storms across tahoe and close to the bay area. we'll track our chances at 6:00. on our broadcast tonight, violent threat. 80 million americans in the potential path as severe storms are on the move with a dramatic drop on the way in some places potentially record cold in july. late word of a cease-fire on the table as international pressure mounts now on israel and hamas. and the u.s. is about to step up its involve ment in a big way. early detection. how your eye doctor may be a key to spotting alzheimer's years before any signs start to appear. and final journey. it's been over two years since the disaster at sea. tonight, the costa concordia once again on the move. "nightly news" begins now. good evening.

and because of the number of americans who will be affected by severe weather across a wide area, 80 million people, tonight here we begin with a rare meteorological event. this past winter as you may remember we all had to learn that new term, polar vortex, the super cold air that pushed to the south over north america. well, something similar to that is happening this week only in july. and the dramatic temperature extremes are firing off storms as they go. a lot of severe weather over a number of states and some high population areas. it's where we'll begin tonight with nbc's tom costello. >> reporter: late afternoon in the nation's capital and up the east coast today brought high winds, rain and lightning after a weekend of torrential downpours and funnel clouds in the northeast. >> i look and i see the tornado was like -- i just saw it tunneling down. and i'm like, oh, my god. >> reporter: to high temps and forest fires in washington state and california. >> as soon as that wind picks up

and the inversion layer goes away, your fire activity is going to increase a little bit. >> reporter: it's already a volatile start to a typically hot and humid week in mid-july. most surprising that massive cooldown now underway in the midwest and northern plains. 20 degrees below normal. a big story on the noon news in minneapolis today. >> it's 60 degrees midday, mid-july, obviously not normal. >> reporter: at target field it felt more like world series weather than a july all star game. >> this beats our hundred degree weather back home. this is fine. >> it's cold for summer! >> we came with t-shirts and shorts expecting july weather. >> reporter: you can thank a blast of cold air coming straight from canada taking aim at a huge section of the country. with high pressure in the west and low pressure in the east, the country is riding a roller coaster of weather extremes. >> it's going to be very warm for a while, but as the front drops down we expect to see a lot of rain will set up in parts of the southwest. and that could mean some drought relief, particularly in states

such as new mexico and also in west texas. >> reporter: but the unsettled weather has also triggered deadly lightning storms. in colorado over the weekend two killed by lightning near trail ridge road high in the mountains. in just one 15-minute period today 30,000 lightning strikes nationwide. with more rain and lightning predicted for much of the country through the evening, high temperatures now but a cooldown on the way. tom costello, nbc news, washington. >> and al roker is here with us in the studio. al, this covers a huge area. >> it really does, brian. from the rockies all the way into the northeast and new england. you can see the area slight risk of strong storms. we're not talking necessarily tornadoes, but we are talking damaging winds, hail, lots and lots of rain. on the radar already firing up a lot of activity going on right now. we've got severe thunderstorm watches and warnings out there. this is the leading edge of that warm humid air. behind it that cooler air you were just talking about, brian. and you can see we've got flash

flood watches and flood warnings now starting to fire up. a lot of rain out of this system. it's going to be squeezed out of the atmosphere as the cooler air comes in. anywhere from one to two inches of rain generally. but up from new england into the mid-atlantic corridor anywhere up to six inches of rain. here comes that cool air. it is going to be breaking off, a load of polar air comes down. so chicago, 54, very near a record. minneapolis, 54. kansas city, 53 degrees for overnight lows and highs tomorrow anywhere from ten to 20 degrees below normal. brian, chicago 69, they should be in the mid-80s by this time this year. and in fact we'll finally see some moderation by thursday. >> interesting time. here we are in july. al roker with us in the studios. we turn to news from overseas. specifically word of a cease-fire deal on the table amid a lopsided and rising death toll in gaza. many of the dead children and now intense international

pressure building for israel and hamas to move back from this brink of war. our own andrea mitchell telling us secretary of state john kerry now in vienna was considering diverting his trip heading to the middle east as early as tomorrow to take part in the cease-fire talks, though now it's more likely he'll return to the u.s. while giving some talks some time to develop first. we have the situation covered tonight from both israel and gaza. our veteran middle east correspondent martin fletcher starts us off from tel aviv tonight. martin, good evening. >> reporter: brian, good evening. arab and israeli media report hamas and israel will agree to stop the fightingment stop the fighting. according to a deal proposed by egypt, the shooting will end, the siege on gaza will be eased and israel and hamas will go to cairo to work on a longer term agreement. the shooting will stop tomorrow morning 9:00 a.m. local time. this is the urgency. seven days of carnage and chaos in gaza. more than 185 palestinians dead,

most of them civilians, many of them children according to united nations report. it all fueled calls for a cease fire and calls on israel to stop its air bombardment. in its defense, the israeli air force released this operations recording showing how hard they try to avoid hitting civilians. they're aiming at hamas target in gaza. there's a lot of children, the commander says. abort, abort, abort. >> every civilian death is a tragedy. and we're making our utmost effort to avoid it. >> reporter: but not very successfully. >> we are trying to be as surgical as is humanly possible. >> reporter: throughout the day israel bombarded gaza and hamas fired rockets at israel. with the threat of escalation ever present. the israeli army units this massive strategic locations around gaza only one mile in

this direction, they're waiting to see what comes first, a cease fire or the order to invade. israel is called up around 40,000 reserves to form an invasion force with the regular army. all the efforts are now aimed at stopping such an incursion which would lead to much greater loss of life. israel security cabinet will meet tomorrow morning early to make the final decision. hamas says it wants calm, is studying the proposal and is open to longer term deal. it's possible it looks like the diplomats may have won the day. brian? >> martin fletcher starting off our coverage in tel aviv tonight. we're clearly at a decision point while meanwhile in gaza it's an increasingly desperate situation. all these efforts on the diplomatic front are of small comfort to the families who endured another day of attacks from the air, an israeli bombing campaign now in day seven. nbc's ayman mohyeldin has the latest tonight on the ground in gaza.

>> reporter: all along gaza's border with israel, palestinian families are fleeing the front lines. we're at the very northern part of the gaza strip. just beyond those rooftops is the israeli border. this entire area has been ordered evacuated. you can actually see the craters as a result of an israeli air strike. hundreds of homes, maybe thousands of people live here. this morning it has a very eerie feel. you can see no one is out. but on a street we found a 27-year-old, his wife and two daughters. this morning they packed what they could and set out to find shelter. the schools are supposedly safe, he says. it's a rickety ride, but quiet enough for their 1-year-old daughter to sleep in her mother's arms. a five-minute car drive that took them hours to make by cart. then, relief. with their blankets, mattresses and some food, they make it to a u.n. school now serving as a makeshift shelter, one of 20

such schools housing 17,000 palestinians. classrooms now playgrounds, bookcases now kitchen cabinets. on the floor he finds a quiet corner to sleep, relieved his family's out of harm's way for now. but the u.n. is struggling to cope. these schools weren't meant to be shelters. access to water, services and food is limited. and the danger is real. israeli shelling, u.n. officials say, has damaged schools like this one. today, gaza streets are all but deserted. few dare to go out day or night. and people here are feeling increasingly trapped with no way out. brian, this evening the helicopters and drones are still circling above the skies in gaza. an indication that despite the talk of a cease-fire, it is still very much an area that is still under threat of air strikes throughout the night. and that means it is going to be another long night for the palestinian people here in gaza. brian. >> ayman mohyeldin rounding out our coverage from gaza tonight.

thanks. in this country we have an update tonight on the condition of army sergeant beau bergdahl who was rescuedfter five years held captive by the taliban. the army says bergdahl has completed his six weeks so-called reintegration process and is now back to regular active duty at joint base san antonio fort sam houston where he's been recovering. the specifics of his day-to-day duties have not been disclosed. one military official quoted today saying it's a low-impact desk job. tonight, two and a half years since a cruise ship disaster off the coast of italy, the costa concordia is back upright floating, once again on the move on a final journey and a final chapter in one of the more incredible maritime mishaps in recent history. we get our report from nbc's katy tur. >> reporter: for the first time in two and a half years the costa concordia floated today. successfully raised six feet in six hours off its undersea

platform and away from the rocks. a baby step in the final phase of the biggest maritime salvage operation ever attempted. >> it's a relief for everyone. it came off very smoothly. >> reporter: salvage master nick sloan has led hundreds of divers, welders and engineers in stabilizing, righting and now floating the 114,000-ton ship. and there are still major risks including possibly breaking open the hull and releasing a toxic soup of chemicals and debris. >> there's a lot of cracks in her. i mean, she's not pretty underwater. >> reporter: the cruise liner ran aground in january 2012 when it hit rocks and flipped on its side off the italian resort island of giglio. 32 people were killed. one is still missing. and the captain is on trial for manslaughter and abandoning ship. in september, the rusting hulk was finally rolled upright. since then 30 giant filled tanks

of water kept stable on an underwater platform. an eyesore yet unlikely tourist attraction. this week compressed air will be slowly pumped into the tanks to float the ship. once it got to six feet today it was moved away from the cliff. at 36 feet it will be ready to tow to a scrap yard in genoa. all said and done, the concordia should be gone in a week. a final good-bye not a moment too soon. katy tur, nbc news, london. >> and back in this country today one of the largest banks in this country, citigroup, has agreed to pay a huge fine, $7 billion, to settle claims brought by the justice department over citigroup's conduct during the housing crisis. government investigators say internal e-mails made clear the bank knew it was doing something wrong. the attorney general today used some tough words saying, "the bank's activity shattered lives and livelihoods throughout the country and around the world.

they contributed mightily to the financial crisis that devastated our economy in 2008." we'll take a break. and still ahead for us tonight, the fight against alzheimer's and how eye doctors may be the first ones to spot signs of the disease years before the symptoms arrive. and later, a big scare at the beach this weekend caught on video.

there is new hope tonight in the fight against alzheimer's disease. the alzheimer's association estimates that as many as 16 million people over the age of 65 could be diagnosed with alzheimer's disease by the year 2050. that is three times the number of active cases today. and the news tonight is out of a big alzheimer's conference underway in denmark including a lot of talk about how an eye test can help detect signs of alzheimer's years before symptoms appear. we get our report tonight from

our chief medical editor dr. nancy snyderman. >> reporter: imagine a time when a simple trip to the eye doctor could also be your screening exam for alzheimer's disease. looking at back of the eye gives doctors an idea of the brain. it's not a far off idea. researchers in australia and several universities in the united states are looking at a new way to measure plaque buildup in the brain by looking at the retina of the eye. it's non-invasive, not particularly complicated and likely a game changer. >> it may not be the sole indicator of alzheimer's, but it can be an early indicator. an indicator that tells the eye doctor for example that a person should go on and get a more distinct workup. >> reporter: early detection is one thing, prevention is another, and now a landmark study offers the first concrete proof that some of the things people have been doing to

prevent alzheimer's may actually work. here's what they did. researchers recruited more than 1200 people in finland ages 60 to 77 at risk for alzheimer's. one group went on a lifestyle improvement program meaning good nutrition, regular exercise up to six times a week, periodic memory tests and advice on how to manage blood pressure, cholesterol and other cardiac risk factors. the results, astounding. after two years the participants in the special program showed 40% improvement in cognitive tests. more than those who were not in the program. doctors at beth israel medical center in boston hope their program, the brain fit club, will have similar results. >> it gives us a bit more insight into the types of things that are important for maintaining brain health. >> reporter: 69-year-old susan does not have alzheimer's and is counting on exercise to keep it that way. her biggest motivation? family. >> i have young grandchildren. i want to be able to do things with them. and if i'm not healthy, either body or brain, i won't be able to do that.

>> reporter: so important because this is the first time we have absolutely proven that those so-called lifestyle factors, all the things we have talked about for years -- diet, exercise, brain games -- they really do work when used in combination. so this should be a wakeup call for doctors to intervene with their patients in ways they have never done before, brian. >> how nice to be reporting glimmers of good news. >> exactly right. >> nancy, thank you as always. we'll take a break. we're back in a moment with the first comments from a member of the nbc family now back home and on the mend.

video from a beach in siberia shows sunbathers running to take shelter from a freak and violent hailstorm. several were forced to huddle together and take shelter under the same umbrella. hail this size can really leave a mark. the hailstones left divots in the sand on the beach.

also courtesy of mother nature people all over the world remarked of the so-called super moon this past weekend as the moon made an incrementally closer path to the earth. we get another chance in august when the moon will appear even larger in the sky. dick cheney making news at a forum sponsored by politico. the former vice president said president obama is devastating the u.s. military. and he added the military, "ought to be our top priority for spending, not food stamps, not highways or anything else." so it wasn't a high scoring game. in fact, the world cup final had no score after regulation. germany won it in the first overtime period, defeating argentina. and, feeling violently defeated, some argentinians took to the streets where they were met by police including tear gas and rubber bullets and some protesters setting cars on fire. good news, as we mentioned, from tracy morgan. he's out of rehabilitation, back

at home in suburban new jersey outside new york. he's still nursing multile pl injuries, using a walker to get around, but says he's okay and feels strong. he suffered a badly broken leg, broken ribs and a visible scar on his forehead. happy news from boston where boston marathon bombing survivor and double amputee jeff bauman is a new father. he and his fiancee erin hurley announced the birth of a little girl along with the good news that everyone is happy and healthy. when we come back here tonight, mr. smith goes to washington to meet some extraordinary kids who've come a long way, further than they ever imagined.

our final story here tonight is about the people who've come to this country and worked hard and sacrificed in order to give their children a better life and make the place better along the way. and so tonight harry smith, our own mr. smith, goes to washington and finds young people who can hardly believe their good fortune as they find themselves living the american dream. >> reporter: selfies in front of the white house. if you're a college kid with an

internship in d.c., it's what you do. but these college students are different from their peers. frankly, it's a wonder they're here at all. denise cruz has spent most of her young life as a migrant worker. we first met her when she was a 15-year-old with a dream. >> i want to go to college. >> reporter: but back then denise was working six days a week from dawn until dusk with her parents and siblings in minnesota farm fields. >> working in the fields it is hard. i mean, there's times when you just want to give up. >> reporter: families work together to make more money, so school often comes in second when there are crops to harvest. >> my parents have always encouraged me to go to school. breaking the cycle, it is hard because, you know, you're there, you're like should i go to work and help my family, or should i continue taking summer classes. >> reporter: but denise's

parents, both legal residents, made some of those hard choices. and denise is now a student at michigan state. >> you know, from the fields, college, d.c. internship, whoa, how did that happen? i want to pursue a masters hopefully. >> reporter: denise and three other students are chosen to intern in d.c. with the national migrant and seasonal head start association. all those summers working on farms have turned into a summer of opportunity. that selfie in front of the white house. >> as americans we've done big things together. >> reporter: they got to go inside. >> i think we think it's a dream. we might wake up later on. >> reporter: these students have worked hard and dreamt big. and for them america is still the land of the possible. harry smith, nbc news, washington. >> and that is our broadcast on this monday night as we start a new week. thank you for being here with us. i'm brian williams. of course we hope to see you right back here tomorrow evening. right back here tomorrow evening. good night. -- captions by vitac -- www.vitac.com stop stop .

nbc bay area news starts now. right now at 6:00, the clouds hovering this evening. and in some places it's actually raining. a slice of east coast weather here in the bay area. >> i'm jessica aguirre. it is not your normal bay area bo weather. in fact, it is unusual. people are struggling to stay cool with a little bit of humidity thrown in.

jodi hernandez joins us in livermore, but we begin with jeff ranieri with this rain on the radar. >> yeah. the main catalyst to give us this unusual weather at least over the past 24 hours is the monsoonal moisture. it's kicking up and spreading across california with the most numerous lightning strikes around lake tahoe. theie the heaviest zone of moisture is moving off toward the south and out toward the sea. but as it did that we did get a few reports of raindrops in alameda county, right over fremont at 4:50 this afternoon. and likely a few others of you in the east bay seeing a little bit of that activity. on the radar, we're seeing .05 of an inch per hour. close to