There will be an abrupt transition from a negative-phased Arctic Oscillation (AO) to a positive-phase AO over the next two weeks. Precipitation patterns can become enhanced during these transitions. In conjunction with this transition, a split jet stream flow is expected to develop with the southerly branch more active (reference Weekly Water Outlook). I’d like to provide some early insight into possible precipitation trends associated with this transition.
Southeast U.S. – there will be two enhanced periods of precipitation. The first will occur over the next several days. Heaviest rain will align parallel to the coast with amounts 2 or 3 inches along the coast quickly tapering off further inland. The next round of precipitation will likely move a bit further inland, during the April 11-14 time frame. Overall – 2 to 4 inches of rain, with locally higher amounts near the coast, can be expected between April 3-15.
Midwest – Portions of the Midwest will align within the area between the northerly and southerly branches of the jet stream. This region will recive a soaking rain, in the 1-3 inch range, from April 6-12.
In the above graphic, areas shaded in brown are experiencing the more significant upper soil moisture deficits. As you can see, most of the precipitation will be just outside the area that needs rain the most. However, there will be improvement over eastern sections of Kansas, Oklahoma, and Texas.
I will be providing updated information on this trend later this week.