FXUS64 KHGX 111105 AFDHGX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX 425 AM CST THU MAR 11 2010 .DISCUSSION... A GOOD SOUTHERN 2/3RDS OF THE FA UNDER THE GRIP OF DENSE FOG LOWERING VISBIES DOWN TO A MILE INTO THE NORTHERN REACHES OF THE CITY...UNDER A 1/4 MILE FROM HOUSTON AND ALL POINTS SOUTH ALONG THE GULF COAST AND OVER SURROUNDING GULF/BAY WATERS. DENSE FOG ADVISORY WILL BE EFFECT THROUGH 9 AM FOR FAR INTERIOR COUNTIES... EXTENDED FOR THE REMAINDER OF THE MORNING FOR EXTREME SE'ERN COUNTIES INCLUDING HARRIS TO ACCOUNT FOR THOSE WESTERN BAY AND SHIP CHANNEL COMMUNITIES. WITH THE MAIN FRONT NOT MAKING IT TO THE COAST UNTIL EARLY FRIDAY...FOG WILL LINGER FOR THE GOOD PART OF THE DAY AROUND GALVESTON BAY AND NEARSHORE GULF WATERS. MARITIME FOG MAY SLOWLY LIFT AROUND SUNSET TONIGHT...BUT UNTIL THE FRIDAY MIDNIGHT CF SWINGS WINDS AROUND TO THE NW AND MIXES DOWN DRIER AIR...A PESSIMISTIC FOG FORECAST FOR THOSE COUNTIES SURROUNDING GLS BAY. HAVE ADDED SE'ERN FA SLIGHT CHANCE POPS TO ACCOUNT FOR EITHER FOG PRECIPITATING OUT AS -DZ/--RA OR A SCATTERED SHRA OR TWO AFFECTING (NEAR) COASTAL LOCALES. THE 150KT JET STILL RACES ACROSS THE COASTAL BEND AND CENTRAL GULF. THE NEAR VICINITY OF THIS SOUTHERN BRANCH/STJ ...A POSSIBLE OLD NEARSHORE BOUNDARY PROVIDING SOME FOCUS...AND A SATURATED ENVIRONMENT ARGUES THE POINT OF AT PLACING IN LEAST 20 POPS TODAY...A HIGHER PROB OF PRECIP OCCURRENCE WITH VERY LOW COVERAGE/ACCUMULATIONS. ENSEMBLE IN DECENT AGREEMENT THAT ANOTHER ENERGY LOBE WILL SLIDE DOWN AROUND THE SW SIDE OF MAIN CENTRAL PLAINS UPPER LOW. THIS WILL CLIP OUR FAR NE'ERN ZONES (SIMILAR TO TO YESTERDAY'S SET-UP). ALTHOUGH NOT AS STRONG A S/W AS THURSDAY'S...IT WILL HAVE JUST ENOUGH PRECIPITABLE H20 AND LOW-MID LEVEL LAPSE RATES (PER RECENT COOLING BROUGHT ON BY THUR'S S/W PASSAGE)...TO AT LEAST HAVE THE N-NE COUNTIES COVERED WITH A SLIGHT CHANCE OF SCT SHRA/ISO LATE DAY INTO EVENING STORM(S). THE ONE GUARANTEE BROUGHT ON BY THIS PASSING S/W WILL BE THE INITIATION OF AN ESTABLISHED NW'ERLY FLOW IN ITS WAKE. A WEAK AND DRY BOUNDARY PASSAGE IN THE EARLY FRIDAY MORNING HOURS WILL WHISK AWAY ANY LINGERING FOG DECK AND MINOR THREAT FOR CONVECTION. TRANSITORY RIDGING WILL PASS OVER THROUGH THE WEEKEND. WEAKENING NW'ERLIES AS WEAK SURFACE RIDGING DEVELOPS AND SHIFTS EAST BY MID-SUNDAY. THE NEXT IN-A-LINE OF UPPER LOWS HEADS DOWN INTO TEXAS ON MONDAY. RECENT MODELING HAS THIS OPENING UP INTO A BROAD WAVE AND DIGGING DEEP INTO THE BIG BEND/NORTHERN MEXICO THROUGH EARLY TUESDAY. NOT QUITE SURE HOW MUCH THE REGIONAL PWATS WILL RECHARGE AFTER ONLY A DAY OR SO OF DOWNSTREAM MILD RETURN FLOW...BUT THERE SHOULD BE ENOUGH AVAILABLE MOISTURE TO SQUEEZE ISO/SCT -SHRA IN A CONDITIONALLY UNSTABLE ENVIRONMENT LATE MONDAY INTO EARLY TUESDAY (MAINLY ACROSS THE WESTERN CWA IF LOW DOES TRACK AS FAR SOUTH AS RECENT RUNS ADVERTISE). COLUMN SATURATES BY TUESDAY AFTERNOON AND...AS OF NOW...LOOKS LIKE A GOOD CHANCE OF AREAWIDE RAIN/ISO STORMS TUESDAY AS A NEAR-COASTAL SURFACE TROUGH MOVES NE'WARD AHEAD OF AN EVENTUAL LATE TUESDAY COLD FROPA. NORTHERLY FLOW SPELLS DRIER AND COOLER WEATHER THROUGH THURSDAY. AFTER A WARM (70S TO LOW 80S?) AND MILD WEEKEND...TUESDAY'S INCLEMENT WEATHER WILL USHER IN A FEW DAYS OF BELOW NORMAL TEMPERATURES ST PATTY'S DAY THROUGH THE WORK WEEK'S CLOSURE. 31 && .MARINE... DENSE SEA FOG SHOULD PARTIALLY MIX OUT THIS AFTERNOON. DRYLINE MIGHT NOT MAKE IT TO AREAS EAST OF FREEPORT THIS EVENING SO THERE'S A POSSIBILITY IT COULD BRIEFLY RETURN THEN. COLD FRONT PUSHES OFF THE COAST TONIGHT WHICH WILL BRING AN END TO THE FOG BUT USER IN A MODERATE OFFSHORE FLOW IN ITS WAKE. WILL NEED CAUTION OR ADVSY FLAGS OFFSHORE TOWARD FRI MORNING. ONSHORE FLOW RESUMES SUN BUT BACKS TO THE E ON MON AHEAD OF THE NEXT COLD FRONT PENCILED IN TO PUSH OFFSHORE MON NIGHT OR TUE. 47 && .AVIATION... SAT FOG IMAGERY CLEARLY SHOWS WHERE THE DRYLINE IS SITUATED - ROUGHLY ALONG A BRENHAM TO TRINITY LINE. AREAS TO THE S OF THE LINE ARE SOCKED IN WITH LIFR CIGS/FOG. GRADUAL IMPROVING CONDITIONS DURING THE MID AND LATE MORNING HOURS...BUT CONSIDERABLE UNCERTAINTY AS TO WHEN THE DRYLINE WILL ACTUALLY PUSH THRU THE METRO AND GALVESTON AREAS. THOUGH THE 00Z GFS/ECMWF SHOW VFR CONDITIONS BY 18Z AREAWIDE...LATEST RUC/NAM12 RUNS SHOWING LOCATIONS SOUTH OF A FREEPORT-LIVINGSTON LINE REMAINING IN THE WARM SECTOR ALL DAY THEN CLEARING OUT THIS EVENING. CANNOT RULE OUT SOME ISO SHRA/TSTMS IN THIS SECTOR BASED ON NAM 12 FCST SOUNDINGS. WILL LIKELY GO WITH SOME SORT OF COMPROMISE BETWEEN ALL OF THEM IN THE 12Z PACKAGE. MAY SEE SOME SCT SHRA/TSTMS DEVELOP IN NW TX LATER THIS AFTN IN AND PUSH SEWD CLOSE TO CLL/UTS THIS EVNG. AGAIN...WILL KEEP OUT OF TAFS FOR NOW WITH THE CONSIDERABLE UNCERTAINTY. FRONT PUSHES THRU OVERNIGHT WITH MCLR SKIES EXPECTED BY SUNRISE FRI. 47 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 74 46 70 43 74 / 10 20 10 10 10 HOUSTON (IAH) 74 47 69 46 75 / 10 10 10 10 10 GALVESTON (GLS) 64 53 65 52 72 / 20 10 10 10 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR THE FOLLOWING ZONES: FORT BEND...JACKSON...LIBERTY...MATAGORDA... MONTGOMERY...POLK...SAN JACINTO...WHARTON. DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR THE FOLLOWING ZONES: BRAZORIA...CHAMBERS...GALVESTON...HARRIS. GM...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR THE FOLLOWING ZONES: GALVESTON BAY...MATAGORDA BAY...WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM. && $$ DISCUSSION...31/47