MANZANILLO, Mexico -- Hurricane Patricia headed toward southwestern Mexico Friday as a monster Category 5 storm, the strongest ever in the Western Hemisphere that forecasters said could make a "potentially catastrophic landfall" later in the day. 
 
 Residents of a stretch of Mexico's Pacific Coast dotted with resorts and fishing villages on Thursday boarded up homes and bought supplies ahead of Patricia's arrival. 
 
 With maximum sustained winds near 200 mph, Patricia is the strongest storm ever recorded in the eastern Pacific or in the Atlantic, said Dave Roberts, a hurricane specialist at the U.S. National Hurricane Center. 
 
 Astronaut Scott Kelly tweeted a photo of the hurricane from space: 
 
 Patricia's power was comparable to that of Typhoon Haiyan, which left more than 7,300 dead or missing in the Philippines two years ago, according to the U.N.'s World Meteorological Organization. 
 
 "This is really, really, really strong," WMO spokeswoman Clare Nullis told a U.N. briefing in Geneva, according to Reuters. 
 
 In Mexico, officials declared a state of emergency in dozens of municipalities in Colima, Nayarit and Jalisco states that contain the bustling port of Manzanillo and the posh resort of Puerto Vallarta. The governor of Colima ordered schools closed on Friday, when the storm was forecast to make what the Hurricane Center called a "potentially catastrophic landfall." 
 
 Teams of police and civil protection were walking along Puerto Vallarta's waterfront Friday morning advising people to evacuate. 
 
 According to the 2010 census, there were more than 7.3 million inhabitants in Jalisco state and more than 255,000 in Puerto Vallarta municipality. There were more than 650,000 in Colima state, and more than 161,000 in Manzanillo. 
 
 REUTERS 
 
 Evacuations were under way in Puerto Vallarta Friday, with officials taking people to 14 shelters, mostly in schools, according to the Jalisco government's webpage. Exact numbers of those evacuated were not immediately available. 
 
 Luis Felipe Puente Espinosa, national coordinator for civil protection, said that three airports in the path of Patricia in southwestern Mexico have been shut down as the storm approaches. 
 
 Roberto Ramirez, the director of Mexico's National Water Commission, which includes the nation's meteorological service, said that Hurricane Patricia will be powerful enough to lift up automobiles, destroy homes that are not sturdily built with cement and steel and will be able to drag along people caught outside when the storm strikes. 
 
 Ramirez said that the people in the most danger from the hurricane will be those on the coast, especially in the state of Jalisco. 
 
 Rain pounded Manzanillo late Thursday while people took last-minute measures ahead of Patricia, which quickly grew from a tropical storm into a Category 5 hurricane, leaving authorities scrambling to make people safe. 
 
 At a Wal-Mart in Manzanillo, shoppers filled carts with non-perishables as a steady rain fell outside. 
 
 Veronica Cabrera, shopping with her young son, said Manzanillo tends to flood with many small streams overflowing their banks. She said she had taped her windows at home to prevent them from shattering. 
 
 Alejandra Rodriguez, shopping with her brother and mother, was buying 10 liters of milk, a large jug of water and items like tuna and canned ham that do not require refrigeration or cooking. The family already blocked the bottoms of the doors at their home to keep water from entering. 
 
 Manzanillo's "main street really floods and cuts access to a lot of other streets. It ends up like an island," Rodriguez said. 
 
 In Puerto Vallarta, restaurants and stores taped or boarded-up windows, and residents raced to stores for last-minute purchases ahead of the storm. 
 
 The Hurricane Center in Miami warned that preparations should be rushed to completion, saying the storm could cause coastal flooding, destructive waves and flash floods. 
 
 "This is an extremely dangerous, potentially catastrophic hurricane," center meteorologist Dennis Feltgen said. 
 
 Feltgen said Patricia also poses problems for Texas. Forecast models indicate that after the storm breaks up over land, remnants of its tropical moisture will likely combine with and contribute to heavy rainfall that is already soaking Texas independently of the hurricane, he said. 
 
 "It's only going to make a bad situation worse," he said. 
 
 In Colima, authorities handed out sandbags to help residents protect their homes from flooding. 
 
 Patricia's maximum sustained winds had increased to 200 mph - a Category 5 storm, the highest designation on the Saffir-Simpson scale used to quantify a hurricane's wind strength. 
 
 By late afternoon, Patricia's center was about 60 miles west of Manzanillo, and about 110 miles south-southeast of Cabo Corrientes. The Hurricane Center said Patricia was expected to remain an "extremely dangerous" Category 5 storm through landfall late afternoon or evening, before weakening over the inland mountains. 
 
 A hurricane warning was in effect for the Mexican coast from San Blas to Punta San Telmo, a stretch that includes Manzanillo and Puerto Vallarta. A broader area was under hurricane watch, tropical storm warning or tropical storm watch. 
 
 The Hurricane Center said Patricia was expected to bring rainfall of 6 to 12 inches, with isolated amounts of up to 20 inches in some locations. Tropical storm conditions were expected to reach land late Thursday or early Friday, complicating any remaining preparation work at that point. 
 
 "We are calm," said Gabriel Lopez, a worker at Las Hadas Hotel in Manzanillo. "We don't know what direction (the storm) will take, but apparently it's headed this way. ... If there is an emergency we will take care of the people. There are rooms that are not exposed to wind or glass." 

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 / Updated By Alex Johnson and Jason Cumming 
 
 Hurricane Patricia became the strongest storm ever measured on the planet early Friday, with experts warning it could trigger 40-foot waves along southwestern Mexico and "life-threatening" flash flooding. 
 
 More than 7 million residents — and an estimated tens of thousands of U.S. citizens visiting or living there — were told to prepare for the "worst-case scenario" as the ferocious storm was expected to race ashore on Mexico's Pacific coast between 6 to 10 p.m. ET Friday. 
 
 At 5 p.m. ET, Patricia was about 60 miles west of Manzanillo, and about 110 miles south-southeast of Cabo Corrientes. 
 
 The U.S. National Hurricane Center said Patricia was expected to make landfall "in the next several hours." A hurricane warning was in place for San Blas to Punta San Telmo. 
 
 The tourist magnets of Puerto Vallarta and Manzanillo were directly in the Category 5 storm's projected path, and Puerto Vallarta's airport was closed Friday out of precaution as some stranded vacationers described their inability to fly out of a "nightmare." 
 
 By 5 p.m. winds had weakened slightly to 190 mph, the Hurricane Center said. Winds of 200 mph were measured earlier, and the Hurricane Center labeled Patricia as the "strongest hurricane on record" in the Atlantic and eastern North Pacific Basins. 
 
 Mexico has not formally requested help from the U.S., but State Department spokesman Mark Toner told reporters Friday that America "stands up to offer any assistance that we can in the aftermath of what at least appears to be a pretty epic event in terms of the intensity and size of the storm." 
 
 NBC News meteorologist Bill Karins warned that Patricia would be "the most devastating storm to ever hit Mexico" with "catastrophic damage" likely between the posh resort of Puerto Vallarta and the bustling port city of Manzanillo. 
 
 While typhoons Nancy and Violet had stronger estimated winds, Patricia was the strongest storm ever actually observed, Karins added. Patricia already has "put on quite a show" in how rapidly and unexpectedly it has strengthened, he said. 
 
 Typhoon Haiyan, which devastated the Philippines in 2013, made landfall with 190 mph winds. 
 
 While Patricia weakened slightly to 190 mph winds since the afternoon, "Patricia is expected to remain an extremely dangerous category 5 hurricane through landfall," the NHC said. “Preparations to protect life and property should be rushed to completion.” 
 
 Hurricane warnings stretched from San Blas to Punta San Telmo, an area that includes Puerto Vallarta and Manzanillo. CONAGUA, the Mexican national water commission, predicted waves about 40 feet at landfall. 
 
 The National Hurricane Center said the hurricane was expected to produce deadly rip currents and "life-threatening flash floods and mudslides." 
 
 It added: "Some fluctuations in intensity are possible today, but Patricia is expected to remain an extremely dangerous Category 5 hurricane through landfall." 
 
 Up to 20 inches of rain was predicted for the Mexican states of Jalisco, Colima, Michoacan and Guerrero through Saturday, the NHC said. 
 
 The Mexican government declared a state of emergency. 
 
 The U.S. Consulate General in Guadalajara urged Americans in the hurricane warning area to "make preparations immediately to protect life and property." 
 
 Rogelio Estreda, a representative for the Grand Fiesta Americana Resort in Puerto Vallarta, told NBC News that the site would be evacuated at 7 a.m. local time (8 a.m. ET). 
 
 "We are expecting something bad, but maybe nothing will happen," Estreda said. "It can change at any time." 
 
 Patricia would be only the second Category 5 hurricane to hit the entire Pacific coast since full record-keeping began in 1949. An unnamed storm struck in late October 1959 near Manzanillo, killing an estimated 1,800 people — 800 of them from mudslides alone. 
 
 Karins added that 10 inches of rain were already predicted for Texas over the next three days, warning that "what's left of Patricia will make flooding in south Texas even worse" on Sunday. 
 
 Laura Diane Rebholz, who co-owns a modeling agency in Scottsdale, Arizona, told NBC News early Friday that she felt it was "safer to ride the storm out" at the Puerto Vallarta hotel where she's vacationing. 
 
 "It's almost as if it's literally 'the calm before the storm,'" she said. "It's very much business as usual around the resort with staff seemingly unfazed by the hurricane." 
 
 But Australian newlywed Natalie Griffin said Friday that she and her husband were trying to catch an early flight out of Puerto Vallarta after five days of vacationing. At the hotel on Thursday, she said, guests were told that they could be evacuated by bus to Guadalajara, Jalisco's capital city located further inland. 
 
 Griffin said she decided to take her chances at the airport early Friday, but flights out were looking grim. 
 
 "We were all excited as we thought we were about to board, and now they have said the airport is closed but they want to get special permission to fly this plane out," she told NBC News. "Everyone wants to know if we are flying or not so we can make plans to leave the area." 
 
 Among those hunkering down include Atlanta-born Ian Hayden Parker, who founded the Vallarta Daily News in Puerto Vallarta, which has established 18 hurricane shelters. 
 
 "We live in a resort town, but outside of the tourist zone, there is still a lot of poverty and people without computers, Internet or phones," said Parker, who hopes to continue to inform locals about the storm's impact. 
 
 After residents were urged to begin storm preparations Thursday, Parker said, "many people followed our advice and are now just playing the wait and see game."
– Hurricane Patricia may turn out to be "the most devastating storm to ever hit Mexico," and millions of residents have been told to prep for a "worst-case scenario," reports NBC News. It's the most powerful hurricane ever recorded in the Western hemisphere, with maximum sustained winds of 200mph, Weather.com reports, and the NOAA is labeling it "potentially catastrophic" when it touches down. The eye of the storm, expected to still be a Category 5 hurricane when it reaches the Mexican coast, is set to make landfall Friday night in Jalisco state, which includes Puerto Vallarta and Guadalajara—making it the first time in eight years North American land has been threatened by a Category 5 hurricane (that time was from Hurricane Felix). Expected in Jalisco and adjoining states are floods, mudslides, and "large, battering ocean waves" up to 39 feet crashing onshore, Weather.com reports. While Mexico will be bearing the brunt of the storm, Texas can also expect to be affected, CBS News reports. Already being battered by heavy rain, Texas will likely also draw in Patricia's tropical moisture, which is "only going to make a bad situation worse," a National Hurricane Center meteorologist tells the network. Residents in a 25-county swath of central and south Texas, as well as along Interstate 35 from the Austin-San Antonio region to Dallas-Fort Worth, should look out for downpours of up to 12 inches and flash floods. The only other time a Category 5 hurricane has settled onto Mexico's Pacific coast was in 1959, a storm that resulted in 1,800 deaths, the site notes. Patricia is breaking other records, too: Per Weather.com, it has the lowest minimum central pressure of any hurricane ever recorded, beating out Wilma's 882 millibars with an 880.