Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS64 KHGX 271120
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
620 AM CDT WED AUG 27 2014

.DISCUSSION...

SEE AVIATION.

&&

.AVIATION...

A FEW SHWRS NEAR THE COAST THIS MORNING...BUT MOST ACTIVITY IS
WELL OFFSHORE. WILL SEE SCT SHWRS AND ISO TSTMS DEVELOP INLAND
AROUND MID/LATE MORNING. ALTHOUGH I AM PRETTY CONFIDENT THAT WE
WILL SEE SCT ACTIVITY AS FAR INLAND AS SGR-HOU BY EARLY AFT...NOT
SURE HOW MUCH COVERAGE WE WILL SEE AT IAH AND AT CXO. OPTED TO
JUST HAVE AFT/EVE VCSH FOR NOW. WINDS WILL SHIFT FROM THE NE TO E
DURING THE DAY AND INCREASE ACROSS INLAND AREAS TO 10-12 KTS AROUND
MID-DAY. 33

&&

.PREV DISCUSSION... /ISSUED 411 AM CDT WED AUG 27 2014/

DISCUSSION...
WATER VAPOR IMAGERY THIS MORNING SHOWS CLOCKWISE FLOW AROUND AN
UPPER LEVEL RIDGE OVER THE CENTRAL GULF WITH A WEAK STRETCHED OUT
TUTT LOW OVER THE UPPER TX COAST. THIS IS SANDWICHED WITH ANOTHER
RIDGE CENTERED OVER THE OZARKS. UPPER LEVEL TROUGH REMAINS OVER
THE GREAT BASIN WITH WEAKLY AMPLIFIED FLOW ACROSS THE N PLAINS
THROUGH NEW ENGLAND STATES. SFC ANALYSIS THIS MORNING SHOWS TROUGH
OF LOW PRESSURE OFF THE UPPER TX COAST. RADAR SHOWS CONVECTION
FROM THE OFFSHORE WATERS OF THE UPPER TX COAST TO THE LA COAST.
NHC GIVES THIS DISORGANIZED TROUGH A 10 PERCENT CHANCE OF TROPICAL
DEVELOPMENT OVER NEXT 5 DAYS. IR SATELLITE IS SHOWING SOME COLDER
CLOUD TOPS WITH THE CONVECTION AS IT BEGINS TO MOVE CLOSER TO THE
COAST. OVERALL CONDITIONS ARE NOT FAVORABLE FOR TROPICAL
DEVELOPMENT UNLESS THE SYSTEM CAN BECOME BETTER ORGANIZED.

SFC ANALYSIS ALSO SHOWS A BAND OF SLIGHTLY DRIER AIR WITH
DEWPOINTS IN THE 60S MOVING INTO E TX FROM LA. GOES SOUNDER PW
IMAGERY SHOWS LOWER PRECIP WATER VALUES OF LESS THAN 1.5 INCHES
OVER THE AREA AS WELL. THERE SHOULD BE A SUBSTANTIAL GRADIENT IN
THUNDERSTORM CHANCES DUE TO THIS MOISTURE GRADIENT. FORECAST WILL
KEEP HIGHER POPS OF 50/60 PERCENT ALONG THE COAST AND TIGHTEN UP
AGAINST LOWER POPS INLAND. DO THINK THUNDERSTORM CHANCES SHOULD
INCREASE ALONG THE COAST BY THE AFTERNOON WITH DAY TIME HEATING
BUT AGAIN THERE SHOULD BE A TIGHT GRADIENT IN PRECIP. THAT SAID
GIVEN HIGH MOISTURE CONTENT...SOME STORMS COULD DROP 1-2 INCHES OF
RAIN IN AN HOUR SO LOCALIZED FLOODING COULD BE AN ISSUE ESPECIALLY
IF STORMS TRAIN OVER THE SAME AREAS. THIS WILL BE MAINLY ALONG THE
COAST LATE THIS MORNING INTO EARLY AFTERNOON.

FORECAST WILL KEEP THUNDERSTORM CHANCES IN THE FORECAST THROUGH
THE END OF THE WEEK. UPPER LEVEL LOW OVER THE GREAT BASIN WILL
MOVE INTO THE PLAINS THUR/FRI WHICH WILL CONTRIBUTE TO A WEAKNESS
IN THE UPPER LEVEL RIDGE OVER TX. PRECIP WATER VALUES OF AROUND 2
INCHES WILL REMAIN AROUND THE AREA INTO THE WEEKEND. MODEL
SOUNDINGS SUPPORT CONVECTIVE TEMPS IN THE UPPER 80S TO LOW 90S SO
THUNDERSTORM DEVELOPMENT IN THE EARLY AFTERNOON SEEMS POSSIBLE
EACH DAY. BEST MOISTURE APPEARS TO MOVE INTO THE AREA TODAY AND
THEN AGAIN FRI INTO SAT. DECIDED TO KEEP MAINLY 40/50 POPS IN THE
FORECAST THROUGH SATURDAY. PRECIP WATER VALUES START TO DROP OFF
ON SUNDAY INTO MONDAY SO HAVE 20/30 POPS IN THE FORECAST FOR THOSE
DAYS. THE UPPER LEVEL TROUGH ALSO LIFTS OUT SATURDAY SO RIDGING
BEGINS TO INCREASE ALOFT SUN INTO MON. EARLY NEXT WEEK BOTH
GFS/ECMWF MAINTAIN A WEAK RIDGE WITH ZONAL FLOW ACROSS THE
NORTHERN TIER STATES.

MAIN HAZARD TODAY AND THE NEXT COUPLE OF DAYS WILL BE LOCALLY
HEAVY RAINFALL MAINLY ALONG THE COAST. TROUGH AXIS SHOULD MOVE
INLAND TOMORROW INTO FRI WHICH WOULD STILL PROVIDE LIFT FOR
THUNDERSTORM ACTIVITY. WITH PRECIP WATER VALUES POSSIBLY TOPPING
OUT AROUND 2.4 INCHES...COULD EASILY SUPPORT STORMS WITH 1-2
INCHES AN HOUR RAIN RATES. OVERALL THINK FLASH FLOOD THREAT IS
SMALL EXCEPT FOR URBAN AREAS WITH POOR DRAINAGE OR TYPICAL LOW
LYING AREAS. THERE MAY BE SOME QUICK RESPONSES TO HEAVY RAINFALL
WITH HOUSTON`S BAYOU SYSTEM BUT AGAIN WOULD THINK RUNOFF WOULD
REMAIN IN BANKS.

TEMPERATURES WILL BE DIFFICULT SINCE THE FORECAST INVOLVES
CONVECTION. CLOUD COVER AND CONVECTION MAY HOLD MAX TEMPS TODAY
INTO THE LOW 90S ALONG THE COAST WITH MID/UPPER 90S FARTHER INLAND
MAINLY NORTH OF HOUSTON. LOOK FOR SIMILAR GRADIENT IN TEMPS THE
NEXT COUPLE OF DAYS BUT THINK MAX TEMPS MAY BE CLOSER TO THE LOW
90S FARTHER INLAND FOR THUR/FRI/SAT. MIN TEMPS IN THE 70S LOOKS ON
TRACK FOR THE NEXT WEEK. MAX TEMPS MAY INCREASE AGAIN MON/TUE NEXT
WEEK AS THE RIDGE BEGINS TO GRADUALLY BUILD OVER THE AREA.

39

MARINE...
EAST/NORTHEAST WINDS WILL CONTINUE ACROSS THE COASTAL WATERS AS A
TROUGH OF LOW PRESSURE OFFSHORE PRODUCES NUMEROUS SHOWERS AND
THUNDERSTORMS. THIS TROUGH WILL CONTINUE TO PRODUCE SHOWERS AND
THUNDERSTORMS ACROSS THE COASTAL WATERS THROUGH EARLY FRIDAY AS IT
DRIFTS TO THE SOUTHWEST. SEAS OFFSHORE HAVE BUILT TO 4 TO 5 FEET
AND WINDS WILL BE CLOSE TO CAUTION LEVELS IN THE 15 TO 20 KT RANGE
TODAY AND TONIGHT. TIDES WILL REMAIN SLIGHTLY ABOVE NORMAL THIS
WEEK WITH THE MODERATE ONSHORE FLOW.

33

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      97  75  95  75  94 /  20  10  30  20  50
HOUSTON (IAH)              94  76  92  77  91 /  50  30  50  20  50
GALVESTON (GLS)            90  80  89  81  88 /  60  40  50  30  50

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION THROUGH THIS EVENING 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...39
AVIATION/MARINE...33



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.