Prognostic Discussion for Week 3-4 Temperature and Experimental Precipitation Outlooks
NWS Climate Prediction Center College Park MD
300PM EST Fri Jan 14 2022
Week 3-4 Forecast Discussion Valid Sat Jan 29 2022-Fri Feb 11 2022
A La Nina advisory is still in effect as mature La Nina conditions persist across the equatorial Pacific. While earlier RMM-based Madden Julian Oscillation (MJO) guidance depicted a weak, but enhanced signal meandering over the western Pacific, the most recent guidance has weakened and stalled the MJO. Destructive interference between La Nina and a strong Rossby wave has contributed to the weakening of the MJO signal. Though La Nina is forecasted to persist, circulation patterns in Week 3-4 are less consistent with a typical La Nina pattern. Given the stalled MJO and inconsistent circulation pattern related to a canonical La Nina, the impacts of the tropics on the extratropical pattern over North America did not largely contribute to the Week 3-4 forecast.
Week 3-4 dynamical model 500-hPa height forecasts from CFS, ECMWF, JMA, as well as the multi-model ensemble (MME) from the Subseasonal Prediction Experiment (SubX) show a consistent ridge over the Gulf of Alaska with a tendency toward above-average heights. The 500-hPa height anomaly forecast from CFS depicts a Week 3 pattern with ridging in the Gulf of Alaska and above-average heights over Alaska and the western US, along with downstream troughing over the Great Lakes, Ohio Valley, and parts of the northeast, and a ridge off the east coast. This pattern supports warmer temperatures over Alaska and the western US, with cooler temperatures over the eastern US. A pattern shift in Week 4 favoring troughing over Alaska and above-average heights over the contiguous US adds uncertainty to the Week 3-4 forecast period.
Above-average temperatures are forecast for eastern Alaska, including the Panhandle, due to the presence of the strong ridge and consistent model agreement. Dynamical models show higher probabilities of above-average temperatures over Alaska in the earlier part of the period, with the circulation pattern change leading to a weakening of probabilities in Week 4, particularly in eastern and northern regions. Equal-chances (EC) of above- and below-average temperatures are depicted over the western part of the state. Strong anomalous ridging that persists throughout the Week 3-4 period across the western US favors above-normal temperatures with highest probabilities across the Great Basin. There is more uncertainty with respect to the temperature signal over the eastern CONUS during the Week 3-4 period due to a potential pattern shift in the middle of the forecast period. Dynamical model guidance and a manual blend of the Multiple Linear Regression (MLR) statistical tool, ECMWF, JMA, and CFS favors a weak cold signal for parts of the Great Lakes, Ohio Valley, southeast, and mid-Atlantic, due to troughing in Week 3. As that circulation pattern shifts toward a higher probabilities of above-average heights in Week 4, weak above-normal temperatures are favored. Given higher confidence in Week 3 forecasts, a weak probability of below-average temperatures is favored for the Week 3-4 period. Model guidance is mixed for the northeast and Florida, and probability of EC is favored.
The precipitation outlook is based primarily on a blend of the MLR, ECMWF, CFS, JMA, and the SubX MME. A consistent enhanced wet precipitation signal for Week 3, Week 4, and the Week 3-4 periods are seen for the Pacific Northwest and northern Great Basin, and the east coast of the US. Chances for frontal boundaries related to the shifting circulation pattern in the Pacific Northwest and eastern US support these enhanced probabilities. Some uncertainty in precipitation over Alaska is depicted with EC favored across much of the state given mixed model guidance and the potential for a shift in the circulation pattern from Week 3 to Week 4. A consistent signal for above-average precipitation is favored for southern Alaska, including the Panhandle, given potential for onshore flow in the first week of the period.
Above-average sea surface temperatures in the vicinity of Hawaii, as well as the SubX MME probabilistic temperature forecast favor above-average temperatures across Hawaii during Week 3-4. Slightly elevated probabilities of above-average temperatures in the SubX MME are forecasted for Kahului and Honolulu. Dynamical model precipitation forecasts are mixed, thus EC is depicted for Hilo, Kahului, and Honolulu, however, models agree on slightly elevated above-average precipitation for Lihue.
| Temperature | Precipitation |
| FCST | FCST |
| Hilo | A55 | EC |
| Kahului | A60 | EC |
| Honolulu | A60 | EC |
| Lihue | A55 | A55 |
Forecaster: Johnna Infanta
The next week 3-4 outlook will be issued on Friday, Jan 21, 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