HARRIS COUNTY, Texas (KTRK) -- Emergency officials in Harris and Montgomery counties are alerting people living close by the San Jacinto River's East Fork of threatening water levels heading into Wednesday.
On Tuesday, the National Weather Service issued a Flood Warning for the east fork near New Caney, impacting Liberty, Harris, and Montgomery counties.
NWS added that major flooding is being forecast, with water levels potentially rising 10 to 15 feet, due to heavy rains upstream from storms on Sunday and Monday.
According to the Harris County Office of Emergency Management, widespread lowland flooding is expected along the river, affecting numerous streets. FM-1485 will be submerged under several feet of water and considered impassable, the OEM added.
In addition, emergency officials identified five neighborhoods that are expected to be impacted: Idle Glen Subdivision, Northwood Country Estates, River Terrace, Cypress Point, and the Kingwood area.
However, they said the flooding will primarily affect Kingwood's non-developed lands and backyards with bulkheads along the river, and structural flooding isn't anticipated.
In response, the county asked for the voluntary evacuation of Idle Glen and Commons of Lake Houston along and a couple of blocks from the river. County Judge Lina Hidalgo issued that request during an evening news conference, also urging other subdivision residents to leave but "not going as far" for a wider evacuation order.
The county offered the Leon Grayson/Baldree Community Center as a place the shelter. It's at 13828 Corpus Christi St. in Houston.
According to the county, if residents are already seeing high water near their home, they're being urged not try to drive themselves to the shelter. Instead, officials directed people to call 911, and first responders will bring them to a safe location.
The shelter will have cots, blankets, food and water available, the county added. This shelter will also accept pets if they are crated.
Montgomery County's Office of Homeland Security and Emergency Management also ordered a voluntary evacuation for the Idle Wilde and Idle Glen neighborhoods along FM-1485 in the eastern part of the county.
Citing the NWS, Montgomery County said the river is predicted to crest near 72 feet in a major flood stage by noon on Wednesday.
Nearby school districts began issuing campus closures due to the threat. Cleveland ISD said all campuses and facilities will close Wednesday with a Thursday reopening planned.
WATCH: ABC13 livestream coverage of Harris County leaders preparing for flood threat
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