While not extensively evident yet, La Nina is on its way out as we approach late spring and summer. Cold SST anomalies in the equatorial Pacific have shifted east, with overall warming occuring in the central Pacific. The atmosphere has been trying to jump start for the past couple weeks. Trade winds have weakened while shifting poleward, and a large spike in frictional torque recently has contributed to tugging us out of the deep low index regime. Now the GWO is getting ready to rotate back through phase 4. This general +dAAM/dt tendency is likely to continue through at least the next few weeks.

In the medium range, this should support another round of higher amplification in northern stream for the 8-10 day range. ECMWF and GFS ensembles have been focusing in on negative height anomalies aligning along 140W. Whether they center toward Alaska, or further south over the Gulf makes a huge difference. Over Alaska, and the much of the country heats up; Over the Gulf of Alaska, and downstream wave dispersion would support a trough over the east. I think considering the AAM ramping up, we could be looking at more favorable conditions for the GOA trough and downstream western ridging / east coast trough. Incidently, the GFS and ECMWF have also been displaying the potential for another east coast storm around March 17-18. Climotology argues against much potential for snow south of 40N, but across New England, March is still in the heart of winter.

This pattern should shift east by the 20th, with energy in the GOA spitting out troughs across the western US, pushing ridging east. Ramifications include the potential for severe weather impacting the central states.

---

I've done a bit of work with roll-forward analogues matching with time-averaged anomalies from this past December and January. First, the analogs support the general trend toward neutral, or positive neutral ENSO conditions for the summer. Second, from these analogs, I've formulated a preliminary outlook for hurricane season: 13 to 14 named storms, 7 hurricanes, and 3 to 4 major hurricanes. Frequented tracks appear to be mainly recurvature east of the United States east coast, as well as some favorability in the Gulf of Mexico. Also there is a signal for the chance that Cape Cod and eastern Maine could be targetted in August.