Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 241132
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
632 AM CDT FRI APR 24 2015

.DISCUSSION...
SEE THE 12Z AVIATION DISCUSSION BELOW.

40

&&

.AVIATION...
THE BIGGEST CONCERN WILL BE THE CHANCES FOR THUNDERSTORMS TODAY.
LIKED THE HRRR MODEL FOR HOW IT INITIALIZED AND CONTINUES TO
DEPICT THE THUNDERSTORMS IN THE HILL COUNTRY.

THE THUNDERSTORMS OCCURRING OVER THE HILL COUNTRY WERE APPROACHINGKCLL
AT 11Z. THE HRRR BRINGS THE BEST CHANCES FOR THUNDERSTORMS ACROSS
KCLL AND KUTS THROUGH 18Z. ALTHOUGH WIDESPREAD STORMS WILL LIKELY
OCCUR TO THE NORTH...BOTH KCXO AND KIAH SHOULD SEE A WINDOW OF
HIGHEST CHANCES FROM ABOUT 15Z THROUGH 18Z.

THE HIGH PRESSURE RIDGE OVER THE GULF WAS PROVIDING A STRONGER
CAP OVER THE REMAINING SITES...ALTHOUGH THE MODELS ERODE THIS CAP
LATER THIS MORNING. BECAUSE OF THIS...KHOU AND KSGR SHOULD SEE
SHOWER OR THUNDER CHANCES AFTER 14Z. KLBX AND KGLS WILL HAVE A
MORE DIFFICULT TIME. THE BEST CHANCES WILL LIKELY BE DURING THE
MID AND LATE MORNING PERIOD AS THE REMNANTS OF A MESO-SCALE
CONVECTIVE COMPLEX THAT AFFECTED SOUTH TEXAS EARLIER THIS MORNING
MOVE UP THE COASTAL AREAS. THESE REMNANTS MAY PROVIDE ENOUGH LIFT
FOR ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORM THROUGH MIDDAY.

40

&&

.PREV DISCUSSION... /ISSUED 547 AM CDT FRI APR 24 2015/

UPDATE...
RAISING POPS PER RADAR TRENDS.

DISCUSSION...
WILL RAISE POPS FOR THIS MORNING AS CONVECTION IS FIRING ALONG A
WEAK 850 MB BOUNDARY. CONVECTION IS BACKBUILDING TO THE E-SE IN
LESS MODIFIED AIR. NEW ZONES OUT SHORTLY. 43

PREV DISCUSSION... /ISSUED 401 AM CDT FRI APR 24 2015/

DISCUSSION...
AT 2 AM...A WEAK SURFACE TROUGH EXTENDED FROM ABOUT TYLER TO HONDO
TO DEL RIO. A WEAK MESO-HIGH WAS LOCATED NEAR SAN ANGELO. RADAR
SHOWS A DECAYING MCS OVER DEEP SOUTH TEXAS. THIS FEATURE COULD
SEND A PATCH OF LIGHT RAIN INTO THE SOUTHWEST ZONES THIS MORNING
BUT WILL PROBABLY SEND A WEAK BOUNDARY THAT COULD SERVE AS A
FOCUS FOR SHRA/TSRA DEVELOPMENT LATER THIS MORNING. FURTHER
WEST...A CLUSTER OF STRONG STORMS IN DIMMIT AND LA SALLE COUNTIES
IS MOVING E-NE AND WILL BE APPROACHING SE TX BETWEEN 13-14Z. NOT
SURE THESE STORMS WILL HOLD TOGETHER BUT AGAIN COLD SEND OFF AN
OUTFLOW TO SERVE AS FOCUS FOR ADDITIONAL DEVELOPMENT.

MOISTURE LOOKS PLENTIFUL TODAY WITH PW VALUES PROGGED TO EXCEED
2.00 INCHES OVER PARTS OF SE TX. 850 MB TD AT BRO WAS 17 C AND 15C
AT CRP AT 00Z. THERE ALSO LOOKS LIKE THERE IS A WEAK TROUGH AT 850
MB EXTENDING THE LOUISIANA COAST TO AROUND LAREDO. THERE IS ALSO
EVIDENCE OF WEAK 850 MB HIGH PRESSURE OVER THE WESTERN GULF. 700
MB LOOKS DRY WITH MORE PRONOUNCED RIDGING ALONG THE TEXAS COAST.
AT 250 MB...A RIBBON OF FASTER SPEEDS EXTENDED ACROSS THE
TENNESSEE VALLEY AND A SECONDARY SPEED MAX NEAR EL PASO. WEAK
RIDGING WAS AGAIN NOTED OVER THE WESTERN GULF.

MODELS NOT IN THE BEST AGREEMENT TODAY OF WHEN AND WHERE
CONVECTION WILL DEVELOP. THE TEXAS TECH WRF DID NOT INITIALIZE
WELL BUT IT SEEMS TO BE HANDLING THE CONVECTION OVER SW TX FAIRLY
WELL WHILE THE HRRR AND RAP SEEMED TO INITIALIZE WELL AT 08Z.
THE JET STRUCTURE DOES NOT LOOK FAVORABLE TODAY WITH THE BEST
DIVERGENCE OVER NORTH TEXAS BUT SE TX REMAINS VERY UNSTABLE AND
FCST SOUNDINGS SHOW TREMENDOUS INSTABILITY WITH CAPES AOA 3000
AND LI VALUES -10 AND LAPSE RATES ABOVE 7.0. HOWEVER THIS
INSTABILITY NEEDS TO BE TAPPED BY A PASSING S/WV OR SOME KIND OF
SFC TRIGGER AND THIS IS WHERE THINGS BECOME LESS CLEAR. OTHER THAN
OUTFLOW BOUNDARIES...JUST CAN`T FIND A WELL DEFINED CATALYST TO
TRIGGER SHRA/TSRA. THE OTHER CONCERN REGARDING CONVECTION IS THE
850-500 RIDGE OVER THE GULF THAT IS IMPINGING ON SE TX. AM A BIT
NERVOUS THAT THIS FEATURE WILL IMPART A BIT OF SUBSIDENCE ALONG THE
COAST AND SHUNT MUCH OF TODAYS PRECIP TO THE WEST. WILL MAINTAIN
LIKELY POPS OVER THE NORTH AND CHANCE POPS CENTRAL. WILL ALSO
MAINTAIN SEVERE WORDING OVER THE NORTH BUT YOU CAN`T RULE A SEVERE
STORM ANYWHERE IN THE CWA AS INSTABILITY IS IMPRESSIVE OVER THE
ENTIRE AREA.

PRECIPITATION POTENTIAL WILL INCREASE AGAIN TONIGHT INTO EARLY
SATURDAY AS SE TX LIES IN A RRQ FOR A TIME. THE SPEED MAX WILL
EXIT BY LATE SATURDAY MORNING AND RAIN WILL DIMINISH QUICKLY WITH
A W-SW SFC WIND DEVELOPING. CLOUDS WILL BREAK IN THE AFTN AND WITH
A W-SW WIND...AM EXPECTING TEMPS TO WARM UP QUICKLY. SUNDAY STILL
LOOKS IFFY AS WINDS ALOFT STAY OUT OF THE SW. WILL INTRODUCE 20
POPS FOR SUNDAY. BY SUNDAY NIGHT...AN UPPER LEVEL LOW WILL
APPROACH TX FROM THE WEST. THIS FEATURE WILL TRIGGER ANOTHER ROUND
OF SHRA/TSRA SUN NITE INTO MON NITE. SOME OF THE STORMS COULD
AGAIN BE STRONG. A COLD FRONT WILL CROSS THE COAST ON TUES
MORNING. MUCH COOLER AND DRIER WEATHER IS EXPECTED IN THE WAKE OF
THE FRONT. 43

MARINE...
ONSHORE WINDS WILL PERSIST THROUGH THE WEEKEND. THERE IS A SLIGHT
CHANCE FOR THUNDERSTORMS TODAY...WITH BETTER CHANCES LATE TONIGHT
INTO SATURDAY. A COLD FRONT IS EXPECTED TO MOVE OFF THE COAST EARLY
TUESDAY. MODERATE TO STRONG OFFSHORE WINDS FOLLOWING THE FRONTAL
PASSAGE MAY REACH INTO ADVISORY CRITERIA AS EARLY AS TUESDAY
AFTERNOON AND PERSIST INTO TUESDAY NIGHT.

40

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      84  70  88  68  88 /  60  50  20  10  20
HOUSTON (IAH)              84  72  88  70  88 /  50  40  50  10  20
GALVESTON (GLS)            78  73  83  73  80 /  30  40  50  10  10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&

$$

DISCUSSION...43
AVIATION/MARINE...40



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