Chilly End to May in U.S.
05/19/2025, 6:13 am EDT
GFS and ECM Rainfall Forecast Bias across U.S. AG Belt
05/28/2025, 12:31 pm EDT
Climate Impact Company Madden Julian Oscillation Outlook
Issued: Tuesday, May 27, 2025
Highlight: MJO influence on climate may increase in the 8-14-day period bringing changes to the U.S., Brazil, and Australia.
Fig. 1: The MJO 2-week forecast reveals potential for moderate intensity in the 8-14-day period in phase_7/phase_8 (east of Dateline in the tropics).
Discussion: Operational models are indicating increased risk of anomalous wet weather across much of the Southern U.S. and Brazil during early-to-middle June. Support for the wetter tropical/subtropical weather is increasing as forecasts (Fig. 1) of the convection phase of the Madden Julian oscillation (MJO) are trending stronger east of the Dateline in the tropics to the American longitudes (phase_7 and phase_8). Operational forecasts for the U.S. into the extended range are quite warm. However, based on MJO P7/P8 climatology, U.S. forecasts may shift wetter and therefore not as warm (Fig. 2-3). Additionally, in the southern hemisphere, operational forecasts shifting Brazil wetter during June have support from the emerging MJO presence (Fig. 4). Additionally, wet forecasts for early-to-mid June across Australia could ease drier if the subsidence phase of the MJO appears as forecast by various models.
Fig. 2-3: During MAY/JUN/JUL when MJO enters phase_7 and phase_8 the historical potential influence on U.S. temperature and precipitation.
Fig. 4: During MAY-SEP the outgoing longwave radiation anomalies in the tropics associated with MJO phase_7 and phase_8.
