Volatile pattern arrives with multiple storm chances across US

The days of prolonged warm and benign weather have begun to come to a close across the Central and Eastern USA as we begin the work week, as a volatile weather pattern begins to set in. Happy Monday! After discussing impending changes for several days, and looking to the Pacific Ocean for signals as to when and why the changes would occur, they will finally arrive – with a dramatic pattern change especially across the Central United States.

As a large ridge builds along the Western USA shores, in response to a retrograding Pacific Ocean pattern, colder air will surge south into the Central United States by way of a deep, anomalous trough sliding southward from Canada. Air temperatures will fall much below normal across the majority of these regions as the trough shifts southward, and a low pressure system will develop from the Upper Midwest into the Great Lakes later this week.

First storm across the Northeast States early this week

Prior to the arrival of truly cold air, a low pressure system will develop along a frontal boundary in the Eastern United States during the beginning of the upcoming week. This storm system will remain largely disjointed at the surface, without a central or deep low pressure system, but is still very likely to produce moderate to significant impacts in some areas. Heavy rain appears likely from the Ohio Valley to the East Coast from Monday through Tuesday.

In addition, the potential for severe weather exists on both Monday and Tuesday, especially in the Southeast States on Monday and then in the Northeast states on Tuesday. Heavy rainfall and localized strong winds are expected along with the potential for a few isolated tornadoes. Localized flooding will obviously be a concern as well, as heavy rain shifts along the frontal zone in all aforementioned areas.

The front will eventually clear the east coast as colder air surges in behind it.

Second storm across the Upper Midwest could bring first snowfall 

A second, more potential and significant trough will shift through the Northern Plains during the latter half of the week, specifically from Thursday through Saturday. Forecast models are in good agreement that the deep trough will drive southward and then strengthen, allowing a low pressure system to form in the Northern Great Lakes during the latter half of the week.

Colder air will gradually work into all levels of the atmosphere, especially in Southern Canada and then gradually building southward into Minnesota and Wisconsin. With support for precipitation continuing, precipitation could transition from rain to snow across Northern parts of the Great Lakes and Upper Midwest. Both the ECMWF and GFS agree that an early-season snowfall is possible across the mentioned regions.

In addition to wintry weather potential will come anomalously cold air, as mentioned, and very gusty winds with the low pressure system’s passage. The details of the storm itself will have to be ironed out as we draw closer, and analyzed on a more mesoscale level for local impacts as well, but confidence in the storm system’s formation is increasing – and the cold air it will draw southward with it will be impressive.

Colder than normal, volatile pattern will continue

Even in the absence of significant storm systems, forecast models are in good agreement that anomalously cold air will become entrenched in the Central part of the United States. As a Western USA ridge remains stout, colder air will be available in the Northern 1/3 of the United States and predominant throughout Canada. The ECMWF and GEFS long range ensembles suggest an impressive colder than normal temperature anomaly could be stout across the Central USA through Mid-November.

The Eastward extend of the cold, towards the Ohio Valley and East Coast, will largely depend on the presence of high latitude blocking. This aspect of the long range forecast remains uncertain, and will be a wild card in terms of the eastward extent and longevity of the colder than normal air in general. We will continue to analyze the latest data as we hone in on the medium and long range forecasts over the next few weeks.

For now, a volatile pattern looks likely to settle in over the next few days. Buckle up!