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Summary- A trough will redevelop over Calif for June 26th thru July 2nd. High pressure will rebuild into Calif during July 4-8th. Another period of showers appears to develop during July 19-20 in N Calif, mostly apparently associated with mountain TSTMS. A pool of unusually cold water remains in the tropical region S thru WSW of southern Baja Calif. This will discourage development and intensification of tropical cyclones during the first part of summer 2017, continuing into early July. It also contributes below normal moisture into Baja Calif, resulting in drier than normal conditions in Baja and W Mexico during late June thru most of July. El Niño has become weak as is normal in our summer. Some redevelopment in El Niño may occur during Dec – Feb 2018, but forecasted results are currently inconclusive.

Summary- The occurrence of active westerlies will decrease, and strong warm upper high pressure will build from the Pacific into most of Calif. A pool of unusually cold water has retreated further west of Calif, and its influence is diminished. A pool of unusually cold water remains in the tropical region S thru WSW of southern Baja Calif. This will discourage development and intensification of tropical cyclones during the first part of summer 2017, continuing into early July. It also contributes below normal moisture into Baja Calif, resulting in drier than normal conditions in Baja and W Mexico during late June thru most of July. El Niño has become weak, as it usual does, in our summer. Some redevelopment in El Niño may occur during Dec – Feb 2018, to produce above normal rainfall in Central and S Calif.

Summary- Occurrence of active westerlies will decrease, and troughing will focus in the Rockies and Great Basin, with dry NNW flow recurring in Calif. A pool of unusually cold water will retreat further to the west of Calif. A pool of unusually cold water remains in the tropical region S thru WSW of southern Baja Calif. This will discourage development and intensification of tropical cyclones during the first part of summer 2017, continuing into early July. Though weak and intermittent during summer, the basic signature of El Niño continues in the equatorial Pacific. The bottom line is that we will need to deal with El Niño again in the fall and next rainy season when it redevelops. The usual result for El Niño is above normal rainfall during winter and early spring months in central and S Calif.

Summary- The basic pattern consists of periods of active westerlies, and troughing near and west of N Calif and the Great Basin. A pool of unusually cold water remains W of Calif, and colder than normal sea surface is near and south of southern Baja Calif. The area of cold sea surface temperatures near southern Baja includes most of the region in which tropical cyclones form off the SW coast of Mexico. This argues for a weak or slow start to the tropical cyclone season off W Mexico this June and July. El Niño has developed. While El Niño’s Influence is mostly minimal during the mid-summer, the typical moderate to strong El Niño pattern is expected to continue thru the summer. As the season changes in the fall, El Niño has potential to become more important in modifying the prevailing pattern across Calif and the western U.S. for the 2017-18 winter wet Season, producing support for above normal rainfall.

Summary- The basic pattern consists of the tendency for troughing near and over N Calif and the S Great Basin. A pool of unusually cold water remains W of Calif, while warmer than normal sea surface temperatures are WSW of SOCAL. The sea surface temperature anomaly (SSTA) pattern in the central N Pacific is strong and persistent enough to continue the tendency for W flow towards N Calif and troughing near or just W of Oregon into early June. El Niño has developed, and is already interrupting the transition to the warm season. A typical moderate to strong El Niño anomaly pattern is expected to develop per the current SSTA pattern and the NMME (North American Multi-Model Ensemble forecast) for later in the summer and autumn.

Summary- The basic pattern consists of the tendency for troughing near and over northcentral and N Calif. A pool of unusually cold water off the coast of central and N Calif, while warmer than normal sea surface temperatures are W and SW of SOCAL. The sea surface temperature anomaly (SSTA) pattern in the central N Pacific is strong and persistent enough to continue the tendency for WSW flow towards N Calif and troughing near or just W of Oregon into early June. El Niño has developed, and is already interrupting the transition to the warm season. A typical moderate to strong El Niño anomaly pattern is expected to develop per the current SSTA pattern and the NMME (North American Multi-Model Ensemble): time frame- later in the summer and autumn.

Summary- The basic pattern consists of the tendency for troughing near and over Central and N Calif. A pool of unusually cold water is off the coast of central and N Calif, while warmer than normal sea surface temperatures are W and SW of SOCAL. The sea surface temperature anomaly (SSTA) pattern in the central N Pacific is strong and persistent enough to continue the tendency for WSW flow towards N Calif and troughing near or just W of Oregon through the remainder of May and even into early June, as suggested by the CFSDaily. El Niño has developed, and is already helping to delay the transition to the warm season. A typical moderate to strong El Niño anomaly pattern is expected to develop per the current SSTA pattern and the NMME (North American Multi-Model Ensemble): time frame- later in the summer and autumn.

Summary- The basic pattern consists of the tendency for troughing near and just west of N Calif. The sea surface temperature anomaly (SSTA) pattern in the central N Pacific is strong and persistent enough to continue the tendency for WSW flow towards N Calif and troughing near or just W of Oregon through the remainder of May. A classic, moderate to strong El Niño anomaly pattern is expected to develop per the current SSTA pattern and the NMME (North American Multi-Model Ensemble): time frame- later in the summer and autumn.

Summary- There is a tendency for troughing near and just west of N California, before and after May 1st. The sea surface temperature anomaly (SSTA) pattern in the central N Pacific is strong and persistent enough to continue the tendency for troughing through May and possibly into early June near and over the Calif coast. Forcing for troughs over western Mexico will continue. A classic, moderate to strong El Niño anomaly pattern is expected to develop per the current SSTA pattern and the NMME (North American Multi-Model Ensemble): Time frame- later in the summer and in autumn.

Summary- The tendency for troughing near and west of N California continues, even as we approach the normal end of the season. The sea surface temperature anomaly (SSTA) pattern in the central N Pacific is strong and persistent enough to continue the tendency for troughing through May and possibly into June. Forcing for troughs over the southwestern US may still be related to the currently weak El Niño, although seasonal factors that affect El Niño’s influence decrease with approach of summer. A classic, moderate to strong El Niño anomaly pattern is starting to develop, as shown by the current SSTA pattern, and the forecast developments shown by the North American Multi-model Ensemble (NMME) in the early fall.

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