Tropical Storm Humberto is expected to reach shore late tonight just south of Galveston, dumping heavy rain from Victoria to eastern Louisiana.

Some spots along the upper coast could receive 10 inches or more of rain by tomorrow, forecasters said. They hope the storm moves quickly to minimize rain totals in isolated areas.

"It's a slow moving storm," said Gene Hafele, meteorologist with the National Weather Service. "But we don't think it'll stall out. It should move steadily inland."

The storm is expected to creep ashore between Freeport and Galveston near midnight, Hafele said. He said rain, high winds and rough seas are already lashing coastal areas. Hafele said rain would stretch as far south as Victoria, but be concentrated between Sargent and the Sabine River.

The storm has sustained winds of 50 mph with high winds extending 60 miles from the center, according to the National Weather Service. The slow-moving storm is 50 miles south of Galveston and moving north at about 7 mph. It is expected to turn slightly north-northeast during the next 24 hours. A tropical storm warning is in effect from Port O'Connor to Cameron, La.

Emergency management officials earlier today were watching the storm development to determine how best to prepare, but stepped up preparations late today as the weather worsened along the coast.

A statewide conference call between state and local emergency management officials is scheduled for 4 p.m. today to assess the weather and determine what further preparations are needed. Night classes were canceled at Houston Community College, College of the Mainland, Alvin Community College and Westwood College Houston-South. Texas Southern University canceled all classes and events scheduled for Thursday.

By late today the Coast Guard reported that rough seas off the Galveston forced operations at the Houston Ship Channel to be halted.

Ship pilots at the channel, said Petty Officer Mario Romero, shut down until the heavy weather passed. Without pilots aboard, ships can't enter or leave the port, he added.

At least a dozen ocean-going cargo ships are waiting to leave the port while at least 14 are waiting to enter late today, Romero said.

Romero said the Coast Guard has received no distress calls or rescue requests related to weather.

Bruce Clawson, Texas City emergency management director, said the city closed the flood gates that are part of the Texas City levy system to seal Moses Lake and protect it from tidal surges.

Clawson said all city drainage is directed toward pumping stations that send excess water over the levy into Moses Lake. The pumps should be able to handle the predicted rainfall as long as it's spread over time, but 2 inches of rain over two hours could dump water faster than it can be pumped into the lake, he said.

The Galveston Police Department sent extra patrol cars to the vulnerable West End of Galveston Island where low lying areas are beyond the protection of the 10-mile long sea wall on the East End, police Capt. Mike Putnal said.

Putnal said the move was precautionary because no flooding is expected according to early weather predictions. He said officers are ready to switch from patrol cars to high-water vehicles, which could include city-owned trucks, if the weather takes a turn for the worse.

John Simsen, Galveston County emergency management coordinator, said the state was sending a half dozen high-water military vehicles to be used for rescue in case of flooding. Simsen said those in the storm's path should watch its development closely and ''postpone evening activities that might put them in harm's way.''

''We're encouraging people to stay home and stay safe,'' Simsen said.

Peter Davis, chief of the Galveston Beach Patrol, said the rain and high tide had thinned the beach crowd. The oncoming storm increased the strength of dangerous rip tides near the numerous jetties on Galveston beaches, he said.

The storm also increased wave size, drawing a few surfers, but surfing conditions were not good because of the wind. Light rain was falling in Surfside and Galveston by late today, but there no reports of flooding, officials said.

Tides were predicted to peak at 2.5 feet above normal, too low to cause flooding on low-lying FM 3005, which runs near the beach for 20 miles west of Galveston's protective seawall, officials added.

Brazoria County Emergency Management Director Kenneth "Doc" Adams said his office is taking a wait-and-see attitude. He said the good news was that the storm is expected to hit at low tide and surge should be minimal.

If predicted heavy rains come, some coastal roads and low parts of Highway 288 in Brazoria County could flood, Adams said.

"What we're expecting is mainly a rain event," Adams said.

School officials in the Houston area said they will monitor the storm and determine by 5 a.m. Thursday if classes should be cancelled.

"Several roads in our district flood quite easily so we have, of course, already met and will make a decision early tomorrow morning should school need to be canceled," Galena Park spokesman Craig Eichhorn said. "We are hoping for the best, but this system appears to be bringing quite a bit of rain with it."

Before sunrise today, rain soaked Galveston Island and spread into Harris County during the rush hour. Commuters plowed through scattered heavy thunderstorms that rolled in off the Gulf of Mexico and dropped two inches or more of rain in coastal counties early in the day.

Galveston city spokeswoman Alicia Cahill said weather concerns caused cancellation of groundbreaking for a $3.6-million recreation center in the city's beach-front Menard Park this morning. No other activities were canceled and government offices were open, she said.

Chronicle reporters Jennifer Radcliffe, Harvey Rice and Richard Stewart contributed to this report.