Monday, 11:30 a.m.
It may be the middle of summer now, but there's still plenty of weather to go around these days. There is still a fair amount of heat over the interior West, though not quite as bad as it was a week ago. Meanwhile, the heat in the East is infused with lots of high humidity, and that's fueling showers and thunderstorms in many places. And while the eastern third of the country is feeling more tropical than not, some real tropical activity has begun with the naming of Chantal in the central Atlantic.
Let's start in the West today for a change, where another heat wave is in place. It may have 'only' been 105 in Las Vegas yesterday, down more than 10 degrees from the peak of last week's record-setting heat wave, but it's still plenty hot. More impressive are the 90+ readings up into central and eastern Washington state on Sunday. They weren't alone in that heat, as many locations in Kansas and Oklahoma reached the 100-degree mark on Sunday.
By this time in an average summer, the monsoon circulation has begun to kick in, providing more moisture to the thunderstorms that tend to pop up many afternoons over the mountains. That just isn't happening on a widespread basis just yet, and it looks as if it will be delayed perhaps as much as another week or so. Here's a snapshot of forecasteprecipitation from this morning through Thursday evening from the 12z July 8 NAM model:
That appears to be fairly impressive, but it will probably end up being less than advertised, especially up in Colorado. There are some indications, though, that things will begin to change this weekend and next week to bring some much needed rain to these areas.
If the West is hot and dry, the East is just downright steamy. I rode ALL DAY Saturday in that stuff at Total200 - more details at the very end if you care to read - and it is just unrelenting. Another three to four days of temperatures well into the 80s and lower 90s can be expected, with dew points at the very least in the mid-60s, more often than not in the upper 60s and lower 70s. Those types of dew points mean nighttime lows struggle to below 70 in many rural areas and generally don't make it that low in the suburbs.
With all of that moisture in place, it's not hard to trigger a couple of showers and thunderstorms on most days. As the western Atlantic ridge expanded westward for a time going into the weekend, it did a good job of cleaning out the atmosphere and reducing the number of thunderstorms east of the mountains. Since then, however, the ridge has begun to shrink a bit, and that's been enough to foster more showers and thunderstorms once again. They're being enhanced by an upper-level disturbance tracking across the mid-Atlantic today:
Look for more of them tomorrow, then again on Wednesday ahead of a much stronger upper-level trough that will push a cold front into the northern Plains this afternoon and tonight, then into the Midwest tomorrow. Severe thunderstorms are likely tonight in parts of North Dakota, then tomorrow into Minnesota, Iowa, Wisconsin, northern Illinois and over into Michigan. These could well extend into tomorrow night ahead of that front. By Wednesday, those strong to severe thunderstorms will be on the rampage across the Great Lakes and into the Ohio Valley, northern mid-Atlantic and western New England.
This front will slow down as it moves into New England and the mid-Atlantic states, basically because it will again run out of full support. Going into Thursday night and Friday, that western Atlantic ridge appears ready to flex its muscles yet again, enough to force the front either to come to a complete standstill or even to retreat a bit this weekend.
And if that weren't enough, we now have a tropical storm in the southern part of the North Atlantic basin, Chantal. As of the most recent advisory, top winds had reached 45mph, and it was zipping along at about 25 mph to the west-northwest. That speed and trajectory will bring it into the eastern Caribbean tomorrow and bring it close to Haiti and the Dominican Republic Wednesday evening. The projected path would bring it to the northern Bahamas by Saturday morning, not far from the southeast coast of Florida. My fear is that once the system gets there, assuming it remains a viable entity (not necessarily a given since it will probably cross the mountainous terrain of Hispaniola and eastern Cuba), it may be left to drift for the weekend with weak steering winds aloft. At the very least, it will enhance the amount of moisture in the atmosphere throughout the Southeast going into and through the weekend.
Lastly, an epic journey Saturday, Total200. It was hot, and it was humid. I was sweating standing waiting for the start at 6 a.m., and I wasn't doing a thing! As we rode into the U.S. Capitol from Anacostia Park, seeing it illuminated by the morning sunshine, the sweat was already pouring out - and we were hardly exerting ourselves at this point! But once back out of the city and rolling into southern Maryland, the pace picked up... as did the temperature.
I got a twinge of cramping in my left leg around mile 90. The electrolyte loss was mounting. I managed to limp to the next stop at mile 103, resting for a while, eating whatever I could to best replace what I had lost, and I managed to get to the next stop at mile 120 on my own. Then the cramping began again into the next 17-mile stretch. I kept fighting it off and on, even choosing to walk one hill around mile 160. But I kept pushing on. Finally to Stop 8, mile 168. Then to the last stop, mile 179. At that point, a whole group of us joined forces, and we stayed together in the dwindling daylight to the end. Total200, finishing 205 miles in pretty much TotalDarkness. It was a fitting end to the day when it seemed dark at times. Glad I did it! And survived!
Summer has ended astronomically, but from a meteorological standpoint, there's plenty more warm weather heading into October from the Plains to the East.
Two strong cold fronts will charge across the country in the next week, eventually taking out the current hot and humid air mass from the Plains to the East Coast.
Over the next three days, hot and humid air will expand across the Mississippi Valley all the way to the East Coast. This will be followed by even more heat and humidity leading into the weekend.
Hermine will head across the Florida Panhandle late tonight, then cut across the coastal Carolinas and become a headache for the mid-Atlantic and southern New England over the Labor Day weekend. It will be followed by a heat wave later next week.
The heat and humidity will be erased from much of the East later this week, but warmth will spread from the Plains eastward over the weekend. The tropics could still play an important role in the weather along the Eastern Seaboard this weekend.
A dominant ridge will keep it hot from the Ohio Valley to the East into next week, while the disturbance north of Cuba is slow to develop as it approaches the southeastern Gulf of Mexico.