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As of the May 19th, 2017, release, Week 3-4 outlooks precipitation outlooks are experimental, whereas the temperature outlooks are operational. Both are issued Friday between 3pm & 4pm Eastern Time.
HOME> Outlook Maps> Week 3-4 Outlooks

Week 3-4 Outlooks
Valid: 30 Nov 2019 to 13 Dec 2019
Updated: 15 Nov 2019

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Temperature Probability


Week 3-4 Outlooks - Temperature Probability
Precipitation Probability
(Experimental)


Week 3-4 Outlooks - Precipitation Probability

Click HERE for information about how to read Week 3-4 outlook maps

Prognostic Discussion for Week 3-4 Temperature and Experimental Precipitation Outlooks
NWS Climate Prediction Center College Park MD
300PM EST Fri Nov 15 2019

Week 3-4 Forecast Discussion Valid Sat Nov 30 2019-Fri Dec 13 2019

There is some consistency this week among dynamical model forecasts for the week 3-4 period average circulation, however there is considerable uncertainty related to a fast moving MJO and a variable atmospheric circulation pattern over the next several weeks. The MJO has rapidly progressed eastward from the Maritime Continent across the Pacific into the Western Hemisphere during the last two weeks, and dynamical models predict continued eastward progression in the next couple weeks. The week 3-4 temperature and precipitation outlooks are based primarily on dynamical model forecasts from the operational CFS, ECMWF and JMA ensembles and the Subseasonal Prediction Experiment (SubX) multi-model ensemble (MME) mean from a suite of operational and experimental models. Statistical model forecasts from a multivariate linear regression (MLR), using MJO, ENSO and trend indices as predictors, was used to a lesser extent as a tool for the week 3-4 outlook, as it may not be representative of the current fast rate of MJO propagation.

Dynamical models predict a variable mid-level circulation pattern from week 2 though week 4. Week 2 forecasts indicate ridging over western North America and troughing over the northeastern CONUS and over the Southwest. Ridging and above normal 500-hPa heights are predicted to build over the eastern CONUS from week 3 into week 4 by the operational ECMWF, CFS and JMA ensembles. Troughing over the Southwest weakens in most model forecasts from week 2 to week 3 and then amplifies in week 4 in the ECMWF and CFS ensemble mean forecasts. The SubX multi-model ensemble forecast primarily indicates ridging over the west and troughing over the east in the average of weeks 3 and 4, emphasizing the evolution of the mean circulation pattern from week 2 model forecasts and indicating a less progressive pattern change than the ECMWF ensemble mean. With a highly variable circulation pattern forecast and inconsistencies among various models, uncertainty is high over some areas of the forecast domain.

Dynamical model forecasts from the CFS, ECMWF and JMA ensembles and the SubX MME are consistent in predicting high probabilities of above normal temperatures in the average of weeks 3 and 4 over Alaska, much of the western CONUS outside of the Southwest, and the Northern and Central Plains, under an amplifying ridge. Probabilities exceed 70 percent for the western and northern coasts of Alaska, where climate trends are large. While the CFS, ECMWF and JMA indicate above normal temperatures are more likely over the eastern CONUS in week 4 under a weakening trough and developing ridge, the ECMWF ensemble predicts likely below normal temperatures over the east in week 3, and the SubX MME predicts likely below normal temperatures in the week 3-4 mean temperatures. Equal chances of above and below normal temperatures are indicated over the eastern CONUS where temperatures are predicted to begin as below normal in weeks 2 and 3, but a mean of CFS, ECMWF and JMA calibrated model forecasts indicates an increase in the probabilities of above normal during the week 3-4 period. Below normal temperatures are likely along the US border with Mexico from Arizona to southern Texas ahead of troughing in the week 3-4 model forecasts.

There is large spread among dynamical model forecasts from the CFS, ECMWF, JMA and SubX, with a variable circulation pattern during the week 3-4 period. This uncertainty leads to a forecast of equal chances of above and below median precipitation over much of the western and eastern CONUS, where differences among the various forecast tools are greatest and signals are weak. The week 3-4 precipitation outlook relies somewhat on the uncalibrated ECMWF precipitation forecasts, as this tool has been shown to have a greater likelihood of producing a skilful precipitation forecast relative to other models. Troughing over the Southwest in a consensus of ensemble models and a large signal in the ECMWF ensemble mean leads to a forecast of likely above median precipitation for an area of the Southern Plains from eastern New Mexico northeastward to the central Mississippi River. Equal chances of below and above median precipitation is indicated over parts of the Southwest where a weaker signal for above median precipitation is predicted by the ECMWF ensemble in conflict with the CFS and JMA precipitation forecasts. Below median precipitation is likely across much of the northern central CONUS from the Northern Plains into the western Great Lakes region under a predicted ridge, as indicated by a consensus of the CFS, ECMWF and JMA ensembles and by the SubX MME. Above median precipitation is likely along the south coast of Alaska from the Aleutians to the Alaska Panhandle, along a predicted storm track, while below median precipitation is predicted for western Alaska. Above median precipitation is consistently forecast for the north coast of Alaska by the CFS, ECMWF and JMA operational ensemble models and the SubX MME consensus.

Consistently above normal sea surface temperature (SST) anomalies surrounding Hawaii and dynamical model guidance from the SubX MME indicate that above normal temperatures are likely for Hawaii with probabilities exceeding 80 percent. Above median precipitation is predicted to be likely for the Hawaiian Islands by the ECMWF ensemble mean.







Temperature Precipitation
FCST FCST
Hilo A80 A60
Kahului A80 A55
Honolulu A80 A55
Lihue A80 A55


Forecaster: Dan Collins

The next week 3-4 outlook will be issued on Friday, Nov 22, 2019

These outlooks are based on departures from the 1981-2010 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



An ASCII (w/ HTML markup tags) text version of the written forecast is available.

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6 to 10 Day Outlooks
8 to 14 Day Outlooks
30-day Outlooks
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