As Greg wrote last night, winter is not quite done with us just yet, and it will make its return on Friday with accumulating snow for the state courtesy of an Alberta clipper system. While not a significant snow event, the timing will be just right to mess up the morning commute, so make sure to plan ahead and leave some extra time for Friday morning!
Models and Trends
Guidance has been in good agreement on a clipper system impacting the region in this period. Over the last few cycles, the track has shifted north somewhat, and, concurrently, the storm has begun to appear a bit better defined on the models, generating stronger dynamics aloft and more precipitation at the surface.
To show the trend, here’s a look at the most recent GFS(18z today) vs the 18z GFS from yesterday. You can see that the storm is both further north and stronger, leading to a broader precipitation field.
Ignoring the NAM, when weighting the rest of the guidance, I don’t see any clear reason to favor one scenario over the other. The difference between the two camps is relatively minor(50 miles or so), and in the model world at this range, that’s little more than a rounding error. So for this forecast, we’ll go with a consensus blend of the guidance, discounting the NAM.
As far as total liquid goes, most models are in good agreement for around a quarter to a third of an inch of QPF across the state, with a band of heavier precipitation bringing totals of up to a half an inch where it sets up. Unlike some of our other systems this winter, this one should be a fairly standard 10:1, and ratios may even be a bit lower on the shoreline where temps will be marginal for the start of the event.
Here’s total QPF from the GFS, RGEM and GGEM. Notice the band of heavier precipitation, with lighter amounts on either side. Pinpointing where that band sets up will be the tricky part of this forecast.
Here’s our forecast snowmap for this event.
Further north, things are a bit more unclear. A more northerly track, like what is shown on the RGEM, would actually flip this map, with the higher totals in the northern portion of the state and initial rain keeping totals down on the shoreline. However, given that the RGEM and GGEM are the only two models that are that aggressive with pushing the system north(and the RGEM has been overly aggressive at times this winter), I am inclined to play it a bit more conservative for now and, if needed, increase totals in this area tomorrow. As such, will go with a general 1-3” for the area for now and will revisit a potential upgrade tomorrow once we have a few more rounds of data.
As far as timing goes, expect snow to move in west to east late tomorrow evening, with the heaviest snow very early on Friday morning. The guidance is again split here on the end time, with the southern solutions (GFS and Euro) having most snow out of the state by the end of the morning rush hour, while the northern solutions keep snow going through the morning into the early afternoon. Clipper systems generally like to come in and head out quickly, and given that we are leaning towards the southern solutions with our snowmap as of now, I’d lean towards an earlier finish rather than a later one. More details on timing tomorrow as we hopefully get into a bit better of a consensus.
- A minor to moderate snowfall for the state, with low-end plowable amounts possible, especially in southern areas. Localized rates of up to 1" per hour are possible for a short period of time.
- Snow falling during the morning commute will lead to delays and slippery road conditions. Leave extra time for your commute and take it slow!
- School delays are possible – I think closings are unlikely, but not out of the question, especially in southern and eastern areas where it will take longer for snow to clear out.
We’ll have a final call out tomorrow evening, until then, feel free to ask any questions you may have on our social media platforms. Thank you for reading and trusting SCW!