 |
| High humidity helped lead to this brief but very torrential downpour in St. Albans on Wednesday. |
The sun was out, the temperature was reasonable and so was the humidity. The dewpoint, the best measure of how humid it is, was under 60 degrees in northern Vermont, which is terrific for July.
Temperatures will get into the low to mid 80s this afternoon, and the humidity might creep up a bit, but it'll be a nice day.
It's a nice break from the downpours and the oppressive, soupy air of yesterday, and the brief but intense bout of potentially stormy heat and humidity we're about to get.
Dewpoints were over 70 degrees yesterday and any little shower cloud that formed took advantage of the wet air and dumped lots of rain in short periods of time. I've heard Westford, Vermont got an inch of rain in 30 minutes.
Luckily, the storms were small in size and moved right along, so we didn't get any real flash flooding, like the spot flash floods that occured in southern New England and the Mid-Atlantic states.
Overnight and especially Friday, the heat and humidity is still expected to blast in. I'm betting the National Weather Service in South Burlington will issue some sort of heat advisory for Friday and Saturday as heat indexes go into the upper 90s.
Actual temperatures during the day Friday and Saturday will probably top 90 degrees, with lows in many areas of Vermont not getting below 70 degrees at night. Yuck.
The thunderstorm outlook for this hot spell that we've been talking about is more uncertain. I suppose as the hot, humid air comes in early Friday, there might be some pre-dawn storms, especially near the Canadian border.
The heat and humidity will provide the ingredients for some strong storms Friday afternoon and evening, but the triggers to set them off are lacking. So there might not be much in the way of fireworks.
You want temperatures to cool with elevation as another ingredient for storms. But there is likely to be a warmer layer of the atmosphere above us on Friday. That's known as a cap, and these caps inhibit storms. Sometimes an updraft can break through the cap, leading to an isolated strong storm or two.
That'll probably happen Friday afternoon and evening, but it will be hit and miss, mostly a miss. The majority of us won't get a storm.
Saturday is iffy when it comes to storms. It surely will be hot and humid, with highs getting past 90 again and heat indexes approaching 100.
Again, the ingredients are there for strong storms. But will they materialize? It's tricky. It all depends on the position of a cold front to our north in Canada. If it gets close to the International Border, that would cool off the air aloft and help trigger strong updrafts with potentially severe storms.
If, as other computer models suggest, the front stays way north - north of Montreal - that cap I talked about would stay intact and we won't get much in the way of storms.
Finally, that cold front will come through Sunday. As it stands now, central and southern Vermont would get the most storms on Sunday. Current forecasts have the front coming through in the late morning across northern Vermont, which would be too early in the day to take advantage of heat and humidity to trigger big storms
The front would hit southern Vermont later, leading to a chance of strong storms. This forecast is very much subject to change.
The good news is this cold front still looks like it will represent a weather pattern change. It looks like temperatures next week in Vermont will be near to a bit below normal. Humidity levels will crash downward, too.
Long-range forecasts suggest this relatively cool pattern could last through the end of the month. So we just have three or so days of awfullness to get through. Not as bad as last summer, right?
For an idea how soupy the air was over the Northeast yesterday, watch this time lapse of a storm moving into New York City. The rain is so heavy eventually in the video that even nearby high rises seem to disappear:
No comments:
Post a Comment