Tropical Depression Bill Inland Over Texas; Major Flood Threat Ramps Up For Texas, Oklahoma, Ozarks (FORECAST)
Weather Channel --
Highlights
Bill is now a tropical depression, and is spreading bands of locally heavy rain through parts of east and north Texas.
Additional torrential rain and flash flooding/river flooding is likely for parts of Texas, Oklahoma, Arkansas and Missouri over the next three days.
A few wind gusts topping 40 mph and isolated tornadoes are also threats.
The official forecast calls for further weakening; however, a phenomenon known as the "brown ocean" effect may slow or even stop that weakening trend at times through the next couple of days.
Water levels remain above normal tide levels along parts of the Texas and Louisiana Gulf Coast, but should return closer to normal as Bill moves farther inland Wednesday.
Tropical Storm Bill made landfall along the Texas coast on Matagorda Island at 11:45 a.m. CDT Tuesday with top sustained winds of 60 mph. Matagorda Island is located between Houston and Corpus Christi.
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As Bill continues to move north, more locally heavy rain and flash flooding will occur flood-weary parts of the South.
Flood watches are posted from Texas to southern Illinois in advance of Bill and its remnant.
(MORE: Latest News on Bill)
Locally heavy rain can be expected both in the core of the system – mainly to the north and northeast of Bill's center – and in narrower rain bands farther away from the center of circulation.
A Lower Colorado River Authority rain gauge measured over 11 inches of rain west-southwest of El Campo, Texas as of Wednesday morning, with rain rates of 3-4 inches per hour. El Campo is about 90 miles southwest of downtown Houston.
(MORE: 6 Incredible U.S. Rainfall Records)
Generally, widespread additional 3 to 5 inch rain totals can be expected, with locally much higher amounts likely where rainbands remain stationary or train over the same areas. This is likely to occur through Wednesday evening in a corridor from the middle Texas Gulf Coast through parts of the Houston metro into east Texas. Rain rates of 2 to 4 inches per hour, at times, are possible.
(MORE: Texas No Stranger to Flooding From Tropical Storms)
This is an area that has already had record rainfall and flooding in May, so additional heavy rainfall will quickly trigger renewed flash flooding and may eventually worsen river flooding still ongoing.
(MORE: Texas/Oklahoma Already Saturated)
Here is a general timeline by region when we expect the flash flood threat from this tropical system to be highest:
Texas (east, north, central): Continues through Wednesday night or Thursday morning.
Oklahoma, western Arkansas, southwest Missouri: Later Wednesday into early Friday
(FORECASTS: HoustonDallasFt. SmithTulsaSpringfield)
Note there will be scattered thunderstorms ahead of (to the north and northeast of) Bill in the southern Plains and Ozarks through Wednesday that may also trigger local flash flooding.
The tropical moisture surge from Bill has already started to intercept an old frontal boundary draped from the Ozarks to north Texas. These intersections have been notorious flash flood producers in the past.
(MORE: Brown Oceans: Some Tropical Systems Strengthen Over LandVideo: Dr. Shepherd ExplainsWunderground blog)
Late this week, the remnant system and its moisture will get drawn northeast, then east into the mid-Mississippi Valley and Ohio Valley, leading to a threat of locally heavy rain, there.
In all, Bill or its remnant may produce heavy rainfall over at least seven states from Texas to Indiana through the end of the week.
(MAPS: 7-Day Weekly Planner)
Model trends even suggest that the remnants of Bill may survive all the way to the East Coast by the weekend, bringing the potential for locally heavy rainfall. However, any remnants will likely get tangled up in the jet stream by then and that should prevent Bill from becoming a tropical cyclone again off the East Coast.
Tropical Storm Bill's Landfall
Tropical Storm Bill made landfall on Matagorda Island, Texas, at 11:45 a.m. CDT Tuesday. Bill was then downgraded to a tropical depression at 1 a.m. CDT Wednesday.
The peak storm surge from Bill occurred Tuesday morning and early Tuesday afternoon, coinciding with an early morning high tide along the Upper Texas and southwest Louisiana coasts.
(MORE: Expert Analysis)
At least a foot of water covered areas along FM 2031 south of Matagorda. Highway 87 was closed early Tuesday morning from Gilchrist to highway 124 on the east edge of the Bolivar Peninsula due to debris on the road. Galveston County emergency management reported yards were flooded in parts of Hitchcock and Bayou Vista, across the bay from Galveston Island. The water level at Port Lavaca, Texas, was more than three feet above normal early Tuesday afternoon.
Tropical storm-force winds were reported near the Texas coast on Tuesday morning. Port O'Connor, Texas, clocked sustained winds of 44 mph and a gust to 54 mph.
Stronger winds were reported on oil rigs off the Texas coast Tuesday morning. One elevated rig just east of Port O'Connor measured a 66 mph gust at 9:10 a.m. CDT Tuesday.
Another burst of high winds developed several hours after landfall in an area just east and southeast of Bill's center. This included a gust to 58 mph in Palacios, Texas, at 6:20 p.m. CDT.
Bill became the second landfall in the U.S. in the 2015 Atlantic hurricane season.
According to a preliminary check of mainland U.S. tropical storm and hurricane landfall data from NOAA's Hurricane Research Division, senior meteorologist Stu Ostro found the last time the U.S. had a pair of tropical storm or stronger landfalls this early in the season was 1871.
Bill also became the fourth mainland U.S. landfall of at least tropical storm intensity since the start of the 2013 hurricane season. This is yet more proof that landfalls can and do occur even in somewhat "quieter" hurricane seasons.
Check back with us at weather.com and The Weather Channel for updates on this system.
Senior meteorologist Nick Wiltgen and meteorologists Jonathan Erdman and Chris Dolce contributed to this report.
