Prognostic Discussion for Week 3-4 Temperature and Experimental Precipitation Outlooks
NWS Climate Prediction Center College Park MD
300PM EST Fri Mar 22 2024

Week 3-4 Forecast Discussion Valid Sat Apr 06 2024-Fri Apr 19 2024

Robust climate signals continue to dominate the tropical Pacific characterized by the consistent albeit weakening El Niño signal and the strong Madden Julian Oscillation (MJO) propagation. The MJO-related convection is currently in the western Pacific, associated with Phase 7 of Realtime Multivariate MJO (RMM) indices , and is forecast to continue its eastward propagation for at least the next week. The Arctic Oscillation (AO) is neutral, but dynamical forecasts indicate a trend toward a slightly negative AO in the next two weeks. This transition could further be reinforced by the current MJO phase as well as the ongoing major sudden stratospheric warming. The negative AO is often associated with the below normal temperatures across CONUS, though less impactful during this time of year. These climate signals are taken into account when interpreting the model guidance for this week's forecast.

With regard to the large-scale circulation pattern, the manual blend of dynamical and statistical guidance indicates broad anomalous ridging across Canada and anomalous troughing across the southern tier of the CONUS, a continuation of the Week-2 pattern. However, there is some uncertainty in this pattern as agreement among the individual dynamical models is mixed, particularly on the extent of the troughing. In particular, the CFS solution confines the anomalous troughing the East Coast, and the ECMWF favors weak anomalous ridging. Much of the disagreement is related to the evolution of this pattern during the Week 3-4 period. The models are in stronger agreement in Week 3, but consistency breaks down in Week 4 potentially due to differences in the progression of shorter, transient waves across CONUS.

The discrepancies in the circulation pattern as well as the uncertain role of the negative AO both play a role in the Week 3-4 temperature outlook. Much of the northern tier of the CONUS tilts toward above normal temperatures with highest probabilities for the Pacific Northwest where model guidance is strongest and further supported by the El Niño signal. Below normal temperatures are favored for Arizona and New Mexico under the anomalous troughing. Equal Chances (EC) of above or below normal temperatures are forecast for the rest of CONUS due to inconsistencies with the guidance and the timing of pattern evolution. The majority of the dynamical models slightly lean toward above normal temperatures, but the associated anomalies are weak. Furthermore, the statistical guidance and considerations for the negative AO would lean toward below normal temperatures for the East and Southeast.

Probabilities for above normal temperature are elevated for much of Alaska, with the exception of the western coast. It should be noted that some dynamical models hint at a slightly below normal signal for western Alaska in Week-3, but the overall temperature pattern across the two week period is above normal.

For the Week 3-4 Precipitation Outlook, dynamical guidance favors above normal precipitation across much of the southern tier under the anomalous troughing. Weak offshore flow is indicated for the Pacific Northwest, resulting in a below normal precipitation for that region. Elsewhere EC is forecast to due to weak and inconsistent model signals. The anomalous flow is onshore for the south coast of Alaska, promoting an anomalous wet signal there.

Across Hawaii, temperature probabilities tilt toward below normal across the majority of the Sub X multimodel suite with highest probabilities for Hilo. The dynamical models are mixed on the precipitation signal so EC is forecast for the region.








Temperature Precipitation
FCST FCST
Hilo B70 EC
Kahului B60 EC
Honolulu B60 EC
Lihue B55 EC


Forecaster: Laura Ciasto

The next week 3-4 outlook will be issued on Friday, Mar 29, 2024

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