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 Jun 06 2025

Week 3-4 Forecast Discussion Valid Sat Jun 21 2025-Fri Jul 04 2025

The Weeks 3-4 Temperature and Precipitation Outlooks, valid June 21 to July 4, are based on dynamical model forecasts (CFS, GEFS, ECMWF, and JMA) along with a statistical Multiple Linear Regression tool which includes input from the El Niño Southern Oscillation (ENSO), Madden Julian Oscillation (MJO), and decadal trends. Soil moisture influence on temperature and precipitation was also considered.

ENSO-neutral conditions continue with equatorial sea surface temperatures (SSTs) near average across much of the Pacific Ocean. The MJO has remained weak throughout the spring, but the 200-hPa velocity potential anomalies have recently become better defined with a wave-1 structure of anomalous upper-level divergence (convergence) over the Maritime Continent and Western to Central Pacific (Americas, Atlantic, and Africa). The GEFS and ECMWF models depict an eastward propagation of these 200-hPa velocity potential anomalies during the next two weeks which would be consistent with a strengthening MJO. However, the RMM index ensemble mean forecasts feature a weakening trend as the MJO shifts through phases 7 and 8. Despite uncertainty on the longevity of the MJO later in June, anomalous upper-level divergence progressing east over the Western Hemisphere would favor tropical cyclone development initially across the East Pacific and then expanding to the Atlantic basin. This MJO response in the tropics was a factor in the precipitation outlook leaning on the wetter side across the Gulf Coast States and Southeast.

During early to mid-June, the dynamical models forecast a transient pattern over the contiguous U.S. (CONUS) but heading into Week-3, the GEFS and ECENS agree that anomalous ridging becomes established from the Southwest northeastward to the Midwest. The CFS, GEFS, ECMWF, and JMA models are in excellent agreement that the largest positive 500-hPa height anomalies are centered over the western CONUS where the largest above-normal temperature probabilities are forecast. Although there could be a trough extending south over the North Pacific with onshore flow at times from late June through the beginning of July, the outlook leans slightly towards above-normal temperatures (probabilities of 50 to 55 percent) along the coastal Pacific Northwest and northern California due to the broad anomalous 500-hPa ridge over the West. To the east of the Mississippi River, dynamical models differ with the GEFS depicting near average 500-hPa heights while the other dynamical models have more substantial positive height anomalies. Based on positive height anomalies in the manual 500-hPa height blend and consistent with the calibrated dynamical model output, the Week 3-4 Temperature Outlook favors above-normal temperatures for much of the central and eastern CONUS. However, high soil moisture coupled with favored wetness leads to a forecast of equal chances of below- or above-normal temperatures for parts of the Southern Great Plains, Lower Mississippi Valley, and Southeast.

Elevated above-median precipitation probabilities are forecast across the Southern Great Plains, Lower Mississippi Valley, Gulf Coast, and the Southeast where there is good model agreement along with additional support from MJO and soil moisture influences. The ECMWF, GEFS, and JMA models depict an increased chance for above-median precipitation across much of the Southwest and the outlook followed these model solutions. This lean towards above-median precipitation would be consistent with a predicted warmer-than-normal mid to late June over the interior West, which would lead to enhanced southeasterly flow and Monsoon precipitation by week-4 (June 28-July 4). Along and just east of the amplified ridge axis over the western CONUS, below-median precipitation is favored from the Great Basin northward to the northern Rockies and northern Great Plains. Equal chances of below- or above-median precipitation are forecast for the Corn Belt, Northeast, and Mid-Atlantic due to conflicting signals among the dynamical models along with uncertainty with convective summertime rainfall.

The dynamical models agree on an amplified ridge over the Aleutians with a downstream trough across Alaska with varying longitudinal placement of its axis. The ECMWF model had the strongest signal for below-normal temperatures across northwestern Alaska and the outlook favors that solution with a predicted trough aloft along with nearby negative SST anomalies. The trough aloft would also favor a wetter outcome and the outlook follows the model consensus with elevated above-normal precipitation probabilities for the northern two-thirds of Mainland Alaska.

Calibrated dynamical model output and positive SST anomalies favor above-normal temperatures throughout Hawaii. Probabilities are slightly lower at Hilo where the SST anomalies are smaller. Based on good agreement among the CFS, GEFS, ECMWF, and JMA models, elevated above-median precipitation probabilities are forecast for Hawaii.

Temperature Precipitation

FCST FCST

Hilo A60 A55

Kahului A70 A55

Honolulu A70 A55

Lihue A70 A55

Forecaster: Brad Pugh

The next week 3-4 outlook will be issued on Friday, Jun 13, 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.