Meteorology ‘101’ Of The Potentially Historic Snowstorm In The Rockies This Weekend

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This weekend elements of the Rockies together with Colorado and Wyoming are prone to expertise a doubtlessly historic snowstorm. In not less than one National Weather Service map, I noticed a high-end forecast for 50 inches of snowfall in elements of the area. While that’s most likely an outlier, the extra seemingly vary of options continues to be spectacular and life-altering. The National Weather Service issued the next assertion for the occasion, “Winter Storm Warning issued for Mountains, Front Range Foothills and the Urban Corridor from midnight Friday into early Monday. Travel will be difficult to impossible through the weekend.” As I learn by way of their forecast dialogue, a number of key meteorology phrases had been used. Here is a meteorological breakdown of what all of it means.

Snow totals are anticipated within the 2 to three ft vary (graphic above) within the mountains and main cities of the Front Range area. For historic perspective, this storm has a big likelihood to surpass the March 23, 2016 heavy snow event in accordance with the National Weather Service. By Saturday and Sunday, peak wind gusts (graphic under) might exceed 30 mph so folks within the area must be ready for related dangers akin to energy outages. Clearly, there are some vital issues anticipated within the environment as we method Spring.

The National Weather Service (NWS)-Boulder highlights a number of issues that I need to clarify. One key component of the storm is lee cyclogenesis. The Friday morning NWS dialogue stated, “….lee cyclogenesis will develop over northeastern New Mexico and southeastern Colorado today through tomorrow….Cold air damming to the east of the Rockies should keep the center of the surface cyclone towards the southern edge of the model solutions perhaps ending up in northeastern New Mexico.” Ok Dr. Shepherd, what does all of that imply?

The American Meteorological Society Glossary defines lee cyclogenesis as, “The synoptic-scale development of an atmospheric cyclonic circulation on the downwind side of a mountain range.” The time period “lee” is relative to the background airflow, in accordance with the Glossary. The mountain barrier is important for formation of a low (”cyclogenesis”) as it might redistribute vorticity (”fluid rotation”) because the wind flows over the mountains. Intensity of the cyclogenesis could be stronger if the mountains work together with a creating baroclinc wave, a wave featured related to variations in temperature, wind shear, and floor frontal options. The National Weather Service web site has a wonderful evaluation of a case from 2019 at this link since my phrase depend is restricted herein.

The NWS forecast dialogue for this storm additionally mentions, “There are many factors that this system has going for it that will come together to create significant lift across our area.” Lift is the important thing with most of these occasions. Here are a few of the main meteorological gamers:

  • A left exit area of an higher stage jet streak overhead. The left exit region of jet streak, a area of stronger winds throughout the jet stream, is commonly related to rising movement due. The map above reveals a few of the higher stage jet stream options for this storm.
  • Positive vorticity advection (PVA) forward of the trough. PVA is normally a superb indicator of the potential for rising air.
  • TROugh of Warm Air ALoft (TROWAL) that may carry heat air advection and moisture to the realm. According to the National Weather Service Glossary, a TROWAL is “a tongue of relatively warm/moist air aloft that wraps around to the north and west of a mature cyclone….During a winter storm, the heaviest snowfall amounts frequently occur along and north of the TROWAL axis.”
  • Strong upslope move out of the east at as much as 45 knots.
  • Instability in the course of the day Saturday and into Saturday night time. In reality, I might not be stunned to see thunderstorms in elements of the storm as properly.

If there may be one optimistic factor in regards to the storm, it’s taking place in the course of the weekend. However, vital climate occasions like this are at all times high-impact occasions and on this time, our combat towards COVID-19 compounds them too.

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