Prognostic Discussion for Week 3-4 Temperature and Experimental Precipitation Outlooks
NWS Climate Prediction Center College Park MD
300PM EDT Fri Jul 01 2022
Week 3-4 Forecast Discussion Valid Sat Jul 16 2022-Fri Jul 29 2022
The Madden-Julian Oscillation (MJO) is active between phases 3 and 4, according to the real-time multivariate MJO (RMM) index. Dynamical model forecasts from the ECMWF and GEFSv12 indicate possibility of eastward propagation and continuation of the MJO into phase 5 in the upcoming weeks, though there is some uncertainty in the forecasts particularly toward the end of the RMM forecast period (15 July 2022). MJO played a role in the forecasts given the potential for eastward progression, but the influence is weak due to uncertainty in the forecast. La Niña conditions continue and impact the outlook, but the impact is also weak as below-average sea surface temperature anomalies (SSTAs) have weakened recently in the NINO3.4 region. The Week 3-4 Temperature and Precipitation Outlooks are primarily based on dynamical model guidance including GEFSv12, ECMWF, JMA, and CFSv2, predictions from the Subseasonal Prediction Experiment (SubX) multi-model ensemble (MME), influence from La Niña and MJO, antecedent soil moisture, local SSTAs, and decadal trends.
Dynamical model predictions of 500 hPa height anomalies from CFSv2, ECMWF and GEFSv12 depict ridging off the western coast of Alaska and the Aleutians, though the position and strength of the ridge varies among the models. Weak troughing is possible for southwestern Alaska and the Gulf of Alaska, but dynamical models disagree on the strength and positioning of the trough. Large scale ridging is forecast for the western US in CFSv2, ECMWF, and GEFSv12, while a weak trough is forecast over the Great Lakes and eastern US in CFSv2 and ECMWF. Ridging is favored over parts of New England. A manual blend of these 3 models and the Multiple Linear Regression (MLR) tool favors ridging off the western coast of Alaska and the Aleutians, weak troughing over western Alaska, weak ridging over the Northwestern US, and a weak trough over the Great Lakes and mid-Atlantic.
The Week 3-4 Temperature Outlook favors probability of above normal temperatures for the region stretching from the Pacific Northwest through parts of Texas and the Southeast. The highest probability of above normal temperatures (60-70%) over Texas is supported by good agreement in CFSv2, ECMWF, GEFSv12 and the SubX MME, as well as coinciding with a region of negative soil moisture anomalies. Ridging over the western US, possible influence from the MJO, and warm decadal trends support elevated probability of above normal temperatures over western and central CONUS. Though dynamical models predict enhanced probability of above normal temperatures for the Pacific Northwest due to the ridge and potential MJO impacts, probability of above normal temperature is damped due to potential weak influence from La Niña, which would favor cold in the Pacific Northwest. Probability of above normal temperature is also favored for New England consistent with forecasted ridging, warm coastal SSTAs, and decadal trends. Mostly neutral SSTAs off the California coast, with a weak region of cooler SSTAs near central California, and a small weak region of warmer SSTAs near northern California, along with model disagreement along the west coast, led to Equal Chances (EC) of above and below normal temperatures for the region. EC is also favored for the Great Lakes and Mid-Atlantic due to possibility of weak troughing over the region along with cooler forecasts in CFSv2 and ECMWF, which are at odds with a warmer GEFSv12 forecast. Uncertainty in dynamical model guidance over Alaska on the position of the trough and ridge resulted in a large region of EC over the central part of the state and Alaska Panhandle. Decadal trends favor enhanced probability of above normal temperatures over northern Alaska, while the possibility of a ridge off the Alaska west coast and Aleutians suggests probability of above normal temperatures for portions of southwest Alaska.
The Week 3-4 Precipitation Outlook depicts probability of below median precipitation over the Central Great Basin and southwestern Texas given high model agreement among CFSv2, ECMWF, GEFS, JMA and SubX, as well as dry soil moisture anomalies in these regions. A slightly enhanced monsoon and above median precipitation is favored for the Desert Southwest, consistent with dynamical model agreement and a manual blend of CFSv2, ECMWF, GEFS, and the MLR. Above median precipitation is also favored for parts of the Mid-Atlantic, consistent with dynamical model forecasts for the Week 3-4 period. A weak probability of above median precipitation is favored for southwestern Alaska due to the potential for onshore flow and troughing over the Gulf of Alaska. EC is favored for the remainder of Alaska given weak or inconsistent signals between models.
Above-average sea surface temperatures in the vicinity of Hawaii, as well as the SubX MME probabilistic temperature forecast favor above average temperatures over Hawaii during Week 3-4. The highest probability of above normal temperatures in the SubX MME is over southern parts of Hawaii (Hilo). Below median precipitation is favored for Hawaii, and the SubX MME favors slightly higher probability of below median precipitation in the northern parts of Hawaii.
| Temperature | Precipitation |
| FCST | FCST |
| Hilo | A60 | B55 |
| Kahului | A55 | B55 |
| Honolulu | A55 | B60 |
| Lihue | A55 | B60 |
Forecaster: Johnna Infanti
The next week 3-4 outlook will be issued on Friday, Jul 08, 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