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Week 3-4 outlooks are experimental at this time, and are issued Friday between 3pm & 4pm Eastern Time.
HOME> Outlook Maps> Experimental Week 3-4 Outlooks

Experimental Week 3-4 Outlooks
Valid: 13 May 2017 to 26 May 2017
Updated: 28 Apr 2017

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Temperature Probability

Experimental 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 Experimental Week 3-4 Outlook
NWS Climate Prediction Center College Park MD
300PM EDT Fri Apr 28 2017

Week 3-4 Forecast Discussion Valid Sat May 13 2017-Fri May 26 2017

There is currently a weak projection of the Madden-Julian Oscillation (MJO), as indicated by the RMM index, indicating enhanced convection in the Western Pacific. Dynamical model forecasts indicate no clear signal for the enhancement or progression of the MJO over the next several weeks, so the MJO does not play a role in this forecast for Week 3-4. The weekly ENSO Nino 3.4 SST index is now +0.7 degrees Celsius, with forecasts indicating the possible development of El Nino conditions in later seasons. However, current atmospheric conditions are still considered ENSO neutral. Decadal trends in temperature play a role in the Week 3-4 forecast, with significant positive temperature trends over many areas of the CONUS and Alaska.

Dynamical model guidance from the CFS, ECMWF and JMA ensemble prediction systems was used as the primary guidance for the Week 3-4 temperature and precipitation outlooks. The available ensemble prediction systems indicate high uncertainty with large spread among ensemble members. Though there are significant differences in the temperature and precipitation forecasts from the CFS, ECMWF and JMA ensembles, areas of consensus were used to make the Week 3-4 outlooks. Mean 500-hPa height forecasts from the CFS, ECMWF and JMA ensembles show some agreement on a forecast of above normal height anomalies stretching from north and west of Alaska to the southeast. However, models are in disagreement on the location of anomalies over much of the North American region. Mid-level height forecasts from the available models generally indicate relative troughing over the western CONUS and ridging over Alaska and western Canada.

An area of increased probabilities of below normal temperatures is indicated for an area just to the east of the Rocky Mountains extending from Montana and the Dakotas southeast through parts of the Central Plains into parts of the Southern Plains. Models indicate relative troughing at 500-hPa in this region and forecast above median precipitation. Increased probabilities of above normal temperatures are indicated for California, Nevada, and parts of the Southwest, as well as for parts of the Southeast and Northeast CONUS, where calibrated probability forecasts from the CFS, ECMWF and JMA models are in agreement. The greatest probabilities of above normal temperatures are for Alaska, with probabilities exceeding 70 percent in the southeast regions of the state and the Alaska Panhandle.

The Week 3-4 precipitation outlook indicates an area of increased probabilities of above median precipitation stretching through western areas of the Great Plains from the Canadian border to the Gulf Coast of Texas, ahead of the mean location of troughing in the ensemble model forecasts. Areas of enhanced probabilities of below median precipitation are indicated to the west over the Alaska Panhandle into the Pacific Northwest and to the east stretching from parts of the Southeast through the Ohio Valley into the Mid-Atlantic states.

Anomalously warm SSTs continue to be observed around Hawaii and are likely to persist into the Week 3-4 outlook period, leading to a forecast of above-normal temperatures. Model precipitation forecasts generally indicate increased probabilities of below median for the Week 3-4 period.







Temperature Precipitation
FCST FCST
Hilo A60 B55
Kahului A60 B55
Honolulu A60 B55
Lihue A60 B55


Forecaster: Dan Collins

The next week 3-4 outlook will be issued on Friday, May 05, 2017

These outlooks are based on departures from the 1981-2010 base period

These are experimental two category outlooks and differ from official operational 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.




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