Sunday Morning Storm Update: For Now, Flood Threat Increases A Bit, But Wind Threat Diminishes Slightly

Not a snow prediction map for a change. Here's the
National Weather Service in South Burlington's idea
of how much rain will fall with the upcoming storm.
Click on the map to make it bigger and easier to see.
Note that the forecast is subject to change.

 We're in what we call the windshield wipering phase of forecasts for the storm that will soon strike Vermont, the one that is already making Florida miserable and is or will do the same to the entire eastern U.S. 

By windshield wipering I mean that the expected storm track goes a little west, than a little east, then back and forth with each new computer weather forecast.

 Up here in Vermont the exact track of the storm will determine if this will be more of a flood risk or more of a wind risk. More info on that in a bit

The big pictures shows one bit of preliminary good news. So far at least, I've seen no reports of tornadoes in Florida or the Southeast. That's a good thing, of course, but the threat is not over yet. 

Flood watches, wind alerts and coastal flood watches extend from Florida to Maine, and on into southeastern Canada. 

Under normal circumstances this time of year, this would be one humdinger of a snowstorm or blizzard to the west of the storm's track. But there is incredibly little cold air available for this storm. 

On the tail end of the storm, snow showers will fall in the Appalachians from North Carolina to New England, but that part of the storm won't be a big deal. It's rain and wind that's the problem here. 

VERMONT EFFECTS

If you remember, the last time we had a storm, a week ago, we started with flood threats from expected heavy rains, but that diminished as the threat of snow pushed into that forecast.

That's absolutely not the scenario that's playing out here, so I think we'll have a flood threat throughout this storm and its immediate aftermath. The rain begins in earnest tonight and continues Monday. How much flooding still depends on the track of the storm. 

Flood Threat

Early, uncertain indications are the storm will go right overhead or just to our east. That would in general put us in some fairly heavy rain.  All of Vermont is under a flood watch for good reason. 

Current forecasts are for 1 to 2.5 inches of rain, with more on the southeast facing slopes of the Green Mountains, Adirondacks and New Hampshire's White Mountains.  Also the southeastern corner of Vermont is in play for up to three inches of rain 

What makes the flood threat a little worse this time is the early snow pack in the mountains. This is such a warm storm that above freezing temperatures will reach up to 10,000 feet overhead.

Snow doesn't melt all that much if temperatures in the 30s to around 40 while it's raining. This time, though, it'll be in the upper 40s and 50s for many of us. Dew points - a measure of how much moisture is in the air, will be at near record highs for this time of year even up on the mountain summits. 

High dew points allow snow to melt much faster than it otherwise would. This means the rain and melting snow would all gush down from the mountains at once Monday, filling up rivers statewide.

The flooding won't be nearly as bad as what we dealt with in July, but it could still cause problems. 

All rivers in Vermont will rise sharply. Many will go into minor flood stage, with a couple maybe reaching moderate flood stage. That's high enough to close some roads, flood basements and maybe even surround the lowest lying buildings with water.

At this point - and the forecast could still change - the best chances of moderate flooding seem to be along the Hoosic River in southwestern Vermont and possibly the Winoosk in and near Essex Junction

Downtown Montpelier, Barre, Johnson and Ludlow are safe from the kind of flooding that wrecked those communities in the summer.  But even there, people might want to take stuff out of their basements if they are especially prone to flooding, even if the storm isn't extreme.

If you have to drive anywhere Monday and early Tuesday, be alert for road closures due to flooding.  Remember the adage, "turn around don't drown."  Getting caught in flooding is even more dangerous than it is in the summer, since the water is so cold this time of year. 

Also, Monday night, note that you can't see flooding ahead of you easily in the dark. 

Strong Winds 

Winds were already gusty this morning along some of the western slopes of the Green Mountains, but those winds won't really ramp up until later tonight and Monday. 

Strong, damaging winds are definitely possible along the western slopes of the Green Mountains, and the Taconics of southwestern Vermont. 

Again, this could change, but the threat of high winds has diminished a bit with the latest forecasts. Enough questions remain about the wind to keep the high wind watches up for the areas most in danger.

There's no question winds will get gusty everywhere, especially the western slopes in this storm. But once again, how strong those winds get depends on the storm's track.

If the storm goes overhead or just to our east, as forecasters are indicating this morning, winds won't get as strong as they could.  If the storm goes more to our west, the amount of rain will be cut a bit, but the western slope winds would roar much more intensely and cause more damage.

In any event, it looks the best chance of the strongest winds would hit between 3 a.m. and noon Monday.

Bottom Line

We're in for a stormy time tonight and Monday.  Today will be overcast, breezy and warm for the season. Rain chances will ramp up this afternoon and especially this evening. 

Rain will come down moderately to heavy at times later tonight and much of Monday. There might be lulls in the rain at times, but this is yet another very wet storm for this time of year.

Especially for those who live in or near the western slopes, get your LED candles ready today and charge up your devices. Scattered power outages are definitely something to watch for.

Rain will wind down Monday night and change to snow in the higher elevations especially but we don't expect much accumulation. The big "winners" might be the northern Green Mountains, which could get three inches of snow. 

That's not much compensation considering how much snow will disappear from Vermont, just in time for Christmas. 

After this mess goes by, no big storms are in the cards between now and Christmas Day.  Tomorrow will be the fourth Monday in a row with a nasty, potentially damage storm in Vermont, which is quite a streak.  

The Monday after tomorrow is Christmas.  The good news is that current forecasts indicate the weather on Christmas Eve and Day will be quiet.  That could change, but so far, I see no signs of big storm trouble for the holiday.