Thursday, November 12, 2015

Long Range Outlook (Published 11/12/15)

Current Analysis

Strong low pressure is currently moving into Canada after igniting tornado-producing thunderstorms on Wednesday. This severe weather event struck over the Midwest, particularly in Iowa, Missouri, and Illinois. As the system moves into Canada it will flush cold air deep into the United States with northerly winds.
With respect to global weather, we do see tropical forcing located over the Central Pacific, exerting some influence on the Pacific jet stream as a jet streak pushes eastward over the Aleutian Islands. This will likely allow for another risk for cyclogenesis, potentially strong, in the United States over the next week or so.

Forecast Discussion

Upper-level divergence will intensify and shift east to the East Pacific over the next five days, eventually branching off into North America. Expect a raised threat for tropical cyclone formation in the East Pacific between 11/14 - 11/22 per latest model guidance, as strong divergence will persist over the area. Expect stronger than normal low pressure systems over the United States from the current time (11/12) to about 11/22. Model guidance favoring what could be one or more strong surface low pressures not unlike the one that is currently pushing into Canada, which could bring about additional chances for severe weather, as well as snowfall. Expect the strongest of these potential system(s) around 11/18 - 11/20.
Pattern then looks to quiet down by Thanksgiving, with upper level convergence advecting over North America from the North Pacific. Expect elevated chances for cooler weather to round out the month.

Very Long Range Outlook
Time period covered: Early to Mid December

As we head into December, a quieter and warmer pattern is expected to take hold over North America, primarily in the central and western parts of the continent, including the North US, South Canada, and the Pacific Northwest. There are early signals for a typical El Nino pattern setting up as tropical forcing shifts around. Those in the Southeast and East should monitor the pattern for an increased risk for winter storms and cold weather.

The next update will be posted on November 19th at 5:00 PM Central Time.