If you live in the Plains states, this is a week you’ll want to pay close attention to weather forecasts because you are likely to witness the winter’s biggest snow, maybe the biggest in about 4 to 6 years.

A strong upper system that is currently up over the Gulf of Alaska is going to dive rapidly into the Southwestern US later Monday into Tuesday and as it does so, expect a very sharp temperature drop all the way to Southern California where Santa Ana winds Friday through Sunday has produced 80-degree weather. Highs by Tuesday likely won’t get out of the mid-50s for the LA Basin and across the region and windy, showery conditions which will bring snow up over the San Gabriel and San Bernardino mountains.

As the system drives colder air into the entire West, a big snow event is also likely from the Sierra Nevada to Wasatch across to the Colorado Rockies.

Below is the 100-500mb thicknesses including precip by 24 hours out. Note the powerful storm system departing the Canadian Maritimes after bringing a fierce blizzard from Nova Scotia to Newfoundland as well as being responsible for bringing a band of heavy snow to the Carolinas and cold all the way to the Florida Keys.

The culprit which is likely to bring a major temperature drop, spells of heavy rain and mountain snow and a likely Plains blizzard later in the week, can be seen up over the GOA.

Expect some big rains to develop over the Southern Plains into the South once this system drops into the Southwest and the mid and upper levels cool while lower atmosphere warms and moistens up. The Southern Plains will become a breading ground for storminess and multiple inches of rain is likely to bring some nasty flooding from central Texas all the way to the Carolinas over the next 7 day period.

Here’s the latest QPF showing rain totals for the next 5 days.

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By 36 hours, A FRONT RUNNING storm, centred up over the Great Lakes will bring heavy rains not only across the South but up into the Mid-Mississippi and Ohio Valley with backside snows once the front passes through. This leading systems carves the way for the bigger storm to follow in behind. This main feature will bring a second round of severe weather as well as flooding rains across Texas and eventually the Southeast later in the week.

Here’s storm one seen on the GFS 100_500mb thickness chart by 48 hours.

 

By 48 hours, the lead system brings the first round of sporadic severe weather across Texas and eventually the South with this perhaps extending north into the Mid-Mississippi and Ohio Valleys along with big rains. Snow falls on the backside once the front passes through.

By 144 hours the main feature takes centre stage with the second round of severe weather and flooding rains but it’s on the north and west side of the system with plenty of cold arctic air in the mix, brought down by the lead system, will crank a major snowstorm from perhaps as far west as the Ront Range of the Rockies, across the Central as well as Northern Plains. This storm may bring a 12-18 inch swath of snow from eastern Colorado through Nebraska, northern Kansas across Iowa and even Illinois before weakening into the Ohio Valley.

The above chart is looking out at 120 hours. This could bring a major severe weather situation across Louisiana, Mississippi and perhaps Alabama and Georgia by Friday. Look at the energy lifting north ahead of the front. While major snows and a blizzard is unfolding to the north and west of the surface low.

Below is the GFS snow chart (10.1 ratio) looking out over the next 144 hours.

Stay tuned for new updates!

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