Good evening from Southern Connecticut Weather!
Well, the first storm of Meteorological Winter isn't taking it easy on forecasters, as a slight trend warmer overnight and this afternoon has quickly eroded confidence in any type of significant snow event for most of the state. That said, this is about as marginal a case as you can get, with just 1C of additional cooling or warmth aloft makes the difference between a mostly rain event and a mostly snow event.
Let's get right to it.
Well, the first storm of Meteorological Winter isn't taking it easy on forecasters, as a slight trend warmer overnight and this afternoon has quickly eroded confidence in any type of significant snow event for most of the state. That said, this is about as marginal a case as you can get, with just 1C of additional cooling or warmth aloft makes the difference between a mostly rain event and a mostly snow event.
Let's get right to it.
Above: The final call snow map. The 2-5" zone was eliminated completely, as we expect more cold rain for most of the state. While there's a risk even NW CT flips to rain, I think that is overdone on the guidance, and as a result I am keeping the 3-6" zone, with a little more of a gradient zone if you look closely from about northern New Milford up through far north central CT.
Overall Setup
Although you see a sizable change in the map above, there's honestly not a whole heck of a lot different in the overall setup. Tonight we're quickly cooling off in the wake of our cold front, and our storm is approaching. As our storm approaches early Tuesday, the high pressure holding the cold air in the region will begin retreating. As I said last night, a retreating high is a normal evolution for a winter storm, especially this early in the season.
Overall Setup
Although you see a sizable change in the map above, there's honestly not a whole heck of a lot different in the overall setup. Tonight we're quickly cooling off in the wake of our cold front, and our storm is approaching. As our storm approaches early Tuesday, the high pressure holding the cold air in the region will begin retreating. As I said last night, a retreating high is a normal evolution for a winter storm, especially this early in the season.
Above: A current image of the developing storm in the Great Lakes region and southeast.
Not to belabor the point from earlier in the day, but essentially what we've seen today on guidance is a track that remains less than ideal for snow production, and with a retreating high, a more stout push of warmer air into the region that's eroding the cold in place faster.
My only concern is that this is such a marginal case that a place like Hartford could overperform if the cold in place is a little tougher to dislodge than modeled. I account for some of that in the snow map, but there's just not enough confidence to do that for central CT.
Here are the factors we're using to grade our final call forecast.
Timing
Nothing has changed here. Although there may be a few flakes before 8am, we expect precipitation to begin from SW to NE between 8am and 11am. The heaviest precipitation is likely in the afternoon and early evening (4-8pm), so expect impacts to the PM commute regardless of precipitation type. The precipitation should be fully out of the state early Wednesday morning, well before sunrise.
Snow & Ice Accumulation
Big changes here as we removed the 2-5" zone altogether. Last night we did say it was an extremely close call, and it didn't take much modeled warming aloft to really erode confidence in a snow event. In most of southern CT, a coating might be generous, but with a cold night on tap with very low dew points it's still possible there's a brief period of snow before a quick flip to rain.
Inland (in this case the northern four counties) is more difficult, and I do think there will be accumulating snow, hence keeping the ceiling at 2". The easiest part of the forecast is not so easy now, but we still expect 3-6" in NW CT where you are least likely to flip to rain. Once again it's important to note that even though we may have periods of mixing in the state on Tuesday, we expect any mixing to be sleet rather than freezing rain, and for any icing from mixed precipitation to be minor at best. That said, temperatures will crash after the storm passes even to the coast, so expect whatever lingering water out there to ice up. Plan accordingly.
Wind & Power Outages
No changes here. The lack of a significant pressure gradient and the lack of a closed off and well organized low means that we do not expect significant wind or power issues.
Overall Impact
With the expectation of a more wet than white storm, the impact in most of the state is now moved to minor impact. In NW CT however, with a more marginal air mass you may see more in the way of paste, which may cause some road issues if you stay below freezing all day (and higher elevations should). It is likely a moderate impact storm there if you can stay all snow. Given the potential for more rain, widespread cancellations seem unlikely outside of NW CT. Delays will be possible however in inland areas that start off as snow.
As always, please like, share, and interact with us on our social media--on Facebook to share our discussions, and follow us on Twitter @southernctwx to retweet our posts. Hit the buttons below to join.
Thank you for reading SCW.
-DB
Not to belabor the point from earlier in the day, but essentially what we've seen today on guidance is a track that remains less than ideal for snow production, and with a retreating high, a more stout push of warmer air into the region that's eroding the cold in place faster.
My only concern is that this is such a marginal case that a place like Hartford could overperform if the cold in place is a little tougher to dislodge than modeled. I account for some of that in the snow map, but there's just not enough confidence to do that for central CT.
Here are the factors we're using to grade our final call forecast.
Timing
Nothing has changed here. Although there may be a few flakes before 8am, we expect precipitation to begin from SW to NE between 8am and 11am. The heaviest precipitation is likely in the afternoon and early evening (4-8pm), so expect impacts to the PM commute regardless of precipitation type. The precipitation should be fully out of the state early Wednesday morning, well before sunrise.
Snow & Ice Accumulation
Big changes here as we removed the 2-5" zone altogether. Last night we did say it was an extremely close call, and it didn't take much modeled warming aloft to really erode confidence in a snow event. In most of southern CT, a coating might be generous, but with a cold night on tap with very low dew points it's still possible there's a brief period of snow before a quick flip to rain.
Inland (in this case the northern four counties) is more difficult, and I do think there will be accumulating snow, hence keeping the ceiling at 2". The easiest part of the forecast is not so easy now, but we still expect 3-6" in NW CT where you are least likely to flip to rain. Once again it's important to note that even though we may have periods of mixing in the state on Tuesday, we expect any mixing to be sleet rather than freezing rain, and for any icing from mixed precipitation to be minor at best. That said, temperatures will crash after the storm passes even to the coast, so expect whatever lingering water out there to ice up. Plan accordingly.
Wind & Power Outages
No changes here. The lack of a significant pressure gradient and the lack of a closed off and well organized low means that we do not expect significant wind or power issues.
Overall Impact
With the expectation of a more wet than white storm, the impact in most of the state is now moved to minor impact. In NW CT however, with a more marginal air mass you may see more in the way of paste, which may cause some road issues if you stay below freezing all day (and higher elevations should). It is likely a moderate impact storm there if you can stay all snow. Given the potential for more rain, widespread cancellations seem unlikely outside of NW CT. Delays will be possible however in inland areas that start off as snow.
As always, please like, share, and interact with us on our social media--on Facebook to share our discussions, and follow us on Twitter @southernctwx to retweet our posts. Hit the buttons below to join.
Thank you for reading SCW.
-DB
