Winter Weather Forecast Discussion: St. Patrick’s Weekend

Snow is in the forecast for Friday night into Saturday, true, but we could be talking about two separate systems that will split the weekend and reduce overall impacts.

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  • There’s been many questions about this weekend, so I wanted to break down what we know so far, dispel some of the myths of doom and gloom and give a concise map of what exactly we are seeing as meteorologists.
  • I understand many have plans and there is much riding on this weekend – having that said the forecast has only slightly developed and confidence is fairly low at this point.
  • What we can tell you, is that moisture is being pumped into the Northern Plains from Friday all the way through next week… it’s figuring out how it’ll manifest and if the stars align with storm movement, moisture content, temperatures – aside a long list of other factors.
  • That’s why I have light snow in the forecast from Friday night through next week… because we will have cool air and moisture. More than likely, this will develop into something more broken up, more concise, with dry periods and snowy periods. Once we get to Thursday and Friday we’ll have a much better idea of what things look like.
  • For those looking to get a leg up on making long range decisions though, let’s break down what we know.

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  • A low pressure system will eject from the four corners and head for the great plains sometime Friday into Saturday.
  • THUS FAR – The system looks to track South of us and bring most impacts to Nebraska, Colorado, Kansas and Southeastern Wyoming, but giving us enough of a graze to induce snow bands across the Black Hills.
  • If this system tracks further North, we’ll have larger impacts – further South and we could be left high and dry – so far its trending in the Northward direction.

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  • By late Friday evening, the main bulk of snow should be crossing the Central Plains, with snow bands moving through the Black Hills region as well.
  • This is expected to last through at least Saturday morning if not longer.

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  • Something to note: Saturday’s system is NOT a clipper, this will be snow moving from South to North.
  • These bands will have good amounts of moisture and generally be on the warmer side temperature wise – so there could be travel impacts Friday night into Saturday morning.

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  • There does appear to be a break between the passing warm front and when the next system arrives Sunday.
  • This means snow could taper off by Saturday afternoon and evening – leaving a lull in the action so to speak.

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  • Should we get a break Saturday afternoon through Sunday morning, these are the expected amounts -thus far- that we are looking at accumulation wise.
  • Notice a good amount of snow for the Central Hills… as opposed to the Northern Hills, this will be due to our South to North moving system as opposed to our Northwesterly Clippers that generally induce upslope for our northern neighbors.
  • So far, accumulations don’t look outrageous. If i’m having to throw out numbers this early i’m looking for 6″+ of snow for Custer, Hill City, Keystone and Rochford.
  • Once you leave that ring and expand outwards you’re looking at 3″-6″ amounts in the foothills and Northern Hills and 1″-3″ amounts for the surrounding plains.
  • The exception will be areas to the Southeast that will be closer to the Low pressure engine that could see 3″-6″, particularly towards Central Nebraska.
  • These numbers will fluctuate, but hopefully that gives you a ballpark for Saturday in regards to making plans.

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  • Sunday morning will be determined by the slightest of margins – with just a little more added moisture inducing widespread light snow and additional accumulations.
  • So far, long range guidance shows patchy snow bands and overall dry conditions.
  • Once we get to Thursday and Friday, this will become much more clear.
  • Sunday night does show a good chance of clear conditions, assuming storm speed remains the same through the next couple model runs.

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  • An associated cold front looks likely to move through by Monday, but this is almost 7 days out. This is the system I’m more concerned with.

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  • A system off the West coast will continue to pump moisture into the Northern Plains from the Pacific.
  • If the Polar Jet stream manages to tap into this energy, we could have a storm system cross the Northern Plains with plenty of moisture to play with.
  • Once again, more than 7 days out, but something i’ll continue to watch as we go into the next couple of days.


“So what am I supposed to do with all this information?”

Have contingency plans for this weekend in case things trend in the upward direction – which it very well could. March usually features our snowy systems, and this has all the hallmarks of one of those 32° heavy snow systems. What you should NOT do, is cancel any plans for Saturday. If Saturday’s system ends up being separate from Monday’s system and track southward we’ll be talking smaller impacts overall. If we do manage to get a couple inches of snow Saturday morning, most of it will start melting by the late morning as temperatures could reach the 40s…. and with a possible break that will help things along even further.

So, St. Patrick’s Day parade? Deadwood’s St. Pats celebration? Still looking ok… Just keep an eye on the forecast over the next 48 hours and be ready to make some adjustments if need be. That’s all we need to be doing at this point.

I’ll keep updating the timeline with more information as we get closer to the date. We appreciate you trusting us with these forecasts, we know folks rely on it for more than just entertainment purposes – seeing as we’re getting closer to calving season as well. Stay tuned for more updates over the next couple of days. – Brant



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