Severe Weather Outbreak, Including Threat For Tornadoes, In the Midwest, Plains, and Mid-South Wednesday

November 9,2015

Despite the mid-November date on your calendar, a severe weather outbreak, including the threat of tornadoes, may target parts of the Plains, Midwest and mid-South during the middle part of this week.
A powerful southward dip in the jet stream, which had earlier spun up an impressive storm over Alaska's Aleutian Islands, is expected to swing out of the Desert Southwest Tuesday and punch east into the Plains and Midwest Wednesday.

The meteorological ingredients in play for Wednesday's severe weather threat.

Ahead of this jet stream dip, warmer, more humid air in the lower levels of the atmosphere will flow northward into the Plains from the western Gulf of Mexico as strong low pressure forms to the east of the Rocky Mountains.
The resultant wind shear and instability from the strong jet stream and colder air aloft overlapping warm, humid air near the surface should give rise to severe thunderstorms.
As with virtually all severe weather forecasts a few days out, there are uncertainties. In this case, it pertains to the magnitude of the tornado threat and how far east the severe weather will spread.
Severe weather threats in fall typically have plenty of wind energy from the jet stream, but limited amounts of unstable air. The setup this week is no different.
In these cases, the main threat from severe thunderstorms tends to be widespread damaging wind gusts with embedded tornadoes. The magnitude of the tornado threat is dependent on how unstable the air mass becomes, which remains uncertain at this time. Also, the amount of unstable air will dictate how far east the severe weather will spread into parts of the mid-Mississippi Valley and Ohio Valley.
(MORE: Where November Tornadoes Are Most Common)
Regardless of the tornado threat, damaging thunderstorms winds and large hail appear to be likely. We expect the areal coverage and number of severe weather reports to be far greater than we saw last week.
Here is our latest forecast thinking.

Severe Weather Forecast

Wednesday's Thunderstorm Forecast

• Tuesday night: A few strong to severe thunderstorms may break out overnight in the Plains, mainly in eastern Nebraska and eastern Kansas.
• Wednesday: The most active day with severe thunderstorms and tornadoes possible in eastern Nebraska, eastern Kansas, eastern Oklahoma, Missouri, Iowa and Illinois. Depending on how the jet stream energy and unstable air interact, the severe weather may also impact parts of eastern Texas, Louisiana, Arkansas, western Mississippi, western Tennessee and western Kentucky.
• Thursday: The jet stream disturbance will blast east, but near-surface air in the Great Lakes, Appalachians, and Northeast may only be marginally warm and humid. However, thunderstorms with damaging straight-line winds are certainly possible in these areas. Details at this time are uncertain.

For specific tornado threat forecasts, check out the latest TOR:CON forecasts from severe weather expert, Dr. Greg Forbes.
(MORE: View National Interactive Radar Map | Difference Between a Watch and a Warning)
Severe weather and tornado outbreaks are not unusual in November. In fact, November is a climatological "second season" of severe weather, not simply in the Deep South but, occasionally, in parts of the Midwest.
Almost two years ago, an outbreak of 72 tornadoes raked through parts of seven states, including a pair of EF4 tornadoes in Washington, Illinois, and near New Minden, Illinois.
This outlook is subject to change in the days ahead. Check back with us at weather.com for the latest on this potential severe weather event.

High Winds Will Blast Through the Plains, Midwest and Great Lakes Midweek

The strong low pressure system associated with the severe weather outbreak will also bring high winds to a large area of the Plains, Midwest and Great Lakes this week.
Computer model forecasts show that the low may have a barometric pressure reading in the low 980 millibar range Thursday morning. This means the low will be very intense, and capable of producing strong winds.
High wind watches have already been issued for portions of the central and southern Plains beginning Tuesday night for gusts up to 60 mph.
(FORECAST: Dodge City, Kansas | Omaha, Nebraska | Chicago | Detroit)
On Wednesday, strong northwest winds will impacts much of the Plains, from parts of the Dakotas to Texas. Those winds could combine with snow in the High Plains of Colorado, Wyoming, northwest Kansas and western Nebraska to result in low visibility and dangerous driving conditions.
(MORE: Rockies, High Plains Snow)
Thursday, strong winds gusting to 45 mph will blast through areas from the northern Plains into the Midwest and Great Lakes, potentially resulting in air travel delays and downing some tree limbs. The winds will also be a hazard to marine interests in the Great Lakes.

PHOTOS: Tornadoes, Flooding in the South (Late Oct. 2015)