I wanted to pass along the latest Premium forecast update, which I created last night through our Premium service. That service will have updates throughout the day, though I’ll be posting free updates as well. Below you will find some of the latest expectations for the storm.
Almost all the differences in the forecast will be timing. I’ll run through that first. It now looks like precipitation begins between 11 AM and 1 PM across the area, bumped up fairly significantly from the 3 PM start time I had in the original forecast. Models as a whole really sped up the front part of this system, which partially makes sense as this is a warm air advection event, and models have been known to under due the speed of overrunning precipitation in a warm air advection event. With that in mind, I am siding with the quicker model guidance in indicating that the first flakes now look to fly between 11 AM and 1 PM across the region. The storm should remain all snow through 4 PM at the earliest, resulting in around an inch of snow at the coast and up to 2 inches of snow inland. Between 4 and 6 PM sleet mixes in with freezing rain and takes over with the snow, and by 7 PM the storm is likely to already be all rain south of the Merritt/Hutchinson Parkway. Thus, travel issues ease between 7 and 8 PM in coastal towns. Further inland, from inland towns just north of the Merritt/Hutchinson Parkway to Interstate 84, freezing rain will last until around 9 PM. Around Interstate 84, that freezing rain could last until 10 PM, and north of I-84 there is a chance that pockets remain under freezing through 11 PM. I would be very surprised if any areas of inland Fairfield or New Haven county are still below freezing by 11 PM or 12 AM, and I expect by 11 PM or so travel conditions begin to improve inland unless the cold shows much more staying power than our weather models currently forecast. Plain rain continues lightly through the night, and then the next burst of rain looks to come late Sunday morning into Sunday afternoon before conditions dry out and the cold front swing through Sunday night. Again, a slight chance of icy roads Sunday night, but I’m not too concerned about that. Some rumbles of thunder may be possible with temperatures into the 50s on Sunday ahead of the cold front, but I don’t think winds should gust above 35 mph or so, so no real wind issues to talk about.
In terms of accumulation, around an inch of snow and sleet at the coast and up to 2 inches of snow and sleet inland are likely. Recent model estimates show accumulating snow all the way down to the coast, so I scrapped the “up to” and replaced it with “around” under the assumption that everyone will see at least some accumulating snow before we turn over to all rain. The quicker precipitation comes in before the cold air aloft has time to recede, thus allowing more time for that snow to fall, and with temperatures near or below freezing, it is likely that it will stick, especially on grassy surfaces that will still be frozen from tonight. No ice accumulations are expected at the coast, and between the Merritt/Hutchinson Parkway and the I-84 the forecast now is for a few hundredths of an inch of ice, which is only minor icing. From I-84 on north the forecast is for .05-.1 of an inch of ice, still not very significant but enough to cause some travel troubles. I do believe that inland areas should still have Winter Weather Advisories due to the freezing rain threat, though they have not yet been issued. Sleet will make roads especially icy, more so inland, and I am concerned that many could be unprepared. I want to emphasize that in coastal areas, travel between 3 PM and 7 PM is discouraged, and inland, travel from 3 PM to 10 is discouraged. Roads will be quite dangerous, and until temperatures rise above freezing except roads to be especially icy. After the turn over to rain, we can expect an additional inch or so of rain to fall across the region.