Forecast #178: Mar. 16, 2022 - Mar. 22, 2022
Wet storm for the Front Range from Wednesday to Thursday, snow totals are in question for the mountains and lower elevations, but lots of precipitation is in the forecast. An even stronger storm is possible early next week.
San Juans: Telluride, Red Mountain Pass, Silverton, Coal Bank Pass, Purgatory, Wolf Creek
6am New Snow
6am Powder Potential
Denver and surrounding suburbs: Lakewood, Westminster, Aurora, Highlands Ranch
6am New Snow
6am Snow Accum. Chance
Wet storm tomorrow and into Thursday, mostly impacting the Front Range.
Double digit snow totals likely in parts of the foothills to the east of the Divide, at least from Ward to Conifer.
3-8” of snow possible for the eastern I-70 ski resorts (Loveland, Winter Park, etc.) but only Trace to 5” for most other ski areas.
However, a late Wednesday morning surprise seems quite possible for Steamboat.
Also expecting decent totals at Monarch (5-10”) and in the Sangres.
The Denver metro area is now favored over Colorado Springs for highest precipitation totals. Actual snow totals are a bit of a mystery due to warm temperatures – likely twice as much snow in the western/southern suburbs compared to in central and NE Denver. Initially, rain on Wednesday, changeover possible by 7 to 9pm. Generally 4-8” in the western/southern ‘burbs, (and half of that as you go NE towards the airport) but possible to bust high.
Storm largely wraps up by noon on Thursday, though snow lingers in the northern mountains.
Potential for an even stronger system on Monday/Tuesday, but can’t really predict this until tomorrow’s system clears out.
Forecast Discussion: Storm Wednesday and Thursday
As we mentioned yesterday, a warm, wet storm will be impacting the Front Range from Wednesday to Thursday, with decent snow totals in the foothills but not much snow progged for the mountains nor the Plains.
The biggest issue yesterday was some disagreement in some fairly crucial aspects of the storm system, such as its track and intensity, but after 24 hours we’ve managed to shake out a lot of that uncertainty and have a better idea of potential impacts.
In particular, the ensembles were much drier than the deterministic models for the Front Range. This resulted in the Blend being much drier than the deterministic models. Today, the deterministic models are a bit drier and the ensembles have leveled off their drying trend and bounced back a bit. Everything is in more agreement, with the Blend looking a little bit wetter and largely mirroring the guidance of the more reliable deterministic models.
With that said – how are we looking now?
On a broad scale, not much has changed:
Colorado’s high country to the west of the Divide still isn’t progged to get that much snow (likely T-5”), due to less available moisture and a suboptimal near-surface flow direction.
Things get more interesting near and along the Divide (such as the eastern I-70 ski areas like Loveland and Winter Park), but we think this is overdone and mostly attributable to low resolution models being unable to resolve a tight moisture gradient from the Front Range to the Divide itself. Still our general forecast for those ski areas is 3-8”, and areas to the east of the Divide (like Eldora) have a good chance of hitting double digits by Thursday.
Monarch should also do pretty well with perhaps 5-10” of new snow, along with much of the Sangres.
We also think Steamboat has a chance of sneakily picking up some powder early on Wednesday before anywhere else due to some mid-level dynamics at play in far northern Colorado early on in the storm – maybe a sneaky surprise up there on Wednesday!
The Front Range
The foothills to the west of Denver are most favored for the highest snow totals. The snow forecast drops off pretty quickly as you starting looking north of Boulder and south of Colorado Springs. The Palmer Divide will also do pretty well thanks to the the northerly component of the moist upslope.
While the Denver metro area will get a decent amount of precipitation, the major question is just how much of it will fall as rain before it switches over to slushy snow that has trouble accumulating. For areas east of I-25 and north of I-70 – snow totals may not be very appreciable, though it will certainly be a decent period of wet, chilly conditions. More pragmatically, travel conditions late Wednesday and early Thursday could be rough, especially if the wet road surfaces freeze.
It’s close though – and temperatures become less and less of a concern towards the western and southern suburbs (where a Winter Storm Warning is now in place), and these areas will be more efficiently able to transform the 0.5 to 0.8” of liquid precipitation into 4-8” of snow.
If we add in some smaller scale dynamics which are being resolved on some of the high resolution models, we can bump that forecast up even a bit higher. Still, we think it’s likely that’s where a majority of totals end up, considering poor snow-liquid ratios early on in addition to melting upon contact with the ground initially.
In the foothills, double digit snow totals should be fairly widespread from Ward to Conifer, though areas like Idaho Springs and Evergreen look less favored. The Palmer Divide should pick up 6-12” of snow, with totals dropping off quickly on the south side and down into Colorado Springs, which is no longer favored for snowfall now that downsloping winds are more of a sure bet.
The Blend deterministic shows some of that enhanced snow potential in the foothills nicely:
For timings, not much of a change. On Wednesday morning, some light precipitation on the Front Range and perhaps some heavier snow in northwestern Colorado (from Steamboat and westward) due to mid-level dynamics. There looks to be perhaps a surge of better moisture later in the morning on the Front Range, but that’s not the main event. That’s kicked off by heavy banded precipitation which should develop across much of Colorado by the early afternoon, with the Front Range moisture really kicking in by the evening.
For areas above 6,000ft., this should all be primarily snow. In Denver, we’re in agreement with our friends at Weather5280 that the changeover to snow likely wont be any later than 9pm and could in fact be a bit earlier. With heavy precipitation (evaporative cooling) and some reinforcing cold air likely moving in a bit faster than models expect, we wouldn’t be surprised to see flakes falling in central Denver by 7pm, but it’s not a lock.
By the morning hours of Thursday, the heaviest precipitation should have moved south to Pueblo and the New Mexico border, but widespread moderate precipitation remains in place over the Front Range until the late morning.
Some northwesterly snow keeps flakes flying in the northern mountains that afternoon, but things have otherwise mostly wrapped up elsewhere. By Thursday night, snow will likely be wrapped up.
Here’s the simulated radar from the NAM:
Forecast Discussion: (Much!?) More Snow Early Next Week
If this storm doesn’t prove to be enough for you, we have another lined up for Monday / Tuesday ish.
We’ll show you an image, but you have to promise to treat it as the drunken ramblings of a mad weather model. It’s definitely doing that thing though:
A couple feet of snow for Denver? That’s entirely unreasonable, but what it’s getting is the potential for a classic mid-latitude cyclone:
Just look at that rotation!
Of course, the GFS is really the only model calling for this sort of tantalizing setup. In fact, what we’re seeing right now is a pretty classic example of how ensembles, despite introducing uncertainty into their forecasts, can still get locked to the same overall solutions.
Compare and contrast the GFS ensemble, which has most members showing a strong surface low in SE Colorado…
…with the Euro ensemble, which has most members showing a weak surface low on the New Mexico / Texas border:
Not much overlap there. That’s unlikely to change until we get this next storm out of the way first. Still, the Euro solution isn’t horrible, and we’re already seeing some decent snow in the forecast even when looking at a fairly conservative Blend product:
Exciting times ahead – stay tuned!
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