Oct 26, 2010: Extreme Midwest Storm Approaches

Note: No full update will be posted tonight. The next full update, including a discussion on the longer range and a potential cold spell for Sunday-Tuesday followed by a storm for November 2-4.

8:35 PM: The storm in the Midwest that has been forecasted for the last 9 days is reality, and is even more extreme than the models early on suggested it would be. The low pressure earlier today dropped to nearly 954 mb in northern Minnesota, making it the 2nd, if not the strongest non-tropical low pressure in the United States. In comparison, the nor’easter we had early in the month only reached 985 mb, and Hurricane Karl, a devastating Category 3 hurricane this season that caused billions of dollars in damage in Mexico, had a low pressure of 955 mb, which is even weaker than this storm!

The storm brought a wide range of extreme weather to the central United States, including blizzard warnings in the north central US, wind advisories covering over 1/3 of the United States at one point, widespread high wind warnings covering almost all of the north central US, a high risk of severe weather in the Ohio Valley with over 250 reports of wind damage and 21 tornado reports so far, and a very large size with the storm extending from the Gulf of Mexico to Canada.

How will the storm affect the area? Like I expected for the last few days, the strong cold front will approach the area tonight, moving through tomorrow, and the cold front will bring locally heavy rainfall and strong to potentially severe thunderstorms. While the best chance of severe weather will be to the south and west of the area, as the cold front will slightly weaken once it reaches the area and the best parameters will remain to the south, thunderstorms are still expected, which could be strong with gusty winds being the main concern. As the cold front also significantly slows down while over the region, with precipitable water values over 2 inches, locally heavy rainfall is also expected with these storms.

Brief 7-Day Outlook: The storms will start late tonight, and should end by tomorrow evening. For the several days afterwards, expect a much colder air mass to move in for Thursday night, with Friday’s highs in the lower to upper 50s across the area. Friday night will be cold, with lows from the upper 20s-lower 30s inland to the lower-upper 30s in the N/W suburbs of NYC and southern CT, and the lower-mid 40s in NYC. Saturday will have similar temperatures to Friday, and while there is uncertainty on the longer range, it is possible that a strong trough moves into the region, bringing the coldest temperatures of the fall yet for Sunday night and Monday.

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