also from CPC,
http://www.cpc.ncep.noaa.gov/products/p ... /index.php
(about this experimental product:
http://products.weather.gov/PDD/PDD_CPC ... tlooks.pdf )
Prognostic Discussion for Experimental Week 3-4 Outlook
NWS Climate Prediction Center College Park MD
300PM EST Fri Nov 27 2015
Week 3-4 Forecast Discussion Valid Sat Dec 12 2015-Fri Dec 25 2015
The RMM based MJO index continues to reflect amplitude over the Indian Ocean, but significant eastward propagation of the signal has not been established. The enhanced convective signal over the Indian Ocean appears to be relatively stationary, with other modes, including Kelvin Waves propagating out from the Indian Ocean and Equatorial Rossby Wave activity over the Pacific, causing most of the intraseasonal modulations to the ongoing strong El Nino background state. Therefore, climate anomalies associated with ENSO are the favored contribution from the global tropical pattern considered in this outlook.
There are substantial differences among the dynamical model 500-hPa height anomaly forecasts, with subsequent implications for the forecasted temperature and precipitation patterns. The CFS, ECMWF, and JMA all depict large negative height anomalies centered near the Bering Sea and Aleutians, as well as above-normal heights over northeastern North America. The ECMWF forecasts ridging over the northeastern Pacific, with a downstream trough over the south-central CONUS. In contrast, the CFS depicts troughing over the northeastern Pacific, with near to above-normal heights across most of the CONUS.
Consistent with these forecasted height anomalies, the ECMWF-based probabilistic temperature forecast favors below-normal temperatures across much of the interior West and south-central Plains, with above-normal temperatures forecasted across the remainder of the U.S. The CFS forecast favors above-normal temperatures across all of the CONUS and Alaska, with below-normal temperatures limited to far southern Texas. The JMA forecast more closely resembles El Nino composites, with below-normal temperatures favored across the central and south-central U.S., and the Southeast.
The Week 3-4 temperature outlook is a blend of the CFS and ECMWF solutions, with a consideration of El Nino impacts. Above-median temperatures are favored across the Northwest, far northern Rockies, much of the northern Plains and Midwest, and almost everywhere east of the Mississippi except for the central Gulf Coast. The highest probabilities for above-median temperatures based on both model guidance and ENSO composites are from the northern Plains through the western Great Lakes region. Below-normal temperatures are favored across parts of the Southern Plains. Across Alaska, greater chances for above-median temperatures are forecast, except across the North Slope.
There is also significant disagreement among the precipitation tools, with the CFS and JMA favoring above-median precipitation across California, and the ECMWF forecasting drier conditions. The CFS also depicts a pronounced dry signal extending from the lower Mississippi Valley northeastward through the Great Lakes region, while the ECMWF has a broad wet signal across the entire eastern half of the CONUS. The JMA solution generally lies between the CFS and ECMWF, and again resembles winter El Nino composites. All of the dynamical guidance favors below-normal precipitation across the northern Rockies and northern High Plains.
Based on the dynamical model guidance and ENSO composites, the Week 3-4 precipitation outlook favors above-median precipitation across Arizona and New Mexico, the southern Plains, and the entire eastern seaboard south of New England. While a greater than 50 percent chance of above-median precipitation is indicated along the Gulf Coast, equal chances for below or above-median precipitation were maintained across the remainder of the Mississippi Valley and Midwest. Enhanced chances for below-median precipitation are forecast across the northern and central Rockies, and the northern High Plains. Across Alaska, the only substantial precipitation signal among the dynamical models favors above-median precipitation across the southern coastline and the Panhandle.
For Hawaii, forecasts for above-normal SSTs and positive height anomalies generally favor above-median temperatures. Additionally, climate anomalies associated with El Nino favor suppressed rainfall, which is consistent with the dynamical model forecasts.
Temperature Precipitation
FCST FCST
Hilo A60 B60
Kahului A60 B60
Honolulu A60 B60
Lihue A55 B55
Forecaster: Adam Allgood
The next week 3-4 outlook will be issued on Friday, Dec 04, 2015
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.
![Image](http://www.cpc.ncep.noaa.gov/products/predictions/WK34/gifs/WK34prcp.gif)