AFDHGX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX 852 PM CDT WED MAY 11 2011 .DISCUSSION... A QUASI-LINEAR MCS IS ONGOING ACROSS CENTRAL TX AND THE HILL COUNTRY FROM HILLSBORO TO KILLEEN TO FREDERICKSBURG WHERE WARM MOIST SOUTHERLY FLOW IS COVERGING WITH A SFC COLD POOL. AHEAD OF THE MCS...SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS MANAGED TO DEVELOP ACROSS SE TX THIS AFTN AS MOISTURE DEEPENS AHEAD OF THE UPPER TROUGH OVER THE ROCKIES. MOST OF THIS ACTIVITY HAS REMAINED VERY SHALLOW AND UNDERNEATH THE CAP EXCEPT IN THE FAR NW ZONES. THE 4KM NMM-WRF SEEMS TO HAVE INITIALIZED WELL AND HAVE A GOOD HANDLE ON THE POTENTIAL FOR OVERNIGHT CONVECTION. MOST OF THE ACTIVITY OVER SE TX IS EXPECTED TO DISSIPATED IN THE NEXT COUPLE OF HOURS WITH THE LOSS OF DAYTIME HEATING. THE EXCEPTION IS OVER THE FAR NW ZONES WHERE THE CAPPING IS WEAKER. THE MCS OVER THE HILL COUNTRY WILL PERSIST FOR A FEW MORE HOURS BUT IS EXPECTED TO WEAKEN AS IT APPROACHES THE NW ZONES LATER TONIGHT. THEREFORE... HAVE KEPT POPS ON THE LOW SIDE OVERNIGHT (30S NW THIRD...20S ELSEWHERE). WILL MONITOR RADAR TRENDS AND WILL MAKE ADJUSTMENTS LATER THIS EVENING IF NEEDED. ON THURSDAY...CAPPING WEAKENS SIGNIFICANTLY ACROSS THE AREA WITH GFS BUFR SOUNDINGS SHOWING CONVECTIVE TEMPS ONLY IN THE MID 80S. LITTLE PRECIP IS EXPECTED IN THE MORNING WHICH SHOULD ALLOW STRONG INSTABILITY TO DEVELOP (LIS -8 TO -1O AND CAPES AROUND 3000 J/KG). THE 4KM NMM-WRF SHOWS SCATTERED SHOWERS/T-STORMS DEVELOPING THU AFTN BOTH OVER THE CWA AND IN ANOTHER AREA JUST TO OUR WEST ALONG THE DRYLINE. THIS ACTIVITY SHOULD INCREASE AS WE GO INTO THURSDAY EVENING AS THE CWA GOES IN THE LEFT FRONT QUAD OF AN UPPER JET MAX. HAVE KEPT HIGH CHANCE POPS BLANKETED ACROSS THE AREA THU AFTN/THU NIGHT. SPC HAS THE ENTIRE CWA IN SLIGHT RISK FOR DAY 2 AND WILL KEEP SEVERE MENTIONED IN THE FORECAST. THE RAIN...HOWEVER LIGHT...WAS A WELCOME SIGHT ACROSS THE AREA THIS EVENING. A FEW HUNDREDTHS OF AN INCH OF RAIN FELL AT HOUSTON/IAH. HOUSTON/HOBBY ONLY RECORDED A TRACE THEREBY KEEPING ITS RECORD-SETTING STREAK OF RAINLESS DAYS IN TACT (NOW 58 DAYS INCLUDING TODAY). 35 && .PREV DISCUSSION... /ISSUED 748 PM CDT WED MAY 11 2011/ AVIATION... BASED ON SATELLITE IR LOOP...CONVECTION OVER SOUTHERN PORTIONS OF CWFA SHOULD BE ABATING BY MID EVENING. LOW LEVEL HORIZONTAL MIXING NOT AS STRONG COMPARED TO 24 HOURS AGO. CEILINGS MAY LOWER TO IFR LATE TONIGHT. LIGHT FOG INDICATED FOR NORTHERN TAF SITES AFTER MIDNIGHT. NAM12 MORE AGGRESSIVE TOMORROW AFTERNOON WITH HIGHER PWATS AND POPS FOR IAH. WE SHALL CONTINUE WITH VCNTY SHRA/TSRA THURSDAY AFTERNOON AND EARLY EVENING HOURS ALONG W/CB CLOUD GROUP. 37 PREV DISCUSSION... /ISSUED 351 PM CDT WED MAY 11 2011/ DISCUSSION... SOUTHEAST TEXAS RECEIVING A TEASE OF RAIN AS -SHRA TRAVEL NORTHEASTWARD AHEAD OF AN APPROACHING NM-WEST TX TROUGH. AS THIS TROUGH ENCOUNTERS GULF RIDGING IT IS BECOMING MORE NEGATIVELY-TILTED. DRY-LINE BOUNDARY REMAINING WELL WEST OF CENTRAL TEXAS...OR WEST OF ABILENE. AS TROUGH PULLS UP AND OVER GOM RIDGING...THIS WILL AID IN DRAGGING TOMORROW`S DRY LINE CLOSER TO THE I-35 CORRIDOR. AS THE SURFACE COLD FRONT CLOSES IN FROM THE WEST...OUR REGION WILL FALL WITHIN THE WARM SECTOR. THE MAIN POSITIVES TO THE NEXT 24 TO 36 HOUR INCREASING POPS WILL BE IN THE UPPER LEVELS. AS WAS OBVIOUS IN WATCHING MATAGORDA BAY REGION CONVECTION PETER OUT OVER THE LAST FEW HOURS...MOST OF THE AREA IS STILL TOO STABLE FOR ANY SIGNIFICANT BOOST AND/OR CONVECTIVE SUSTAINABILITY. EASTERN TEXAS WILL STILL BE UNDER A FAVORABLE 25H LFQ AND...WITH A DIFFULENT JET OVER NORTH CENTRAL-CENTRAL TEXAS...BELIEVE SCATTERED CONVECTION WILL INITIATE WEST (OR SOUTHWEST) OF FA EARLY TOMORROW AND RIDE UP INTO CENTRAL CWA THROUGH MID-DAY. PROFILES ARE MARGINALLY UNSTABLE ENOUGH...WITH PWATS APPROACHING 1.5 TO 1.7 INCHES...TO SUPPORT AS TEMPERATURES ACHIEVE THE MIDDLE 80S. BY THE LATE AFTERNOON...WITH THE UPPER TROUGH AXIS SWINGING ACROSS NORTH CENTRAL TEXAS...THERE SHOULD BE A PRIMED ENOUGH ENVIRONMENT FOR MANY TO EXPERIENCE THEIR FIRST MEASURABLE RAIN IN WEEKS. SPC HAS US UNDER A SLIGHT SEVERE RISK AND...WITH WEAKLY SHEARED AND SOMEWHAT INVERTED-V PROG SOUNDINGS...HAVE PLACED ISOLATED SEVERE WORDING IN TOMORROW`S ZFP IN MIRRORING EARLIER SHIFT`S HWOHGX PHILOSOPHY. ALTHOUGH ISOLATED RAINFALL AMOUNTS COULD EXCEED AN INCH...DUE TO THE SCATTERED NATURE OF THE EVENT...HAVE BEEN MORE PESSIMISTIC ON OVERALL QPF WITH AN AVERAGE SUB-0.5 INCH. SWATH OF NORTHERLY CONVECTION AHEAD OF THE DRY LINE/CF MERGING WITH WEST-SOUTHWEST ACTIVITY LATE TOMORROW COULD FOCUS HIGHER RAIN AMOUNTS OVER EASTERN CWA THROUGH FRIDAY MORNING. THE ACTUAL COLD FRONTAL PASSAGE FRIDAY AFTERNOON INTO EVENING IS EXPECTED TO BE A FAIRLY DRY ONE...WITH THE COOLER AND DRIER AIR MASS IN ITS WAKE KEEPING THE WEEKEND MX/MN TEMPERATURES IN THE SEASONABLE CATEGORY. UPPER RIDGING BUILDS IN FROM THE WEST SUNDAY THROUGH TUESDAY AND KEEPS THE CLAMP ON ANY RETURNING RAIN. ADJMOS NUMBERS SEEM TO BE SLUGGISH (MX TEMPS IN THE UPPER 70S TO LOW 80S) IN THE SUBSEQUENT WARM UP SO...AS 10-5H THICKNESS VALUES LIFT BACK UP INTO THE LOWER 570`S UNDER PARTLY CLOUDY SKIES AND ADDED SUBSIDENCE .FEEL THAT MIDDLE TO UPPER 80S IS THE WAY TO GO. IF UPPER RIDGING AMPLIFIES...PER DEEPENING PAC NW AND EASTERN U.S. LOWS...THIS OMEGA BLOCK PATTERN COULD NOT ONLY PLACE US UNDER A STATIC WEATHER PATTERN .BUT ALLOW AFTERNOON TEMPERATURES TO ONCE AGAIN VISIT THE 90S. 31 MARINE... WINDS ARE EXPECTED TO DECREASE OVERNIGHT. SEAS HAVE BEGUN TO DECREASE AND WILL CANCEL THE SCEC FOR THE BAYS AND ADJACENT NEAR SHORE WATERS. WILL CANCEL THE SCA AND REPLACE WITH AN SCEC FOR THE OFFSHORE WATERS FOR SEAS AROUND 6 FEET. THESE SEAS WILL ALSO BEGIN TO DROP OVERNIGHT. SLIGHTLY ELEVATED TIDES WILL ALSO RETURN TO NORMAL LEVELS ON THURSDAY. A COLD FRONT WILL CROSS THE MARINE AREA EARLY FRIDAY WITH MODERATE OFFSHORE WINDS IN ITS WAKE. OFFSHORE WINDS WILL PREVAIL THROUGH TUESDAY WITH ONSHORE WINDS RETURNING TUESDAY NIGHT. 43 CLIMATE... LOOKS LIKE PARTS OF SOUTHEAST TEXAS WILL RECEIVE SOME RAIN OVER THE NEXT 24 HOURS. HOBBY AIRPORT IS CURRENTLY AT 57 CONSECUTIVE DAYS WITHOUT MEASURABLE RAIN (LAST RAIN MARCH 14TH). IT HAS BEEN SO DRY THAT EVEN AN INCH OF RAIN WILL NOT CHANGE THE RECORDS. IT IS CURRENTLY THE DRIEST OCT 1 THROUGH MAY 11TH FOR COLLEGE STATION AND HOUSTON. COLLEGE STATION WILL NEED 2.93 INCHES OF RAIN TO MAKE THIS THE SECOND DRIEST OCT 1 THRU MAY 11TH AND HOUSTON WILL NEED 1.64 INCHES OF RAIN TO MAKE THIS THE SECOND DRIEST OCT 1 THRU MAY 11TH. SINCE FEB 1ST...CLL...IAH...HOU AND DANEVANG ARE THE DRIEST ON RECORD. IT WOULD TAKE 2.18 INCHES OF RAIN AT HOU TO MAKE THIS PERIOD THE 2ND DRIEST... 1.63 INCHES AT CLL...2.14 INCHES AT IAH AND 1.69 INCHES OF RAIN AT DANEVANG TO MAKE THESE LOCATION THE 2ND DRIEST FEB THROUGH MAY 11TH. NOT EXPECTING THAT MUCH RAIN SO IT LOOKS LIKE THE DRIEST STRETCH OF WEATHER THIS AREA HAS EXPERIENCED IS LIKELY TO CONTINUE. NEW DROUGHT STATEMENT WILL BE ISSUED BY NOON THURSDAY. 43 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 74 85 68 83 55 / 40 50 40 20 10 HOUSTON (IAH) 73 88 71 88 61 / 20 40 40 30 10 GALVESTON (GLS) 76 84 74 84 66 / 20 30 40 30 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 11 PM CDT THIS EVENING FOR THE FOLLOWING ZONES: GALVESTON BAY...MATAGORDA BAY... WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM. && $$