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 Jul 25 2025

Week 3-4 Forecast Discussion Valid Sat Aug 09 2025-Fri Aug 22 2025

The Weeks 3-4 Temperature and Precipitation Outlooks issued this week are based on dynamical model guidance, trends, soil moisture and sea surface temperature (SST) anomalies, and expected forcing from large-scale organized tropical convection.

SST anomalies in the equatorial Pacific are slightly below zero in the Niño-3.4 region. The El Niño/Southern Oscillation (ENSO) is currently classified as neutral. Current and forecast Outgoing Longwave Radiation (OLR) anomalies indicate a very weak low-frequency positive anomaly over the central equatorial Pacific, indicating slightly suppressed convection in that region. Given the weak amplitude of the anomalies, and the lack of a strong ENSO teleconnection in summer, the current ENSO state largely does not factor into the Weeks 3-4 Temperature and Precipitation Outlooks.

The Madden Julian Oscillation (MJO) is currently active in Realtime Multivariate MJO (RMM) index phase 6, forecast to soon enter phase 7, with a suppressed phase located over the eastern Indian Ocean and western Maritime Continent. Forecasts from ECMWF indicate that the MJO wave may weaken as it enters phase 8, and remain borderline-coherent into phases 1 and 2 by early August. Composites of the large-scale extratropical circulation two weeks following August MJO phases 1 and 2 during ENSO-neutral conditions indicate anomalously high 500-hPa geopotential heights near the west coast, as well as the northeastern Contiguous United States (CONUS). Anomalous troughing is indicated in the composites over much of the central CONUS. Given the expected weak MJO amplitude, and the overall weak signal in the composites, the MJO was only given slight consideration in the production of this week’s final Weeks 3-4 outlooks.

Current coastal SST anomalies are generally below normal along coastal California, with very warm SST anomalies located along the Gulf Coast states and the Atlantic seaboard. The cool SSTs along the California coast have contributed to generally near or slightly below normal air temperatures throughout much of the summer from the San Francisco Bay Area down along the coast to San Diego, and the boundary conditions are not expected to evolve substantially heading into weeks 3 and 4, suggesting a continuation of this influence.

Soil moisture anomalies indicate generally dry conditions from the West Coast into the Rocky Mountains, with anomalously wet soil moisture extending across much of the Great Plains, parts of the Ohio Valley and the mid-Atlantic states. Small pockets of very dry soil moisture anomalies can also be found centered over Chicago, and across the Florida peninsula. Generally, the regions of anomalously wet soil moisture reinforced cooler and wetter forecasts in regions where models indicated the possibility of such conditions, helping reduce some of the uncertainty in those regions.

The latest dynamical model guidance shows general agreement in the large-scale circulation pattern. Positive 500-hPa geopotential heights are favored over most of North America, with the strongest anomalies located near the Pacific Northwest, and the Northeastern CONUS. However, some differences in smaller-scale features, especially the potential for a weakness in the positive height anomalies centered over the central and northern Great Plains, have led to substantial discrepancies in the probabilistic temperature forecasts from one model to the next, with some smaller differences in the already-uncertain precipitation forecasts as well. For example, the ECMWF and JMA indicate a more robust weakness in the ridge, and, correspondingly, both show substantial negative temperature anomalies extending from eastern Montana all the way down through northern Texas. Some of the signal in the ECMWF is likely associated with the wet soil moisture anomalies; that model tends to strongly emphasize the influence of anomalous soil moisture. To the contrary, the GEFS and CFS indicate higher heights over the Great Plains, and thus indicate high probabilities of warm temperature anomalies over the region. This is more consistent with warming trends.

Given all of the factors mentioned above, the Temperature Outlook for the Week 3-4 period favors warmer than normal temperatures across most of CONUS, with the highest probabilities over the Pacific Northwest, Florida, and the Northeast. Equal chances are indicated over the Great Plains due to the uncertainties mentioned above, and along the California Coast associated with the aforementioned cool SST anomalies. Enhanced probabilities of above normal temperatures are also indicated for most of southern Alaska, with good model agreement for warm temperatures over that region.

The Precipitation Outlook for the Week 3-4 period is highly uncertain, given the weak forcing and model discrepancies. Slightly enhanced probabilities for above normal precipitation are forecast for Arizona, as the models continue to indicate a slightly enhanced monsoon over the region. Above normal precipitation is also forecast over a swath from Louisiana to the mid-Atlantic, potentially associated with return-flow around the large-scale ridge over the eastern CONUS. Slightly enhanced probabilities of below normal precipitation are indicated for parts of eastern Kansas and Nebraska, across Illinois, and into Michigan, with a slightly enhanced chance of dry northerlies over the region. Wet conditions are forecast over the Alaskan Panhandle, associated with the possibility of anomalous southwesterly flow aloft.

SST anomalies near Hawaiʻi are generally near zero, with warm anomalies to the northwest, and cool anomalies to the southeast. The temperature outlook for Hawaiʻi indicates equal chances across the islands, with no coherent signal in the models for anomalously warm or cool conditions. Model guidance favors enhanced below median precipitation probabilities across the Hawaiian Islands, with the most enhanced dry probabilities indicated for the eastern islands.

Temperature Precipitation

FCST FCST

Hilo EC B70

Kahului EC B60

Honolulu EC B55

Lihue EC B55

Forecaster: Michael Goss

The next week 3-4 outlook will be issued on Friday, Aug 01, 2025

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

These are two category outlooks and differ from official current three category outlooks currently used for the monthly and seasonal forecasts.

The shading on the temperature map depicts the most favored category, either above-normal (A) or below-normal (B) with the solid lines giving the probability ( >50%) of this more likely category (above or below).

The shading on the precipitation map depicts the most favored category, either above-median (A) or below-median (B) with the solid lines giving the probability ( >50%) of this more likely category (above or below).

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