000
FXUS64 KHGX 210855
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
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 THROUGH 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...45