The Madden Julian oscillation forecast by NCEP indicates a strengthening phase_7 during the 8-14 day period (Fig. 1). Phase_7 represents heavy convection shifting east across the equatorial Pacific toward and east of the Dateline. During this regime convective currents increase in South America including Argentina lending support for model forecasts that indicate wet conditions.
Note to analysts: During a precipitation pattern change in South America, particularly Brazil and Argentina almost always support of this rainfall pattern change is associated with (or caused by) the MJO.
Today’s 1200 GMT GFS Operational (model) indicates 2 to 5 times the normal rainfall across Argentina in the 8-14 day period (Fig. 2). Forecast models have varied since late last week (dry and wet). But confidence in the MJO supporting a wetter regime is increasing.
Fig. 1-2: The NCEP MJO forecast indicates strengthening phase_7 in the 8-14 day period. Normally, phase_7 favors wet weather in South America. The 12Z GFS indicates 2 to 5 times normal rainfall in Argentina.
The MJO shift from weak phase_6 (West Pacific) to phase_7 (near and east of the Dateline) also caused the northern U.S. to trend colder again (Fig. 3-4).
Fig. 3-4: Today’s Climate Impact Company medium-range forecast of U.S. temperature anomalies.
The somewhat benign MJO regime favors a drier climate across Australia this week (Fig. 5). However, as MJO strengthens days 8-14 a wetter than normal regime possibly featuring extreme amount emerges across eastern Australia (Fig. 6).
Fig. 5-6: ECM ensemble indicates a dry pattern across Australia days 1-7 turning wet eastern Australia days 8-14 due to intensification of the MJO.
Elsewhere excessive rainfall is likely this week across southern Europe. Heaviest rainfall is across Italy to Southeast Europe (but north of Greece). The 8-14 day period looks much drier. The temperature regime maintains very mild conditions in Western Russia as snow cover has disappeared while Europe slowly trends warmer.
