Bobgram

Bob McDavitt’s ideas for sailing around the South Pacific. Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the patterned world. Compiled 27 September 2026 NOLO To POLO Cyclones Nolo Odalys and Polo Thursday, Sept. 24, 2026. Tropical Storm Nolo is south of Hawaii. Hurricane Polo, right, is off the coast of Mexico. Hurricane Odalys is in the middle. NOAA via AP/NOAA It's been an extreme hurricane season in both the Atlantic and Pacific Oceans — but for vastly different reasons. The Pacific Ocean has seen 18 hurricanes so far and 41 named storms overall, which are unusually high numbers for this point in the season. The Atlantic Ocean is experiencing the exact opposite. For the first time in over 100 years, no full-blown hurricanes have formed in the Atlantic as of September 25. Only seven named storms have formed, all of which were less-intense tropical storms. Hawaii is one place bearing the brunt of this shift. Hurricane Nolo is expected to bring heavy rainfall and potential flooding to Hawaii this weekend. It's the third hurricane to threaten the islands this year, following Hurricane Lala in August and Hurricane Lowell in early September. El Niño happens when water temperatures increase in the Pacific Ocean, near the equator. That warmer water provides fuel for hurricanes, driving bigger and more powerful storms. That means when a storm forms, it's more likely to reach hurricane strength. In the North Atlantic, El Niño tends to increase wind shear, making it more difficult for hurricanes to form by tearing storms apart. This year, El Niño is more intense than usual. Pacific water temperatures are already hitting record highs, even though the phenomenon won't reach its peak until later this year. On Tuesday, Hurricane Polo, off Mexico's Pacific coast, strengthened from a tropical storm to a Category 5 hurricane in less than 24 hours. Such rapid intensification can make storms more dangerous, in part by limiting the time people have to prepare. Polo has just been found to have a central pressure of 889Mb. This is the lowest recorded in the eastern pacific since hurricane Patrica back in 2015. That’s a drop of 90hPa in 12 hours. The unit for rapid cyclogeneses is the Bergernon . Introduced by Swedish Meteorologist Tor Bergeron. He defined 1B to be a drop in the central pressure of a Low system by 24 hectoPascals within a 24-hour period. Fred Sanders and John Gyakum formally refine the metric in 1980 to normalise it to 60 degrees latitude. In this case the 24-hour pressure drop was 90 hPa making 3.75B but applying the latitude correction this becomes 1.9B TROPICS • At least 10 people perished in flooding and mudslides around Tokyo due to downpours from passing Typhoon Dujuan. • India’s Andhra Pradesh and Odisha coasts were drenched by Cyclone One. • Outer bands from super Hurricane Polo raked Mexico’s Guerrero and Michoacán states. • Fay continues to travel north across the north Atlantic. WEATHER ZONES SPCZ is weak and mainly over Tuvalu and Tokelau . Low L1 south of Chatham Islands tonight is expected to move off to the east and allow High H1 over Tasmania on Monday to travel northeast across the Tasman Sea and then weaken to north of New Zealand. H1 may enhance some trade winds between Southern Cooks and Fiji during the week L1 is expected to bring some cold air aloft into the Tasman Sea . This is expected to turn into a cold pool over Norfolk Island, and that may descend to form a surface trough near New Caledonia by Friday and that will then be on the NW shoulder of H1 so might form a Low. Models differ. Low L2 is expected to cross southern NZ on Fri and Sat 2 and 3 of October .. making room for H2 to follow H1. Note that after Monday there are no troughs expected to visit northern New Zealand this week —there is a window of OK sailing weather from the tropics to NZ/Aus. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> If you would like more details about your voyage, check metbob.com Or Facebook at /www.facebook.com/metbobnz/ Weathergram with graphics is at metbob.wordpress.com (subscribe/unsubscribe at bottom). Weathergram archive (with translator) is at weathergram.blogspot.co.nz. Contact is bob@metbob.com or text 64277762212. >>>>>>>>>>>>>>>>