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 03 May 2026 Some good news:  Thanks to the persistence and generosity of Max on Y2K The link listing useful weather links for the South Pacific is back www.y2ksail.com/meteo-link.html Try this out and if you like it Buy him a beer (it’s the bottom link) 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/GjGUycWtUYo Cyclone Vaianu breezed across NZ quickly on 11 April and a cold pool convergence zone flooded Wellington on 20 April The 500hPa heights and anomalies shows that prolonged upper low  over Tasman sea late in the month From 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 coming. The cool zone around NW of Australia is relaxing . There is a well established warm zone between Hawaii and LA. The cool (dry) zone around NW Australia is shrinking. Average isobars for past month (below) The subtropical ridge in the southern hemisphere has further  intensified and shifted north. The HIGHS over Siberia, over the Aleutians and in the North Atlantic have all weakened . Pressure anomalies for past two months (below) The anomaly pressure pattern for last month still shows a low breeding area around Hawaii.   The southern subtropical ridge intensification is well developed east of NZ, but there is still a low breeding area between Tonga and NZ, and another over Australian Bight. The 1015 isobar has shifted north over Australia to Cairns and the 1020 spans from Melbourne to Brisbane. TROPICS No named storms around the planet this evening. WEATHER ZONES SPCZ is weak and scattered this week, but there is some severe convection associated with the clouds around L1, a tropical low that is expected to form on Wednesday around the Southern Cooks --- on the NW shoulder of the large High H1 that is travelling east along 40S and to east of NZ.  L1 is expected to deepen as it travels south near 160W this weekend and early next week. There are two lows and troughs crossing the Tasman Sea /NZ area this week. L1 is expected to weaken over central NZ on Thursday. Then L2 should be followed by a strong cold SW flow on Saturday. If L2 then moves off to the east without leaving behind a secondary development, and if the High following L2 travels steadily along 40S with a central pressure between 1025 and 1030 (no more, no less), then this pattern is consistent with what I call a Southerly flush…. The arrival of the cold air in Northland is such that the marinas are flushed empty of those yachts seeking the warmth of the tropics.  I’m not sure yet, and we may have to wait until Wednesday before the differing models start agreeing. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>  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. >>>>>>>>>>>>>>>>