRETTY GOOD CAPE VALUES NEAR 4715 J/KG BUT THE PWAT IS ONLY AROUND 1.60 INCHES WITH THE BEST MOISTURE VALUES CONFINED TO THE LOWEST LEVELS OF THE ATMS. THE MAV AND MET MEAN RH VALUES REMAIN PRETTY LIMITED OVER THE BRO CWA AND CONFINED FURTHER TO THE NORTH OVER NORTHERN AND EASTERN TX. THE ECMWF IS WETTER VERSUS THE GFS AND NAM AND IS THE OUTLIER AT THIS TIME. WILL GO WITH THE DRIER SOLUTION PROVIDED BY THE GFS AND NAM AND WILL MENTION 20 TO 30% POPS IN THE SHORT TERM WITH THE BEST POPS POSTED FOR THURS AND THURS NIGHT AS THE MID LEVEL CLOSED LOW MOVES INTO KS. ALTHOUGH THE SWODY2 PLACES ALL OF SOUTHERN AND EASTERN TX IN THE SLGT RISK FOR TOMORROW WILL NOT MENTION ANY POTENTIAL FOR SVR CONV FOR THE REGION AS THE BETTER SVR POTENTIAL WILL BE LOCATED OVER CENTRAL AND EASTERN TX REGIONS WHERE THE BETTER MID LEVEL DYNAMICS AND INSTABILITY WILL BE LOCATED. FOR TEMPS WILL GO CLOSER TO THE SLIGHTLY COOLER MAV GUIDANCE FOR HIGH TEMPS AND A MAV/MET BLEND FOR LOWS. LONG TERM/FRIDAY THROUGH WEDNESDAY/...A WEAK COLD FRONT WILL MOVE THROUGH DEEP SOUTH TEXAS FRIDAY SHIFTING THE WINDS TO THE NORTH AND NORTHEAST. LIGHT TO MODERATE NORTHERLY WINDS WILL PREVAIL ACROSS THE RIO GRANDE VALLEY FRIDAY AND SATURDAY. A HIGH PRESSURE RIDGE WILL BUILD ACROSS THE CWA IN THE WAKE OF THE FRONTAL BOUNDARY. THE WINDS WILL SHIFT TO THE EAST ON SUNDAY AS THE HIGH PRESSURE RIDGE SHIFTS TO THE EAST. LIGHT TO MODERATE EAST TO SOUTHEAST WINDS WILL PREVAIL ACROSS THE CWA MONDAY THROUGH FRIDAY. THERE IS A SLIGHT CHANCE FOR SHOWERS MOVING ACROSS PORTIONS OF DEEP SOUTH TEXAS ON FRIDAY. TEMPERATURES WILL REMAIN ABOVE NORMAL THROUGHOUT THE FORECAST PERIOD. MARINE /FRIDAY THROUGH MONDAY...A WEAK COLD FRONT WILL MOVE THROUGH THE MARINE AREAS ON FRIDAY SHIFTING THE WINDS FROM THE SOUTHEAST TO THE NORTH AND NORTHEAST. THERE IS A SLIGHT CHANCE FOR SHOWERS AND ISOLATED THUNDERSTORMS MOVING ACROSS PORTIONS OF THE MARINE AREAS ON FRIDAY ALONG THE WEAK COLD FRONT. MODERATE NORTHEASTERLY WINDS AND MODERATE SEAS WILL PREVAIL ACROSS THE COASTAL WATERS FRIDAY AND SATURDAY AS A HIGH PRESSURE RIDGE BUILDS ACROSS THE MARINE AREAS. THE WINDS WILL SHIFT TO THE EAST ON SUNDAY. LIGHT TO MODERATE EAST TO SOUTHEAST WINDS AND LOW SEAS WILL PREVAIL ACROSS THE MARINE AREAS EARLY NEXT WEEK. && .PRELIMINARY POINT TEMPS/POPS... BAYVIEW/PORT ISABEL 88 78 86 76 / 10 20 20 30 BROWNSVILLE 90 77 87 75 / 10 20 20 30 HARLINGEN 91 77 89 75 / 10 20 20 30 MCALLEN 93 76 93 77 / 10 20 20 30 RIO GRANDE CITY 98 76 95 74 / 10 20 30 30 SOUTH PADRE ISLAND 87 76 84 75 / 10 20 20 30 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...SMALL CRAFT ADVISORY UNTIL 7 AM CDT THURSDAY FOR GMZ150-155-170- 175. && $$