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 07 June2026 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 youtu.be/1pKfA8c4s2U May was a LOW INDEX month, with blocking Highs traveling slowly east along around 45S and a series of lows crossing Australia and then traveling east across the Pacific at around 25s. For more information about "Low index weather pattern nz" The index being referred to is the Zonal index, usually Z1, and that is simply the barometric pressure difference (Auckland-Christchurch). When this is high, NZ has westerly winds. Well last month is was low and sometimes negative. Another impact of Low index has been the rainfalls . Parts of eastern Australia have had their wettest May of record. And parts of NZ have a record-breaking DRY month. The thing about the Low index pattern is that it usually flips into a high index pattern after a few weeks. I think this low index pattern is acting as a herald for a switch to a high index pattern. And El Nino encourages a high index. The 500hPa heights and anomalies shows that prolonged upper low over Tasman sea late in the month as seen at http://www.cpc.ncep.noaa.gov/products/intraseasonal/z500_sh_anim.shtml Sea Surface temperature anomalies from psl.noaa.gov/map/clim/sst.shtml The waters over eastern equatorial Pacific are warming --- El Nino is kicking in. There is a well-established warm zone between Hawaii and LA. Since most of the North pacific is now on the warm side, the projections towards a super El Nino seem to be on target. The cool zone around NW of Australia has almost gone. Average isobars for past month From www.psl.noaa.gov/map/images/fnl/slp_30b.fnl.html The subtropical ridge in the southern hemisphere has further intensified and expanded both to north and south. The Monsoon has arrive over southern India around normal. Pressure anomalies for past two months The anomaly pressure pattern for last month now shows a low breeding area between Hawaii and Galapagos. . The southern subtropical ridge intensification is well developed over NZ, and there is still a low breeding area over New Caledonia = Low index. The 1015 isobar has stayed north over Australia near Cairns and there is a 1025 over central New Zealand. TROPICS AMANDA has been named in the northeast pacific. Tropical Storm Jangmi swept across much of Japan, bringing torrential rain, flooding and strong winds from Okinawa to the Tokyo region. At least 23 people were injured and dozens of homes were damaged by the storm. WEATHER ZONES SPCZ is of average intensity but somewhat north of its normal position. GFS model has a low forming near Fiji next week and that would create a squash zone near 20S . Other models disagree but, because of the intensity of a High crossing NZ also have a squash zone stretching across New Caledonia /Fiji to between Samoa and Tonga. Main feature this week is the upper cold pool east of NZ. It is expected to form a series of surface lows and these are expected to produce a burst of long-period southerly swell peaking at 10m near 35S 175W and spreading 4m swells as far west as 175E by Wednesday and as far east as southern Tahiti by local Thursday. This is the sort of swell that Tahitian surfers dream about. Then we have the 1036hPa HIGH slowly crossing Tasman Sea and New Zealand this week. Usually a good pattern for sailing north but complicated this week by those large southerly swells mid-week and a possible squash zone near Fiji early next week. Since the models ideas about the Fiji squash zone early next week may change next few days one idea is to head from NZ to NNW at first, avoiding the larger swells. then neat 25S get an update and if Fiji is getting too yucky then turn left and go to Noumea (Plan B) Lows L1 and L2 in the southern ocean are expected to travel east along 50S , to south of H1. Wind accumulation for next week from windy.com above shows the path of wind accompanying the L1 and the building of squash zone between New Caledonia and eats of Fiji >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 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. >>>>>>>>>>>>>>>>