Monday Briefing: Blizzard in the Plains, unsettled weather East

Good morning, everyone! A new week begins today with much warmer weather in the Eastern United States, particularly the Northeast states where temperatures are running well above average. This is obviously a major change compared to what has been experienced there over the past several weeks. Much of this can be attributed to warmer, Pacific air that has become entrenched in the Eastern United States over the past few days. Temperatures are expected to run 10-20 degrees above normal averages on both Monday and Tuesday!

Meanwhile, the weather will become increasingly unsettled. Increasing moisture and lift in the atmosphere will lead to drizzle and unsettled conditions across the Eastern United States. This issue will be exacerbated by the presence of a strong low pressure system, which is leading to the development of a blizzard across the Northern Plains. The low pressure is bringing warm air to the East, but much more significant weather out west – where very heavy snow and significant travel impacts are anticipated.

The NAM model showing strong mid-level frontogenesis north into Southern Minnesota with the blizzard over the Plains/Midwest.

The NAM model showing strong mid-level frontogenesis north into Southern Minnesota with the blizzard over the Plains/Midwest.

Pictured above, the NAM model suggests the development of very heavy frontogenesis banding along a thermal gradient in the atmosphere across the Northern Plains states today. This will lead to the development of impressive lift, and with plentiful moisture and jet dynamics in place, heavy snow is expected across Northeast Nebraska, Northern Iowa, Southern Minnesota and Wisconsin, with blizzard conditions in many areas and heavy snowfall in cities such as Minneapolis and St. Paul.

Back east, this storm system will drag a strong cold front through the Northeast and Mid-Atlantic region on Tuesday. Strong forcing (lift) and some elevated instability from a 50-70kt southerly low-level jet and anomalously high precipitable water values will be present ahead of this front. As a result, showers and possibly some thunderstorms with moderate to heavy rainfall are expected on Tuesday, particularly from the Northern Mid-Atlantic to Southern New England.

Rainfall totals could reach between 1” to 2” in some spots, and that could result in ponding of water on roadways and poor drainage areas. Breezy conditions are also expected, with wind gusts between 30-40mph as the low-level jet passes through.  Some thunderstorms could produce some isolated wind gusts over 40mph, but a stout low-level inversion should prevent stronger winds aloft from mixing down to the surface. Despite clouds and rainfall, increasing warm-air advection will cause temperatures to rise well into the 50s and perhaps near 60s in some spots.

3km NAM model showing elevated instability or MUCAPE between Northern Mid-Atlantic coast and Southern New England on Tuesday

3km NAM model showing elevated instability in the form MUCAPE between Northern Mid-Atlantic coast and Southern New England on Tuesday

The good news? Fair and seasonable cold weather will return during the middle of the week. Even BETTER news? another ridge will build over the Eastern US later in the week and weekend, as another trough digs into Western and Central US. As a result, another warming trend to above normal temperatures is likely next weekend in the Northeast and Mid-Atlantic. Overall, the pattern is expected to remain progressive with transient cold shots followed by warmer than normal temperatures as we go into the first few days of February.

However, we are anticipating some changes. As discussed in our winter forecast from November, our ideas continue to support a transition back to a colder and stormier pattern in the Northeast during the middle of February, as the MJO or tropical forcing gradually continues to propagate into the Western Hemisphere or phases 7 and 8. We will start to see more Eastern Pacific ridging return and build into the Arctic regions again, disrupting the arctic circulations and sending cold air back into the United States.

There’s an old saying about “enjoy it while it lasts”. We’ll leave the interpretation of that up to you. Have a wonderful Monday!