Another Vermont Fog Attack As Gloomy Winter Continues

Crows gather on trees amid dense fog and freezing
drizzle Saturday morning in St. Albans, Vermont. 

 The murk and fog that's been plaguing Vermont this week - all winter, really - intensified last night,  blinding motorists and laying down a very thin but potentially dangerous layer of ice on some road surfaces.  

Meanwhile, far southern Vermont is under a winter storm watch. More in that further below

The dense fog advisory for all of Vermont is in effect until 10 a.m. today. Visibility in some areas was down to a mere 50 feet. If you're caught in that on the roads, you'd better be driving really slowly. It's hard to see even bright tail lights ahead under those conditions. 

I noticed some flights are late or delayed at the Patrick Leahy Burlington International Airport in South Burlington, so check your flights if you're coming in or out of Burlington today. 

Temperatures throughout the Green Mountain State started the day at around 32 degrees, so the fog was freezing on some surfaces. 

Jackson the Weather Dog encountered our icy driveway in St. Albans, Vermont when he went out early today to take observations on the dense fog and temperatures. Jackson noted a little freezing drizzle was also falling here in St. Albans, and I'm sure in several patches elsewhere in the state.

The fog is part of a national weather pattern I posted about the other day which has been socking in wide areas of the nation. Widespread fog broke records midweek for the amount of land they covered.

Traffic cam showed foggy conditions on Interstate 89 in
Georgia, Vermont this morning. 

This morning, there was slightly less fog in the nation than earlier, but it was still remarkably widespread. Especially for midwinter.

In addition to Vermont, dense fog advisories this morning covered most of the states around the western and southern Great Lakes, parts of the northern Plains and numerous spots up and down the East Coast. 

Back here in Green Mountain State, the fog should gradually become less dense as this Saturday morning wears on, but it won't entirely go away.  

We've got another gloomy day ahead of us with a thick overcast, patchy fog, dank conditions and perhaps a few little area of drizzle or a couple wet snowflakes. 

The fog will probably thicken up again tonight, but not become dense in as many areas as it was this morning. Then comes the next little troublemaker

SUNDAY SNOW

That storm we've been watching will pull northeastward out of Mississippi today, carrying boatloads of moisture with it. Flood watches today extend from Alabama to West Virginia.

The storm will move to near West Virginia by Sunday morning. At that point it will fade in favor or a new storm along the Mid-Atlantic coast. That new storm will then scoot east to northeastward away from the U.S.

Still, its projected path has nudged northward a little bit compared to previous forecasts, That puts southern Vermont in play for some snow. 

Snow forecast for Sunday/Monday from the National
Weather Service. Six inches possible in far southern
Vermont, perhaps nothing near Canadian border.
Map is subject to change by tomorrow. 

A winter storm watch has been posted for Bennington and Windham counties Sunday into Monday. Four to eight inches of snow is a decent bet there, especially in higher elevations.

This will be a wet snow, so a few power outages are a risk.

Snow amounts will diminish quickly as you head north.  The National Weather Service has storm totals of around two inches up to about Route 4, and an inch or less up to Route 2, with little or nothing near the Canadian border.

There's a HUGE caveat with that forecast, though.  If the storm track continues to nudge north, heavier snow than that will fall in southern and central Vermont. Whatever happens, Sunday will be another overcast, dreary day. 

If you're looking for a literal bright side, I have just a teeny morsel of good news. The weather during the upcoming week still looks like it will actually be boring. - a little warmer than average with no notable storms. 

However, it doesn't look like we'll be seeing much sun, either. 

Oddly Foggy Winter Locally In Vermont, And In Nation

Once again, dense fog obscures the forest behind my
St. Albans, Vermont home today. Dense fog has been
unusually prevalent this winter in Vermont. It has 
also been strangely widespread across
the United States this week. 

 Once again Thursday afternoon, my area around St. Albans, Vermont was encased in a cold, dense fog.

It's happened a lot this winter. It's very strange for a season in which cold, dry, gusty air usually flushes out any trace of fog.  Even on days without dense fog this winter, a low overcast and lighter fogs and haze have given us a truly gloomy winter. 

Vermont isn't the only place in the nation to have strange bouts of dense winter fog. 

The past three days have set records for the most widespread areas in the United States to fall under dense fog advisories. This morning parts or all of 27 states were under dense fog advisories. That's 100 million people who were under those fog alerts. 

Fog was widespread in other states today, too, but in those areas like in Vermont the fog wasn't dense or widespread for long lasting enough to trigger those advisories. 

Dense fog can obviously be dangerous or at best inconvenient. The Washington Post noted that a pedestrian died when they were hit by a car in dense fog in Indiana, and a Louisiana causeway was closed because of a highway pileup in the fog.

Over the past two days, fog  is mostly responsible for the cancellation of roughly 7 percent of flights at Chicago's O'Hare airport and delayed roughly 17 percent more. 

WHY IT'S HAPPENING

The vast areas of fog in the Midwest, Plains, Ohio Valley and Great Lakes had their roots in last week's cold snap. Snow covered most of this area, and the ground got quite cold, actually freezing in many of these places.

The vast gray area on this National Weather Service
map from this morning is all dense fog advisories. 

That same fire hose of moisture I talked about the other day - the one that produced severe flooding in parts of Texas, Louisiana and Mississippi - also features a much wider, broader flow of warm, moist air from the Gulf that infiltrated most the nation east of the Rockies.

That warm, wet air passing over the cold and often snow covered ground. This moist air is chilled by the cold ground, so that moisture condenses into fog.  

Strong winds that usually blow in the winter would disperse a lot of this fog. But this flow of wet air has featured just light winds 

The past few days featured the biggest fog attack of the winter in the U.S. But there were other ones around Christmas and New Year, some of which disrupted holiday travel. 

Here in Vermont, we've had frequent bouts of slow, warm, wet air flowing over us since November, hence our many days in the fog. 

This latest bout of fog should clear up toward the weekend in most places as windier, drier air makes inroads across the Lower 48. 

Foggy Vermont Morning Today. Get Used To It, Autumn Is Fog Season

Early morning visible satellite map shows fog
crawling through the river valleys of 
Vermont and surrounding areas. The Champlain
and Connecticut River valleys were also
quite fogged in.

 The National Weather Service office in South Burlington early this morning saw fit to issue a special weather statement warning commuters to be alert to dense fog.  

There was indeed a lot of dense fog around, especially in river valleys. This is obviously dangerous on the roads, as you could be zooming down the Interstate at 70 mph in clear air and suddenly drive into a wall of fog with near zero visibility. 

You might not see the accident or obstruction ahead of you until it's too late. 

Get used to these foggy mornings. Pretty much any relatively clear, calm night in the late summer and autumn will yield patchy dense fog during the early morning hours. 

The nights are starting to get cooler. As the chillier nights arrive, water vapor condenses into tiny droplets, which is the fog.

Rivers, lakes and the ground itself have warmed up after a long summer. The water and ground cool off much slower during the autumn than the air does. 

The warm water or soil heats up a very thin layer of air right above.  Then this slightly heated air rises and mixes with the cool air just above. The moisture in that formerly warmer air is then forced to condense into those tiny droplets and - viola! - you have dense fog.

Transpiration from leaves on the trees also contributes to the fog. The rising sun mixes and warms the air, so usually the fog dissipates by mid-morning. 

Since we expect at least a couple more clear, calm nights, expect more fog Friday and Saturday mornings, and maybe Sunday, too. 

Traffic cam shows dense fog along Route 7 in 
Brandon, Vermont this morning. 

By the way, these autumn dense fogs are great for leaf peepers when the foliage arrives. 

For photographers and others who admire nature, try to position yourself in an area you know is pretty, but on a particular morning is fogged in. 

Then wait for the sun to start eroding the fog.  The sunlight cutting through the mist is a sight to behold. The combination of that mist, the sun, the colored leaves, ponds and landscape are just gorgeous.

Fog becomes less likely late in the autumn.  It tends to be windier then, so fog can't form as easily.  By stick season, the leaves are gone, so they're not adding moisture to the air. 

In the meantime, take care driving in these foggy Vermont mornings. But also take the time to admire the beauty of it all.