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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: 27 Oct 2018 to 09 Nov 2018
Updated: 12 Oct 2018

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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 EDT Fri Oct 12 2018

Week 3-4 Forecast Discussion Valid Sat Oct 27 2018-Fri Nov 09 2018

While the most recent weekly Nino 3.4 sea surface temperature anomaly is greater than +0.6 C, ENSO-neutral conditions are present in atmospheric conditions across the equatorial Pacific Ocean. The RMM MJO indices indicate that the MJO remains active across the Western Hemisphere during the past week. Some eastward propagation of the MJO signal is favored over the next couple of weeks, according to statistical forecasts, while dynamical ensembles indicate significant uncertainty in the RMM-based MJO forecast. The Week 3-4 temperature and precipitation outlooks rely primarily on dynamical model forecasts from the NCEP CFS, the ECMWF, and the JMA operational ensemble prediction systems, as well as forecasts from the Subseasonal Experiment (SubX), a multi-model ensemble (MME) of experimental ensemble prediction systems. Consideration is also given to the possible evolution of the predicted circulation pattern for Week-2.

Dynamical model guidance from the various models is broadly consistent, depicting a trough over the Aleutian Islands into the North Pacific in the ECMWF and JMA or over mainland Alaska in the CFS, and a ridge over western North America. Most dynamical model ensembles, including the CFS and ECMWF, predict a relative trough over the eastern CONUS, with near or below normal 500-hPa heights over the Southeast CONUS. The JMA, as well as some member models of the SubX, indicate broader above normal 500-hPa heights across the northern CONUS. Statistical guidance from a multivariate linear regression (MLR) model indicates impacts into the Week 3-4 period of the currently active MJO, more closely aligned with the prediction of a broader ridge centered over the Northeast CONUS. The Week 3-4 temperature and precipitation outlooks are broadly consistent with evolution of the Week 2 circulation forecasts, including de-amplification of predicted troughs and ridges over North America.

Predicted anomalous southerly flow and anomalously low sea ice cover near much of the northern Alaska coast leads to enhanced probabilities of above-normal temperatures over most of Alaska. Likely above-normal temperatures are indicated for most of the western CONUS across the Northern and Central Rocky Mountains into the Northern and Central Plains, according to dynamical model forecasts including the CFS, ECMWF, and JMA ensembles, and the SubX MME consensus. The ECMWF ensemble and the SubX MME probabilities indicate an increased chance of below-normal temperatures over the Northeast CONUS. However, statistical guidance using the current state of MJO and decadal temperature trends indicates greater probabilities of above-normal temperatures for this region. Equal chances is indicated in the Week 3-4 outlook over the Northeast, where there is greater uncertainty in climate signals. Below-normal temperatures are more likely over parts of the Southern Plains, the Lower Mississippi and the Tennessee Valleys, and much of the Southeast region to the Mid-Atlantic and southern New England. Above-normal temperatures are forecast for the Florida Peninsula, consistent with probabilistic guidance from the SubX MME.

While there is greater uncertainty in the precipitation outlook compared to the temperature outlook, the various model guidance indicates some areas of agreement on the Week 3-4 period. Above-normal precipitation is likely for the southern coastal region of mainland Alaska and the Alaska Panhandle, ahead of a predicted trough to the west. Forecast positive 500-hPa heights over the northwestern CONUS support increased probabilities of below-normal precipitation for inland areas of the northwestern CONUS, including the Northern Rocky Mountains and Northern Plains. Above-normal precipitation is likely over parts of the Atlantic coast of the Southeast and the Florida Peninsula, related to troughing over the eastern CONUS in dynamical model guidance. Above-normal precipitation is also likely for parts of the Southwest along the Mexico border, following most operational and experimental dynamical model guidance.

Positive SST anomalies surrounding the Hawaiian Islands, support increased chances of above-normal temperatures and precipitation, as indicated by consensus probability forecasts from the SubX MME.







Temperature Precipitation
FCST FCST
Hilo A70 A60
Kahului A70 A60
Honolulu A70 A55
Lihue A60 A55


Forecaster: Dan Collins

The next week 3-4 outlook will be issued on Friday, Oct 19, 2018

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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