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| One of today's "appetizer storms" approaches Fairfax, Vermont this afternoon with hail, gusty winds and torrential rains. Those rains "pre-treated" the ground, soaking it and making it easier for subsequent downpours to runoff, worsening expected flooding. |
Very, very bad.
Don't let the scattered nature of storms and torrential rain early and mid afternoon today fool you. The main show is just beginning in Vermont, and it is one ugly, ugly show.
I wish I had better news, but forecasters are now calling for possible catastrophic flooding in Vermont, on par with the horrible Tropical Storm Irene flood disaster of 2011.
Clues to how awful things might get are in the National Weather Service South Burlington office Sunday evening forecast discussion. These are usually sober, technical explanations of why meteorologists made their forecasts the way they did.
If there's scary language in these discussions, you know you are in trouble. Here's what they wrote:
"Widespread significant to potentially catastrophic flash flooding are expected overnight tonight into Monday night."
Overall, forecasts call for two to five inches of rain, with a few places seeing seven, eight or even 10 inches of rain by Tuesday morning. That's historic levels of rain, on par with the Great Flood of 1927 or Tropical Storm Irene.
Need more evidence of how bad this could get?
NOAA's Weather Prediction Center keeps us in a scary moderate risk for flash flooding through early Monday. Then, they put most of Vermont in a worst-case scenario high risk for Monday and Monday evening.
The Weather Prediction Center has four categories of flood risk, and they're similar to severe thunderstorm risks.
From best to worst, they're ranked marginal, slight, moderate and high.
High risk is panic button level. According to Weather Underground, a high risk for flash flooding is issued on only about four percent of calendar days each year. I think the last high risk in Vermont was during Irene.
High risk of flood days account for 83 percent of all flood damage and 39 percent of all flood deaths.
Worrisome stuff indeed.
THE PARTICULARS
For most of this afternoon, I suppose Vermont has been seeing the appetizers before the main event. Scattered strong to severe storms have popped up here and there, dumping an inch or two of rain in some spots within a half hour.
Some isolated instances of damaging wind and hail have been reported.
One afternoon storm northeast of Montpelier dumped two to three inches of rain in an hour or two, with more coming at the time a flash flood warning was issued for the area late this afternoon.
Even where the scattered thunderstorms did not cause flash flooding, they pre-soaked the ground to make the runoff from coming downpours even more damaging.
The first main show was moving into southern and central Vermont late this afternoon. That will continue to spread north this evening. This is the overnight deluge we've been talking about. This will be the surge of downpours that will trigger the start of widespread flash flooding.
Coming at night, it's particularly dangerous, as I discussed this morning. Be ready to evacuate in a moment's notice. Keep a phone by your bedside tonight so warnings will wake you up.
By dawn, if the forecast is anywhere close to correct, there will be widespread damage in Vermont. Also at dawn, the rain will be noticeably tapering off. But that doesn't mean it's over.
During the afternoon, another wave of heavy rain is forecast to move over Vermont. Rather than a bunch of thunderstorms, this will be a big patch of drenching rains moving over the state. Scattered torrential downpours will probably be embedded in this area of rain.
This will obviously worsen the flash flooding that's going on, and send main rivers across the state into flood stage.
There could even be a third round of heavy rain, especially north and in the mountains, Monday evening.
This flood will likely be a more drawn out affair than Tropical Storm Irene. That storm basically mugged us in a day. We honestly started to suffer flood damage in Vermont Friday. It's back and intensifying across the state as I write this.
BOTTOM LINE
Just be extra careful tonight and tomorrow. In the coming weeks, some of our neighbors and friends will require a lot of help. We're going to need to be Vermont Strong, just as we were in the aftermath of Irene.
It won't be just us Vermonters dealing with this. Flash flooding was ongoing across much of the Northeast as I write this, and it will only get worse overnight.
As you can tell by my tone, I'm upset about all this, as I'm sure many of you are. I'm pretty sure climate change is making this worse than it otherwise would be. It's an example of the new world we've created.
This summer has at best been uncomfortable, with bouts of wildfire smoke, insufferable, persistent humidity and now this. It's just so far removed from an idyllic Vermont summer, isn't it?
Stay safe tonight, everyone! And make sure you have each others' backs.
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