Significant Winter Storm to Impact Most of Connecticut Friday…

Here were go.

After a period of quiet and spring-like weather, winter roars back with a winter storm that is poised to bring much of Connecticut its most snow so far in a season that has been lackluster in the snowfall department for many. This is a discussion that you should share with your family and friends. With the storm creeping up on us at short range, even at this hour I hear from folks who think nothing significant is coming tomorrow. We all have an obligation (whether you share SCW or local news or the NWS forecasts) to inform people about potentially hazardous weather. Snow has an impact too--especially on the roads.

Before I dive in, I’d like to make two observations as a weather lover, not a forecaster. 

1. If you love snow, you dream about this kind of situation. In a difficult winter, you are on the brink of a “comeback” with a snowstorm that wasn’t even forecasted by anyone a few days ago. Virtually every trend has been in your favor, and you almost at the finish line for producing a nice event. 
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2. What a strange winter. The areas that are normally favored, i.e., northwest CT, have been getting the least (or most depending on perspective) out of this winter. The snake bit northwest corner is in that position again tomorrow. In other news, up is down and the sky is green. Strange times.
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Let’s get down to business. 

Bottom Line

• A significant winter weather event is poised to impact most of Connecticut on Friday. Areas in eastern Connecticut are most likely to receive the highest snow totals, and areas in far western Connecticut (especially northwest) are expected to see the least
  
  
• If you are in a town that is on the line, I would anticipate being on the higher end of our totals, if not in the higher zone next to you. Further shifts are possible and the trend has been toward a more impactful event
  
  
• The event starts as rain for many, with areas further north and west that do change over changing over quickly and areas further south and east changing later in the morning hours
  
  
• Snow is expected to impact the state most during the morning commute, between 7am and 11am
   
• We expect snow to be heaviest during this period. With the combination of heavier wet snow (especially in eastern areas) and breezy conditions, this will likely be a high impact event for commuters across the state
  
  
• Widespread delays and cancellations should be expected, and road conditions will be treacherous for most as temperatures drop near or below freezing during the event
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• Most of the accumulating snow ends by noon, with lingering snow showers possible in the afternoon

Expanded Discussion
If you have been paying attention the last few days, the trend has been to develop an area of low pressure along the cold front that passed the state recently and has meandered offshore. This shortwave has trended stronger, bring more precipitation further north and west. This trend has not stopped, and as a result, we believe most of Connecticut will see a substantial event tomorrow. 

Notice the GFS--which was an outlier just a few days ago, being more robust now...

18z run today for 7am Friday

Compare that to the 18z run just yesterday (!) for 7am Friday. What a difference a day makes. 

Timing 
Our timing remains essentially the same. 

Now-1AM Friday: Rain showers will continue to overspread the state from SE to NW, becoming a steadier rain for most.

1-5 AM Friday: Rain transitions to snow, beginning in NW CT and working its way south and east.

5-9 AM: Snow becomes steadier and heavier as temperatures aloft and at the surface continue to drop near and below freezing. Expect periods of moderate to heavier snow with breezy conditions, especially in coastal areas. 

​9 AM – 12 PM: Snow begins to taper off from west to east, with lighter snow/snow showers lingering into early afternoon in eastern areas especially in the later hours. Conditions should improve over the course of the day but as temperatures drop during the evening hours ice will be an issue.

Above is the RGEM's latest run, from roughly now through 4pm tomorrow afternoon. Note the progression of the rain, the rain/snow line, and ending. This guidance is being blended with the European model and other short range high resolution data to make our forecast. 

Impacts

• Scattered power outages are possible in areas (think eastern CT) where snow is heavier and wet and the winds are breezy
  
  
• Widespread commuting problems in much of the state with snow coinciding with rush hour
  
  
• Widespread delays and cancellations 

What could go wrong
Alright, what could go wrong with this forecast? This is a moderate confidence forecast. We think this will be an impactful event for most, and a high impact event for many, especially in eastern areas of the state. 

I have two areas of concern in terms of a forecast bust—western Connecticut, and far southeast Connecticut. 

1. Precip struggles to make it to western Connecticut, cutting totals
   This is the same problem that you’ve had all winter seemingly…will enough precipitation make it to the western portions of CT? Right now, that answer is yes. You won’t see the same totals as folks in central and eastern parts of the state, but we do think there is enough moisture to bring snow.
   
   However, if there is an east shift at the last minute, or dry air overcomes the precipitation that is falling, western CT could be at the lower end or even below our projected totals. Chance of occurrence: 20%
   
   
2. Temperatures stay above freezing aloft and at the surface longer in southeast Connecticut, cutting totals
   This is quickly becoming the million dollar question. Right now, the NWS out of NYC thinks temps are a problem in southeast CT, and instead of issuing a Winter Storm Warning like NWS Boston did for Windham County, they opted for a Winter Weather Advisory for New London County. We think that much of New London County verifies a winter storm warning tomorrow.
   
   However, there is the chance that this trend, while bringing more precipitation brings higher chances of the rain/snow line slowly collapsing through southern Connecticut. Southern folks you know the drill, temps are not always your friend in these situations. The people of Groton will be watching their thermometers tomorrow morning. Chance of occurrence: 30%

The bottom line is that we are watching a dynamic situation unfold again, with the dividing line being right over Connecticut, again! We will be doing rapid fire updates and answering questions all through the night and tomorrow to keep you ahead of the storm.

Follow us on Twitter, like us on Facebook (all it takes is a click below to do both) and stay tuned for updates on this event. 

Thank you for reading. 

-DB

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