Climate Prediction Center - Week 3-4 Outlook

Prognostic Discussion for Week 3-4 Temperature and Experimental Precipitation Outlooks
NWS Climate Prediction Center College Park MD
300PM EDT Fri May 20 2022

Week 3-4 Forecast Discussion Valid Sat Jun 04 2022-Fri Jun 17 2022

La Niña conditions are currently present across the tropical Pacific Ocean with below average sea surface temperatures (SSTs) across most of the central and eastern equatorial Pacific Ocean. Low-level easterly wind anomalies are evident over most of the equatorial Pacific Ocean, while upper-level westerly wind anomalies and an anomalous cyclonic couplet were observed over the central and east-central tropical Pacific Ocean. The Real-time Multivariate Madden Julian Oscillation (RMM) index depicts an elevated amplitude across the Maritime Continent, West Pacific and Western Hemisphere during the last two weeks. This is likely due to constructive interference of a Kelvin and Rossby Wave. Dynamical models generally show a high amplitude intraseasonal signal as it propagates eastward to the Western Pacific by the end of week-2. The Week 3-4 temperature and precipitation outlooks are based primarily on dynamical guidance including the GEFS, CFSv2, Canadian, ECMWF, JMA, and the Subseasonal Experiment (SubX) multi-model ensemble (MME) of experimental and operational ensemble prediction systems, with additional considerations for the Madden Julian Oscillation (MJO), El Nino Southern Oscillation (ENSO), decadal climate trends, and the predicted evolution of the pattern from the Week-2 forecast.

Dynamical model 500-hPa height anomaly forecasts during Week 3-4 show a fairly consistent evolution from Week-2 forecasts. A blend of the CFSv2, ECMWF, GEFS, and JMA 500-hPa height pattern forecasts plus a small contribution from the Multivariate Linear Regression (MLR) height forecast based on the RMM index, La Niña, and decadal trends, predicts anomalous troughing and negative 500-hPa height anomalies over parts of the northwestern CONUS. Near to above normal 500-hPa heights are forecast over the remainder of the CONUS. Near to above normal 500-hPa heights are also forecast over Mainland Alaska and the Aleutians, while negative 500-hPa height anomalies are predicted across the Alaska Panhandle. Most dynamical models feature above normal 500-hPa heights over Hawaii.

Predicted troughing over the northwestern CONUS favors elevated probabilities for below normal temperatures over the Pacific Northwest eastward across the Northern Rockies and Northern Plains. Near to above normal temperatures are favored over the remainder of the CONUS due to predicted near to above average 500-hPa heights and/or long-term trends, supported by most of the dynamical forecast tools. Above normal temperatures are likely over Mainland Alaska and the Aleutians, underneath forecasted above normal 500-hPa heights, while below normal temperatures are favored over the Alaska Panhandle associated with predicted negative 500-hPa height anomalies .

The Week 3-4 precipitation outlook favors above normal precipitation over parts of the Northern Plains across the Great Lakes and Northeast, due to the predicted troughing and increased potential for frontal activity. Above normal precipitation probabilities are also elevated along the Gulf Coast, parts of Arizona and New Mexico, consistent with most of the dynamical and statistical guidance. Enhanced chances for below normal precipitation is likely from California extending eastward across the Central Rockies, Central Plains, Middle and Lower Mississippi Valley associated with above normal 500-hPa heights. Elevated probabilities of below normal precipitation is favored for Mainland Alaska and the Aleutians due to the above normal 500-hPa heights.

The outlook favors above normal temperatures for the Hawaiian Islands due to above normal 500-hPa heights in the vicinity. Dynamical model guidance from the SubX MME shows increased probabilities for below median precipitation over the Hawaii Islands.

Temperature Precipitation

FCST FCST

Hilo A50 B50

Kahului A60 B50

Honolulu A60 B50

Lihue A70 B50

Forecaster: Luke He

The next week 3-4 outlook will be issued on Friday, May 27, 2022

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.

As of May 19, 2017, the temperature outlook is operational, while the precipitation outlook is still experimental