October Chill Targets the Midwest, East This Weekend

http://www.wunderground.com/news/pattern-change-ahead-20140927

As the calendar shifts to October, expect a plunge of chilly air to arrive in time for the month's first weekend in the Midwest and East.

If you long for summer's return in these areas, we hope you enjoy the next few days.

Parts of the northern Plains and southern Canada saw record hot temperatures so late in the season at the end of last week. Williston, North Dakota and Miles City, Montana both saw temperatures soar to 97 degrees this past Thursday. 

Sunday, Caribou, Maine basked in 84-degree warmth, the hottest temperature on record so late in the season, there. Daily record highs were also set Sunday in at least a dozen other northern cities, including Newark (87), Providence (86), Sault Ste. Marie (80) and Duluth (81). 

Changes, however, are on the way late this week into the weekend. An upper-atmospheric trough will carve southward into the East and Midwest, while a corresponding upper-atmospheric ridge builds into the West. The past few days we have had a ridge in the East and a trough in the West.

This pattern change will bring temperatures that are 20-30 degrees colder for some locations in the northern Plains. Temperatures will also be cooler in parts of the Midwest and Northeast, where highs will go from the 70s and 80s this past weekend, to the 50s and 60s next weekend.

With this fresh plunge of cold air, expect some frost and even freeze conditions from parts of the northern Plains into the Upper Midwest, Great Lakes and Ohio Valley during the morning this weekend.

As it cools down in the East, the warmth will make a comeback along the West coast, with highs 15-20 degrees warmer by next weekend. Los Angeles will go from highs in the 70s to highs in the 90s or triple digits in some inland locations. The forecast for hot weather, very low humidity and offshore winds has already prompted fire weather watches for the Los Angeles area beginning Wednesday.

Also, the Gulf Coast will remain quite pleasant for early October, with highs remaining generally in the 80s.

In addition to the changes in temperature, many locations will go from wet to dry and vice versa. 

A cold front will drive eastward late this week, with rain and thunderstorms sweeping from the Mississippi Valley and Great Lakes Thursday into the East Friday, and lingering in New England Saturday.

From Thursday night through Saturday, we can't rule out a few wet snowflakes mixing in with a cold, wind-driven light rain from northern North Dakota into northern Minnesota, northern Wisconsin and northern Michigan. 

In fact, there should be bands of lake-enhanced rain, and yes, perhaps some wet flakes in the hills away from the lakes, Friday through at least early Sunday from Upper Michigan to central and Upstate New York. Quite a calling card for fall, eh?

So fall conditions will likely return to the Midwest and Northeast next weekend, while summer won't let go of the West coast yet. Fall is definitely a season of change and this will be apparent to many as we head through early October.