We're past the forecast stage now. This is a live event.
I told you yesterday the data had locked in. Since then, the overnight model runs have only reinforced what we already knew while revealing some critical details that change the conversation in specific areas.
The Ice Situation Has Escalated
I'm going to start here because this is where the conversation has shifted most dramatically overnight.
The latest guidance is now showing ice accumulations exceeding one inch across portions of northern Mississippi and northeast Louisiana. One inch of ice is catastrophic. It's not a power outage. It's infrastructure failure. Trees that have stood for a century will snap. Power lines will come down in numbers that overwhelm utility crews for a week or more.
The bullseye for the worst icing has crystallized over the Delta region. If you're in Corinth, Oxford, Clarksdale, Tupelo, Holly Springs, Grenada, Greenwood, Belzoni, Indianola, or Cleveland, you need to be prepared to shelter in place for 72 hours minimum with no power and no ability to travel. The forecast ice totals in this corridor are running 0.8 to 1.1 inches. That's not survivable for the power grid.
One bit of good news on the icing front. The model consensus freezing rain forecast has been trending down since yesterday across most of North Carolina. The high-resolution models are sniffing out a low-level cold nose that may favor more sleet than freezing rain in the Piedmont. Sleet is still bad for travel but doesn't accumulate on power lines the way freezing rain does. We're still going to get at least a solid glaze from this storm across the Carolinas no matter what. The question is whether it's enough of a glaze to cause widespread power outages. The ceiling on that threat appears lower than it did 24 hours ago.
The Tennessee Valley remains in significant danger. The corridor north of I-40 is looking at heavy snow totals in the 3 to 7 inch range, but that transitions to a nasty mix of sleet and freezing rain as you move south into the Nashville metro and across the Cumberland Plateau. Dangerous travel and power outages are likely.
New England Just Got Upgraded Significantly
The overnight data surprised me here.
NWS Boston issued their initial snowfall forecast this morning and the numbers are eye-opening. They're showing 12 to 18 inches across most of southern New England from Hartford through Worcester to Boston and up toward Lawrence. The confidence level is listed as medium at 70 to 80 percent for a foot or more of snow.
That's a big jump from what we were talking about yesterday. Boston was barely on the map three days ago. Now we're talking about a potentially historic event for southern New England.
Timing breakdown. Snow likely arrives Sunday morning into early afternoon. The heaviest rates will occur Sunday evening into early Monday. Light to moderate snow lingers through much of Monday before tapering.
Travel impacts are rated high confidence. The NWS explicitly states travel will be difficult, especially Sunday night into Monday morning when snowfall rates are highest.
The south coast and Cape Cod remain lower confidence because of the potential for mixed precipitation. That's the only area in their forecast zone where the 12 to 18 inch totals might not verify.
The NYC Wildcard
New York City remains the biggest uncertainty in the Northeast.
No current data supports a maximum snow swath over or south of NYC. What the models are showing is the heaviest snow tracking to the north with sleet very likely spreading into the NYC metro at some point during the event.
Realistic range: NYC could see anywhere from 5 to about 12 inches depending on snow-to-liquid ratios in the front end of the system and how quickly the sleet moves in. If you're looking at forecasts showing 15+ inches for the city, that's a low-probability outcome that would require everything to break perfectly for snow.
The uncertainty here is real. A shift of 50 miles in the storm track still matters. But the most likely scenario is a moderate to significant snowfall with a period of sleet mixing in that caps the upper end of totals.
The Deformation Band Wild Card
There's one piece of the puzzle that could blow the high-end forecasts out of the water across parts of southern New England. You're going to see this discussed a lot over the next 24 hours.
The setup looks a lot like December 17, 2020, but positioned further south. That means we're likely going to see a significant deformation band set up across southern New England. These bands are regions of intense frontogenesis where snowfall rates can briefly exceed 2 inches per hour.
The problem is deformation bands are extremely difficult for models to resolve accurately. They're mesoscale features that can set up in slightly different locations than the guidance suggests. Some forecasters are pointing out that a stripe of 24 to 36 inches wouldn't be surprising if one of these bands trains over the same location for several hours.
The official forecasts of 12 to 18 inches account for typical band behavior. But the potential for localized blowout totals in the 2-foot range is real. We just can't tell you exactly where that will happen until we see it on radar.
The Central Corridor Remains on Track
The Southern Plains through the Ohio Valley snow totals haven't changed much. Confidence is high.
Eastern Oklahoma into northern Arkansas and southern Missouri is the bullseye. We're looking at 8 to 12 inches across this corridor with locally higher amounts up to 15 inches possible where mesoscale banding persists. Snow-to-liquid ratios remain favorable in the 15:1 to 20:1 range.
The Ohio Valley from western Kentucky through southern Indiana along the Ohio River is solidly in the 6 to 12 inch range. Some guidance is pushing 14 inches for parts of southwest Ohio. The I-64 corridor in particular could see the higher end of that range.
Something to keep an eye on. The high-resolution HRRR model is showing incredibly bullish snowfall Friday night into Saturday morning with totals that meet or exceed what the European model is showing. But then it shows a 6+ hour lull in precipitation that would put a significant pause on the event. The reason for this is unclear. It could be a model artifact or it could be signaling something about how the energy phases. We'll know more with the next few runs.
The Cold Behind This System
I talked about this yesterday but I need to emphasize it again because the cold air is just as dangerous as the precipitation.
Wind chills of 40 to 50 below zero are expected across the Northern Plains today and tomorrow. That's life-threatening exposure in under 10 minutes.
What really matters for the areas getting hit by ice and snow: this cold is coming for everyone. By Monday morning, temperatures across the eastern half of the country will be running 20 to 30 degrees below average. Single digits from Texas into the Carolinas. Below zero across the Ohio Valley. The Arctic air trailing this system is unusually deep and unusually widespread.
Any power outages in the icing zone will become life-threatening very quickly. You cannot shelter in place in an unheated home when temperatures drop into the teens and single digits overnight.
This cold pattern isn't going anywhere through at least early February. Another Arctic reinforcement is signaled for January 29-31 with an even stronger push around February 2-4. We are locked into a pattern that will keep temperatures 10 to 20 degrees below normal for the next two weeks minimum.
Updated Timeline
Friday, January 23 (Today): Snow is already developing across the Texas Panhandle and will spread into western Oklahoma by late morning. Precipitation expands into Arkansas by this evening. Freezing rain and sleet begin across central Texas and the Lower Mississippi Valley overnight. Arctic air surges into the Northern Plains with dangerous wind chills.
Saturday, January 24: The most dangerous day for travel. Heavy snow rates exceeding 1 inch per hour develop across Oklahoma, Arkansas, and southern Missouri. The deformation zone sets up and produces significant accumulations. Significant icing occurs from northern Texas through the Mid-South. Do not be on the roads anywhere in the impact zone.
Sunday, January 25: The system reaches the Mid-Atlantic and Northeast. Heavy snow develops from Virginia into Maryland, Pennsylvania, and spreads into New York and New England. This is when secondary cyclogenesis begins off the Carolina coast. Snowfall rates may briefly exceed 2 inches per hour across portions of the interior Northeast and along the I-95 corridor north of Philadelphia between late morning and early evening.
Monday, January 26: Snow continues across New England through the morning hours before tapering. The pressure gradient between the departing low and a massive high building over the Great Lakes produces gusty winds. Significant blowing and drifting snow maintains hazardous visibility well after the falling snow ends. Lake effect snow bands activate downwind of Lakes Erie and Ontario.
Tuesday and Beyond: Arctic air remains locked in place. Lake effect snow continues in the snowbelt. Recovery efforts hampered by bitter cold. Secondary clipper systems may bring additional light snow to parts of the Northeast and Great Lakes later in the week.
What You Need to Do Right Now
If you haven't prepped yet, you're running out of time. Snow is already falling. The window is closing.
If you're in the icing zone from Texas through Mississippi into Tennessee and the Carolinas: Assume you will lose power for multiple days. Have a plan that doesn't involve your home heating system. Know where warming centers are located. Check on elderly neighbors who may not have the resources to stay warm.
If you're in the heavy snow zone: Stock up on essentials today. Schools that close Friday may not reopen until Wednesday or Thursday given the extended cold keeping snow and ice on roads. Have supplies for a week of reduced mobility.
If you were planning to travel this weekend: Cancel it. Rebooking fees have been waived across most major airlines. This is not a storm to get caught in. Interstates including I-10, I-20, I-30, I-35, I-40, I-44, I-49, I-55, I-64, I-70, I-81, I-84, I-90, and I-95 will all see hazardous to impassable conditions at various points over the next four days.
Bottom Line
Same message as yesterday. The stakes are higher now that we can see the details.
This storm is going to affect a third of the country. High confidence at this point. Ice totals in the Deep South are now pushing into catastrophic territory in spots. New England got upgraded hard overnight. Boston is looking at 12 to 18 inches. The cold behind this thing is no joke.
Multiple state governors have declared emergencies. FEMA has prepositioned resources. The National Weather Service is using words like "crippling" and "potentially historic."
This is it. It's not coming anymore.
It's here.
Be ready.
