NCEP GEFS Week-2 and Week 3-4 Storminess Outlook

For North Pacific, North America, and North Atlantic

Extratropical storm activities have strong societal and economic impacts on mid- and high-latitude regions, including Alaska. To support the NWS Alaska and other regional centers for storm track monitoring and forecasts, a suite of week-2 and week 3-4 storm track outlook products has been developed at CPC based on the dynamical forecast of the NCEP Global Ensemble Forecast System (GEFS).

Extratropical storms are detected and tracked using 6-hourly sea level pressure (SLP) data from the real-time GEFS 16-day and 35-day forecasts and a storm-tracking algorithm (Serreze 1995). The outlooks include storm tracks and track density, storm intensity and duration, precipitation, SLP and 10-m winds, and day-to-day variance of SLP over North Pacific, North America, and North Atlantic, derived from the GEFS week-2 and week 3-4 forecasts for both total and anomaly fields. In addition, GEFS probabilistic forecasts of precipitation and 10-m wind speed exceeding 75th and 90th percentiles, and storm intensity lower than 990, 980, 970, and 960 hPa are also included. Verifications of the real-time forecasts are conducted using the NCEP Climate Forecast System Reanalysis (CFSR). The outlook is updated on a daily basis.

More details about this tool are here. More information can also be found in Chang et al. (2022).

April 2024

Sun	Mon	Tue	Wed	Thu	Fri	Sat
	1	2	3	4	5	6
7	8	9	10	11	12	13
14	15	16	17	18	19	20
21	22	23	24	25	26	27
28	29	30

Outlook Products
Regions:  Alaska/Arctic, North Pacific, North America, North Atlantic
Variables:  Storm tracks, track density, intensity, and duration
7-day precipitation, sea-level pressure, 10-m wind vector and wind speed
Upgrade:  Starting from September 24, 2020, forecasts are GEFSv12 based.
GEFSv12:  124-member ensemble forecast

2024
| January | February | March | April | May | June | July |
| August | September | October | November | December |

Forecast Archive