Evolution of a super high latitude/high pressure blocking pattern is forecast to develop this weekend and next week in the southern hemisphere. The result is a negative Antarctic oscillation (-AAO) which goes “off the charts” to values near -6 according to some forecast models.

The polar ice cap has constricted to 80% of the 1980-2010 climatology and rivals July 2012. The European heat wave has ended however the warmth shifts north and strikes Greenland this week accelerating ice melt.

We now have 3 tropical waves in the outer tropical North Atlantic basin. Each tropical wave is located over 80-81F water which is marginally supportive for development. The upper shear axis stretches across the southern Caribbean Sea and northwest of the tropical waves. However, the shear axis is not particularly strong. Meanwhile upper shear is very light across the northern Caribbean Sea and Bahamas (where surface water is generally warmer than normal).

The most impressive upper level feature in the northern hemisphere since springtime has been the persistent and vigorous upper level cool and showery trough over Western Russia. Occasionally, upstream from the deep trough an amplified ridge forms to bring heat wave conditions to Europe centered on France. Otherwise the trough takes over and squashes heat and this time leads to wet weather over France next week after the torrid heat this week.

The Australian Bureau of Meteorology has updated their Indian Ocean Dipole outlook which indicates a robust positive phase evolving for AUG/SEP/OCT 2019.

Dynamic global SSTA forecast models including NCEP CFS V2, NMME and GFDL are suddenly forecasting La Nina cooling in the eastern equatorial Pacific Ocean for AUG/SEP/OCT 2019. The possible cause for this sudden change picked up by most global models is the rapid cooling off the West Coast of South America the past few weeks forced northward into the East Pacific tropics by the reactivated Humboldt Ocean Current. The just-ending El Nino warm waters shift west to the Dateline. Interestingly, if the La Nina cooling forecast is less dramatic an El Nino Modoki may form.

During the past 3 months the number of large regions of soil moisture change across the globe favored drier conditions (18) versus wetter adjustments (11). Currently, the most profound drought areas stretch across Canada which is mostly unchanged during the past 3 months except drier into Northwest Territories, northern and western Europe which expanded east into Western Russia, a strengthening intense dry region in northeast Russia and ongoing drought which gained intensity since March in southwestern Africa and much of Australia.

During the past several weeks a very La Nina looking SSTA pattern has emerged off the west coast of South America as the Humboldt Current is actively churning to the surface cold subsurface water and surging that chill toward the equatorial region. The influence on ENSO forecast models is to cause suppression of the weak El Nino and introduce a La Nina risk later this year.

A tropical disturbance is forecast to form in the northeast Gulf of Mexico later Wednesday and drift southwestward and then west while intensifying to a tropical storm eventually making landfall (as a tropical storm) Saturday on the central Louisiana coastline. The preliminary forecast track is based on the highly reliable ECMWF model.

Despite approaching mid-summer, forecast confidence of the 2019 North Atlantic tropical season is not particularly confident and with good reason. Expected is the inhibiting influence of upper westerly shear across the tropical North Atlantic caused by El Nino holding number of hurricanes down BUT potentially offset by a forecast of a warmer than normal tropical North Atlantic. As it turns out, on July 6 the North Atlantic tropics have unexpectedly cooled and the El Nino is fading (and NOAA is more concrened about La Nina develping).