The mountains have held onto the moisture so far this week but that's about to change for Thursday and Friday; the metro areas will have a chance for moisture too.
This won't be a major system but has the potential to bring us the most moisture we've had since early February. This isn't saying too much as we haven't had much of any kind of system since that Groundhog Day storm.
As the wind increases and temperatures drop Thursday evening you will also notice increased/lowering cloud cover. For Fort Collins and others north of the city, this will be happening Thursday afternoon into the evening. For Denver, rain and snow chances will increase a tad bit later – through Thursday evening into the overnight and linger Friday.
The system will exit by the weekend leaving us sunshine and warming temperatures for Saturday and Sunday.
Rain vs Snow
Should the timing of the system change, the amount of rain versus snow will also be adjusted. As it looks right now there is a brief period of rain possible before turning into an all snow event.
There are differences in how the models are handling the cold air. GFS is colder than the NAM and drops temperatures below freezing and gives Denver/Fort Collins nothing but snow. The NAM is warmer with temperatures near and above freezing and gives Denver/Fort Collins rain, then snow.
I believe a blend of the two seems appropriate; it is common for rain/snow systems this time of the year. And, this difference in temperatures explains, in part, the difference in forecast snowfall amounts between the models.
The models indicate a quarter to around a half-inch of liquid water coming. If that all falls as snow we are looking at about 3 to 7 inches of snow – depending on the ratio of liquid water to snowfall.
The higher forecast snowfall amounts are north of Denver. Here is the model average snowfall of the NAM, GFS, GF ensembles, and Canadian ensembles. It should also be noted that the EURO is the most bullish with snowfall amounts from this storm system. Its deterministic and ensemble suite in very good agreement with roughly 4" of snow for the greater Denver area. Even higher totals are showing up for areas near Boulder and Fort Collins. However, what falls versus what sticks (especially to the pavement) will likely be two different things.
Regardless of location note that this is snowfall amount, not the accumulation amount. We are now well into spring and with warm ground temperatures, the accumulation will likely be much less than snowfall. Since most precipitation falls after dark, I'm not factoring sun angle into the accumulation versus snowfall forecast.
So, here is our snowfall accumulation forecast, again for Thursday night through Friday.
We'll keep an eye on the latest data as it comes in tonight and tomorrow and pass along any updates as needed. While maybe not a huge storm for the region, certainly a BIG change after weeks of very mild weather. Stay tuned!