Alert archive / Texas / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 71, NWS Houston/Galveston, TX

April 18, 2009Chambers County, Texas

NWS Houston/Galveston, TX issued this severe thunderstorm warning at Apr 18, 2009, 3:33 PM CDT for Chambers County, Texas. It was in force for 42 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Apr 18, 2009, 3:33 PM CDT (20:33 UTC)
Expired: Apr 18, 2009, 4:15 PM CDT
In force: 42 min
Issued by: NWS Houston/Galveston, TX
Area: Storm-based polygon

County Chambers County, TX

The radar

The Houston radar (KHGX), 47 km from the middle of the area, began a volume at 20:34 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Apr 18, 9:53 AM CDT	Tornado Watch	SPC	6 hr

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 12:00Z, 8.6 hours before the alert went out and 149 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 778 J/kg
Mixed-layer CIN: -108 J/kg
Mixed-layer LCL: 573 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: 160 m²/s²
0-3 km storm-relative helicity: 499 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 8.3

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Houston/Galveston, TX wrote its last area forecast discussion before this severe thunderstorm warning went out at Apr 18, 3:23 PM CDT, 10 minutes earlier.

Area forecast discussion, Apr 18, 3:23 PM CDT, 10 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
323 PM CDT SAT APR 18 2009

.DISCUSSION...
ISSUED A COASTAL FLOOD STATEMENT FOR THE GALVESTON BAY AREA.

&&

.MARINE...
VERY STRONG EASTERLY FLOW HAS JACKED TIDES UP TO 2 TO 4.5 FEET
AND HAVE A SHORT DURATION COASTAL FLOOD STATEMENT OUT FOR THIS
EVENT.
45

&&

.PREV DISCUSSION... /ISSUED 319 PM CDT SAT APR 18 2009/

DISCUSSION...
THE STRONGEST SHOWERS AND THUNDERSTORMS...SOME PRODUCING EXTREMELY HEAVY
RAINFALL AND SUSTAINED WINDS EASILY REACHING 40 TO 50 MPH...CONTINUE
TO WORK THEIR WAY FURTHER TOWARD THE EAST AND THE COAST WHERE THE BEST
INSTABILITY RESIDES. AMAZINGLY IMPRESSIVE HEAVY RAIN PRODUCING STORMS
ARE BEGIN FED BY STRONG EAST TO SOUTHEAST WINDS...EAGLE POINT AT 2:36
PM HAD SUSTAINED ESE WINDS AT 37 KNOTS. RAINFALL RATES OF AT LEAST 3
TO 4 INCHES PER HOUR HAVE BEEN COMMONPLACE WITH TODAYS STORMS RESULTING
IN SERIOUS FLOODING AS PRECIPITABLE WATER VALUES HAVE TOPPED 2 INCHES
PER GPS MET DATA. PEARLAND RECORDED 1.53 INCHES OF RAIN IN 12 MINUTES
BETWEEN 2:25 PM AND 2:37 PM. FOR NOW...THE FLOOD WATCH FOR THE REMAINING
COUNTIES IS STILL SET TO EXPIRE THIS EVENING. THIS LOOKS TO BE ON TRACK.
THE RISK FOR SEVERE WEATHER HAS DIMINISHED FOR LOCATIONS FURTHER INLAND...AND
WELL ADDRESS THIS AGAIN AROUND THE EXPIRATION TIME FOR TORNADO WATCH
165. THE REST OF THE FORECAST HAS NOT CHANGED. EXPECT A DRIER AIRMASS
TO BEGIN TO FILTER INTO THE AREA THIS EVENING WITH ALL RAINS COMING
TO AN END OVERNIGHT. PATCHY FOG IS POSSIBLE OVERNIGHT AND EARLY TOMORROW
MORNING IF WE CAN GET SKIES TO CLEAR. A DRY NORTHWEST FLOW ALOFT WILL
BRING COOLER NIGHTS AND MILD DAYS TO THE AREA THROUGH MIDWEEK. A RETURN
FLOW SETS UP FOR THE SECOND HALF OF THE WEEK RESULTING IN A WARMING
TREND. AFTER A DRY WEEK...WE COULD SEE SOME STREAMER SHOWER DEVELOPMENT
NEXT WEEKEND.  42

AVIATION...
A CLUSTER OF STRONG STORMS WILL PERSIST OVER HOUSTON AREA TAF
SITES THIS AFTERNOON. HAVE BUMPED WINDS UP IN THE TAFS NEAR
STORMS. MISERABLE FLYING WEATHER EXPECTED WITH CIGS MVFR TO LIFR.
CLEARING CONDITIONS EXPECTED OVER N/NW TAF SITES THIS AFTERNOON.
SKIES WILL BRIEFLY CLEAR TONIGHT BUT WITH ABUNDANT LOW LEVEL
MOISTURE...LIGHT WINDS AND SFC DEW POINTS IN THE LOWER 60S...FEEL
DENSE FOG IS A GOOD BET. VFR CONDITIONS EXPECTED AFTER 15Z SUNDAY.
43

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      74  59  79  50  76 /  30  30  10   0   0
HOUSTON (IAH)              76  63  82  52  77 /  70  60  10   0   0
GALVESTON (GLS)            74  67  78  60  75 /  70  70  10   0   0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...FLOOD WATCH UNTIL 9 PM CDT THIS EVENING FOR THE FOLLOWING ZONES:
     AUSTIN...BRAZORIA...CHAMBERS...COLORADO...FORT BEND...
     GALVESTON...HARRIS...JACKSON...LIBERTY...MATAGORDA...
     MONTGOMERY...POLK...SAN JACINTO...WALLER...WHARTON.

GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 11 PM CDT THIS EVENING
     FOR THE FOLLOWING ZONES: GALVESTON BAY...MATAGORDA BAY.

     SMALL CRAFT ADVISORY UNTIL 1 AM CDT SUNDAY FOR THE FOLLOWING
     ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL
     OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM.

     SMALL CRAFT ADVISORY UNTIL 7 AM CDT SUNDAY 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...30
AVIATION/MARINE...45

Hazardous weather outlook, Apr 18, 3:44 AM CDT, 11 hours 49 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
344 AM CDT SAT APR 18 2009

GMZ330-335-350-355-370-375-TXZ163-164-176>179-195>200-210>214-226-
227-235>238-191200-
AUSTIN-BRAZORIA-BRAZOS-BURLESON-CHAMBERS-COLORADO-FORT BEND-
GALVESTON-GALVESTON BAY-GRIMES-HARRIS-HOUSTON-JACKSON-LIBERTY-
MADISON-MATAGORDA-MATAGORDA BAY-MONTGOMERY-POLK-SAN JACINTO-
TRINITY-WALKER-WALLER-WASHINGTON-
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-
WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM-WHARTON-
344 AM CDT SAT APR 18 2009

...LOCALLY HEAVY RAINFALL AND FLOODING POSSIBLE ACROSS SOUTHEAST
TEXAS THROUGH THIS EVENING...

...SLIGHT RISK OF SEVERE THUNDERSTORMS THROUGH THIS EVENING...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST TEXAS.

.DAY ONE...TODAY AND TONIGHT

DISTURBANCES ROTATING AROUND A STRONG STORM SYSTEM WILL CONTINUE TO
SUPPORT THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS ACROSS SOUTHEAST
TEXAS. AT LEAST ONE MORE ROUND OF SIGNIFICANT THUNDERSTORMS IS
EXPECTED ACROSS THE AREA TODAY THROUGH THIS EVENING.

VERY HIGH MOISTURE LEVELS WILL PERSIST. AN ADDITIONAL 1 TO 3
INCHES OF RAIN IS EXPECTED ACROSS SOUTHEAST TEXAS THROUGH
TONIGHT...WITH AN ADDITIONAL 4 TO 8 INCHES POSSIBLE IN ISOLATED
SPOTS. THIS RAIN...FALLING ON TOP OF ALREADY SATURATED GROUNDS...
WILL RESULT IN THE POTENTIAL FOR FLOODING. THE GREATEST THREAT OF
FLOODING WILL BE FOR AREAS NORTH OF A COLUMBUS TO CONROE TO
LIVINGSTON LINE WHERE THE HEAVIEST RAIN HAS FALLEN SO FAR. A FLOOD
WATCH IS IN EFFECT FOR ALL OF SOUTHEAST TEXAS THROUGH THIS EVENING.

A FEW STORMS WILL HAVE THE POTENTIAL TO BECOME SEVERE. THE PRIMARY
SEVERE WEATHER THREAT WILL BE HAIL...WITH AN ADDITIONAL THREAT OF
ISOLATED DOWNBURSTS OR TORNADOES.

A FRONT WILL CROSS THE AREA DURING THE LATE EVENING HOURS ENDING
THE THUNDERSTORMS FROM WEST TO EAST.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED AT ANY TIME THROUGH THIS EVENING.

In the hours before

Local storm report, Apr 18, 3:12 PM CDT, 21 minutes before

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Local storm report, Apr 18, 3:13 PM CDT, 20 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
313 PM CDT SAT APR 18 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0308 PM     FLASH FLOOD      PEARLAND                29.56N 95.28W
04/18/2009                   BRAZORIA           TX   ASOS

            RAINFALL AMOUNT OF 1.33 INCHES IN 12 MINUTES AT CLOVER
            FIELD IN PEARLAND.

&&

CMM

Local storm report, Apr 18, 3:17 PM CDT, 16 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
317 PM CDT SAT APR 18 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0257 PM     FLASH FLOOD      MISSOURI CITY           29.57N 95.54W
04/18/2009                   FORT BEND          TX   AMATEUR RADIO

            WATER OVER THE ROAD AT FORT BEND PARKWAY AND HIGHWAY 6
            AND OLYMPIAN PARKWAY AND HIGHWAY 6.

&&

CMM

Local storm report, Apr 18, 3:21 PM CDT, 12 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
321 PM CDT SAT APR 18 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0257 PM     FLASH FLOOD      PASADENA                29.66N 95.15W
04/18/2009                   HARRIS             TX   AMATEUR RADIO

            16 INCHES OF WATER STANDING IN THE ROAD IN FAIRMONT
            HEIGHTS. STREETS IMPASSABLE.

&&

CMM

Local storm report, Apr 18, 3:26 PM CDT, 7 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
326 PM CDT SAT APR 18 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0312 PM     FLASH FLOOD      CLEAR LAKE SHORES       29.55N 95.03W
04/18/2009                   GALVESTON          TX   AMATEUR RADIO

            LARGE TREES DOWNED IN CLEAR LAKE FOREST SUBDIVISION.

&&

CMM

Local storm report, Apr 18, 3:33 PM CDT, 0 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
333 PM CDT SAT APR 18 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0306 PM     FLASH FLOOD      FRIENDSWOOD             29.51N 95.20W
04/18/2009                   GALVESTON          TX   AMATEUR RADIO

            ROADWAY FLOODING AT FM 528 AND FM 518. NEARBY GAUGE HAD
            2.32 INCHES OF RAIN WITHIN 30 MINUTES.

&&

CMM

The office that day

Everything else NWS Houston/Galveston, TX issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 17, 9:25 PM CDT	River Flood Warning	HGX	Jackson, Lavaca	3 days
Apr 17, 9:25 PM CDT	River Flood Warning	HGX	Jackson, Lavaca	4 days
Apr 17, 9:25 PM CDT	River Flood Warning	HGX	Jackson	5 days
Apr 17, 11:51 PM CDT	Severe Thunderstorm Warning	HGX	Liberty	39 min
Apr 18, 2:37 AM CDT	Severe Thunderstorm Warning	HGX	Polk	38 min
Apr 18, 6:41 AM CDT	Marine Weather Statement	HGX		2 hr
Apr 18, 7:39 AM CDT	Areal Flood Advisory	HGX	Burleson, Washington	3 hr
Apr 18, 9:35 AM CDT	Small Craft Advisory	HGX		9 hr
Apr 18, 9:37 AM CDT	Tornado Warning	HGX	Grimes, Madison, Walker	23 min
Apr 18, 9:47 AM CDT	Tornado Warning	HGX	Austin, Colorado, Washington	43 min
Apr 18, 9:54 AM CDT	River Flood Warning	HGX	Jackson	4 days
Apr 18, 10:32 AM CDT	Tornado Warning	HGX	Washington	28 min
Apr 18, 10:49 AM CDT	Tornado Warning	HGX	Grimes, Walker	26 min
Apr 18, 10:52 AM CDT	Areal Flood Advisory	HGX	Austin, Colorado, Washington	3 hr
Apr 18, 11:12 AM CDT	Areal Flood Advisory	HGX	Grimes, Harris, Montgomery, Waller	3 hr
Apr 18, 11:33 AM CDT	Areal Flood Advisory	HGX	Grimes, Harris, Montgomery, Waller	2 hr
Apr 18, 11:40 AM CDT	Severe Thunderstorm Warning	HGX	Wharton	50 min
Apr 18, 11:44 AM CDT	Areal Flood Advisory	HGX	Fort Bend, Wharton	2 hr
Apr 18, 12:02 PM CDT	Severe Thunderstorm Warning	HGX	Brazoria, Fort Bend, Wharton	43 min
Apr 18, 12:08 PM CDT	Tornado Warning	HGX	Brazoria, Fort Bend, Wharton	37 min
Apr 18, 12:15 PM CDT	Severe Thunderstorm Warning	HGX	Liberty, Montgomery, San Jacinto	45 min
Apr 18, 12:26 PM CDT	Special Marine Warning	HGX		64 min
Apr 18, 12:43 PM CDT	Severe Thunderstorm Warning	HGX	Brazoria, Fort Bend	47 min
Apr 18, 12:46 PM CDT	Flash Flood Warning	HGX	Harris, Montgomery	119 min
Apr 18, 1:22 PM CDT	Flash Flood Warning	HGX	Brazoria, Fort Bend, Galveston	3 hr
Apr 18, 1:29 PM CDT	Severe Thunderstorm Warning	HGX	Brazoria, Fort Bend, Galveston, Harris	46 min
Apr 18, 1:30 PM CDT	Severe Thunderstorm Warning	HGX	Fort Bend, Wharton	45 min
Apr 18, 1:42 PM CDT	Flash Flood Warning	HGX	Chambers, Harris	3 hr
Apr 18, 2:02 PM CDT	Flash Flood Warning	HGX	Austin, Colorado, Fort Bend, Wharton	3 hr
Apr 18, 2:06 PM CDT	Severe Thunderstorm Warning	HGX	Brazoria, Galveston, Harris	24 min
Apr 18, 2:13 PM CDT	Special Marine Warning	HGX		92 min
Apr 18, 3:04 PM CDT	River Flood Warning	HGX	Austin, Fort Bend, Wharton	55 hr
Apr 18, 3:05 PM CDT	Special Marine Warning	HGX		55 min
Apr 18, 3:05 PM CDT	Severe Thunderstorm Warning	HGX	Chambers, Galveston, Harris	40 min
Apr 18, 3:20 PM CDT	Coastal Flood Statement	HGX	Chambers, Galveston	3 hr
Apr 18, 3:46 PM CDT	Tornado Warning	HGX	Brazoria, Galveston	29 min
Apr 18, 4:04 PM CDT	Tornado Warning	HGX	Galveston	19 min
Apr 18, 4:07 PM CDT	River Flood Warning	HGX	Galveston, Harris	38 hr
Apr 18, 4:07 PM CDT	Special Marine Warning	HGX		53 min
Apr 18, 4:12 PM CDT	Severe Thunderstorm Warning	HGX	Galveston	33 min
Apr 18, 4:15 PM CDT	Flash Flood Warning	HGX	Brazoria, Chambers, Galveston, Harris	3 hr
Apr 18, 4:19 PM CDT	Severe Thunderstorm Warning	HGX	Chambers	41 min
Apr 18, 4:23 PM CDT	Areal Flood Advisory	HGX	Harris	3 hr
Apr 18, 4:24 PM CDT	River Flood Warning	HGX	Harris	18 hr
Apr 18, 4:24 PM CDT	Special Marine Warning	HGX		96 min
Apr 18, 4:46 PM CDT	Areal Flood Advisory	HGX	Brazoria	3 hr
Apr 18, 4:59 PM CDT	Areal Flood Advisory	HGX	Brazoria, Matagorda, Wharton	2 hr
Apr 18, 4:59 PM CDT	River Flood Warning	HGX	Harris	17 hr
Apr 18, 5:21 PM CDT	River Flood Warning	HGX	Montgomery	52 hr
Apr 18, 5:21 PM CDT	River Flood Warning	HGX	Harris, Liberty	17 hr
Apr 18, 5:21 PM CDT	River Flood Warning	HGX	Montgomery	17 hr
Apr 18, 5:21 PM CDT	River Flood Warning	HGX	Harris, Montgomery	4 hr
Apr 18, 5:21 PM CDT	River Flood Warning	HGX	Harris, Montgomery	17 hr
Apr 18, 5:37 PM CDT	River Flood Warning	HGX	Galveston, Harris	27 hr

Nearby

Severe Thunderstorm Warnings in Texas, 2009 Every severe thunderstorm warning in 2009

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.