Spring's progress is blocked in the Northeast
Updated Apr 13, 2021 7:43 AM EDT
The strongest surges of new cold air masses will be from the Rockies into the central and northern Plains during the next week, but the Northeast will share at least the chill later. It won't be the first time that winter has staged an encore in the Northeast in the second half of April, or even early May. Consider this quote:
May 4, 1774: "the Blue Ridge Mountains covered with snow. 5th: a frost that destroyed almost everything...At Monticello, near half the fruit of every kind killed; and before this no instance had ever occurred of any fruit being killed here by frost" Thomas Jefferson p55 in The Garden Book
The reason for the chilly outlook is a blocking pattern centered over northeastern Canada and Greenland. You can see the large blocking high pressure area on this map:
On Monday morning there was some interesting cloudiness to my northeast as I walked Scotty the dog:
The white area near the bottom of the picture is a layer of fog. The fog formed after it rained and the sky temporarily cleared. This allowed the temperature to drop to the saturation point. So, we had a cool stratified layer of air close to the ground. Farther up in the picture above the mountain tops, you can see clouds with some vertical development. That layer was sandwiched between the low-level fog and higher cloudiness that was also stratified.
The satellite radar composite below shows a band of precipitation from North Dakota to New York and Pennsylvania. The eastern section of that is what is left of the slow-moving storm that crossed the country during the last week.
The regional radar picture below the satellite radar composite expands our view of the shower zone extending from the Great Lakes to the Middle Atlantic states as of early Monday evening. Some of the showers were heavy and there were even a few thunderstorms scattered about.
This map shows the forecast the GFS made for 8 p.m. Monday:
By Tuesday afternoon, most of the showers look like they've evaporated and there could be some breaks in the clouds.
On Wednesday, a storm crossing the southern Rockies will be causing snow over a large area from the central Rockies into the High Plains. It looks rather damp and dreary for the Middle Atlantic region, but it should also be fairly mild. On the other hand, we see more moisture coming in from the Gulf of Mexico and a general area of low pressure over the Great Lakes. Note the blue dotted line stretching from Iowa to just north of Lake Erie. In winter we sometimes use that line to assess where the snow versus rain line will be. Let's watch where it goes.
On Thursday, that blue dotted line drops all the way into the Virginias and it looks cold enough to snow over the higher terrain of western Pennsylvania. For the Interstate-95 corridor, it looks like a dreary and dull damp day, drab by design and dismal by definition, with cloud-stuffed skies dropping varying amounts of rain. A snowstorm is shown to be hitting the north-central Rockies.
On Friday, we see a storm consolidating off the East coast and causing snow in parts of New York and New England!
While this could be a heavy, wet snowstorm in parts of that area, the GFS ensemble mean forecast is much tamer. Still it isn't every April 16th when a forecast of snow accumulation can be an item on the Northeast forecast map.
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Weather Blogs / Northeast US weather
Spring's progress is blocked in the Northeast
Updated Apr 13, 2021 7:43 AM EDT
The strongest surges of new cold air masses will be from the Rockies into the central and northern Plains during the next week, but the Northeast will share at least the chill later. It won't be the first time that winter has staged an encore in the Northeast in the second half of April, or even early May. Consider this quote:
May 4, 1774: "the Blue Ridge Mountains covered with snow. 5th: a frost that destroyed almost everything...At Monticello, near half the fruit of every kind killed; and before this no instance had ever occurred of any fruit being killed here by frost" Thomas Jefferson p55 in The Garden Book
The reason for the chilly outlook is a blocking pattern centered over northeastern Canada and Greenland. You can see the large blocking high pressure area on this map:
On Monday morning there was some interesting cloudiness to my northeast as I walked Scotty the dog:
The white area near the bottom of the picture is a layer of fog. The fog formed after it rained and the sky temporarily cleared. This allowed the temperature to drop to the saturation point. So, we had a cool stratified layer of air close to the ground. Farther up in the picture above the mountain tops, you can see clouds with some vertical development. That layer was sandwiched between the low-level fog and higher cloudiness that was also stratified.
The satellite radar composite below shows a band of precipitation from North Dakota to New York and Pennsylvania. The eastern section of that is what is left of the slow-moving storm that crossed the country during the last week.
The regional radar picture below the satellite radar composite expands our view of the shower zone extending from the Great Lakes to the Middle Atlantic states as of early Monday evening. Some of the showers were heavy and there were even a few thunderstorms scattered about.
This map shows the forecast the GFS made for 8 p.m. Monday:
By Tuesday afternoon, most of the showers look like they've evaporated and there could be some breaks in the clouds.
On Wednesday, a storm crossing the southern Rockies will be causing snow over a large area from the central Rockies into the High Plains. It looks rather damp and dreary for the Middle Atlantic region, but it should also be fairly mild. On the other hand, we see more moisture coming in from the Gulf of Mexico and a general area of low pressure over the Great Lakes. Note the blue dotted line stretching from Iowa to just north of Lake Erie. In winter we sometimes use that line to assess where the snow versus rain line will be. Let's watch where it goes.
On Thursday, that blue dotted line drops all the way into the Virginias and it looks cold enough to snow over the higher terrain of western Pennsylvania. For the Interstate-95 corridor, it looks like a dreary and dull damp day, drab by design and dismal by definition, with cloud-stuffed skies dropping varying amounts of rain. A snowstorm is shown to be hitting the north-central Rockies.
On Friday, we see a storm consolidating off the East coast and causing snow in parts of New York and New England!
While this could be a heavy, wet snowstorm in parts of that area, the GFS ensemble mean forecast is much tamer. Still it isn't every April 16th when a forecast of snow accumulation can be an item on the Northeast forecast map.