Good afternoon from Southern Connecticut Weather.
Winter storm warnings are being issued as consensus continues to build on a high impact winter storm that threads the needle to bring much of Connecticut its biggest storm in at least 2-3 years. Despite the broader trend, as of this first call forecast we still have some concerns for part of southern CT due to remaining track uncertainty.
Even if the maximum potential isn't realized, we anticipate a high impact snowfall statewide.
Winter storm warnings are being issued as consensus continues to build on a high impact winter storm that threads the needle to bring much of Connecticut its biggest storm in at least 2-3 years. Despite the broader trend, as of this first call forecast we still have some concerns for part of southern CT due to remaining track uncertainty.
Even if the maximum potential isn't realized, we anticipate a high impact snowfall statewide.
Above: The SCW first call snowfall map. We have a general 3-6" for part of southern CT with 6-12" for the rest of the state. At this time, it looks like the warmer solution possibilities are diminishing, and if that holds our numbers may change with our final call tomorrow.
Overall Setup
The setup remains the same. We have been tracking a system in the Midwest that is moving east. Early Tuesday it slides off the East Coast and begins to explosively develop. As it does so, it runs into a marginal airmass over New England, but the rapid intensification and dynamic nation of the storm is likely to overcome marginal temperatures and bring significant snowfall statewide.
In the absence of a classic block to our north and lack of full phasing with the northern stream of the Jet Stream, this looks like an impressive system but fast mover. This should put a ceiling on snowfall potential.
While the GFS and Euro remain consistent in depicting a major snowstorm, some of the other guidance (which is being discounted at this time) are only now starting to align themselves with the GFS and Euro. What is particularly impressive is the ensemble support for a major storm even to the coast on the GFS and Euro. At this juncture in forecasting, ensembles aren't used much, but here I think they provide some value in illustrating the higher potential with this system.
What is unanimous among reliable guidance is how explosively this system develops once it reaches the coast. Here are the 500mb depictions of the storm aloft on today's Euro and GFS. It's quite impressive. With a full early phase this likely would have been much further north, and with a weaker system we'd be battling temperatures and barely accumulating in much of the state. We're really threading the needle to receive a major storm.
Overall Setup
The setup remains the same. We have been tracking a system in the Midwest that is moving east. Early Tuesday it slides off the East Coast and begins to explosively develop. As it does so, it runs into a marginal airmass over New England, but the rapid intensification and dynamic nation of the storm is likely to overcome marginal temperatures and bring significant snowfall statewide.
In the absence of a classic block to our north and lack of full phasing with the northern stream of the Jet Stream, this looks like an impressive system but fast mover. This should put a ceiling on snowfall potential.
While the GFS and Euro remain consistent in depicting a major snowstorm, some of the other guidance (which is being discounted at this time) are only now starting to align themselves with the GFS and Euro. What is particularly impressive is the ensemble support for a major storm even to the coast on the GFS and Euro. At this juncture in forecasting, ensembles aren't used much, but here I think they provide some value in illustrating the higher potential with this system.
What is unanimous among reliable guidance is how explosively this system develops once it reaches the coast. Here are the 500mb depictions of the storm aloft on today's Euro and GFS. It's quite impressive. With a full early phase this likely would have been much further north, and with a weaker system we'd be battling temperatures and barely accumulating in much of the state. We're really threading the needle to receive a major storm.
What's not depicted here is the 700mb low track, which is critical for analyzing how much warmth moves into CT. Yesterday there was significant concern for the coast that we'd see continued northward ticks of both the surface and 700mb low, but the opposite has happened since late last night. The adjustments south have been slight, but make a huge difference for coastal CT.
Now is the time when we start to get into the details of banding, timing, wind, and impact. This looks like another high precipitation event, and with such a dynamic system we can have surprises in either direction. To illustrate this, let's look at two different versions of the hot-off-the-presses NAM model.
The first one below is the 12km NAM. It shows one end of the spectrum where we see strong banding that leads to subsidence (read: dry slotting) across much of CT. Snow totals suffer as a result. As an outlier, this is discounted but we watch for trends. While the general solution is discounted, tote that even with weaker precipitation it's virtually all snow even at the coast. This does lend greater confidence that this is a snowstorm for the whole state.
Now is the time when we start to get into the details of banding, timing, wind, and impact. This looks like another high precipitation event, and with such a dynamic system we can have surprises in either direction. To illustrate this, let's look at two different versions of the hot-off-the-presses NAM model.
The first one below is the 12km NAM. It shows one end of the spectrum where we see strong banding that leads to subsidence (read: dry slotting) across much of CT. Snow totals suffer as a result. As an outlier, this is discounted but we watch for trends. While the general solution is discounted, tote that even with weaker precipitation it's virtually all snow even at the coast. This does lend greater confidence that this is a snowstorm for the whole state.
The second depiction however, the 3k and more high resolution NAM, shows the opposite. It goes nuclear, as the NAM tends to do at times, with the banding as the storm rapidly intensifies to our south. The result is a truly high end storm with double digit totals across most of the state, even down to the coastline. This is also discounted, but I will note that another high resolution model, the RGEM, is also looking similar. That's interesting, but we're not locked onto that kind of solution...yet...
Anything close to this would be very high impact.
Anything close to this would be very high impact.
So what are we actually expecting? Let's take a look below.
Timing
This is a fast mover. We expect snow to begin from SW to NE very early Tuesday morning, shortly after midnight. It may start off as brief mixing or rain at the coast but that should quickly change over to snow. The worst of the storm is through the daylight hours--that's both morning and afternoon, and we see the snow end from west to east between 6-8pm.
Wind/Power Outages
It looks like this will be a windy storm, but not overwhelmingly so. Maximum gusts look to be between 30-45mph statewide with highest gusts at the coast as usual. As a result, it'll have an impact, but it doesn't look too bad. That said, we are closely watching how pasty the snow ends up in southern CT. The combination of heavy snow and gusty winds will not only create low visibilities, but the possibility of heavy wet snow in southern CT could create isolated to scattered power outages.
Snow Accumulation
As the map above shows, our first call is 3-6" in part of southern CT and 6-12" in the rest of the state. We have a low floor for the state because of the continuing uncertainty over track and banding. You have to take that seriously. As it stands however, most would probably see 4-6" in the southern CT zone and 8-12" in the northern zone.
Folks, these numbers could change substantially between now and tomorrow. Warmer solutions look less likely now, but as we get into the high resolution guidance wheelhouse, if they continue to show exceptional banding across CT watch out--for both dry slotting and bigger snow amounts.
Impact
This is a high impact event statewide. School closures statewide are about as close to a lock as I remember forecasting in recent years. Even if you end up with heavier wet snow at the coast which reduces overall snow totals, the heavier paste with wind gusts of 30-45mph will cause issues. Inland, as long as we don't end up with a track too far south or subsidence (read: dry slotting) a big snow is likely. Further inland the snow should be drier which lessens the risk of power issues, but increases ratios which should allow for higher snow totals. This is looking like a major storm around the state.
Stay tuned for our final call discussion and snowfall map tomorrow afternoon.
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
This is a fast mover. We expect snow to begin from SW to NE very early Tuesday morning, shortly after midnight. It may start off as brief mixing or rain at the coast but that should quickly change over to snow. The worst of the storm is through the daylight hours--that's both morning and afternoon, and we see the snow end from west to east between 6-8pm.
Wind/Power Outages
It looks like this will be a windy storm, but not overwhelmingly so. Maximum gusts look to be between 30-45mph statewide with highest gusts at the coast as usual. As a result, it'll have an impact, but it doesn't look too bad. That said, we are closely watching how pasty the snow ends up in southern CT. The combination of heavy snow and gusty winds will not only create low visibilities, but the possibility of heavy wet snow in southern CT could create isolated to scattered power outages.
Snow Accumulation
As the map above shows, our first call is 3-6" in part of southern CT and 6-12" in the rest of the state. We have a low floor for the state because of the continuing uncertainty over track and banding. You have to take that seriously. As it stands however, most would probably see 4-6" in the southern CT zone and 8-12" in the northern zone.
Folks, these numbers could change substantially between now and tomorrow. Warmer solutions look less likely now, but as we get into the high resolution guidance wheelhouse, if they continue to show exceptional banding across CT watch out--for both dry slotting and bigger snow amounts.
Impact
This is a high impact event statewide. School closures statewide are about as close to a lock as I remember forecasting in recent years. Even if you end up with heavier wet snow at the coast which reduces overall snow totals, the heavier paste with wind gusts of 30-45mph will cause issues. Inland, as long as we don't end up with a track too far south or subsidence (read: dry slotting) a big snow is likely. Further inland the snow should be drier which lessens the risk of power issues, but increases ratios which should allow for higher snow totals. This is looking like a major storm around the state.
Stay tuned for our final call discussion and snowfall map tomorrow afternoon.
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
