Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000 FXUS64 KHGX 022323 AFDHGX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX 523 PM CST MON MAR 2 2015 .DISCUSSION... SEE 00Z AVIATION DISCUSSION. && .AVIATION... POOR AVIATION CONDITIONS ARE EXPECTED AGAIN OVERNIGHT INTO TUESDAY MORNING. FCST SOUNDINGS AND HRRR VSBY PROGS SHOW STRONG POTENTIAL FOR DENSE FOG OVERNIGHT WITH VISIBILITIES DROPPING TO 1/4 MILE OVER ALL TAF SITES. CIGS WILL ALSO LOWER TO BELOW 200 FEET AT ALL TAF SITES AS WELL. SLOW IMPROVEMENT IS EXPECTED TUESDAY MORNING AFTER 16Z WITH MVFR CONDS EXPECTED TO OCCUR BRIEFLY ON TUESDAY AFTN. WINDS WILL REMAIN LIGHT OVERNIGHT AND GRADUALLY VEER TO THE E-SE BY MORNING. S-SE WINDS EXPECTED ON TUESDAY AFTN AND SPEEDS WILL PROBABLY GET A BIT GUSTY OVER THE WESTERN TAF SITES DURING THE AFTN. 43 && .PREV DISCUSSION... /ISSUED 337 PM CST MON MAR 2 2015/ DISCUSSION... FRONTAL BOUNDARY HAS REMAINED IN THE GULF OF MEXICO TODAY ALLOWING FOR COOL DAMP CONDITIONS MOST OF THE DAY. TEMPS HAVE NOT RISEN MUCH BUT WITH THIN ENOUGH CLOUD COVER A FEW AREAS HAVE REACHED THE UPPER 50S TO LOW 60S ALONG THE COAST. AREAS FROM KCLL TO KUTS REMAIN IN THE 40S. KCLL HAS NOT REACHED THE 50S SINCE HAVING A HIGH OF 50F ON FEB 25. BEFORE THAT IT WAS FEB 22. WATER VAPOR IMAGERY DOES SHOW STRONG SHORT WAVE TROUGH OVER THE DESERT SW WHICH SHOULD PUSH INTO THE C PLAINS BY 12Z TUE. THIS SHOULD ALLOW FOR SFC CYCLOGENESIS IN THE HIGH PLAINS AND FOR SOUTHERLY WINDS TO DEVELOP. FRONTAL BOUNDARY SHOULD MOVE NORTH AS A WARM FRONT BRINGING BACK TEMPS IN THE 70S AND DEWPOINTS IN THE 60S. FORECAST WILL KEEP A CHANCE OF SHOWERS AND MAYBE AN ISO THUNDERSTORM. FORECAST SOUNDING STILL SHOW A DECENT CAP AND LIMITED INSTABILITY SO AN ISO STORM MAYBE A STRETCH. THE MAIN FORECAST CHALLENGE WILL BE THE CHANGES IN THE WEATHER WED INTO THUR. FORECAST MODELS ARE IN DECENT AGREEMENT WITH STRONG TROUGH PULLING THROUGH THE PLAINS WEDNESDAY WITH AN UPPER LOW OVER CALIFORNIA MOVING EAST ACROSS MEXICO AND S ROCKIES PHASING WITH THIS SYSTEM. A STRONG COLD FRONT IS EXPECTED TO PUSH INTO THE AREA WED BUT THE NAM/GFS/ECMWF ALL HAVE DIFFERENT TIMING. FORECAST LEANED MORE ON THE FASTER GFS AND EVEN ABOUT 3 HRS FASTER THAN THAT. THERE IS GOOD SUPPORT FOR A FASTER FRONTAL MOVEMENT GIVEN THE DEEP TROUGH OVER THE PLAINS. THE ONLY PROBLEM IS THAT THE PHASING TROUGH MAY KEEP JET STREAM FLOW SW AND HELP STALL THE FRONT. THAT SAID...JUST LOOKS LIKE THERE WILL BE A COLD ENOUGH AIRMASS TO KEEP IT PUSHING THROUGH. THE RACE IS THEN ON BETWEEN FREEZING TEMPS AND PRECIP FALLING FOR WED NIGHT INTO THUR. SYNOPTICALLY JET STREAM BECOMES FAVORABLE WITH LIFT DUE TO RIGHT ENTRANCE REGION POSITIONED OVER MUCH OF C AND E TX. FRONTOGENETIC LIFT INCREASES IN 850-700MB OVER THE AREA. MODEL SOUNDINGS AT KCLL/KUTS SHOW A NICE MIX OF PRECIP FROM RA/FRZRA TO SLEET. IF THE COLD AIR DEEPENS ENOUGH AND SATURATES...COULD GET MORE SLEET TO FALL. MAIN AREAS OF CONCERN WILL BE FOR COLLEGE STATION TO LIVINGSTON NORTHWARD. THIS ALSO HINGES ON TIMING OF FREEZING TEMPS AND IF PRECIP WILL BE FALLING THROUGH THAT AIR. PRECIP IS EXPECTED TO DECREASE THROUGH THE MORNING AS LIFT EXITS THE REGION AND SUBSIDENCE BEGINS TO TAKE OVER. ICE/SLEET AMOUNTS WILL BE DIFFICULT TO DETERMINE SINCE THERE WILL BE TIMING ISSUES WITH THE COLD SUB FREEZING AIR AND PRECIP FALLING INTO IT. ISSUED A SPECIAL WEATHER STATEMENT TO HIGHLIGHT MAIN THINKING ON WHAT WHEN AND WHERE WITH IMPACTS. EXTENDED FORECAST IS STILL QUITE UNCERTAIN FOR THE WEEKEND AND INTO EARLY NEXT WEEK. GFS/ECMWF BOTH BRING ANOTHER UPPER LOW TOWARDS TEXAS SATURDAY INTO SUNDAY. FORECAST WILL KEEP SOME RAIN CHANCES GOING TO ACCOUNT FOR THIS WAVE BUT STILL LOTS OF TIMING ISSUES. BOTH MODELS HAVE RUN TO RUN CONSISTENCY BUT NOT WITH EACH OTHER. 39 MARINE... THIS BREAK IN THE SEA FOG EXPECTED TO BE BRIEF WITH THE RETURN OF ONSHORE SFC WINDS THIS EVENING/OVERNIGHT. THE LIMITED/LOWERED VISIBILITIES WITH THE FOG SHOULD LINGER FOR MOST OF TOMORROW AND WEDS...EVEN WITH THE ONSHORE WINDS STRENGTHENING/DEEPENING OUT AHEAD OF THE NEXT COLD FRONT. MODELS STILL BRINGING THIS FRONT INTO THE BAYS LATE WEDS AFTN AND INTO THE COASTAL WATERS WEDS EVENING. TIGHT GRADIENT IN THE WAKE OF THE FRONT WILL PRODUCE VERY STRONG/GUSTY N/NE WINDS FOR WEDS NIGHT ON THROUGH MOST OF THURS. WIND GUSTS MAY EXCEED GALE FORCE BUT THE PROGGED SUSTAINED FLOW WILL LIKELY KEEP US IN THE SMALL CRAFT ADVISORY CATEGORY FOR THAT TIME FRAME. 41 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 50 72 61 63 30 / 30 30 30 70 70 HOUSTON (IAH) 56 76 64 70 34 / 20 20 20 50 70 GALVESTON (GLS) 57 72 61 66 37 / 20 20 20 30 60 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...DENSE FOG ADVISORY UNTIL 10 PM CST 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. && $$

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