The 1970 Pacific typhoon season has no official bounds; it ran year-round in 1970, but most tropical cyclones tend to form in the northwestern Pacific Ocean between June and December. These dates conventionally delimit the period of each year when most tropical cyclones form in the northwestern Pacific Ocean. The scope of this article is limited to the Pacific Ocean, north of the equator and west of the International Dateline. Storms that form east of the date line and north of the equator are called hurricanes; see 1970 Pacific hurricane season. Tropical Storms formed in the entire west Pacific basin were assigned a name by the Joint Typhoon Warning Center. Tropical depressions in this basin have the "W" suffix added to their number. Tropical depressions that enter or form in the Philippine area of responsibility are assigned a name by the Philippine Atmospheric, Geophysical and Astronomical Services Administration or PAGASA. This can often result in the same storm having two names. Systems 27 tropical depressions formed this year in the Western Pacific, of which 24 became tropical storms. 12 storms reached typhoon intensity, of which 7 reached super typhoon strength. Typhoon Nancy (Atang) Nancy originated from the interaction between an active ITCZ and a cold front near the Caroline Islands and the equator in mid February. An increase in convection was shown by weather satellites on February 18 and by the following day a recon aircraft found a weak depression to the south of the Caroline Islands. The depression moved west, suppressed south by a high pressure ridge to the north, and gradually strengthened into a tropical storm and was given the name Nancy early on February 20. Nancy became a typhoon on the 22 about 100 miles northwest from Woleai. On February 23 Nancy passed to the north of Yap where strong gale winds occurred. Continuing to encounter more favorable conditions Nancy was able to achieve a peak intensity of 140 mph (220 km/h) and a pressure of on February 24. This was the equivalent of a category four hurricane. It is rare to have a typhoon of this magnitude during the month of February, as noted by the JTWC, only Irma of the 1953 season reached the same intensity at the time. As Nancy approached the Philippine Islands the typhoon traversed to the western ambit of the ridge that had kept it to the south, allowing it to