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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: 06 Oct 2018 to 19 Oct 2018
Updated: 21 Sep 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 Sep 21 2018

Week 3-4 Forecast Discussion Valid Sat Oct 06 2018-Fri Oct 19 2018

ENSO-neutral conditions currently are present across the equatorial Pacific Ocean. Equatorial sea surface temperatures (SSTs) are near to above average across most of the Pacific Ocean. The CPC velocity potential based and RMM MJO indices indicate an inactive MJO. The GEFS depicts the MJO to strengthen and emerge over the Western Hemisphere during the next two weeks. 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 CFS and ECMWF is broadly consistent, depicting a trough over the Aleutians, while a strong ridge is forecast over Mainland Alaska and along the Pacific Northwest of the CONUS. Downstream a trough is centered over parts of the Upper Midwest and Great Lakes region, and ridging is forecast to persist in parts of the Southeast. The CFS and ECMWF ensemble means favor near-normal 500-hPa heights over Hawaii, while JMA favors above-normal 500-hPa heights there.

Ridging and large positive 500-hPa heights over Alaska lead to enhanced probabilities of above-normal temperatures over the entire state. Dynamical model forecasts (CFS, ECMWF and JMA) are in general agreement on increased chances of above-normal temperatures for the western CONUS and parts of the Southeast. Below-normal temperatures are favored over the Southern Plains, the Lower Mississippi Valley, and the Tennessee Valley, extending northeastward across the Middle and Upper Mississippi Valley, the Ohio Valley, the Middle Atlantic, the Great Lakes region, and over the Northeast, consistent with dynamical model guidance from SubX.

The various model guidance is in fairly good agreement on the precipitation outlook for the Week 3-4 period. Forecast ridging across the Pacific Northwest supports increased chances of anomalously dry conditions for the northwestern CONUS. The greatest probabilities for above-normal precipitation are indicated over the Pacific Northwest. Above-normal precipitation is favored across the southeastern seaboard, consistent with dynamical model predicted Week 3-4 precipitation amounts. Above-normal precipitation is likely in southern Alaska and the Alaska Panhandle due to troughing over the Aleutians.

Persistent positive SST anomalies continue to surround Hawaii, supporting increased chances of above-normal temperatures and precipitation across the island chain. Dynamical model precipitation forecasts generally favor above-normal rainfall over Kahului and Honolulu.







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


Forecaster: Luke He

The next week 3-4 outlook will be issued on Friday, Sep 28, 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.

Related Topics

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