The weather pattern will continue to be extremely active through the end of the week and into the weekend under the influence of an energetic jet stream with multiple storm systems traversing the country.
Article continues below
An amplifying upper-level trough over the Southwest U.S. and ejecting over the Southern Plains will help rapidly deepen an area of surface low pressure tracking northeastward from the Southern Plains through the Mississippi Valley and into the Midwest.
Widespread showers and thunderstorms are expected Thursday evening and through the overnight hours ahead of the system/trailing cold front from eastern Oklahoma/Texas into the Middle and Lower Mississippi Valley as Gulf moisture rapidly surges northward.
An Enhanced Risk of severe weather (level 3/5) has been outlined by the Storm Prediction Center centered over the ArkLaTex where the greatest threat for damaging winds, large hail, and tornadoes, including a strong tornado, exists through the overnight hours Thursday.
An isolated instance or two of flash flooding will also be possible.
The chance for storms will continue from the Lower Mississippi Valley into the Tennessee Valley and Southeast Friday ahead of the eastward moving cold front.
An additional Enhanced Risk of severe weather is in place for portions of the Mid-South where significant damaging wind gusts will remain a concern, with the threat for a few tornadoes across the region as well.
Further to the northeast, the poleward advance of Gulf Moisture will lead to another round of heavy rain stretching northward into the Mid-Atlantic and southern New England.
While rain totals between 1-2" will likely be less than the previous event earlier this week, saturated ground conditions as well as higher than normal stream/river levels due to snowmelt could lead to the risk of flooding, particularly for urban areas, and a Slight Risk of Excessive Rainfall (level 2/4) is in effect.
In addition to the severe weather and heavy rain, very gusty winds as well as coastal flooding, particularly from the Mid-Atlantic into New England, will once again be a concern.
The impacts continue within the colder air to the north and west of the system track as a swath of moderate to heavy snow is forecast from the Middle Missouri Valley beginning Thursday afternoon and spreading towards the Great Lakes by Friday.
Storm total snowfall of 6-12 inches, locally higher, is expected from Omaha to Des Moines, Chicago and Milwaukee.
In addition, strong, gusty winds upwards of 40 to 50 mph may lead to blizzard conditions, with near-zero visibilities making travel very difficult to impossible.
Continued cold and gusty northwesterly flow over the Great Lakes will also help lead to lake-effect snow in favorable locations downwind of the Great Lakes, including into the Lower Great Lakes by Saturday.
Blowing snow will remain a concern.
Additional moderate to locally heavy snowfall is also expected Saturday into the Interior Northeast/northern New England.
The storms and winter weather are yet only the first part of the story as a surge of Arctic air into the heart of the country will follow in the storm system's wake.
Bitterly cold temperatures in the Northern Plains Thursday will spread into the Central Plains Friday and reach the Mississippi Valley/Southern Plains Saturday.
Temperatures will remain below zero for the Northern Plains starting Friday, with highs only into the single digits for the Central Plains by Saturday.
Record low temperatures in the -20s, -30s, and even as low as -40 are forecast for the Northern Plains Saturday morning.
The widespread, gusty winds will factor in here as well, leading to dangerously cold wind chills as low as -35 to -50 for parts of the Northern Plains and as low as -15 to -30 into the Central Plains.
Wind chills of this nature can lead to frostbite on exposed skin within minutes.
This frigid air will spread further south and eastward into the Midwest and deeper into the Southern Plains Sunday.
Upstream over the West, colder air following a frontal boundary settling south through the Pacific Northwest/northern Great Basin/Northern Rockies will bring another threat of heavy snow, not only for the mountains but also for lower elevation valley/coastal locations that have so far mostly avoided winter weather this season.
Heavy snowfall measured in feet is likely for the higher elevations of the Cascades and Wasatch overnight Thursday and into Friday, spreading south to the Sierra by Saturday.
Other regional mountain ranges can expect heavy snow totals of 12"+.
At lower elevations, Winter Storm Watches/Warnings are in place for locations such as Portland, OR and Boise where several inches of snow are expected through the day Friday.
Precipitation chances will remain heightened through the weekend as the frontal boundary remains entrenched across the region and a Pacific system approaches from the west.
Snow will come to an end Thursday evening for portions of the Southern Rockies/Southwest as the upper-level trough associated with the Plains system moves out of the region.
Conditions will likely remain dry here and to the west through the southern Great Basin/Desert Southwest and into southern California.
However, temperatures will generally be below average, with some chilly morning lows possible. ■