Thursday, November 19, 2015

Long Range Forecast (Posted 11/19/15)

This is the long range forecast published on November 19, 2015. 

Over the last seven days, we’ve seen strong negative geopotential height anomalies over the Gulf of Alaska, leading to ridging in Canada and a warmer pattern here in the U.S. A strong storm system is currently moving out of the United States, showing the reasoning behind that small swath of negative anomalies in the Plains.

The SLP map (brown lines) and 500mb contours (blue lines) show our upper level low finally moving off into Canada, with the cold front continuing east into the East US, as infrared satellite presentation shows.

Water vapor imagery over the North Hemisphere shows a strong Pacific jet stream blasting into the Pacific Northwest, delivering the next chance at active weather. We also see an upper level low in the Bering Sea, which is expected to contribute some energy to our pattern over the next week or two.

Analysis of the jet stream over the Northern Hemisphere shows a rather inactive pattern in the North Central Pacific, but a strong jet streak or two over East Asia indicate the potential for some stronger storm systems over the next 10-20 days in the United States.

Current tropical forcing imagery over the globe shows strong divergence across Central America into the United States. Additional divergence is seen in southern Africa and near India. This pattern is conducive to cooler conditions in the United States (Phase 8-1 MJO).

Pattern should quiet down over Thanksgiving, with tropical forcing moving into areas more favorable for warmer weather for much of the country into the opening 5-10 days of December. Heading into mid-December, tropical forcing should re-organize in a pattern more favorable for cooler weather in the United States.
Storm concerns… Anticipating storm system around 11/20 – 11/25. Watch for a potential storm system around 11/30 – 12/5, as well as a second system around 12/4 – 12/9.

Early analysis of pattern around Christmas does favor another round of stormy and cooler weather in time for the holidays. Tropical forcing indicates we may need to monitor for a significant storm system not unlike the one currently moving into Canada, which brought tornadoes and heavy snow to the Central US this past week.

Next Long Range Outlook
November 26th, 2015 at 5:00 PM CDT


1 comment:

Shawn said...

Awesome forecast Andrew! I love the new look of the forecasts! It looks like it could be an awesome beginning to winter, maybe an early start to winter! :)