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 04 October 2026 A review of last month's weather Here is a link to a YouTube clip giving an animated loop of the isobars and streamlines For last month is at https://youtu.be/6j7UxmBp9a8 Several anticyclones entered the south Tasman then travelled northeast and then faded into the subtropical ridge along 30S. This pattern repeated 1-3 Sep 14-16 Sep 24-26 Sep and 29-30 Sep. There continue to be several near equatorial lows , a facet of this El Nino. In an El Nino the Walker Circulation over the Pacific equator shifts so that its rising pillar gets close to 180deg/Kirimati. The 500hPa heights and anomalies shows that prolonged upper low over Tasman sea late in the month From www.cpc.ncep.noaa.gov/products/intraseasonal/z500_sh_anim.shtml Sea Surface temperature anomalies from psl.noaa.gov/map/clim/sst.shtml El Nino 's warmth in the eastern equatorial pacific continues, and that cooler patch on its southwest side over Southwest pacific is bringing dry conditions . Average isobars for past month From www.psl.noaa.gov/map/images/fnl/slp_30b.fnl.html In the northern hemisphere the Siberian anticyclone is forming quickly heralding an early winter there. The Pacific equatorial Low and Tasman High have intensified, as expected in El Nino. Pressure anomalies for past two months From www.psl.noaa.gov/map/images/fnl/slp_30b.fnl.html The anomaly pressure pattern hasn't changed much in the past month. New Zealand Details The 1020 isobar has shifted south over Tasmania. The saddle point between NZ and Chile has dropped from around 1017 to about 1013. The SAM Southern Annular Mode ( as shown using the AAO) was positive in September and is forecast to be neutral or positive for much of October TROPICS . Hurricane Polo made landfall on the Baja California peninsula, knocking out power as it brought life-threatening rain and winds to northwestern Mexico. Its tropical moisture also triggered widespread flooding across the southwestern United States. . Hurricane Rachel skirted Mexico's Pacific coast. . Hawaii's Big Island was soaked by Hurricane Nolo. . Typhoon Surigae became the second such storm to skirt Japan's Honshu Island in just over a week. . Tropical Storm Gonzalo formed briefly WEATHER ZONES Weather Zones Mid-week GFS model showing isobars, winds, waves (purple), rain (red), MT (Monsoonal trough), STR (Subtropical Ridge), SPCZ (South Pacific Convergence Zone) CZ (Convergence Zone) High H1 east of NZ tonight is expected to travel off to the northeast There was a cold pool trough between Norfolk and Noumea on Friday Thar has been an easterly punch cold front over Northland today, pushed quickly north by H1. This cold air is expected to meet the left over cold pool and forma a surface low south of Minerva by Tuesday and that should fade as it moves southeast by Thursday. Low L2 is expected to enter the Tasman Sea from the west as a trough on Tuesday and then form on Wednesday and become blocked and pushed off to the north on Thursday and Friday as High H2 travels east along 45S. L2 then travel southeasts , decaying over the North Island by next - and followed another Tasman trough early next week. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 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. >>>>>>>>>>>>>>>>