​Good evening to you from Southern Connecticut Weather!
 
Well, March came in like a lion and never really showed it’s lamb side. We saw one of the biggest snowstorms of the season and some of our most sustained cold during the month, and never really got the spring side of March that we often see. In fact, it’s quite possible that March could end up having a colder average temperature than both January and February, which is certainly a rare sight. This month isn’t going out quietly either, as we’ve got a storm system on our hands to deal with for tomorrow into Saturday.
 
Models and Trends
 
We walked through the setup extensively last night here, and that hasn’t changed much if at all. The synoptics have remained remarkably consistent on the models, with a low pressure system moving northeast, running into high pressure to our north, and moving due east from that point to redevelop off the coastline. The difference in the guidance has been and continues to be the temperature profiles during the system, that is, how far north can midlevel warmth make it into the state before the storm starts to bomb out and dynamic cooling takes over? Let’s take a look at the various model solutions to that question.
 
Solution #1: The Snowstorm (GFS)
 
The GFS continues to be the snowiest solution. It tracks the storm along the PA/MD border, and holds warm air aloft well south of the area. As a result, the whole state save the immediate shoreline would see at least some snow from the system, and accumulations would be significant in the northern portions of the state, with the northern tier never flipping over to mix or rain.
 
Here’s a quick simulation of the progression of the storm from the GFS sim radar. Note that in a situation like this one where dynamics and marginal temperatures are in play, forecasting off a precipitation type algorithm will get you burned every time. As such, a disclaimer that we’re only using these maps for illustration purposes and to show the general progression from the various guidance.

​An important thing to highlight on this map is that there is an elevation component to the system. You can see during the day tomorrow that the NW and NE hills are remaining snow while the warmer boundary layer is causing the valley to switch over to rain despite a colder profile aloft. As we move towards darkness and precipitation becomes heavier, the rates are enough to overcome the boundary layer and we switch back to snow.
 
In this solution, I would expect warning level (6”+) accumulations in the northeast and northwest hills, with at least a few inches of snow for most of the area away from the shoreline. I would weight the chances of this solution at 40%
 
 
Solution #2: The Icy Mix(RGEM, Euro, NAM)
 
In the second solution, the storm takes a bit further north of a track, allowing warmer air to intrude in the midlevels, resulting in a quick initial period of snow before a change to rain across most of the state. In the hills, however, colder air hangs on at the surface despite the warming temperatures, and so the result is an extended period of sleet/freezing rain at elevation. Here’s the simulated radar for that solution from the RGEM – again, remember this is for illustration purposes only J. In reality, I’d expect a bit more coverage of frozen precipitation if such a scenario were to verify as the model is likely being a bit too aggressive (as usual) in warming the last few hundred feet of the column.

​With this solution, I’d expect a couple of inches of snow to a couple tenths of an inch of ice for the hills. Outside of the hills, I’d expect a slushy coating to an inch at best, with nothing but rain for the southern counties. I would weight the chances of this solution at 50%.
 
Solution #3: Rain(GGEM)
 
Finally we have the GGEM. This solution is pretty straightforward; the storm tracks the furthest north of all the models, the midlevels and surface warm above freezing, and we see a day and a half of cold rain. Sounds like springtime in New England. While the trends have clearly been colder over the past day, we can’t completely rule this solution out, and therefore we’ll weight it at 10%.
 
Forecast and Timing
 
For this forecast, I essentially took a blend of the GFS and RGEM solutions, weighting slightly more towards the RGEM to account for the slim possibility that the storm could shift back warmer and the end result would be mostly rain. Here’s the end result on our forecast map.

​For this forecast, we’ve broken the state up into four zones. The first is also the easiest forecast; on the shoreline, we’ll see mostly rain. While a bit of sleet could mix in at times, temps will just be a bit too warm to see any sort of accumulation.
 
Next, in the southern half of the state, I’m expecting mainly rain. However, we will likely see some snow at the start of the event and then potentially again on the backend as the low departs and colder air comes in from the northwest. That, combined with the chance of accumulating sleet, leads me to believe that at least some accumulation is a possibility there, and so I’ll go with a slushy coating to two inches for this zone.
 
For the Hartford metro area and north, there should be enough latitude to see a period of accumulating snow at the start of the event and again towards the end on Saturday. While snow will almost certainly mix with and then change to sleet/freezing rain/rain, a minor to moderate accumulation is expected, with 1-3” currently forecast. This area has the highest bust potential, as even a slight shift colder in the consensus towards the GFS would result in several inches of additional snow for the area and an increased risk of sleet & freezing rain as opposed to just plain rain.
 
Finally, in the elevated portions of the NE and NW hills, this should be a mostly frozen event. I expect periods of snow through most of the day tomorrow, and again on Saturday, with a changeover to sleet and freezing rain in the middle tomorrow night into Saturday morning. There is a non zero probability that this area could remain all snow, in which case amounts would be substantially higher, but for now, 3-6” of snow with accumulating sleet and ice in the middle seems like a safe bet to me.
 
Here’s the timeline:
 
Friday morning: Light precipitation moves in; rain for the shoreline and a wintry mix of snow/sleet/freezing rain for the rest of the state. We could see some slippery roads for the morning commute, especially in the Hartford metro and north
 
Friday afternoon: Precipitation gradually intensifies throughout the day, with a wintry mix expected in the north and mostly rain in the south. Again, could see some slippery roads for the PM commute in northern areas.
 
Overnight: Most of the state flips to moderate to heavy rain, with a wintry mix continuing in the hills. Ice accretions are possible in the hills.
 
Saturday morning: Precipitation begins to gradually taper to scattered showers. As the storm pulls away and colder air comes in, we could see a change back to snow in some areas.
 
Saturday afternoon: Scattered rain/snow showers persist through the afternoon before finally tapering off Saturday evening.
 
Impacts
 

• A mixed bag of wintry precipitation, with plowable snow likely in the hills and possible in northern valley areas. NWS has issued Winter Weather Advisories for the northern four counties.
• Isolated slippery travel during both commutes tomorrow.
• Scattered power outages from heavy wet snow and icing.
• Minor flooding in areas that see mostly rain – 1-2” of QPF is likely.

 
As we’ve said throughout the discussion, this is a volatile forecast where small changes in the setup can have a big impact on the overall output. We’ll keep an eye on the models tonight and if needed, issue a final call tomorrow morning. As of now, I think that any bust potential is towards the snowier side, but if I were to go for a snowier forecast, I’d need to see another tick colder on the models tonight. We’ll see what happens!
 
As always, thanks for reading SCW!
-SA

​Good evening to you from Southern Connecticut Weather!
 
As Greg mentioned yesterday, we’re looking at a powerful coastal storm that will impact the region from Friday into Saturday. Over the past couple of model cycles, we’ve seen the storm trend a bit stronger and a bit colder, and as such, we’re watching it closely for a chance of wintry weather in the interior portions of the state. Some of the guidance brings a significant snowstorm to the interior elevated areas, while other guidance is further north and would result in a mainly rain event.
 
Generally, we’ll see the storm approach from the west Friday morning, with precipitation making it into the state by early Friday afternoon. As the storm hits high pressure to our north, it will redevelop into a coastal system, bringing the bulk of the precipitation to the state later Friday afternoon through Saturday morning. Precipitation should exit by Saturday afternoon. At first, temperatures will be below freezing through the column away from the shoreline, so any initial precipitation should fall as snow. However, warm air will quickly move in as the system continues to push north, and most areas should quickly flip to rain. It then remains to be seen if we will see a flip back to snow as the system deepens and colder air is drawn in.
 
The main variables that are influencing the eventual result of the system (i.e., if it is able to dynamically strengthen and produce snow across the state) are how far north the midlevels can get and how strong the storm ends up being. Further north midlevels introduce warmer air aloft, which cuts down on snow potential in favor of a messy sleet/freezing rain mix. A stronger storm with better inflow would generally promote a more well defined CCB (Cold Conveyor Belt, or wraparound band), which could lead to dynamic cooling and cause a borderline thermal profile to flash over to heavy wet snow if sufficient precipitation rates present themselves.
 
 To show what these different solutions look like, here are soundings from the GFS and NAM valid for 8 PM Friday night at Bradley Airport, along with the surface reflections for the same time. Soundings are essentially snapshots of the column for a given location at a given point in time; it shows temperature, wetbub and dewpoint through the column from far aloft down to the surface, and also shows mixing and saturation of the airmass. For the purposes of this exercise, we’re focusing on the red temperature line. 

​You can see that on the NAM, the system is further to the northeast compared to the GFS. This is allowing for more warm air to be drawn in, resulting in a much warmer profile. You can see that the temperature warms above freezing both in the midlevels and at the surface, so the result here would be a cold rain for the area. On the GFS, however, the midlevels come close to going above freezing, but never quite get there, and the column remains marginally cold enough all the way down to the surface. As such, this would likely be a heavy wet snow for the interior. Either way you slice it, the coastline is looking at mostly if not all rain.
 
Of course, the question you’re probably asking right now is which set of guidance do I believe and how much snow do I think we’re going to get? Well, at this point, it’s a bit too early to say. There is certainly the potential for a substantial snowfall in the interior elevated portions of the state, but I would say that right now, it’s a coin flip at that we’d see a plowable(3”+) snow somewhere in the state. Should the northern camp of solutions (NAM, GGEM, UKMET) be correct, we’ll just be getting a lot of cold rain, whereas if the southern solutions are correct, we could looking at close to warning level snows in those interior elevated areas. The usual rules for marginal situations apply here; the further north you are and the higher up you are, the more snow you are going to get. We also have to keep an eye out for sleet and freezing rain; with the warm midlevels but colder surface, it’s always a possibility.
 
Hopefully, we will begin to see a move one way or another on the guidance overnight, and will be either able to write off any significant winter threat or issue a snowmap tomorrow morning. Either way, we’ll have an update by mid-day tomorrow, so make sure to check back then. Thanks for reading SCW!
-SA
 

Disc: If you like the weather we are experiencing currently, you'll probably love the pattern that is going to dominate our weather for the next few weeks.

Currently: The backdoor cold front has receded south again, contrary to model predictions, and now runs along the Mason-Dixon line.  Waves of low pressure were moving along that boundary.  Another cold front, this one which will bring in drier air, is along the Allegheny Mountains in PA.

Tonight: Rain and showers will be more numerous in the first part of the night, and tend to slowly diminish after midnight.  Low temperatures will generally be 35-40, but as skies clear, some areas in the NW Hills could get near 30.

Tomorrow: Finally a nice day.  Clearing skies, breezy, with wind gusts to 25 MPH, and near normal temperatures in the 50-55 degree range for highs.

Tomorrow Night/Thursday: Continued nice.  As cool high pressure centers overhead, winds diminish, but overall temperatures will be a few degrees cooler, with highs around 50.  Some areas in the NW Hills may not make it out of the 40s.

Long Term: The long term period will be highlighted by two significant precipitation makers, the first at the beginning of the long term period, and the second at the end, with nice weather in between.

Models are coming into pretty good agreement that a fairly powerful coastal storm will affect the state Friday and perhaps at least part of Saturday.  The main questions that remain are: How long will the storm last, how heavy the precipitation will be, how strong the low will be, how far north the precipitation shield will make it, and if there will be enough cold air around to support wintry precipitation.

To answer some of those questions, the storm has sped up a bit on recent model runs, which would confine most of the precipitation to Friday.  However, since the pattern has become more of a slow-moving pattern, I would not completely rule out that the storm slows into Saturday.  Most models are trending wetter, so heavy precipitation, as  well as the storm spreading far enough north, are becoming resolved now.  Most models have also trended a bit colder, so it is becoming more likely for accumulating snow in the northern part of the state.  At this time, it looks like the potential is there for several inches of snow, mostly on colder surfaces, with localized higher amounts in the NW hills.  Also, in the NW Hills, it is possible that snow sticks to all surfaces, since surface temperatures will be a degree or two lower.  As far as temperatures Friday, expect high temperatures to range from the mid 30s in the NW hills to low 40s along the SW Coast.  As slightly warmer air advects in, temperatures could rise a degree or two Friday night.

After the storm clears out, Saturday should still be quite chilly, with high temperatures only in the 40-45 degree range.  Sunday and Monday should see nicer weather, with temperatures closer to normal- 50-55 degrees.

Yet another slow-moving storm is on track to affect the state centered around Tuesday.  The track actually looks very similar to Friday's storm, but this time, there will be less of a cold air source to the north, so that one should be all rain, at least for now.

Looking into the longer range, a parade of slow-moving, juicy systems looks to continue into the foreseeable future.  In fact, when it all comes down to the statistics, it could very well end up that we see more days WITH measurable rain than without.

Hydrology: For now, other than nuisance flooding, not expecting a lot of problems.  However, the longer this pattern continues, and if anyone gets a decent snowfall Friday before any changeover to rain, the chance for flooding will increase.

Now, let's look at some of the systems affecting our state in graphical format.  First, let's take a look at the system slated to move in on Friday.  

​

By this point, the state has all changed over to rain, but with the storm centered near the Delaware Coast, rain is ongoing.  You can see the heavy rain over NJ poised to head NE right for our state.

Next, we'll take a look at the next system on the pipeline for Tuesday.    You can see this storm riding the Mason-Dixon line, not much of a change from the track of Friday's low.  However, with Friday's system, the cold high pressure is located over New Brunswick, Canada, but on Tuesday, the cold air source is way up over Labrador, so unless that is vastly incorrect, Tuesday's storm will be all rain.

​

That's all for now, have a great rest of your week, and stay dry!

​-GP!

                A wet pattern is in the offing, something we need considering most of the state is still in a moderate to severe drought.

Currently:  The surface warm front that brought showers to the state today is now well north of the state, extending from the thumb of Michigan, then eastward along the US-Canada border.  However, this warm front has now gone stationary, meaning that its northward movement has stopped.  Two low pressure systems are along a cold front- one low is near Chicago and another low near the TX/OK border.  These complex systems will begin to affect our weather, starting tomorrow afternoon.
Tonight: With lots of clouds around and the state being in the warm sector, do not expect temperatures to drop much, or have much difference from one place to the other tonight.   In general, temperatures will be within a few degrees of 40 for lows, with a couple upper 30s possible over the NW hills and sheltered valleys in the north.

Tomorrow: With today’s warm front returning as a backdoor cold front, expect rain to move in from the north from the morning to the afternoon.  Up north, the front will clear the area, so expect rain to only last a few hours and then end.  In the south, generally anywhere south of I-84, expect light rain and drizzle to continue all night once it gets started.  As far as temperatures tomorrow, this will also be tricky both due to timing the frontal passage and onset of rain, but also dealing with any potential sea breeze boundaries.  I will tenuously go with fairly uniform highs in the lower 50s, and try not to worry about the tiny little boundaries that could set up tomorrow, but this is a low-confidence forecast.

Tomorrow Night/Sunday: Across the north, it is very probable that no precipitation will fall until Sunday afternoon, with the approach of the Midwest low.  Across the rest of the state, periods of mainly light rain and drizzle are likely, transitioning to a more steady rain as the day Sunday goes on.  Sunday will be quite chilly, as the entire state will be north of the backdoor frontal boundary.  Expect high temperatures to be in the 40 to 45 degree range.  It should be noted that the north will have warmer high temperatures, due to the fact that it will likely not be raining there.

Long Term: Nothing lasts forever, even cold April rain? Well, we’ll see! Most days through the long term period should feature rain.  The best days of the long term period will likely be Wednesday and Thursday. 

Monday could very well feature a period of heavy rain during the day, morning SW and afternoon NE, as the backdoor front, with the aid of the Midwestern low, will spread a slug of heavy rain into the area.  For now, I am going with a model blend for temperatures on Monday, with highs expected to be around 50 degrees.  It will not surprise me, however, if this forecast ends up being too warm, since models tend to drive warm fronts through too fast.

On Tuesday, the warm front will probably be through the area, if we believe the models, and we’ll wait for the cold front to go through.  Showers will be possible at any time on Tuesday, but especially during the afternoon, and perhaps another round of sprinkles late at night along the actual cold front.  It is not totally out of the realm of possibility for a bolt of lightning or rumble of thunder Tuesday afternoon, but due to very low probability, I am leaving it out of the forecast for now.

Wednesday and Thursday should feature fair weather, albeit with a gusty wind at times, as the cold front will finally clear the rain out of the area, as cold fronts do.  Wednesday should see highs in the upper 50s, with maybe a 60 degree reading in the CT valley, and Thursday should see highs of 50-55.

The next storm system, a coastal low, will threaten the state Friday.  There is more uncertainty with this system, as some of the models show the storm heading a bit too far to the south to really affect the state and only give us a glancing blow, while other models give the state a full-on nor’easter.  There is also a very low probability of this turning into a winter storm if it can deepen and take a favorable track, since there is a good high pressure system to the north.  However, that probability is very low given the time of year, and would be more probable for the northern areas.  Just something to watch.  At any rate, Friday looks to see another possible bout of unsettled weather.

The long range does not look much different.  A parade of storm systems affecting the state every 2 or 3 days with not many breaks in between, looks to be the theme until further notice.  At least we’re drought busting.

Hydrology:  Despite the fact that most of the state, especially up north, still has snow and ice on the ground, hydrologic concerns should be fairly low, considering the fact that we are in a drought, and the rain falls over a long period of time.  But small stream and poor drainage nuisance flooding will be possible, especially Monday.

Now, let's take a look at some of the systems slated to affect our area in graphical format.  First, here is the rain from the back door cold front.  This map is from Saturday afternoon.  you can see the entire state is in light rain.  North of the Massachusetts Turnpike, the rain is ending, and that is pushing south.

Next, here is the shot of heavy rain on Monday from the warm frontal passage.   This map is valid Monday morning.  Note the heavy rain over Northern New Jersey and extreme Eastern PA. This rain will spread NE into CT in the next frame.

That's all for now! Have a great weekend!

​-GP!

Good morning from Southern Connecticut Weather!

​Hope you enjoyed the relatively mild temperatures to start the spring, because, once again, we go back into the freezer. For today, cold returns with a vengeance. Temps throughout the day will continue to plummet through the 30s on a very strong northwest wind, gusting at times to over 50 mph. In fact there are wind advisories in effect throughout the state until 6 pm this evening. Along with the strong winds, there could be some stray flurries or snow squalls, especially in western and northwestern Connecticut. Other than those occasional snow showers, skies will remain mostly clear through this evening. For tonight, winds begin to subside, and skies remain clear, making for perfect conditions for radiational cooling allowing for temps to drop into the teens statewide, with some areas in northern and northwestern Connecticut dropping back into the single digits.

​For Thursday, skies remain mostly clear early with very cold conditions, and temperatures still in the mid to upper teens statewide. This is exceptional cold. These are temperatures 15-20 degrees below average. So make sure to bundle the kids up as they head to the bus stop.  As we head through the day on Thursday, highs recover, but well below average temps will be experienced across the state. Temperatures on Thursday afternoon will be in the mid to upper 30s statewide, feeling more like mid-January than late March. Thursday night looks to remain clear with temperatures not nearly as cold as the night before. Mid to upper 20s at the shore, and low to mid 20s inland for lows. Heading in to Friday morning, temperatures will stay steady in the mid to upper twenties early, and will begin to rise ahead of an area of precipitation as winds begin to blow out of the southwest promoting warming. Along with the warming, skies will cloud over and rain, with the possibility of a period of light frozen precipitation in the hills, will move in for early Friday afternoon. Thus begins a dreary, although warmer, weekend….

​For the weekend period, we have a storm which will be impacting our weather from Friday all the way through late Monday. First impacts will be felt on Friday and Friday night with some showers, and temperatures becoming much warmer than they had been on the previous two days. Temperatures on Friday night will stay steady in the upper 30s to low 40s, and will only continue to rise in advance of a strong low pressure system in the Midwest, which will pump up heights ahead of it allowing for this warming. There looks to be a bit of a break in the precipitation during the day on Saturday, but It will remain mostly cloudy. Temperatures statewide look to jump well into the 50s and even the low 60s in some spots by Saturday afternoon. Showery conditions will return for Saturday night through Sunday, with temperatures only dropping back into the 30s. There could be some frozen precip mixed in early on Sunday but will quickly change back to rain.

​During the day on Sunday, rain could persist, but looks to change back to wintry precipitation from south to north on Sunday afternoon through early Monday morning. At this time, it does not look like a major snow maker for the area, but we are keeping an eye on it. Lingering wintry precip/snow look to continue through Monday. In fact, rain and snow look to continue through Tuesday as well, as this low pressure system is in no hurry to move away from the area. Don’t look now, but there could be gradual clearing later on Tuesday, but the pattern looks to be setting up a storm train of sorts. Another slow moving low pressure system looks to impact the area for later next week, and it’s déjà vu all over again. This time it looks to be more wet than white, but this is a week or more out and will continue to be a fluid situation, but in the general scheme of things, it looks like we are setting up a storm train of sorts, and sunny, spring like weather looks to again be on hold. Temperatures in this time period look to be generally in the mid-40s, with another shot at noteworthy cold air coming late next week, with temps again dropping back into the 30s for highs.

​Extended Forecast:

Wednesday: Mostly clear and cold, chance of stray flurry or snow shower. Gusty winds, up to 50 mph. Temperatures dropping through the 30s throughout the day.

Wednesday night: Clear and cold, winds slacking off, temps dropping into the teens and single digits

Thursday: Clear, very cold early, high temperatures low to mid 30s.

Thursday night: Clear early, clouds moving in late, low temperatures low to mid 20s

Friday and Friday night: Chilly early, temps gradually rising throughout the day, rain with a chance of a period of wintry precip inland for the early afternoon. Highs 35-40. Showers persisting through the evening with temperatures gradually rising through the 40s.

Saturday and Saturday night: Chance of stray shower, otherwise cloudy, highs 55-60. Rain moving back in for the evening and temps dropping back through the 30s, wintry precip could move in late.

​Sunday and Sunday night: Mixed precip early, changing back to rain, highs low to mid 40s. Rain and snow afternoon 4, lows in the low to mid 30s.

​Have a great rest of your day everyone! As always, thank you for making SCW your home for all things Connecticut weather.- TW