Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 251156
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
656 AM CDT MON MAY 25 2015


.AVIATION...
VLIFR AT CXO/IFR AT CLL OTHERWISE THE AREA IS MAINLY VFR. CIGS
SHOULD RISE QUICKLY THIS MORNING TO AROUND 2500 TO 3000FT WITH
EARLY MORNING HEATING...THIS DECK MAY LINGER INTO AROUND MID DAY.
QUESTION STILL ABOUND ABOUT TIMING OF SHOWERS AND THUNDERSTORMS
TODAY AND HOW FAR SOUTH THEY MAKE IT. SO MUCH VARIABILITY IN MODEL
OUTPUT THAT HAVE JUST TRIED TO TIME BEST LIFT  WILL CARRY VCSH
BETWEEN 15-18Z AND VCTS AFTER WITH TEMPO TSRA CONDITIONS AND GUSTY
WINDS FOR MOST FAVORABLE WINDOW ROUGHLY 18-22Z IN THE NORTHWEST TO
221-01Z AT THE COAST. AFTER STORMS DEPART THE AREA VFR CONDITIONS
PRESENT AT LEAST FOR A FEW HOURS BEFORE MVFR CIGS REFORM
OVERNIGHT.
45

&&

.PREV DISCUSSION... /ISSUED 503 AM CDT MON MAY 25 2015/

SHORT TERM...
WARM AND MOIST SOUTHEASTERLY FLOW CONTINUES ACROSS THE AREA WITH A
RAPID EXPANSION OF CLOUDS ACROSS THE NORTHERN AREAS. WATER VAPOR
CLEARLY SHOWS A VERY VIGOROUS S/W MOVING INTO WEST TEXAS WITH
ABUNDANT LIFT IN ADVANCE OF THE S/W. STORMS SHOULD BEGIN DEVELOPING
NEAR MIDLAND SHORTLY AND EXPECT THE TRAJECTORY OF THE S/W TO BE
NEARLY DUE EAST THROUGH MID MORNING THEN BEGIN TO TURN TO THE
NORTHEAST. LLJ IS QUITE STRONG THIS MORNING AND MODELS HAVE REALLY
UNDERESTIMATED THE STRENGTH OF THE LLJ. NAM/ECMWF/GFS/ARW ALL SHOWED
SPEEDS AT 850 OF 25 TO 30 KNOTS WHILE VWP AT CRP SHOWED 50 KNOTS/HGX
40 KNOTS. THIS STRONGER RETURN FLOW MAY HELP TO PULL THE MOISTURE
BACK INTO THE AREA AFTER YESTERDAYS STRONGER AND VERY PROGRESSIVE
MCS SCOURED OUT THE MOISTURE.

VERY CHALLENGING FORECAST FOR TODAY. ATMOSPHERE IS FAIRLY DRY WITH
PW OF 1.2-1.3 OVER THE AREA AND FORECAST TO INCREASE TO 1.7-1.9" BY
LATE AFTERNOON (THIS MAY BE OVERDONE). FULLY EXPECT THIS S/W COMING
THROUGH TEXAS TO CREATE A LINE OF STORMS BUT THAT IT MAY TURN
NORTHEAST TOWARD THE DALLAS-WACO AREA LATE THIS MORNING AND THIS
AFTERNOON...THE TRICKY PART IS THE SOUTHWARD DEVELOPMENT OF THE LINE
OR A SECOND AREA OF STORMS THAT FORMS OVER THE WESTERN HILL COUNTRY
AND TRACKS INTO THE CWA THIS AFTERNOON...AS WELL AS THE POSSIBILITY
OF ISOLATED THUNDERSTORMS DEVELOPING OVER SETX WITH DAYTIME HEATING
BY AROUND NOON. THE ENVIRONMENT OVER SETX LOOKS TO SUPPORT DECENT
INSTABILITY (LI -5 TO -8 AND CAPE OF 2400-4000...THIS MAY AGAIN BE
DEPENDENT ON THE QUALITY OF MOISTURE RETURN) SHEAR AT LEAST EARLY
TODAY WILL BE QUITE HIGH BUT STILL CAPPED. AS THE HEATING GETS FULLY
UNDERWAY LATE THIS MORNING THE AXIS OF STRONG LL WINDS SHIFTS
WESTWARD AND THE SHEAR LESSENS WITH LESS TURNING AND LESS SPEED
SHEAR. SPC HAS MOST OF THE NORTHWEST HALF OF THE AREA IN ENHANCED
FOR SEVERE POTENTIAL. SO WHAT TO DO WITH THE FORECAST... FOR THIS
MORNING THE RAIN CHANCES LOOK A GOOD DEAL LOWER SO HAVE DROPPED THEM
BACK EXCEPT FOR THE FAR WEST WHERE 50 POPS SHOULD STAND AND ADDED
SHRA THROUGH MID MORNING THEN TSRA AFTER. THIS AFTERNOON THE RAIN
CHANCES LOOK GOOD AS DOES THE POTENTIAL FOR SEVERE (HAIL AND
DAMAGING WINDS BUT CAN`T RULE OUT A BRIEF TORNADO).  WITH ALL OF THE
WIND ALOFT AND THE DRY AIR IN THE MID LEVELS THINKING THAT THESE
STORMS COULD ORGANIZE INTO A LINE AND DEPART THE AREA LATE THIS
AFTERNOON OR THIS EVENING BUT HAVE KEPT RAIN CHANCES THROUGH THE
OVERNIGHT HOURS AS GUIDANCE HASN`T ALWAYS BEEN ON THE MARK WITH THIS
HOLIDAY WEEKEND STORM SYSTEM.  SPEAKING OF WHICH THE HEAVY RAIN
THREAT COULD BE A LITTLE LOWER WITH THE DRY AIR IN THE MID LEVELS
HELPING TO KEEP THE SYSTEM MORE PROGRESSIVE BUT THE SOILS ARE STILL
SATURATED AND MAY SEE THE STORMS TRAINING FOR AN HOUR WHICH COULD
LEAD TO SHORT TERM FLASH FLOODING. HEAVIER RAINS WILL PROBABLY BE
OVER THE NORTHERN AREAS BUT WITH THE GREATER MOISTURE POSSIBLE LATE
THIS AFTERNOON HAVE EXPANDED THE FLASH FLOOD WATCH TO INCLUDE THE
SOUTHERN AREAS THOUGH THE SOUTHERN AREAS ARE MORE IFFY THAN ACROSS
THE NORTH.  EXPECT RAIN CHANCES TO FALL OFF BY EARLY IN THE MORNING
EXCEPT PERHAPS THE EXTREME EASTERN AREAS. TOMORROW SHOULD BE
WARMER...WARM ENOUGH THAT IT WILL BE THE FIRST TIME I HAVE FORECAST
TEMPERATURES TO HIT 90 THIS YEAR. THIS YEAR SHOULD TURN OUT MUCH
LOWER THAN THE RECORD. THE RECORD HIGHS SHOW THE SECOND HEAT WAVE OF
DROUGHT RIDDEN MAY IN 2011 HOLDING MANY RECORDS INCLUDING A WHOPPING
98 AT IAH...SO 5-8 DEGREES SHY OF THE RECORD. RAIN CHANCES SHOULD BE
A GOOD DEAL LOWER AS WELL AND DRIVEN BY DAYTIME HEATING AND PERHAPS
A WEAK SEABREEZE.

45

LONG TERM...
THE LONG TERM PORTION OF THE FORECAST WILL BEGIN WITH SHORTWAVE
RIDGING BUILDING ACROSS THE SOUTHERN PLAINS AHEAD OF ANOTHER
APPROACHING DISTURBANCE. WATER VAPOR IMAGERY EARLY THIS MORNING
SHOWS THIS SYSTEM AS A CLOSED LOW LOCATED OVER THE PACIFIC ROUGHLY
NEAR 29 N 144 W... WITH THIS FEATURE EXPECTED TO BECOME AN OPEN
WAVE AS IT REACHES THE SOUTHWESTERN CONUS ON WEDNESDAY. WITH
RIDGING OVERHEAD MID TO LATE WEEK... TEMPERATURES WILL BE NEAR TO
SLIGHTLY ABOVE NORMAL /NORMALS FOR THIS TIME OF YEAR CONSIST OF
HIGHS IN THE MID TO UPPER 80S AND LOWS IN THE LOW TO MID 70S/.
AMPLE SURFACE MOISTURE AND DAYTIME HEATING WILL ALSO PROMOTE A
SLIGHT CHANCE TO CHANCE FOR SHOWERS AND THUNDERSTORMS WEDNESDAY
THROUGH FRIDAY. THE UPPER WAVE IS EXPECTED TO REACH WESTERN TEXAS
BY FRIDAY AND SWING SLOWLY NORTHEAST OF THE REGION ON SATURDAY AND
SUNDAY... WITH RAIN CHANCES INCREASING OVER THE WEEKEND AS THIS
HAPPENS.

HUFFMAN

MARINE...
SCA CONDITIONS DEVELOPING THIS MORNING AS WINDS INCREASE
AND SEAS BUILD AND SHOULD SEE WINDS CLIMB TO AROUND 20 KNOTS THIS
AFTERNOON. WINDS COME DOWN TOWARD MORNING SO HAVE EXTENDED THE SCA
TO 12Z TUESDAY FOR THE 20-60NM WATERS. TIDES WILL CONTINUE TO RUN
1/2 TO 1 FOOT ABOVE NORMAL AND MAY SEE SOME MORE BEACH FLOODING WITH
THE ELEVATED TIDES COMBINED WITH THE RUNUP. RIP CURRENTS SHOULD
STILL BE STRONGER THAN NORMAL AND WILL CONTINUE THE RIP CURRENT
ADVISORY. A LITTLE LIGHTER WINDS TUESDAY AND A RETURN A MORE
SUMMERTIME PATTERN OF SHOWERS EARLY IN THE MORNING WITH A CHANCE FOR
THUNDERSTORMS LATE MORNING AND AFTERNOON.
45

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      85  72  89  73  86 /  70  40  30  20  20
HOUSTON (IAH)              85  72  89  74  87 /  60  50  30  20  20
GALVESTON (GLS)            84  77  86  79  84 /  60  50  20  20  20

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...FLASH FLOOD WATCH FROM 11 AM CDT THIS MORNING THROUGH THIS
     EVENING FOR THE FOLLOWING ZONES: AUSTIN...BRAZOS...
     BURLESON...COLORADO...GRIMES...HARRIS...HOUSTON...LIBERTY...
     MADISON...MONTGOMERY...POLK...SAN JACINTO...TRINITY...
     WALKER...WALLER...WASHINGTON.

     HIGH RIP CURRENT RISK THROUGH THIS EVENING FOR THE FOLLOWING
     ZONES: BRAZORIA...CHAMBERS...GALVESTON...MATAGORDA.

     FLASH FLOOD WATCH FROM 11 AM CDT THIS MORNING THROUGH THIS
     EVENING FOR THE FOLLOWING ZONES: BRAZORIA...CHAMBERS...FORT
     BEND...GALVESTON...JACKSON...MATAGORDA...WHARTON.

GM...SMALL CRAFT SHOULD EXERCISE CAUTION THROUGH THIS EVENING FOR THE
     FOLLOWING ZONES: GALVESTON BAY...MATAGORDA BAY.

     SMALL CRAFT ADVISORY UNTIL MIDNIGHT CDT TONIGHT FOR THE
     FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP
     CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT
     20 NM.

     SMALL CRAFT ADVISORY UNTIL 7 AM CDT TUESDAY FOR THE FOLLOWING
     ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL
     20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO
     60 NM.

&&

$$

DISCUSSION...14
AVIATION/MARINE...45



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