Back when I was in school teachers would always scare me with stories of how my exploits would end up in my permanent record. I believe this is it! – Geoff Fox
Let me concentrate on how the 00Z GFS is different than what I wrote this afternoon. To read that fuller discussion, click here.
The ECMWF is still hours from completion. The GFS is seldom my first choice, but it, and the totally untrustowrthy NAM, are all we’ve got right now.
The NAM is showing scary precipitation numbers. They are difficult to believe and so I won’t.
The GFS has backed off this afternoon’s liquid equivalents and is now forecasting a storm more typical of New England in the winter. Still big. Not BIG.
The GFS is also a little colder than this morning. Snow-rain-snow on the shore. The all snow line shifts south a bit. The hours of rain are shortened slightly.
Eastern Connecticut still has the potential for the most snow, though there’s less of a well defined bullseye than earlier.
Friday morning is still a long way off. If there’s something you need done by Saturday, you now need to do it Thursday.
Oops – I originally called this entry, “Quick Update – Thursday Late.”
Like you, I’ve been reading the hype. It’s only Wednesday. Folks are already breathless over an immense storm coming to New England, Friday.
Say it isn’t so.
At the NWS Forecast Office in Taunton, lead forecaster Nicole Belk opened up in the tech discussion:
CONFIDENCE CONTINUES TO GROW IN A FOOT OR MORE OF SNOW AFFECTING A LARGE PORTION OF THE REGION. WE HAVE BROUGHT UP SNOW ACCUMULATIONS WITH THE LATEST FORECAST…BUT IT MAY NOT EVEN BE ENOUGH IN SOME LOCALES.
The unsigned discussion from the Upton, NY office adds:
NEAR BLIZZARD CONDITIONS ARE POSSIBLE FOR THE EASTERN ZONES…ALONG WITH SIGNIFICANT SNOWFALL.
When Upton says “EASTERN ZONES” they mean New London, Middlesex and possibly New Haven Counties! Upton serves much of the New York Metro area, plus the Connecticut shore.
The European (ECMWF) model is sobering. In one three hour stretch it drops 8″ of snow over Providence, RI. That’s nearly 3″/hour! And that’s not the whole storm, just one little piece of it.
OK… here goes. Just remember, it’s Wednesday. We’re two days out. Nothing I say will happen exactly as forecast. Hopefully I’ll be close.
The precipitation starts Friday morning, probably around drive time. Inland, school closings are likely before the first flake falls. Closed businesses too.
On the shore, where there will be significant daytime rain, schools should open (though many won’t). There will be a huge accumulation difference between shoreline and inland.
Take Groton for example. The GFS has 1.5″ of rain from 8:00 AM to 8:00 PM, then snow overnight. The model shows 13.8″ of snow overnight… but that will not happen!
With daytime temps in the upper 30s and all that rain, much of what falls as snow in Southeast Connecticut will melt in puddles. Not all of it, much of it.
In New Haven it’s also 1.5″ of rain, then 5.8″ of snow. Temperatures will be a few degrees cooler in New Haven, but a good deal of the snow will be sacrificed on the wet ground there too.
The rain snow line will stay close to the shore. Hartford, for instance, has under six hours of rain and sleet. The rest is snow. The GFS says 14.9″, but with wet ground, I’d expect actual accumulation in Hartford to be more than 6″, but less than a foot.
Canaan should be all snow. Bradley too. A foot or more is likely near the Massachusetts border.
In Connecticut the heaviest snow will fall along the Rhode Island border. The GFS output for Willimantic has over two feet of snow, though rain briefly mixing in will mean less… but not much less!
And then there’s the wind.
It will howl with tropical storm force gusts late Friday into Saturday. Power outages are likely, especially in Eastern Connecticut.
The snow tapers Saturday midday. Expect to stay put until Sunday.
My threshold for weather worry has been raised since I’ve been off the air. The potential for Friday goes beyond even that new threshold!
Nor’easter: yes
Big snow potential: yes
Power outage potential: yes
Snow/sleet/rain mix: that too!
This far out I’m making use of the GFS and ECMWF (European) models. They have similar solutions.
You can’t expect them to fully agree… at least I don’t.
Much of the state is in line for one to two inches of liquid. We’ll see rain, sleet and snow at times. Snow totals are impossible to pin down today–Tuesday. Our low pressure system is only now emerging east of the Sierra Madre Mountains in Northern Mexico!
The system moves northeast from Mexico to the Carolinas, hitting the beach early Friday morning. From there the trajectory bends left a little, allowing the low to pass south of Montauk Point, Long Island Friday evening then steam toward the Canadian Maritimes.
As the storm hits the ‘warm’ Atlantic its central pressure drops like a rock. Bombogenesis! Classic Nor’easter.
This will be a 24 hour event (maybe longer). Snow will be heaviest in the north. Winds will strongest in the east. Outages seem likely.
Friday looks to be a sloppy, slippery, difficult to deal with day.
Wednesday will be a stormy day in Connecticut. This is a big systems and it will be tossing its weight around!
As I type this (Tuesday at 4:00 PM) there are three Tornado Watch areas, a Severe Thunderstorm Watch, scattered Winter Storm Warnings and all sorts of flood and wind warnings from this singular system. Most of what’s up in Connecticut today (Tuesday) has been issued in anticipation of tomorrow.
Not so fast Litchfield County.
Light rain starts later tonight statewide. In the Litchfield Hills there’s a chance some of that rain will fall as a liquid, but freeze on contact. There’s a Freezing Rain Advisory for Litchfield, but only until 10:00 PM. That’s because this storm is packed with advection!
ad·vec·tion (d-vkshn) n. The transfer of a property of the atmosphere, such as heat, cold, or humidity, by the horizontal movement of an air mass.
There will be enough warmer air headed our way that temperatures will rise through the night. That’s why the advisory expires at 10:00 PM.
By midday Wednesday the intensity of the rain picks up. Thunderstorms seem probable.
From my trips outside with Doppler I can assure you the ground is frozen or close to it. Little of this rain will ‘perc.’ Flooding from runoff is likely, especially near small brooks and streams and on low lying roads.
By Wednesday evening the wind begins to pick up. Winds of 15-30 mph with higher gusts are likely. Scattered limbs and power lines will fall.
Windblown rain: No fun!
The rain ends Thursday morning, but not before we get a lot–probably an inch or two. Meanwhile, the wind will continue to howl and the mercury will plunge.
On one of my forecasting charts the graph for temperature resembles the climb to the first hill on a roller coaster. Steady up, then a plunge down! We’ll hit Thursday’s high temperature at midnight then tumble for most of the next 48 hours. Low 50s Wednesday, but 20s and low 30s for the high Friday!
The funny thing is, this late January storm will bring everything but snow.
Maybe not funny. Quirky?
There are chances for light snow Saturday and Monday nights. Let’s get through tomorrow first.
This will be brief. I’m not only talking about this entry, but the snow as well! Radar shows snow just to our west, but surface observations have nothing closer than Central New Jersey.
The HRRR model shows the snow arriving within the next hour or two (it’s 3:47 PM) and gone by midnight. Accumulations will be an inch or less for the most part.
The cold is here through the weekend. Snow? Not so much.
4:30 PM EST Thursday. It’s 38° in Anchorage with a wind chill of 29°. It’s 19° at Bradley International with a wind chill of 2°! Something is terribly wrong with this picture.
The jet stream is bringing frigid air from the Canadian Plains across the Great Lakes and spilling it into most of the East Coast. It’s in the 20s this afternoon in portions of North Carolina.
We’re staying bitterly cold through the weekend. Wind chill readings will hover around and often below 0°. Wind chill describes how rapidly your exposed flesh loses heat.
Here’s something 18 year old Geoff never thought he’d say: Try to expose as little of your flesh as possible!
As for Friday/Saturday’s snow, it looks like less of a deal today than yesterday. Maybe an inch or two of powdery snow starting Friday afternoon or evening and ending Saturday morning.
A week ago I was in SoCal where they were complaining about the ‘bitter cold.’ Where’s my violin?
After my week in sunny and (mostly) warm Southern California it seems I’ve returned simultaneously with winter! There is snow on tap for Friday night into Saturday. It doesn’t look to be a major deal, but snow-is-snow and it’s always a bit of a pain.
There are no textbook storms, but this one is mainly an Alberta Clipper with a little Texas moisture drawn in.
Wednesday evening, the low driving the storm is near the British Columbia-Alberta border. It will sink south a little as it moves east. It will also suck up some moisture now over the Southern Plains. That’s the setup.
This will be all snow. Shoreline, inland, everyone gets snow. It looks to be powdery snow–a high snow:water ratio, 15:1 or more.
It will also be a fast mover. Alberta Clippers get the second half of their name from their speedy entrance and exit. The storm starts late Friday afternoon and ends Saturday morning.
Snow lovers will likely be disappointed. This looks like a few inches tops.
Cold lovers will be happy. The temperature will be in the twenties with the wind chill in the teens.
There’s a buzz going around about our weekend warm-up. Doppler already has a snow free arena on the front lawn. The snow’s melted over the septic tank. The rest should be gone in a few days.
High temperatures will be near 50° through Monday. Not bad.
I’d heard talk of sixties earlier. Not likely now.
A January thaw isn’t unusual. That “January thaw” is a familiar term is proof of that. Here’s Wikipedia’s take:
The January thaw is an observed but unexplained temperature rise in mid-winter found in mid-latitude North America.
This year’s thaw comes courtesy of a very deep upper air trough (as seen in the map for Monday at 8:00 AM at the top of this entry). The jet stream crosses Alaska, swings almost due south along the Pacific Coast then curves northeast from Mexico to Quebec.
The area within the trough will be cold. East and west of the trough will be mild. That’s us–east.
Airline travel will be affected. Some of these jet stream winds (purple shade) will be over 150 knots (172 mph).
These upper air patterns tend to slide west-to-east, so the warm-up will be followed a big chill! Early signs show next Thursday’s high in the 20°s!
As I write this our winter storm is getting set to exit. There’s a lot of snow on the ground. Some folks will get close to a foot.
OK — I got the accumulation totally wrong. Accumulation is forecast incorrectly more than anything else. It’s a forecast on a forecast on a forecast. Any small, but incorrect, calculation poisons the output.
It has been my mortal enemy since I started forecasting!
It didn’t really matter. The snow came when expected and will leave when expected. Most folks stay home with the numbers I had forecast over the past few days.
By tomorrow most roads should be passable and life will roll on.
When it comes to forecasting snow I am often the outlier. My forecasts tend to be conservative because over time the computer models tend to over forecast. Now, as the snow begins I’m tempted to up the accumulations, especially toward the Rhode Island border.
Is there a real difference between 2-4″ and 3-6″. Practically, no. The pain is just the same. The plows will be out. Cars will slip and slide.
The map from the HRRR (Rapid Refresh) model shows nearly all the state over the 6″ isopleth¹. That seems high. Well, it seems high today… maybe not by tomorrow morning.
So, let’s go with 3-6″ with the lowest amounts on the shoreline where some rain will mix in. A few inches more are possible in Northeastern Connecticut.
The shoreline from the Connecticut River to the Rhode Island border is an especially difficult part of the forecast. You’ll get more moisture, but a significant percentage will be rain. Get the thought of powdery snow out of your mind.
Statewide from late afternoon into the evening the intensity will ramp up. Don’t be lulled out of the house only to find yourself in snow heavier than you’re comfortable with.
The snow will taper to flurries and snow showers after midnight.
Forecasting snow is the most difficult forecast we do in Connecticut. It’s nearly always a critical forecast for you. The pressure’s on.
¹ – An isopleth is a line on a map connecting points of equal value. Isopleth is the generic term. There are specifics too, like isobars, isotachs, isohyets, etc.
Forecasting weather is an inexact science. You probably didn’t need me to tell you that. Saturday looks a little different than it did 24 hours ago. No surprise.
I won’t be changing much in duration or precipitation type. However, it does look like more snow than originally anticipated.
Unless it’s a massive snowfall the exact amount of snow isn’t very important. All the slippery is in the first quarter inch! The plow guys will tell you water content/weight is more important than height.
The most likely onset for snow is late morning Saturday. Everyone starts with snow. On the shoreline (especially to the east) there will be some waffling between snow and rain before turning back to all snow. Inland Connecticut stays white start-to-finish.
Yesterday I wrote 1-2″. Today I’ll up that to 2-4″, less on the shoreline, an inch or two more from the casinos northward in Eastern Connecticut.
The snow will start light, but a heavier period is likely as the low pressure system driving the storm rapidly deepens toward evening. The snow should taper to flurries and snow showers by bedtime.
It’s a Nor’easter. We’ll have northeasterly winds through much of the day–nowhere as intense as our last storm.
If you’ve got Saturday travel plans, go early. You can beat the storm north and east or hit mainly rain going south.
Weather is like real estate. The three most important factors are location, location, location. That’s the story for Saturday’s storm. It will be a big deal elsewhere, not here.
That’s not to say we won’t get snow. We will. Not a lot.
Unlike yesterday’s multifaceted system this will be all snow for Connecticut. It starts Saturday morning, gone around sundown. An inch or two statewide is likely. Winds will be light and temperatures at or just below freezing.
Call it touch up snow–just enough to brighten what’s already on the ground.
Unbelievably the European, GFS and NAM all agree!
This forecast took a little more time today. My favorite website for the GFS and NAM models is down. It’s not like these aren’t available everywhere, but you get used to your favorite site’s nuances. At least I do.
The 12z model runs are in, including enough of the European to get a feel for tonight. I’m not going to make many changes, though the turnover to rain inland looks a little quicker than my original read.
Everyone starts with a little snow early this (Wednesday) evening. On the shoreline snow will be replaced by rain within a few hours, with a brief interlude of sleet possible in between. The farther inland you are, the longer the period of snow. Duh!
The European is the coldest of the models, followed by the GFS then NAM. Just a few degrees will make a huge difference, because the rain/snow line in each of these scenarios is close by. I’m also using the Rapid Refresh model which is a very high resolution model that only covers 15 hours and makes discrete calls for most likely precipitation type hour-by-hour.
What you wake up to Thursday morning won’t be the peak accumulation. Rain will ‘settle’ the piles and add weight overnight. Expect a slushy inch or two near the shore with lesser amounts the closer you get to the Rhode Island border. Most of inland Connecticut sees 3-7″, except the higher elevations in the Northwest Hills where a foot could fall.
Because there will be a statewide change to rain before dawn, Thursday’s commute will feature slushy, weighty snow on the roads and sidewalks.
Along with the precipitation there will be strong winds from the northeast. Significant coastal flooding is likely at high tide Wednesday night! Wet snow and strong winds also means scattered power outages.
For Southern New England this is the type of storm we get a few times each winter–a moderate p-i-t-a. We will see worse before spring arrives.
My driveway is wet. My lawn is white. Bunnies have left a trail. Except for the occasional sheets of ice that slide off my roof and crash to the ground it’s a quiet and pretty Christmas Day. I’ll take it!
I didn’t want to come back and convert this into a weather blog, but right now weather’s on my mind. There’s another storm due Wednesday afternoon and it won’t be quite as docile.
This next storm caught my eye while it was still in the Pacific. It drenched the fans at the San Francisco – Seattle football game Sunday night. Today it will bring tornadoes to the Gulf Coast states and a blizzard to Southwestern Oklahoma and nearby Texas.
Most likely we feel its effect beginning Wednesday afternoon. This is another storm where location is important.
There might be some snow or sleet at the start, but for the shoreline this is a nasty rainstorm. Overnight, the moderate to heavy rain will be accompanied by strong gusty winds from the east.
Inland is a different story, because I see a significant period of snow before changing to rain. 4-8″ is a reasonable early guess before the snow is capped.
There will be plenty of rain after the snow, but not enough to wash it away. Instead we’ll be left with heavy, icy, slick snow on roads and sidewalks on a windy Thursday morning.
It’s winter weather. The forecast is never 100% right, but if travel is in your plans Wednesday/Thursday you’re going to need to factor this in.
