Potential Wintry Pattern Change for Midwest, Appalachians

By , Expert Senior Meteorologist
October 15, 2013; 3:03 PM ET
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There are some indications that a foretold wintry pattern change for late October and November may unfold a tad early around the Midwest and into parts of the Northeast starting around next weekend.

The pattern could negate some of the above-average warmth that has occurred thus far over the Midwest and the interior Northeast.

While chilly air will come and go to part of the Upper Midwest next week a more persistent southward shift of steering winds from Canada is likely to set up over the region around next weekend (Oct. 19 and 20) and may expand into more of the Midwest and the interior Northeast during the week that follows (Oct. 21-27).

The pattern could yield some of the first lake-effect snow for part of the Upper Midwest to perhaps the eastern Great Lakes. However, despite chillier air moving in, it may still not be cold enough for all snow in areas farther to the east.

Since Great Lakes waters take time to cool off during the autumn, these large water bodies often modify the first cold outbreaks of the season.

Away from the Great Lakes and the Atlantic Ocean, there is the potential for the air to get colder.

According to AccuWeather.com Long Range Expert Paul Pastelok, "A couple of frost events are possible in areas that have not yet had such conditions this season over the Ohio and Tennessee valleys during the last couple of weeks of October."

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Gauging the magnitude and extent of the waves of cold air will be challenging this far out for the warm water reason. The timing of each cold push could shift by a day or so, faster or slower, since we are looking ahead 7 to 14 days. Long range temperature forecasts during that period for individual locations will fluctuate as a result.

Depending on the coordination with the expected chilly air from Canada with a southern storm track containing a great deal of moisture, a storm or two with areas of snow and cold rain could also be in the cards for part of the Midwest and the Appalachians beginning late in October.

Pastelok and his team of long range meteorologists have maintained since late this past summer that November could bring chillier-than average temperatures to part of the Midwest and Appalachians, along with the potential for a storm or two with wintry precipitation, prior to a more benign and warmer December and following a warm October.

Temperatures have averaged well above normal since Oct. 1 from eastern areas of the northern Plains to the Atlantic Coast.

Temperature Departures From Normal Oct. 1 to 13, 2013

Location
Departure (Degrees F)
Minneapolis
+6.0
Chicago
+7.1
Detroit
+6.8
St. Louis
+6.3
Omaha, Neb.
+4.6
Cincinnati
+5.8
Boston
+4.6
New York
+6.6
Washington, D.C.
+6.4
Raleigh, N.C.
+2.7
Atlanta
+3.9

While the chilly air will have an easier path to the Midwest and part of the Appalachians spanning the third and fourth weeks of October, it may fade prior to reaching the the Atlantic Seaboard.

While the East Coast may have its chilliest air of the season so far before the end of October, from a shear numbers standpoint, the final statistics for October over much East Coast will likely go in the books with well above average temperatures.

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