There is a high probability of a Major Midwest winter storm that will impact the region on Thursday December 22 and Friday December 23rd. This system has a greater than 60% chance of being classified as a Blizzard during the height of the event with the heaviest snows and highest winds impacting eastern Nebraska, the eastern half of Kansas, much of Missouri (except for the far southeast Corner), central and eastern Iowa, much of Illinois, Michigan, the southeast third of Wisconsin, Indiana, and Ohio.
If Chicago airports get slammed — all air travel across the USA will get screwed up.
The model agreement in the last 36 hours has moved into a state of amazing consistency. Initially there was some risk that this incredibly powerful dangerous LOW pressure area would develop on the Middle Atlantic coast and impact the Middle Atlantic and New England regions with major if not historic pre- Christmas weekend snowstorm. However, that potential is no longer a valid concern due to significant changes in the jet stream pattern across southeast Canada. These changes will allow the massive Trough in the jet stream that drops into the Rockies and moves through the Plains’ region to intensify into an extremely powerful, large, and dangerous Midwest LOW pressure system that will impact the regions mentioned above on December 22nd and 23rd.
There may be an initial wave LOW pressure on the eastern coast of the Carolinas that could bring moderate rain to North Carolina, Virginia, Maryland, Delaware, southeast Pennsylvania and New Jersey on December 22nd. Temperatures may be cold enough for snow and sleet in the northern half of the Shenandoah Valley and western Maryland into central Pennsylvania on December 22. But the development of strong southerly winds across the entire East Coast from Georgia to New England, will ensure that any frozen precipitation in these areas on December 22nd will quickly change over to all rain.
For the rest of the East Coast strong southerly winds will bring up abundant low- level moisture from Georgia to Maine as temperatures rise into the 40s and 50s even in update New York and New England.
This particular kind of historic Midwest winter storm will undergo rapid intensification late on December 22nd and into the 23rd as it moves from eastern Arkansas across the bootheel of Missouri, into western and central Indiana then into Michigan. The driving mechanism behind this massive system will be a piece of energy in the jet stream coming down from northwest Canada. This strong piece of energy will bring about rapid intensification as it dives southeast, tracking through Montana, the western Dakotas, eastern Kansas, and Missouri. From there, the deep closed 500mb LOW will turn east into the Ohio Valley and finally into the eastern Great Lakes by Friday night. At the same time a strong Ridge in the jet stream will amplify just off the West coast of North America. The position of this Ridge along the immediate West coast of North America (as opposed to being located across the Rockies) is one of the reasons why this system is going to end up being a Midwest blizzard as opposed to an East Coast track.
The movement of this massive piece of energy in the jet stream means that the energy will develop into a closed 500mb LOW with “negative tilt” as it moves from Montana to Missouri and then into Indiana and Ohio. (Negative Tilt = is a term used in the weather business when a piece of energy such as a shortwave in the jet stream or closed 500mb LOW becomes tilted in a NW- SE alignment. When this happens especially during the winter months, it almost always signals an intense surface LOW pressure area is about to develop and become a serious weather event).
As a result, the surface LOW will undergo rapid intensification. The system will pull down a massive amount of Arctic air from western and central Canada into the Plains and the Midwest while at the same time the intensifying and increasingly large LOW pressure area will pull up strong South winds along the East coast into the Ohio Valley.
This will produce incredible temperature contrast and a huge variation in weather conditions around this massive intense LOW pressure area. The 12z operational European model on Sunday afternoon drops 12 to 24 inches of snow in central and northern Illinois, all of eastern Wisconsin, the northern half of Indiana and Southwest Michigan. It also has significant snows between 8 to 14 inches in western Ohio, western and central Michigan, central Indiana, eastern Iowa, and Minnesota, and the model shows several inches of snow (possibly up to 8 inches) in western and central Iowa, most of western and southern Illinois, southern Indiana, and central Ohio.
With the main surface LOW tracking from eastern Arkansas through southeast Missouri into western Indiana and southwest Michigan, it places most of Kentucky, Indiana, Ohio, and Michigan in the rain sector with southerly winds at the beginning of the event late on December 22nd. However, once the intense LOW pressure area moves into southwest Michigan, the Arctic air will race eastward changing the rain to snow in Indiana, Ohio, and Kentucky. With winds gusting over 50mph late on December 22nd into the 23rd across Illinois, Iowa, Wisconsin, Indiana, Ohio, Kentucky, and Missouri. The combination of high winds along with the risk of heavy snow is why I believe that NWS will issue blizzard warnings with this system for much of the Midwest by December 20th. There is a risk of seeing a flash freeze in the Ohio Valley as the arctic front raises eastward, causing temperatures to collapse while the precipitation continues to fall and changes over to snow. For example Columbus Ohio will be around 41 or 42 degrees at 10 am on December 23 with rain. By 1 pm their temperature will be 25 degrees and by 4 pm readings in Columbus Ohio will be around 16 degrees with precipitation still falling
Further east there is some concern that when the Arctic front reaches West Virginia, southwest Virginia, the Shenandoah Valley, western Maryland, the Western half of Pennsylvania and western New York State the rain could turn to heavy snow with minor accumulations of a few inches possible along with a flash freeze as the temperatures crash on strong Northwest winds up to 50 mph.
Behind the system actual min temperatures on Christmas morning December 25 will he range from 15 to 25 degrees below zero across all of Illinois, Missouri, Iowa, Minnesota, and Wisconsin, and below zero in all the Dakotas, Nebraska, eastern Kansas, Indiana, and Northern Kentucky and perhaps in the single digits to near 0 in West Virginia, eastern Ohio, Tennessee, eastern Kentucky, western Maryland, West Virginia and the Shenandoah Valley.