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| A very colorful National Weather Service home page map from this morning means lots of weather hazards and that's certainly the case now through Friday at least. |
This morning, the NWS home page map of the U.S. was lit up like a Christmas tree as a holiday giant storm and Arctic blast begins to make its moves on the nation.
Most of the colors are different shades of blue, indicated various wind chill warnings and alerts. Other blues are winter storm watches. The hot pinks are winter storm warnings. Reds are blizzard warnings.
Here in Vermont, we have kind of an ugly brown, indicating a high wind watch. The browns indicating wind will expand as the storm draws nearer. I've got more details and updates on what to expect in the Green Mountain State a little further down in this post.
I've only seen picky little changes in the forecast for the nation as a whole, so this looks pretty inevitable.
It's hitting hardest on what will be two of the busiest travel days of the year.
The Washington Post reports that there are 47,554 scheduled flights in the United States on Thursday (including two that my husband and I are taking, fingers crossed) and another 44,300 flights on Friday.
Most airlines issued weather waivers to help travelers avoid fees and fare differences if they have to rebook a flight due to the storm. I bet there will be a TON of waivers involved. Conservative estimates in the Washington Post suggest we'll see at least 5,000 flight cancelations or delays on Thursday.
This will extend to the East Coast by Friday. Little to no snow is in the forecast along Interstate 95. But high winds and heavy rain Friday in the entire region are sure to screw up at least some flights.
Meanwhile, an estimated 102 million people will drive at least 50 miles to their holiday destinations between Thursday and January 2.
It seems there are always storms to screw things up during the Christmas holiday, but this one is much worse than usual.
One of the problems is the storm's expected immense size. A 1,000 mile wide swath of the northern United States is expected to see wind gusts of at least 40 mph. Many areas will see gusts much stronger than that.
A vast area from Kansas and Missouri up through the entire Great Lakes region is under winter storm watches, warnings or blizzard warnings. Most of the northern and central Rockies are also under winter storm warnings.
An even more immense area is under wind chill alerts or soon will be. Draw a line from Spokane, Washington, to El Paso, Texas. Almost everyone east of that line will experience bone chilling to highly dangerous wind chills between now and Christmas Day.
It's one of those holidays where everyone will have to take a deep breath (behind a scarf if necessary) be patient and be safe. If you have misgivings about setting off, because it looks a little dangerous on the roads, listen to your gut. Better to postpone that holiday cheer than not live to enjoy it, right?
I'm sure we'll be hearing of some fatalities in the U.S. from this storm, through people getting caught outdoors in Arctic conditions, or being involved in a highway pileup, or a house fire, or something. It's all tragic, but if people take care, we can minimize the danger.
Power outages will be pretty widespread from Minnesota to New England, and from Ontario and Quebec down to the southern United States.
VERMONT EFFECTS
So far only a few more details and minor changes to the storm outlook here in the Green Mountain State.
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| The National Weather Service in South Burlington issued this wind forecast map this morning. Areas in orange could easily see enough wind to cause power outages Friday. Darker orange and red areas feature gusts to at least 60 mph. |
I guess we'll take things in order of when they will happen
MIXED PRECIP
As the storm's warm front comes at us Thursday night, mixed precipitation will break out, especially east of the Green Mountains.
There probably will be some light accumulation of snow, sleet and ice in several areas, but a strong burst of warm air should send temperatures above freezing by early Friday morning. This won't be a huge deal, but will cause some slippery roads.
HIGH WINDS
The wind is forecast to ramp up pretty quickly, probably before dawn Friday morning and last for several hours. Strongest winds will be on the west slopes of the Green Mountains. I wouldn't be surprised to see reports of gusts to 70 or 80 mph in the most vulnerable spots, like Cambridge, Underhill, Huntington, Hanksville, Mendon, Shrewsbury and Wells.
According to the National Weather Service in South Burlington, often, when there's snow on the ground, a temperature inversion sets up in these situations. The inversion can act like a lid, so when high speed air starts descending the west slopes of the Greens, it hits the top of that inversion and bounces off. Which means the strongest winds don't make all the way down the slopes into the valleys.
That might try to happen this time, but the NWS has concluded this storm is so strong and intense, that even if an inversion sets up, the winds stand a good chance of overwhelming any inversions and spread into valleys.
Moreover, the strong winds might not stick close to the western slopes of the Green Mountains everywhere. In the northern Champlain Valley, the damaging winds could extend all the way to Route 7 and Interstate 89. Might happen near Rutland, too. It's not definite, but certainly possible, that damaging winds gusts of up to 60 mph could reach population centers in and around Rutland, Burlington and St. Albans.
Even people who don't get the downslope winds off the Green Mountains will see strong gusts. Power outages are possible everywhere in Vermont, as winds could reach at least 50 mph almost everywhere.
FLOODING
As the storm's powerful cold front approaches, a band of heavy rain will come just ahead of it. This will help squelch the winds to an extent, but cause a new problem: The risk of flooding. Temperatures will rocket upwards into the low 50s.
Most places will see a quick 1.5 inches or so of rain, and melting snow will add the equivalent of about another inch. We'll see rapid runoff, with small streams and brooks being a problem at first during the day.
Then main stem rivers will rise. That will be more dangerous than usual because the water levels in the bigger rivers would peak while temperatures are rapidly falling. (More on that in a sec). Most rivers in the state are at risk of minor flooding, you know, covering some of the roads and things like that.
At this point, the rivers that show the most risk of causing problems are the Mad River and Otter Creek. The Winooski River at Essex Junction/Williston could get interesting, too.
FLASH FREEZE
As the cold front blows through in the late afternoon and evening, temperatures will probably drop from the low teens to below freezing within a couple hours, and continue downward into the teens within a couple hours after that.
Rain would turn to snow, but the snow won't last long or accumulate much. But such a rapid freeze will ice up the roads pretty instantaneously. Even the main roads would have trouble, never mind the back roads. Travel trouble seems inevitable late Friday afternoon and evening across Vermont.
AFTER THAT
Winds will continue to howl all Friday night and into Saturday, but at least not as strong as they probably will have on Friday. It might take awhile to clean up the expected power outages. The low temperatures and nasty wind chills Friday night through the weekend will probably add to the misery and make repairing power lines difficult.
A PROGRAM NOTE
I will be traveling very early Thursday morning, so I will only be able to post what will probably be brief update very early, like 2:30 or 3 in the morning. You'll find the update at www.matttsweatherrapport.blogspot.com. Note the three "t's in matts in the URL. I'll also post the early update to my Twitter and Facebook accounts, so look there.
I'll also try to update through the day if my travel schedule allows.
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