This weekend elements of the Rockies together with Colorado and Wyoming are more likely to expertise a doubtlessly historic snowstorm. In at the very least one Nationwide Climate Service map, I noticed a high-end forecast for 50 inches of snowfall in elements of the area. Whereas that’s in all probability an outlier, the extra possible vary of options remains to be spectacular and life-altering. The Nationwide Climate Service issued the next assertion for the occasion, “Winter Storm Warning issued for Mountains, Entrance Vary Foothills and the City Hall from midnight Friday into early Monday. Journey can be tough to unattainable by means of the weekend.” As I learn by means of their forecast dialogue, a number of key meteorology phrases have been used. Here’s a meteorological breakdown of what all of it means.
Snow totals are anticipated within the 2 to three toes vary (graphic above) within the mountains and main cities of the Entrance Vary area. For historic perspective, this storm has a major probability to surpass the March 23, 2016 heavy snow occasion in response to the Nationwide Climate Service. By Saturday and Sunday, peak wind gusts (graphic under) might exceed 30 mph so individuals within the area ought to be ready for related dangers reminiscent of energy outages. Clearly, there are some vital issues anticipated within the environment as we strategy Spring.
The Nationwide Climate Service (NWS)-Boulder highlights a number of issues that I wish to clarify. One key ingredient of the storm is lee cyclogenesis. The Friday morning NWS dialogue mentioned, “….lee cyclogenesis will develop over northeastern New Mexico and southeastern Colorado immediately by means of tomorrow….Chilly air damming to the east of the Rockies ought to maintain the middle of the floor cyclone in direction of the southern fringe of the mannequin options maybe ending up in northeastern New Mexico.” Okay Dr. Shepherd, what does all of that imply?
The American Meteorological Society Glossary defines lee cyclogenesis as, “The synoptic-scale improvement of an atmospheric cyclonic circulation on the downwind facet of a mountain vary.” The time period “lee” is relative to the background airflow, in response to the Glossary. The mountain barrier is crucial for formation of a low (”cyclogenesis”) as it might probably redistribute vorticity (”fluid rotation”) because the wind flows over the mountains. Depth of the cyclogenesis may 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 Nationwide Climate Service web site has a wonderful evaluation of a case from 2019 at this hyperlink since my phrase depend is restricted herein.
The NWS forecast dialogue for this storm additionally mentions, “There are a lot of elements that this technique has going for it that can come collectively to create vital raise throughout our space.” Raise is the important thing with all these occasions. Listed below are among the main meteorological gamers:
- A left exit area of an higher stage jet streak overhead. The left exit area of jet streak, a area of stronger winds throughout the jet stream, is usually related to rising movement due. The map above exhibits among the higher stage jet stream options for this storm.
- Constructive vorticity advection (PVA) forward of the trough. PVA is often a great indicator of the potential for rising air.
- TROugh of Heat Air ALoft (TROWAL) that can convey heat air advection and moisture to the realm. Based on the Nationwide Climate Service Glossary, a TROWAL is “a tongue of comparatively heat/moist air aloft that wraps round to the north and west of a mature cyclone….Throughout a winter storm, the heaviest snowfall quantities steadily happen alongside and north of the TROWAL axis.”
- Sturdy upslope circulate out of the east at as much as 45 knots.
- Instability through the day Saturday and into Saturday evening. Actually, I might not be shocked to see thunderstorms in elements of the storm as nicely.
If there may be one optimistic factor in regards to the storm, it’s taking place through the weekend. Nonetheless, vital climate occasions like this are all the time high-impact occasions and on this time, our combat towards COVID-19 compounds them too.