Climate Prediction Center - Week 3-4 Outlook

Prognostic Discussion for Week 3-4 Temperature and Precipitation Outlooks
NWS Climate Prediction Center College Park MD
300PM EDT Fri Aug 14 2026

Week 3-4 Forecast Discussion Valid Sat Aug 29 2026-Fri Sep 11 2026

El Niño conditions continue to intensify across the equatorial Pacific, with a robust atmospheric response that will increasingly influence the midlatitude pattern as the northern hemisphere moves into the autumn months. The MJO remains active, though the stationary ENSO pattern is by far the dominant mode of tropical convective anomalies, and the intraseasonal signal is mostly modifying the strength of the atmospheric response to the warming Pacific sea-surface temperatures. Dynamical model MJO index forecasts are mixed, but primarily keep the signal in constructive interference with the El Niño background state over the Pacific through the next few weeks, which may help maintain high tropical cyclone activity over the Pacific basins, and reduced activity over the Atlantic.

A manual blend of operational and statistical model 500-hPa height anomaly forecasts shows a pattern fairly consistent with historical composites of observed El Niño and MJO activity. Anomalous ridging is favored over the north-central Pacific west of the Aleutians. Downstream of this feature over North America, troughing is favored south of the Aleutians, with ridging over western North America. This pattern favors anomalous southerly flow over Alaska, and is favorable for enhanced late Monsoon activity over the Southwest. Across the East, model forecasts are more mixed, but generally depict some degree of weakness or troughing centered near the Great Lakes. This pattern may support some intrusion of cooler and drier Canadian airmasses into the eastern US, which is consistent with the multivariate linear regression (MLR) model that includes ENSO influences, but there is considerable uncertainty regarding how much cold air there would be to work with.

The Weeks 3-4 temperature outlook favors above-normal temperatures across much of Alaska, consistent with anticipated southerly flow, but with reduced probabilities compared to the manual blend. Higher probabilities for above-normal temperatures extend across the West, consistent with forecast ridging. Above-normal temperatures are also favored along the southern tier, especially along the Gulf Coast where convective activity may be more suppressed than usual for the time of year. Equal chances extend across the northwestern quadrant of the contiguous US, with a small area favoring below-normal temperatures across the Great Lakes. With amplified subtropical ridging poleward of the El Niño enhanced convective signal, above-normal temperatures are favored for Hawaii.

Dynamical model precipitation guidance was remarkably consistent across Alaska and the western half of the CONUS, with above-normal precipitation favored due to enhanced southerly flow across Alaska and ridging over western North America favored enhanced monsoonal flow. The forecast is more uncertain across the East, but a potential for drier airmass intrusions into the northern CONUS slightly favors below-normal precipitation across the upper Midwest, Great Lakes, and interior New England. Further south, the height field indicates a potential for a mean frontal boundary set up over the Tennessee Valley region, which would provide a focus for enhanced precipitation. In contrast, below-normal precipitation is favored for far South Texas and the Florida Peninsula. Across Hawaii, dynamical model forecasts generally favor above-normal precipitation.

Forecaster: Adam Allgood

The next week 3-4 outlook will be issued on Friday, Aug 21, 2026

These outlooks are based on departures from the 1991-2020 base period

These are three category outlooks consistent with what is currently used for the monthly and seasonal forecasts.

The shading on the temperature map depicts the most favored category, either above-normal (A), below-normal (B), or near-normal (N) with the solid lines giving the probability ( >33%) of this more likely category (above, below, or near).

The shading on the precipitation map depicts the most favored category, either above-median (A), below-median (B), or near-median with the solid lines giving the probability ( >33%) of this more likely category (above, below, or near).

In areas where the likelihoods of 2-week mean temperatures and accumulated precipitation amounts are similar to climatological probabilities, equal chances (EC) is indicated.