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000
FXUS64 KHGX 211524
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1024 AM CDT TUE MAY 21 2013

.DISCUSSION...
THE MAIN PROBLEM OF THE DAY CONTINUES TO BE THE TIMING AND
POSSIBILITY OF THUNDERSTORMS...MAINLY OVER THE NORTHERN COUNTIES
THIS AFTERNOON AND EVENING. THERE WAS A SPECIAL SOUNDING CONDUCTED
BY TEXAS A&M WHICH STILL SHOWED A CAP AT AROUND 900 MB. THE HIGH
RES MODEL ARW AND NMM DIFFERED A BIT ON THE TIMING...BUT BOTH
INDICATE THAT THE STORMS SHOULD BEGIN TO AFFECT LOCATIONS ALONG
AND NORTH OF A LINE FROM COLLEGE STATION TO CROCKETT DURING THE
EARLY AND MID EVENING. WILL TRY AND TIME THE EVENTS AFTER THE 12Z
MODELS COME IN. FOR NOW THE CURRENT FORECAST FOR TODAY IS ON TRACK
AND AN UPDATE IS NOT ANTICIPATED.

40

&&

.PREV DISCUSSION... /ISSUED 626 AM CDT TUE MAY 21 2013/

DISCUSSION...
SEE 12Z AVIATION DISCUSSION.

AVIATION...
MVFR CIGS CONTINUE TO MIX OUT THIS MORNING AND FCST SOUNDINGS SHOW
CONDS MIXING OUT TO VFR BETWEEN 15-16Z. A FEW SHOWERS ARE SKIRTING
THE NORTHWEST EDGE OF THE CWA AND ADDED A VCSH FOR KCLL FOR MAINLY
THIS MORNING. MODELS ARE IN GOOD AGREMENT WITH CONVECTION FIRING
OVER NORTH TEXAS LATE THIS AFTN AND MOVING SE TOWARD THE NORTHERN
TAF SITES BY 00Z. WILL TEMPO THUNDER FOR KCLL AND KUTS THIS
EVENING. CONFIDENCE SHRINKS FOR SOUTHERN TAF SITES AS THE
CONVECTION PUSHES SOUTH. HI RES MODELS REMAIN QUITE BULLISH ON
POPS BU NONE OF THE HI RES MODELS HAVE INITIAILIZED WELL SO WILL
CARRY VCTS/VCSH FOR KIAH...KHOU AND KSGR OVERNIGHT. 43

PREV DISCUSSION... /ISSUED 355 AM CDT TUE MAY 21 2013/

DISCUSSION...
WARM AND HUMID EARLY MORNING ACROSS THE REGION THE CONTINUED
SOUTHERLY FLOW. UPPER TROUGH OVER THE GREAT PLAINS AND EXTENDING
DOWN TOWARD EL PASO THIS MORNING. VERY STRONG CAP IN PLACE THIS
MORNING WITH A FEW BITS OF LIGHT RAIN AND DRIZZLE SHOWING UP ON
RADAR AND OUT THE WINDOW...MAINLY OVER THE SOUTHERN AREAS. THE
UPPER TROUGH WILL SLOWLY SHIFT EAST WITH S/W OVER AZ/NM THIS
MORNING TRACKING EAST THROUGH THE AFTERNOON THEN ENE. THIS FEATURE
SHOULD COMBINE WITH THE STRONG MID/UPPER LEVEL FLOW TO
DRAMATICALLY INCREASE LIFT AFTER 3 PM AND AROUND THE CLL-DKR AREAS
PEAKING AFTER 7 PM. MODEL SOUNDINGS ARE FAVORABLE FOR STRONG TO
SEVERE THUNDERSTORMS. FRONTAL BOUNDARY PUSHES EAST WITH RAIN
COOLED AIR AND EXPECTING SHOWERS AND THUNDERSTORMS TO EXPAND
RAPIDLY IN COVERAGE BUILDING SOUTH INTO AUSTIN AREA THEN MOVING
EASTWARD. VERY UNSTABLE 3000-4000 J/KG ATMOSPHERE TO WEST OF THE
SETX WILL BE THE INITIATION ZONE BUT SHOULD BE REACHING THE CLL
AREA AROUND 6 PM WITH INSTABILITY DECREASING. EXPECT SEVERE THREAT
OF MAINLY HAIL AND DAMAGING WINDS BETWEEN AROUND 5 PM THROUGH
MIDNIGHT FOR THE NORTHERN AREAS WITH THE ARRIVAL OF S/W AND THE
ASSOCIATED COLD FRONT. TORNADO THREAT LOOKS LOW BUT CAN`T RULE OUT
SHORT LIVED SPIN UPS BUT WILL PROBABLY BE CONFINED TO AREAS NORTH
OF BRENHAM TO GROVETON LINE (GREATEST EHI 2.0+ FROM MADISONVILLE
TO CROCKETT BUT OUT AHEAD OF CAP ERODING). DO HAVE SOME CONCERNS
WITH THE STRONG COOLING ALOFT THAT THE SEVERE THREAT COULD NEED
EXTENDING BEYOND 06Z AND EXPANDING TO THE COASTAL AREAS. TEXAS
TECH WRF AND SOME OF THE HIGH RES ARW/NMM MODELS INDICATING
POSSIBLY SQUALL LINE/BOW DEVELOPING AND MOVING THROUGH HOUSTON AND
TO GALVESTON BETWEEN MIDNIGHT AND 2 AM. DIMINISHING INSTABILITY
AND RETURN OF CAP SHOULD LIMIT THAT OUTCOME. SO AS FOR THE
FORECAST HAVE RAISED RAIN CHANCES FOR AREAS GENERALLY NORTH OF
I-10 THIS AFTERNOON AND OVERNIGHT. BOUNDARY PUSHES TO NEAR THE
COAST AND SLOWS AND WILL RAISE THE RAIN CHANCES FOR WEDNESDAY IN
THE SOUTH WITH THE CAP ERODING IN THE AFTERNOON AND CAPE OF
1800-2500 RETURNING AND SLOW/ERRATIC STORM MOTIONS...MAY HAVE SOME
BRIEF HEAVY DOWNPOURS GIVEN THE LIGHT STEERING WINDS AND COUNTER
TO SEA BREEZE FLOW ALOFT.

UPPER RIDGE EXPANDS UP OUT OF MEXICO THURSDAY THROUGH SUNDAY WITH
THE 500 RIDGE CENTERED OVER SETX SATURDAY AN SUNDAY. THIS SHOULD
LEAD TO WARMER TEMPERATURES RETURNING AND HAVE GONE ABOVE GUIDANCE
FOR THE AFTERNOON FRI-SUN TIMEFRAME TEMPERATURES. RAIN CHANCES
FALL OFF AND MOIST SOUTHEAST FLOW RESUMES. ALSO OF INTEREST LOOKS
TO BE A TROPICAL WAVE MOVING OUT OF THE CARIBBEAN AND POSSIBLY
IMPACTING SETX AND WESTERN GULF MONDAY AND TUESDAY NEXT WEEK.

ON A TECHNICAL NOTE...SURFACE OBSERVATION AND LIGHTNING DATA
OUTAGE 04-07Z APPEARS TO BE CORRECTED.

MARINE...
MODERATE TO OCCASIONALLY STRONG ONSHORE WINDS WILL PERSIST INTO THIS
EVENING BEFORE BEGINNING TO DIMINISH WEDNESDAY AND THURSDAY. LIGHT
TO MODERATE ONSHORE WINDS WILL PREVAIL THROUGH NEXT WEEKEND AS
SURFACE HIGH PRESSURE RIDGES INTO THE NORTHERN GULF COAST. WILL
MAINTAIN AN SCEC FOR TODAY FOR THE GULF WATERS. TIDE LEVELS WILL
REMAIN SLIGHTLY ELEVATED TODAY AND RETURN TO NORMAL LEVELS
WEDNESDAY. 43

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      91  73  89  72  91 /  30  40  20  10  10
HOUSTON (IAH)              91  73  88  72  90 /  20  50  30  10  20
GALVESTON (GLS)            80  75  81  75  81 /  10  30  30  10  20

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 4 PM CDT THIS
     AFTERNOON FOR THE FOLLOWING ZONES: 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.

&&

$$

DISCUSSION...40
AVIATION/MARINE...41