As Don mentioned in his two-week outlook on Thursday, there was the chance for some snow to kick off next week, and that chance appears as if it will materialize. A weak overrunning system looks to move across the state Monday morning, bringing with it the first snow of meteorological winter to most if not all of the state. While amounts will be light, the timing will be sub-par; right in the middle of the Monday morning commute. That, combined with the fact that it’s still early season and people aren’t in the snow routine yet, pushed me to issue a snowmap for this minor event. We’ll do a quick discussion on the upcoming event, and I’ll also include a small forecasters discussion at the end with a summary of the week ahead and the dailies.
Models and Trends
Over the past few model cycles, the trend has been to strengthen this system somewhat. Previously, model guidance shredded it as it approached our area due to the dry air and high pressure in place, but with a slightly stronger system, it is able to fight back enough to bring some snow to the state. To show the trend, here’s a look at the last few cycles of the NAM valid at 7 AM Monday morning.
The differences in QPF are due to differences between the guidance in handling a small mesoscale convergence zone that is forecast to develop. Wherever the zone develops will likely see a brief period of moderate snow, which could put down an additional inch or two in a couple of hours. The Euro and GGEM both bring it north of the region, while the UKMET and hi-res models place it right on top of us. At this time, I’m leaning towards the further north solutions.
The other question to look at is the temperature profile. We’ll see a colder air mass move in this evening that will last through Monday morning, but it is still early season and the profile is borderline, especially with the weak snowfall rates that I expect with this event. As is typical, the GFS tries to warm the area up enough for a flip to cold rain for most outside of the hills, while the Euro and hi-res models keep the whole state below freezing aside from the immediate shoreline. Strongly prefer the Euro/Hi-res combo on temps to the GFS (which has notorious issues at the surface), and will trend the forecast towards a colder profile, with mixing confined to the shoreline except possibly at the very end of the event.
Forecast and Timing
Here’s our forecast snowmap for this event:
3-6 AM: Light snow moves into the state from west to east
6-10 AM: Light snow with occasional moderate snow continues for all areas except the shoreline, which should see a changeover to rain.
10 AM – 1 PM: Snow exits the state from west to east, possibly changing over to rain towards the end of the event.
- A light snowfall during the morning commute may lead to travel delays, slippery roads, and reduced visibility.
- Some school delays are possible – no closures are expected.
We’ll keep an eye on the guidance and will update tomorrow with a final call if needed. Overall, a minor event, but our first widespread snow of the season, and due to the timing, an impact to the commute is likely. Please share with your friends and family to get them back into “winter mode” and to make sure no one is caught unaware!
A much more active pattern is approaching, with several storm threats in the pipeline. Behind Monday’s system, we get a brief break before another system approaches from the southwest on Tuesday. Models are doing the same thing they did with Monday’s system originally where they weaken the storm as it comes northeast, and again I think it is being a bit overdone.
The GFS transfers the system to a secondary low offshore, which brings a moderate event to our area, while the Euro holds onto the primary longer and the result is just some light showers. Temps as of now look warm enough that anything that falls will be rain except in the northwest hills, where the weaker Euro solution is cold enough for a light snowfall. As of now, will keep a chance of rain in the forecast for Tuesday evening into Wednesday and leave it to the next forecaster to determine any possible snow in the NW hills.
Quiet weather does not last as the next system approaches on Thursday. While this was previously modeled as a strong cutter, both the Euro and GFS have trended away from that idea and towards a redeveloping Miller B. While the antecedent airmass is not exceptionally cold, with the right track, we could see enough dynamic cooling to allow for some snow in parts of the state. Again, the NW hills would be favored here. As guidance has been bouncing around here and we are still in the long-term with this system, I will include a chance of rain in the forecast with a chance of snow for the interior and once again defer to the next forecaster to get some more clarity on the guidance.
Behind this second system, a strong arctic cold shot arrives for the weekend into next week. This cold will arrive into the western portion of the country early in the week and then spread east, reaching us by the weekend and lasting into early next week at the soonest. Expect the coldest temps of the season for next weekend, with highs not getting out of the 20s in the interior and lower 30s along the coastline as currently modeled. Active look continues in the long range, with opportunities for wintry weather in the pipeline as we move into December and the start of the winter season.
Here’s a look at temperature anomalies from normal across the US on the GFS on Thursday. While we are still near-normal due to the system that is impacting the area at the time, you can see the cold to our west coming this way behind the system. The scope of the cold shot is quite impressive!
Sunday: Partly sunny, with highs in the upper 30s to lower 40s.
Monday: Snow likely in the morning, then a chance of rain and snow in the afternoon. Highs in the upper 30s to lower 40s. See snowmap above for accumulations. Chance of snow is 80%.
Tuesday: A chance of showers in the evening, otherwise, mostly cloudy, with highs in the low to mid 40s. Chance of precipitation is 50%.
Wednesday: A chance of showers in the morning, otherwise, mostly cloudy, with highs in the low to mid 40s. Chance of precipitation is 60%.
Thursday: A chance of rain (and snow in the interior), otherwise, mostly cloudy, with highs in the mid 30s to lower 40s. Chance of precipitation is 50%.
Friday: Partly sunny, with highs in the mid 30s.
Saturday: Partly sunny, with highs in the upper 20s to lower 30s.
Have a wonderful rest of your weekend and thank you for reading SCW!