Early-season development is underway in the Atlantic basin as two disturbances brew, one of which has already been deemed ‘Potential Tropical Cyclone Two’ by the National Hurricane Center. A second located near Mexico’s Yucatan Peninsula currently has a 70% chance of becoming a Tropical Depression within the next 48 hours and a 90% chance over the next 5 days. It may track into the Gulf of Mexico where it’s eventual fate becomes more uncertain.

Two-day graphical outlook from the NHC:


This sort of early potential in the MDR (main development region) via ‘Two’ has sometimes heralded a more active season overall, which broadly fits with the evolution of the ENSO state in the Pacific which has recently trended away from a potentially more boisterous El Nino episode and closer to ENSO-neutral territory over the longer haul.

The medium range pattern over NA continues to look dictated by upper ridging in the SW USA flexing towards SW BC, a trough over MB & the upper GL and a downstream ridge towards Atlantic Canada which looks to ultimately ease down the line.

This will promote a milder pattern for some parts of the west but cooler and unsettled conditions for much of Central Canada. A stout SW flow for the Atlantic Provinces in the near term looks to degrade farther out as the ‘cool pool’ bleeds eastward.

Support continues for a sizable portion of the east to see above-average precip as the trough axis settles in.

12z EPS 500mb height anomalies, days 1-5:


850mb temp anomalies, same timeframe:


500mb height anomalies, days 6-10:


850mb temp anomalies, same timeframe:


12z NAEFS temp probabilities, days 8-14:


12z GFS ensembles precip anomalies @ hour 360 / day 15: