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 18 2025

Week 3-4 Forecast Discussion Valid Sat Aug 02 2025-Fri Aug 15 2025

ENSO-neutral conditions continue, with sea surface temperature (SST) anomalies remaining weak across the equatorial Pacific. The intraseasonal Madden-Julian Oscillation (MJO) became increasingly coherent over the past week, with a broad-scale enhanced convective envelope propagating eastward across the Maritime Continent. Dynamical model forecasts of MJO activity depict further eastward evolution of the signal, with the enhanced phase crossing the Pacific over the next two weeks, and a more uncertain evolution through Weeks 3-4. Therefore, the MJO may remain influential during the Weeks 3-4 outlook period, with the main impacts tying into environmental favorability for tropical cyclogenesis rather than midlatitude pattern changes. The multivariate linear regression (MLR) statistical model reflects primarily the influence of the long term trend signal, rather than robust tropical signal contributions.

A manual blend of operational dynamical and statistical model guidance reveals a pattern favoring generally above-normal 500mb heights across Alaska and the contiguous United States (CONUS) during Weeks 3-4. Strong ridging over the central CONUS anticipated during Week-2 is generally favored to shift eastward through the forecast period, though model uncertainty introduces some dampening of the signal. More pronounced ridging is also favored to build across the Pacific Northwest region, possibly aided by feedback from increasingly dry soils across the region. Across the Plains and Rockies, while still above-normal, the height anomaly field appears to be weaker than forecast for the Northwest and eastern CONUS.

Given the broadly positive height anomaly field, a warm forecast is reflected for the majority of the US during Weeks 3-4. Above-average temperatures are favored for most of Alaska, with equal chances for below- and above-normal temperatures maintained along the North Slope region due to increased model uncertainty. Across the CONUS, broad-scale enhanced probabilities for above-normal temperatures are favored, with the highest probabilities across the interior eastern third of the CONUS, extending from the southern Great Lakes southward to the Piedmont regions of the Deep South and Southeast. Equal chances for below- and above-normal temperatures are maintained along the immediate coast of California due to adjacent below-normal SSTs. Equal chances also extend across the northern and central Rockies and portions of the Great Plains, due to mixed signals in the guidance and the potential for convective events to boost soil moisture. Equal chances are also maintained for New England, which may experience breaks in high temperatures due to backdoor frontal activity. Across Hawaii, equal chances are maintained for the Big Island, but probabilities for above-normal temperatures increase towards the northwest.

The precipitation outlook for Weeks 3-4 exhibits a characteristic summer season uncertainty, as precipitation is typically driven by short term convective events or tropical cyclones, which are difficult to forecast this far in advance. Given the potential for ridging across the East, there are increased chances for below-normal precipitation across the eastern Great Plains, the Corn Belt, Tennessee Valley, and the interior Southeast. In contrast, above-normal precipitation is favored for the northern Plains due to a potential for organized convective activity progressing over the mean ridge. Above-normal precipitation is also indicated for portions of the Southwest due to a potential for renewed East Pacific tropical cyclone activity — broadly consistent with forecast MJO activity — resulting in increased moisture surging northward into the Monsoon region. Across Alaska, dynamical model forecasts generally support above-normal precipitation across the eastern half of the state. Drier conditions are favored for the Hawaiian islands.

Temperature Precipitation

FCST FCST

Hilo EC B55

Kahului A55 B55

Honolulu A55 B55

Lihue A60 B55

Forecaster: Adam Allgood

The next week 3-4 outlook will be issued on Friday, Jul 25, 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.