 |
| The National Weather Service in South Burlington released this rainfall prediction map. It includes what already fell, and what will come down through Saturday morning. As you can see, New York gets the heaviest rain. We'll have to watch for pockets of locally heavier rain in Vermont that might not be depicted in this map. Still, more than two inches of rain is fairly impressive . |
Unfortunately, it over-performed in central and northern Vermont dumping more rain than predicted in many areas. That primes the pump, so to speak, for possible additional flooding later today.
We can also expect some wind damage in parts of Vermont today, along with isolated instances of severe thunderstorms. There's even a very low, but not zero chance of a brief tornado this afternoon or evening.
Despite the trouble brewing in Vermont, the bigger threat for flash flooding has continued to focus on northern New York and a little less on the Green Mountain State for this event.
Let's take it step by step again.
THIS MORNING
You probably did hear the occasional roar of downpours on your roof overnight and early this morning. One to 1.5 inches of rain, with spot amounts to two inches fell in a band from eastern Addison County, through Barre-Montpelier and on off to St. Johnsbury.
Both Montpelier and St. Johnsbury reported about 1.7 inches of rain already as of 7 a.m. since this all started last night.
This is precisely the wrong area to see the heaviest rain, as that zone has experienced the worst of the flooding this summer.
Already, a flood warning was posted this morning for parts of the Northeast Kingdom from St. .Johnsbury to points north and west including Lyndonville and Barton.
This Northeast Kingdom region is especially prone to added flood damage because the hasty repairs to roads and culverts after the massive July 30 flash flood are not stable or complete. So the added downpours this morning could be causing more damage.
All that said, the biggest flood threat from the remnants of Debby today are across northern New York, where the heaviest rain is falling, and will fall.
The Mad River at Moretown rose by more than three feet in just a few hours early this morning, but appeared to be stabilizing below flood stage at dawn. Still, since river levels are now higher than expected, that increases the chances somewhat that flooding could occur this evening.
All that said, the biggest flood threat remains in New York. But Vermont will need to be watched closely today.
TODAY
You might notice a lull in the rain for awhile this morning but it will pick up again. The steady, heavy rain today and this evening will focus on New York State, but there will be fitful showers and storms throughout the day across Vermont.
The showers, rain and downpours will tend to be out concentrated from mid or late afternoon into the evening. That's probably when we'll have our biggest risk of any flash flooding. Again, it's one of those cases where not everybody has a crisis. Most places should be fine with the amount of rain we received and are about to get.
However, some places will be dealing with washed out roads, basement flooding and other problems you get with intense rainfall rates.
We'll have to watch rainfall rates and whether any particular spot is hit by repeated downpours. If former Debby behaves as expected, Vermont flooding problems will probably be relatively minor - mostly nuisance level - at least in most cases. If former Debby really over-performs with especially heavy downpours, all bets are off.
The National Weather Service and other meteorologists are watching this closely.
There's other trouble brewing today, too:
Wind
The remnants of Debby still have some wind energy. That will channel gusts from south to north up the Champlain Valley. Also, southeast wind going up and over the Green Mountains will tend to grab some higher speed winds from aloft and bring them to the surface.
It's the classic western slope windstorm type deal we sometimes get in the winter. So, the National Weather Service has issued a wind advisory for the Champlain Valley and western slopes of the Greens. A wind advisory like this is fairly common in the winter, but very rare in the summer. But here we are.
For today, all this will result in possible gusts in a few spots of up to 50 or 55 mph. That's enough to break branches and uproot a few trees and take down a few power lines. Remember, trees uproot more readily when the ground is wet and soggy, so that will be an issue.
Severe Storms/Tornado?
With any tropical or former tropical system, you often seen rotating storms, especially along and east of the storm's track. That could happen in Vermont. I would say if this does happen, it's most likely along or south of Route 2.
A few storms could develop strong, damaging winds. Since these storms will be rotating, we can't rule out a brief tornado somewhere in the state. The chances are low, but they're definitely not zero. These kinds of things with tropical type systems can develop and fade fast, so you might not much advance warning, if any warning, in the case of anything developing.
IT ENDS QUICKLY
The heavy rain and wind will shut down quickly in Vermont tonight. Western areas might see things settle down by 9 p.m., and by midnight or so east. Runoff from the heavy rain will continue to be an issue overnight, so we'll need to watch how river levels go.
Most of the river flooding will be in northern New York. But we'll need to keep our eye on the Mad River, and possibly a few others. If any rivers do flood in Vermont, strong chances are it would be minor flooding, not the major flooding we saw in July.
All bets are off, though, if the rain today is much heavier than forecast.
Saturday actually still looks like a nice summer day. Showers should re-develop Sunday afternoon and evening, but they shouldn't be intense enough to cause any new flood worries.
No comments:
Post a Comment