Extreme heat on vacation in the Northeast
Updated Jul 18, 2021 9:47 PM EDT
In Philadelphia, the temperature reached 90 degrees Fahrenheit or higher on eight of the first 18 days of July. Cities such as Hartford, Providence and Boston have only experienced several such days but may have none during the next week or two. The following pressure analysis reveals that a cold front was moving off the eastern seaboard on Sunday, and it looks like there will be several cool fronts during the next week or two to ward off any attempts at a return of sustained heat.
Temperatures on Sunday afternoon were in the 60s and 70s from Wisconsin to central Pennsylvania.
In the middle of Pennsylvania, there were light showers in the morning, then sunshine with lowering humidity in the afternoon. In the Philadelphia to New York City area, it still felt humid in the morning, but the flash flooding rain, frequent lightning and repeated booms of thunder were over. The National Weather Service confirmed an EF-1 tornado ("weakest" category) in Burlington County, New Jersey, Saturday evening.
When thunderstorms are in the area, many of us try to tell how far away each lightning strike was from our location. Light from lightning travels at the speed of light while noise from thunder travels at the speed of sound. It takes five seconds for sound to travel a mile. So, if you count out one AccuWeather, two AccuWeather, three AccuWeather, four AccuWeather and five AccuWeather after seeing lightning and you hear thunder after the five, the closest part of that lightning was about a mile away. The lightning comes and goes in an instant, but the thunder may rumble for many seconds, so how does that affect the distance calculation? To understand the answer, imagine a lightning strike that extends from a distant cloud to the ground somewhere near you. The first sound you hear is from the part of the lightning strike that was closest to you, but later, you hear rumbles from farther and farther away along that same lightning strike. Considering that a cumulonimbus cloud can extend more than 10 miles into the atmosphere, it becomes easy to see why thunder can last so long. When there is frequent lightning, it is often impossible to tell which rumble of thunder came from which lightning strike.
The satellite radar composite from Sunday afternoon showed a large area of dry weather from the Dakotas to the Great Lakes.
The following GFS forecast for Monday morning suggests that the dry weather will extend past New York, New Jersey and Pennsylvania by then.
The following map for Monday evening suggests there may be spotty showers and perhaps a thunderstorm or two in parts of the region, but activity will be much less than earlier in the weekend. Remember that the shaded areas on these maps represent measurable rainfall in the six-hour period leading up to map time, in this case, 8 p.m. Notice that between 8 a.m. and 8 p.m., an area of showers moves southward through Ontario.
The showers that were moving southward through Ontario on Monday were developing along a new cold front that will move through the Northeast Tuesday night and Wednesday.
Based on where showers (and any thunderstorms) are expected Tuesday evening and Wednesday, we can expect some showers and a couple of thunderstorms to cross New York, Pennsylvania and New Jersey on Wednesday.
From this distance, Thursday looks like a nice day across the Northeast with lower humidity and somewhat cooler air than on Wednesday.
However, we see another batch of showers and thunderstorms moving southeastward into the upper Great Lakes by the end of the day Thursday. Judging from the map below on Friday, it seems that we are going to have a repeat of the sequence of events we expect with the earlier front Tuesday and Wednesday.
Indeed, that does look like the case in the forecast for central and northern New England for Saturday, but south and west of there, things were quite a bit different.
The GFS shows a pretty strong storm developing over the Great Lakes along with an extensive area of showers and thunderstorms from there southward through the Middle Atlantic region in the period from late Saturday night through Sunday. This predicted event is almost a week away, so things can change. However, if this idea is correct there could be another round of severe thunderstorms affecting much of the north and Middle Atlantic states.
Here are two forecasts that can give you some idea of what to expect in southern New England and the Middle Atlantic states during the next week or two.
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Weather Blogs / Northeast US weather
Extreme heat on vacation in the Northeast
Updated Jul 18, 2021 9:47 PM EDT
In Philadelphia, the temperature reached 90 degrees Fahrenheit or higher on eight of the first 18 days of July. Cities such as Hartford, Providence and Boston have only experienced several such days but may have none during the next week or two. The following pressure analysis reveals that a cold front was moving off the eastern seaboard on Sunday, and it looks like there will be several cool fronts during the next week or two to ward off any attempts at a return of sustained heat.
Temperatures on Sunday afternoon were in the 60s and 70s from Wisconsin to central Pennsylvania.
In the middle of Pennsylvania, there were light showers in the morning, then sunshine with lowering humidity in the afternoon. In the Philadelphia to New York City area, it still felt humid in the morning, but the flash flooding rain, frequent lightning and repeated booms of thunder were over. The National Weather Service confirmed an EF-1 tornado ("weakest" category) in Burlington County, New Jersey, Saturday evening.
When thunderstorms are in the area, many of us try to tell how far away each lightning strike was from our location. Light from lightning travels at the speed of light while noise from thunder travels at the speed of sound. It takes five seconds for sound to travel a mile. So, if you count out one AccuWeather, two AccuWeather, three AccuWeather, four AccuWeather and five AccuWeather after seeing lightning and you hear thunder after the five, the closest part of that lightning was about a mile away. The lightning comes and goes in an instant, but the thunder may rumble for many seconds, so how does that affect the distance calculation? To understand the answer, imagine a lightning strike that extends from a distant cloud to the ground somewhere near you. The first sound you hear is from the part of the lightning strike that was closest to you, but later, you hear rumbles from farther and farther away along that same lightning strike. Considering that a cumulonimbus cloud can extend more than 10 miles into the atmosphere, it becomes easy to see why thunder can last so long. When there is frequent lightning, it is often impossible to tell which rumble of thunder came from which lightning strike.
The satellite radar composite from Sunday afternoon showed a large area of dry weather from the Dakotas to the Great Lakes.
The following GFS forecast for Monday morning suggests that the dry weather will extend past New York, New Jersey and Pennsylvania by then.
The following map for Monday evening suggests there may be spotty showers and perhaps a thunderstorm or two in parts of the region, but activity will be much less than earlier in the weekend. Remember that the shaded areas on these maps represent measurable rainfall in the six-hour period leading up to map time, in this case, 8 p.m. Notice that between 8 a.m. and 8 p.m., an area of showers moves southward through Ontario.
The showers that were moving southward through Ontario on Monday were developing along a new cold front that will move through the Northeast Tuesday night and Wednesday.
Based on where showers (and any thunderstorms) are expected Tuesday evening and Wednesday, we can expect some showers and a couple of thunderstorms to cross New York, Pennsylvania and New Jersey on Wednesday.
From this distance, Thursday looks like a nice day across the Northeast with lower humidity and somewhat cooler air than on Wednesday.
However, we see another batch of showers and thunderstorms moving southeastward into the upper Great Lakes by the end of the day Thursday. Judging from the map below on Friday, it seems that we are going to have a repeat of the sequence of events we expect with the earlier front Tuesday and Wednesday.
Indeed, that does look like the case in the forecast for central and northern New England for Saturday, but south and west of there, things were quite a bit different.
The GFS shows a pretty strong storm developing over the Great Lakes along with an extensive area of showers and thunderstorms from there southward through the Middle Atlantic region in the period from late Saturday night through Sunday. This predicted event is almost a week away, so things can change. However, if this idea is correct there could be another round of severe thunderstorms affecting much of the north and Middle Atlantic states.
Here are two forecasts that can give you some idea of what to expect in southern New England and the Middle Atlantic states during the next week or two.