The following content was provided by meteorologist David Tolleris of WxRisk.com:
The morning national radar shows several areas of very light and widely scattered showers across the Midwest and over central and eastern KS. But these are really small pockets of showers and nothing very organized. Still the summer best rain to central and Eastern Kansas and Oklahoma has seen in one a while.
Clearly the main issue this week is going to be the strong cold front which is going to bring a real blast of autumn into a good portion of the central and eastern CONUS. The strong cold front will arrive over the upper Plains from south central Canada late on the 13th into the 14th and sweep rapidly to the Midwest reaching the East coast by the morning of the 15th. This HIGH will be the largest and strongest HIGH since MAY 2011 and all the models agree that temperatures will drop into the Low 30s over some areas on the morning of SEPT 15-16 and over the Northeast on the 17th. The FROST risk for ND SD northern IA MN and WI is pretty high.
SHORT TERM -- SEPT 12-16
The morning weather map shows low pressure over southern Manitoba and the cold front running from that LOW pressure area through the western Dakotas into southern Montana. HIGH is over the Deep South. Yesterday was a pretty warm day with a lot of areas seeing temperatures in the upper 80s and lower 90s across the central and upper Plains and the Midwest. That will again be the case today until then 1st of two cold fronts arrive... then temperatures will begin to fall.
On the morning of the 14th temperatures will be in the low to mid 30s but restricted to ND and northern MN. The cold morning will be on the 15th over ND eastern half of SD northern half of IA all of MN and much of WI... with temps as low as 26 degrees possible over northern 50% of MN. Other areas will see temps 28-32 degrees. By the morning of the 16th the cold air mass will have slide east into New England. During the afternoon of the 14th 15th and 16th many areas over the eastern plains and the Midwest will have trouble reaching 62° for an afternoon max temperature
MEDIUM RANGE -- SEPT 17-21
Over NEXT weekend ...a strong trough will move into the Pacific Northwest and British Columbia while the large cool HIGH moves off the Northeast U.S. coast. The return flow around the HIGH will allow for temperatures to warm significantly across most of the Plains and the Midwest. During the weekend the models have been taking this next trough coming in from Western Canada and the Pacific Northwest in developing a significant front with showers and thunderstorms with it moving into the Plains and the Midwest on the 20th and 21st. However the late afternoon European model is much weaker with this front and has a lot less rain associated with the front.
EXTENDED RANGE -- SEPT 22-26
The pattern looks pretty ordinary. It will continue to run warm/ hot -- and dry for Mid and late September over the lower Plain into the southwest states and southern California ...seasonal over the Upper Plains and western Corn Belt and cooler than Normal over the eastern Corn Belt and Northeast.