Evening Update on Mother's Day Storm

The Weather5280.com team has been digesting the latest modeling early this evening and we want to provide you with a quick update on where things stand at this moment regarding our incoming storm. First, many spots across the metro area are already seeing rain associated with this system. Expect periods of light rain to persist through the evening and nighttime hours as temperatures slowly fall through the 40s into the upper 30s. Rain may begin to mix with snow as early as dawn Mother's Day, but the main action will hold off until later in the day for the metro, some of the mountains will have heavy snow through the night.

Though we put less stock in the 18z runs of models, the NAM has slightly decreased its forecast snow amount to about 8 inches for Denver proper in its latest run; the latest run of the GFS also appears to be slightly less bullish about snow totals than previous runs, and perhaps a touch warmer as well. The latest run of the SREF is very close to its previous run, and shows Denver receiving about 9 inches of snow. The Canadian (GEM) and European (ECMWF) models from this morning remain, in many ways, the most impressive, and suggest that 10 inches+ of snow could fall Sunday into Monday. Basically, if you average all the models together, you have a storm capable of delivering 8 inches or more of snow -- but how much of that will stick is the key question.

00z models are starting to come in now, and so far aren't showing much of a shift from earlier either. The NAM may however be coming around to a longer duration event similar to the EURO, extending snowfall well into the day Monday. A slower pattern with this storm is not for-sure yet, but not out of the question as these models are picking up.

Rain will change to snow at different times Sunday depending mostly on your elevation. Locales above 7,000 feet will likely see changeover occur by dawn, but that could take a little longer for lower elevations. Expecting locations at and below 5,000 feet to change to all snow by Sunday evening at this time. Light to moderate snow is expected during the remaining daylight hours Sunday, through much of what falls will have a tough time sticking. We still expect the heaviest snow to hold off until Sunday evening into early Monday, as temperatures drop to freezing or below. It is during this time that snow will have the best shot at actually accumulating.

Reminder: our biggest concern with this Mother's Day storm system is the potential for heavy, wet snow to bring down tree limbs and branches, possibly causing power outages by Sunday evening. Also, expect near-record cold for almost mid-May by Sunday night, with temperatures below freezing, wind chills as low as the upper teens, and north winds of 15-25mph helping to reduce visibility to 0.5 miles at times. If you haven't already protected vulnerable growing things, now is the time to do so.

Overall, things appear on track tonight. More data coming in well into tonight will help confirm this. We'll have more updates to come, and be active on Twitter and Facebook as well. For more, visit our from earlier today as well.


This is a collaborative post from multiple authors at Weather5280.

Denver, Colorado
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