The European model run on Monday morning produced some stunningly high rainfall amounts of a foot or more in much of the Mid-Atlantic region for the 5-day period ending on Saturday, November 1st. Meanwhile, the Canadian model run from Monday night featured what is likely to be a hurricane (Melissa) producing accumulating snow over some of the higher elevations of the Northeast US late next week after it shifts northwest towards the New England coastline and encounters an unusually cold air mass. While odds are against either of these scenarios coming to fruition, they do suggest to me that the models are correctly sniffing out the potential for some energetic weather from later next week into the following week and there are several ingredients likely to come into play for just such a pattern. The ingredients include a powerful jet streak that will push into the western US this weekend from the northern Pacific Ocean, intense blocking in the upper part of the atmosphere that is likely to develop across central Canada by the middle of next week, a cold air intrusion into the US from Canada, and a likely hurricane over the western Atlantic Ocean.
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There have been some notable storms near the east coast during the late stages of October and early parts of November including Hurricane Sandy in 2012, the so-called “Perfect Storm” in 1991, and Hurricane Nicole in 2022 which made landfall in Florida. It is at this time of year where there can be a “last gasp” from the Atlantic Basin tropical season as water is still quite warm in places like the Caribbean Sea, and southwestern Atlantic Ocean. At the same time, there is often an increasing frequency of chilly air masses moving from Canada into the US warning us that winter is not too far away. It is this combination of a waning tropical season combined with increasingly winter-like chill that can cause volatile weather patterns in late October and early November and we could be setting up for something like that for late next week into the beginning of November.
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Lots of players are on the field as we begin the weekend with one upper-level low over the Great Lakes that is dropping slowly to the southeast and a second wave of energy in the southern stream that is helping to spin up a surface low pressure system off the southeast US coast. In addition, there is a strong high-pressure system to our north that continues to shift slowly offshore as we begin the weekend. The combination of the high to the north and low to the south is already producing an onshore flow of air in the Mid-Atlantic region and this will persist for the next few days potentially leading to significant coastal flooding/beach erosion from Long Island-to-New Jersey-to-the Delmarva Peninsula. While there can be some heavy showers and strong wind gusts across inland areas during the next few days, rainfall amounts will be much more limited with the worst impact from this developing storm system confined to coastal sections.
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Low pressure is going to intensify significantly this weekend near the Southeast US coastline, induced by a frontal boundary zone that slides into the region and energized by an upper-level trough that drops southeast across the Great Lakes. It appears increasingly likely that this strong coastal storm will then push far enough to the north to have an impact on the Carolinas, Mid-Atlantic, and Northeast US all the way from later Saturday into late Monday. The worst impact will be along coastal sections where rain will be heaviest, winds will be strongest, and the threat of coastal flooding/beach erosion will be high due to a prolonged period of onshore flow.
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Low pressure is going to intensify significantly this weekend near the Southeast US coastline, induced by a frontal boundary zone that slides into the region. It appears quite certain that this strong storm will then push far enough to the north to pound away at the coastal Carolinas with heavy rainfall and strong winds...another highly impactful event for the Outer Banks of North Carolina. After that, odds continue to increase that this weekend storm system will then push to the northern Mid-Atlantic coastline - act as a classic Nor’easter - and bring impactful rain and wind to coastal sections for an extended period of time. By early next week, the northward progress of this storm system will likely come to an end as strong high pressure builds across southeastern Canada (“confluence”) acting as a barrier in the atmosphere. As a result, the storm should turn east or it may even loop back around for awhile early next week near the Mid-Atlantic coastline before ultimately pushing out to the open waters of the western Atlantic.
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Low pressure is going to intensify significantly this weekend near the Southeast US coastline, induced by a frontal boundary zone that slides into the region. It appears quite certain that this strong storm will then push far enough to the north to pound away at the coastal Carolinas with heavy rainfall and strong winds. It is a little less certain if this strong storm can then extend far enough to the north along the eastern seaboard to produce heavy rainfall and strong winds in the Mid-Atlantic region, but that scenario is certainly on the table. Whether this system becomes a named tropical storm by NOAA’s National Hurricane Center is still too early to say; however, the effects could be much the same along coastal sections of the Carolinas and potentially to the Mid-Atlantic region...namely with heavy rainfall and strong winds...a kind of classic autumnal Nor’easter. Some of the key players involved include strong high-pressure ridging which will set up over southeastern Canada and a cold front that will slide to the southwestern Atlantic Ocean by the end of the week and help to act as a catalyst for the significant intensification of surface low pressure.
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Low pressure is likely to rapidly intensify this weekend over the southwestern Atlantic Ocean and it is a threat for heavy rainfall and strong winds along coastal sections of the Carolinas and potentially to the Mid-Atlantic/Northeast US. Whether this system becomes a named tropical storm is too early to say; however, the effects could be the same along parts of the eastern seaboard…namely with heavy rainfall and strong winds likely in the Saturday night to Monday time period. Some of the key players involved include strong high-pressure ridging which will set up over southeastern Canada and a cold front which will slide to the southwestern Atlantic Ocean later in the week and help to act as a catalyst for the intensification of low pressure.
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The Atlantic Basin is quite active with three tropical systems of note as we head towards the end of September. There is a newly named Tropical Storm Humberto situated to the northeast of the Northern Leeward Islands, a likely-to-be named Imelda which is now located near the Dominican Republic, and a weakening Hurricane Gabrielle in the far eastern Atlantic Ocean. It is the likely-to-be named Imelda that may be of most concern at this point as it could threaten the Bahamas this weekend and potentially has a chance of impacting the Southeast US.
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The Atlantic Basin is quite active as we head towards the end of September with three tropical systems currently on the playing field including a “major” Hurricane Gabrielle which is now racing off to the east-northeast and is no threat to the US. In fact, Hurricane Gabrielle could impact the Azores Islands and Portugal down the road in a weakened state after crossing over the cooler waters of the North Atlantic.
Meanwhile, the other two tropical systems pose more of a challenge in terms of forecasting their eventual paths and magnitudes. It appears quite likely that both systems will reach named tropical storm classification and potentially, both may climb to hurricane status. It also appears quite likely that these two systems will end up doing some sort of a dance around each other for awhile (“Fujiwhara effect”) and at least one may come uncomfortably close to the US east coast and we may not know the end of the story until we get ten or so days out from now.
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The Atlantic Basin tropical season officially extends from June 1st to November 30th, and the climatological peak is right around the 10th of September. This year is quite unusual in that the climatological peak comes with no tropical activity whatsoever in the Atlantic Basin and the overall season is now below normal for this time of year. In fact, global activity across the entire northern hemisphere is below-normal and that breaks down to each of the oceans being quieter-than-normal (Atlantic, Pacific, Indian). One of the possible explanations for the relatively quiet tropical season across the globe is the dramatic cool down in sea surface temperatures from a year ago. Looking ahead, there is another half of the season to go for the Atlantic Basin - at least in terms of climatology - and signs point to a pickup in activity potentially beginning as soon as this weekend.
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