Weather forecasters in the U.S. and Japan will be busy this week, with five named tropical cyclones spinning in the Atlantic and Pacific Oceans and three of them headed for close encounters with highly populated areas in Japan and Hawaii. Typhoon Halong, which peaked at a monstrous Category Five intensity during the weekend, becoming one of the most intense — if not the strongest — storm on Earth so far in 2014.

Halong is forecast to make landfall in Japan on Aug. 9 as a Category One typhoon or a strong tropical storm, and it will be the second tropical cyclone to strike that country so far this season. Given recent heavy rainfall in parts of Japan, Typhoon Halong could cause deadly landslides as well as coastal flooding when it comes ashore.

Tropical Storm Nakri dumped very heavy rain in Japan over the past few days, according to the Japan Meteorological Agency. As Weather.com reported, a spot on the large southern island of Shikoku, which lies in the path of Halong, recorded an astounding 44.82 inches of rain in the three-day period ending around noon on Monday, local time.

Computer model projections of Typhoon Halong's path toward Japan. Image: WeatherBell Analytics

Typhoon Halong was able to intensify to such a strong storm because it traversed some of the warmest waters of any ocean basin, and hurricanes and typhoons (these are the same type of storm, just called different names based on location) draw their energy from warm ocean waters. These storms are like giant heat engines, drawing heat from the water to the atmosphere, and transporting it toward the poles.

Typhoon Halong at its peak intensity on August 2, 2014, when it had sustained winds of about 150 miles per hour. Image: NOAA

The Pacific Ocean is primed for even more intense storms, as both the eastern Pacific and western Pacific have large areas with above average ocean temperatures for this time of year. This is related to the developing El Niño event, which has slowed in recent weeks.

Typhoon Halong will bring severe impacts to Japan late week. Kochi saw 45.00 in rain just last week. pic.twitter.com/IvQtaKqoG4 — Anthony Sagliani (@anthonywx) August 4, 2014

Sea surface temperature departures from average on August 2, 2014. Image: NOAA/ESRL

Meanwhile, two storms are spinning their way toward Hawaii, a state which does not typically see landfalling hurricanes, let alone two in one week. As of Monday morning, Hurricane Iselle, which was located about 1,200 miles east-southeast of Hilo, Hawaii, had maximum sustained winds of 140 miles per hour, making it a Category Four storm on the Saffir-Simpson Scale. It is forecast to continue moving northwest, toward the Hawaiian islands, while maintaining its strength for at least another day.

After that, Iselle will begin encountering cooler ocean temperatures, which should cause it to gradually weaken, according to the National Hurricane Center in Miami. The National Oceanic and Atmospheric Administration (NOAA) is repositioning some of its hurricane monitoring aircraft fleet to Hawaii on Monday, an unusual, though not unprecedented step.

The highly modified Gulfstream jet will fly near the storm, gathering data that will be fed into computer models to improve the accuracy of their projections in the next several days.

Meantime, in the Pacific Ocean, here's menacing Category 4 Hurricane Iselle. Tracking towards Hawaii, but will weaken pic.twitter.com/WACXplJGGV — Jim Loznicka WGCL (@LoznickaCBS46) August 4, 2014

According to the National Hurricane Center, Hurricane Iselle is not your typical hurricane, with many spiral bands of thunderstorms surrounding a "wall" of extremely intense thunderstorms near the storm center. These characteristics make it an "annular" hurricane, according to Weather Underground chief meteorologist Jeff Masters.

Masters says such storms make up just 4% of all hurricanes, and they tend to weaken more slowly than typical hurricanes.

Storms would be a rarity in Hawaii

Although it is an island state in the middle of an active ocean basin for hurricanes, Hawaii does not often see such storms. Hurricanes approaching from the east typically weaken before they reach the state, because cooler ocean waters surround the islands and there tends to be a lot of dry air in that vicinity as well, two factors that weaken hurricanes. The last major hurricane of Category Three intensity or greater was Hurricane Iniki in 1992, and it swung into the island of Kuai from the south, rather than the east.

Hot on Iselle's heels is Tropical Storm Julio, which formed on Monday, and is expected to slowly intensify to become a hurricane in the next few days. Julio could threaten Hawaii during the weekend or early next week, but it too is expected to weaken as it approaches Hawaii.

Satellite view of Hurricane Iselle and Tropical Storm Julio on August 4, 2014. Image: NOAA

Right now, NOAA's National Weather Service is telling Hawaiians to stay tuned to forecasts later this week as the storms get closer. "For Thursday and beyond, there is the possibility for unsettled weather associated with two tropical cyclones beginning late Thursday and continuing into early next weekend," the NWS office in Honolulu posted on its website Monday.

In a forecast discussion, also posted online, NWS forecasters in Hawaii emphasized the significant uncertainties in forecasting such storms several days in advance. The discussion, posted in the NWS' ALL CAPS shouting style, read:

THE NATIONAL HURRICANE CENTER IN MIAMI SHOWS ISELLE REACHING THE VICINITY OF THE BIG ISLAND AS A TROPICAL STORM BY THU NIGHT/EARLY FRI MORNING. THERE IS ALSO POTENTIAL FOR ISELLE TO IMPACT THE SMALLER ISLANDS LATER ON FRI. SIGNIFICANT UNCERTAINTY IN THE FORECAST TRACK FOR THE LONG RANGE MEANS THAT IT IS TOO EARLY TO DETERMINE SPECIFIC IMPACTS IN TERMS OF RAINFALL AMOUNTS OR WIND SPEEDS ATTM... THE LONG TERM MODEL GUIDANCE ALSO SHOW POTENTIAL FOR ANOTHER TROPICAL CYCLONE APPROACHING THE ISLAND CHAIN STARTING SAT NIGHT. THE SITUATION WILL CONTINUE TO BE CLOSELY MONITORED.

Then, in the Atlantic Ocean, the second hurricane of the season formed on Monday: Hurricane Bertha. This storm is expected to continue moving northeast, far enough off the East Coast to spare the U.S. any major impacts, and far enough west of Bermuda to do the same there.

The forecast for the Atlantic calls for an average to slightly below average hurricane season. A major hurricane has not made landfall in the U.S. since 2005, which is a record-long timespan, but the country's luck will run out sooner or later.