Mid-Atlantic could be cooler for start of August
Updated Jul 26, 2021 6:35 PM EDT
This is video is from last month at Horseshoe Curve, near Altoona, Pennsylvania. The day was mostly sunny. Cumulus clouds were capped by drier and/or water air above them. We are looking east. One hundred-plus car freight trains are heading downhill from the Allegheny summit on their way to Altoona.This train moves toward you on the right side and away on the left. A visual comparison shows the train is at a higher elevation on the right than on the left. The Norfolk Southern locomotives (two at the rear, two near the middle and two at the front) on this train run to prevent the train from going downhill too quickly. In the opposite direction, they pull uphill, typically very slowly. The curve was originally designed by engineer J. Edgar Thomson (who later became railroad president), dug out by hand by Pennsylvania Railroad employees and opened in 1854. Trains follow the same route today.
The following picture is from Monday July 26, 2021, at 2 p.m. ET, showing cumulus clouds.
The following picture is an enhanced infrared view.
The highest, coldest clouds are depicted in (mainly) yellow and reddish colors as seen on the key below the map. There are thunderstorms over the higher terrain of the Southwest and other storms from Louisiana to the Carolinas and south to Florida. There are a few thunderstorms in northwestern Minnesota and adjacent Canada. The visible picture below shows smoke from southwestern Canada southward through the Rockies and out into the Plains.
The upper-air flow explains the smoke pattern pretty well, showing it trapped under the huge ridge that covers the western half the country. The floor aloft over the Northeast is coming from south-central Canada and so it travels through much less of a smoky area than was the case with the air that reached the region last week. Notice if you trace the flow backwards from the Northeast, it passes over the area of northern North Dakota where there were a few thunderstorms on Monday.
The surface forecasts below for Tuesday afternoon and Wednesday morning show that some of the showers and thunderstorms will spread southeastward to cross the Great Lakes and then reach the East Coast. The best chance for a few showers and a thunderstorm will be from Wisconsin and Michigan to southern New England. The National Weather Service Storm Prediction Center has outlined an area for a slight risk of severe thunderstorms from eastern South Dakota to Wisconsin Tuesday, and a marginal risk for much of New York state and central and southern New England for late Tuesday and Tuesday night. Places farther south of the zones make it little or nothing from this disturbance, but a weak cold front could cut the heat a little bit.
A slightly stronger cold front is likely to affect parts of the Northeast from Wednesday night into Thursday night. The upper-air forecast for Thursday shows the jet stream shifting a little farther south in the northeast part of the country.
The surface forecast for Thursday afternoon shows a number of areas of showers and thunderstorms over the Northeast. It would not be surprising to see some severe thunderstorms with strong, gusty winds with his system, so I suggest you check later forecasts for specifics.
The upper-air forecast for later in the weekend makes it look like it could become unseasonably cool in the Northeast for the first couple of days of August. Forecast maps a few days ago didn't really show this, and I remain skeptical about the details for the moment. When you look at the sample forecast below, you will see the cool idea emphasized over northern New York state but less so from southern Pennsylvania to southern Ohio.
The surface forecast for Sunday looks a little bit like the set up for Thursday afternoon, but it is clear that the forecast map shows much cooler air spreading into the Northeast.
If later computer model runs confirm the idea of a strong trough coming into the Northeast, you will see temperature forecast being lowered later this week for the Sunday to Monday time period.
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Weather Blogs / Northeast US weather
Mid-Atlantic could be cooler for start of August
Updated Jul 26, 2021 6:35 PM EDT
This is video is from last month at Horseshoe Curve, near Altoona, Pennsylvania. The day was mostly sunny. Cumulus clouds were capped by drier and/or water air above them. We are looking east. One hundred-plus car freight trains are heading downhill from the Allegheny summit on their way to Altoona.This train moves toward you on the right side and away on the left. A visual comparison shows the train is at a higher elevation on the right than on the left. The Norfolk Southern locomotives (two at the rear, two near the middle and two at the front) on this train run to prevent the train from going downhill too quickly. In the opposite direction, they pull uphill, typically very slowly. The curve was originally designed by engineer J. Edgar Thomson (who later became railroad president), dug out by hand by Pennsylvania Railroad employees and opened in 1854. Trains follow the same route today.
The following picture is from Monday July 26, 2021, at 2 p.m. ET, showing cumulus clouds.
The following picture is an enhanced infrared view.
The highest, coldest clouds are depicted in (mainly) yellow and reddish colors as seen on the key below the map. There are thunderstorms over the higher terrain of the Southwest and other storms from Louisiana to the Carolinas and south to Florida. There are a few thunderstorms in northwestern Minnesota and adjacent Canada. The visible picture below shows smoke from southwestern Canada southward through the Rockies and out into the Plains.
The upper-air flow explains the smoke pattern pretty well, showing it trapped under the huge ridge that covers the western half the country. The floor aloft over the Northeast is coming from south-central Canada and so it travels through much less of a smoky area than was the case with the air that reached the region last week. Notice if you trace the flow backwards from the Northeast, it passes over the area of northern North Dakota where there were a few thunderstorms on Monday.
The surface forecasts below for Tuesday afternoon and Wednesday morning show that some of the showers and thunderstorms will spread southeastward to cross the Great Lakes and then reach the East Coast. The best chance for a few showers and a thunderstorm will be from Wisconsin and Michigan to southern New England. The National Weather Service Storm Prediction Center has outlined an area for a slight risk of severe thunderstorms from eastern South Dakota to Wisconsin Tuesday, and a marginal risk for much of New York state and central and southern New England for late Tuesday and Tuesday night. Places farther south of the zones make it little or nothing from this disturbance, but a weak cold front could cut the heat a little bit.
A slightly stronger cold front is likely to affect parts of the Northeast from Wednesday night into Thursday night. The upper-air forecast for Thursday shows the jet stream shifting a little farther south in the northeast part of the country.
The surface forecast for Thursday afternoon shows a number of areas of showers and thunderstorms over the Northeast. It would not be surprising to see some severe thunderstorms with strong, gusty winds with his system, so I suggest you check later forecasts for specifics.
The upper-air forecast for later in the weekend makes it look like it could become unseasonably cool in the Northeast for the first couple of days of August. Forecast maps a few days ago didn't really show this, and I remain skeptical about the details for the moment. When you look at the sample forecast below, you will see the cool idea emphasized over northern New York state but less so from southern Pennsylvania to southern Ohio.
The surface forecast for Sunday looks a little bit like the set up for Thursday afternoon, but it is clear that the forecast map shows much cooler air spreading into the Northeast.
If later computer model runs confirm the idea of a strong trough coming into the Northeast, you will see temperature forecast being lowered later this week for the Sunday to Monday time period.