Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 261446
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
946 AM CDT SUN APR 26 2015

.DISCUSSION...
UPDATING THIS MORNING FOR SHOWERS AND THUNDERSTORMS THAT HAVE
DEVELOPED ALONG A CONVERGENCE BOUNDARY FROM NEAR GALVESTON TO
PALACIOS TO AUSTIN. S/W LIFTING OUT THROUGH WEST TEXAS BRINGING
LIFT WELL TO THE EAST BUT AREA 12Z SOUNDINGS LOW LEVELS LOOK
MOISTURE STARVED AND CAPPED BUT ALOFT MOISTURE SURGING INTO THE
AREA AND THE STORMS DON`T APPEAR TO BE ROOTED IN THE SURFACE. SO
HAVE RAISED POPS ACROSS MOST OF THE AREA TO COINCIDE WITH THE S/W
PASSAGE TODAY. CLOUDS ALSO ABUNDANT SO HAVE ADJUSTED SKY COVER AND
PARED BACK HIGH TEMPERATURES A DEGREE OR TWO.
45

&&

.PREV DISCUSSION... /ISSUED 641 AM CDT SUN APR 26 2015/

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

40

AVIATION...
AN AREA OF SCATTERED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED
ACROSS SOUTH TEXAS THROUGH MATAGORDA BAY. THESE SHOULD APPROACH
KGLS AND KLBX AROUND OR SHORTLY AFTER 12Z...WITH AT LEAST A CHANCE
FOR SHOWERS EXTENDING INLAND DURING THE MID MORNING PERIOD ACROSS
KSGR AND KHOU. THERE IS AN OUTSIDE CHANCE THE SHOWERS COULD WORK
THEIR WAY AS FAR INLAND AS KIAH.

THE LIFR/IFR CONDITIONS SHOULD LIFT DURING THE MID TO LATE MORNING
PERIOD. MIXING IN THE WEST WILL LEAD TO BREEZY CONDITIONS AT LEAST
AT KCLL DURING THE AFTERNOON.

TONIGHT WILL SEE A RETURN TO LOW CEILINGS AS THE MOIST AIRMASS
CONTINUES TO ADVECT IN FROM THE GULF. SHOWERS AND THUNDERSTORMS
WILL BECOME MORE PREVALENT OVER KCLL AND KUTS AFTER 06Z AS A COLD
FRONT APPROACHES FROM NORTH TEXAS. SOME OF THE MODELS BRING THE
STORMS IN KCXO BEFORE 12Z AND INTO KIAH BETWEEN 12Z AND 18Z. THERE
IS A SLIGHT RISK ON MONDAY FOR STRONG OR SEVERE STORMS WITH STRONG
WIND GUSTS...HAIL...AND ISOLATED TORNADOES THE MAIN THREATS.

40

PREV DISCUSSION... /ISSUED 400 AM CDT SUN APR 26 2015/

DISCUSSION...
FOG HAS DEVELOPED OVER MOST OF SE TX EARLY THIS MORNING AND
CONDITIONS LOOK FAVORABLE FOR THE FOG TO PERSIST THROUGH THE EARLY
MORNING HOURS. WILL WATCH TRENDS AND A DENSE FOG ADVISORY MAY YET
BE REQUIRED BUT ONLY ONLY KBYY MEETS THE CRITERIA OF 1/4SM. FLOW
ALOFT REMAINS OUT OF THE SW AND BOTH THE GFS AND NAM SHOW A WEAK
UPPER LEVEL DISTURBANCE THIS AFTN ALONG WITH AN INCREASE IN PW
VALUES. FCST SOUNDINGS SHOW VERY DRY AIR IN THE 850-700 LAYER
STILL FEEL THE WEAK DISTURBANCE COULD GENERATE A FEW SHRA/TSRA SO
WILL MAINTAIN THE 20 POPS TODAY.

AN UPPER LEVEL LOW OVER AZ WILL MOVE EAST AND APPROACH THE TEXAS
PANHANDLE TONIGHT. PW VALUES BEGIN TO INCREASE AND SHOULD 1.7-1.9
INCHES BY MONDAY 12Z. SE TX WILL LIE IN A WEAK COUPLET BETWEEN
12Z-18Z MON. THE BEST DYNAMICS APPEAR TO BE MONDAY MORNING IF THE
GFS/ECMWF ARE TO BE BELIEVED. THE CANADIAN...NAM12...TEXAS TECH
WRF AND ARW/NMM ALL TARGET THE AREA IN THE AFTERNOON PRIMARILY
BECAUSE THEY ARE A BIT SLOWER WITH THE UPPER LEVEL TROUGH. NOT
EXACTLY CONFIDENT WITH REGARD TO THE TIMING ON MONDAY SO WILL
BROAD BRUSH LIKELY POPS AND WAIT FOR THE MODELS TO RESOLVE TIMING
DIFFERENCES. FCST SOUNDINGS ARE IN VERY GOOD AGREEMENT THAT THERE
WILL BE SOME TYPE OF SEVERE WEATHER WITH THE STORMS WHEN THEY
DEVELOP. CAPE VALUES ARE BETWEEN 3000-4000...LI VALUES ARE -10...
SWEAT INDEX IS OVER 400 AND THERE LOOKS LIKE THERE WILL BE PLENTY
OF SHEAR. WILL ADD SEVERE WORDING TO THE NORTHERN ZONES FOR
TONIGHT AFTER 06Z. SPC HAS OUTLOOKED THE NORTHWEST THIRD OF SE TX
IN SLIGHT RISK OVERNIGHT AND ALL OF SE TX IN SLIGHT RISK ON
MONDAY. THERE IS ALSO SOME POTENTIAL FOR HEAVY RAIN ON MONDAY
DEPENDING ON WHERE STORMS DEVELOP AND HOW MUCH TRAINING OF STORMS
OCCURS. WPC HAS OUTLOOKED THE EASTERN HALF OF THE AREA IN
EXCESSIVE RAINFALL FOR MONDAY.

A COLD FRONT WILL CROSS SE TX LATE MONDAY NIGHT WITH BREEZY NW
WINDS DEVELOPING IN THE WAKE OF THE FRONT. WRAP AROUND CLOUD
COVER...BRISK N-NW WINDS AND COLD AIR ADVECTION WILL PREVAIL ON
TUESDAY. THE UPPER TROUGH WILL STILL BE CLOSE AND THIS FEATURE
WILL PROBABLY GENERATE A FEW SHOWERS OVER MAINLY THE NE PART OF
THE AREA. SKIES BEGIN TO CLEAR TUES NIGHT AND GENERALLY CLEAR TO
PT CLOUDY SKIES WILL PREVAIL THROUGH FRIDAY. THE UPPER TROUGH
MOVES EAST ON WED BUT A PIECE OF OF THE UPPER TROUGH RETROGRADES
INTO SE TX ON THURSDAY. IT LOOKS TOO DRY TO GENERATE PRECIP BUT
500 HTS LOWER TO 567 DM SO THURSDAY WILL REMAIN UNSEASONABLY COOL.
MOISTURE RETURNS NEXT WEEKEND ALONG WITH A WARM UP. A WEAK SHORT
WAVE COUPLED WITH THE DEEPER MOISTURE WILL PRODUCE A FEW SHOWERS
BY NEXT SUNDAY. 43

MARINE...
ONSHORE WINDS WILL PERSIST THROUGH MONDAY. ON MONDAY ANOTHER ROUND
OF THUNDERSTORMS ARE EXPECTED WITH ISOLATED STRONG STORMS POSSIBLE. A
COLD FRONT WILL THEN MOVE OFF THE COAST MONDAY NIGHT OR EARLY
TUESDAY MORNING. A CONSENSUS OF THE MODELS GENERATES ADVISORY
CRITERIA WIND SPEEDS TUESDAY INTO WEDNESDAY MORNING...WITH
DIMINISHING WINDS ON WEDNESDAY. HIGH PRESSURE WILL THEN MOVE INTO
THE GULF WATERS BY FRIDAY.

40

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      88  69  81  59  69 /  30  50  60  40  20
HOUSTON (IAH)              88  72  82  64  72 /  30  30  60  50  20
GALVESTON (GLS)            79  74  78  69  73 /  40  20  60  40  10

&&

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

$$

DISCUSSION...45


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