Today’s Forecast: It’s About to Get Messy – and We’re Not Talking About the Election

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A strong cold front will affect the upper Midwest down to the Southern Plains and push east over the weekend posing a risk of strong to severe thunderstorms. In addition to all that, there’s another blizzard watch for heavy snow and strong wind indicated Thursday through Sunday for the northern Plains and southern Canada including Idaho, Wyoming, Montana, North Dakota, Alberta, Saskatchewan and Manitoba.

Meanwhile, the well-advertised nor’easter is no longer a low-confidence forecast six days down the road — it’s happening today as the strong low pressure center pushes off the Georgia/Florida coast and begins to feel the effects of the warm Gulf Stream. As such, the low is poised to strengthen and move north while paralleling the coastline. However, as the forecast comes more into focus there is both good news and bad news.

The good news: The low is expected to track farther east, by some 50 miles. This keeps the low itself farther offshore of course, but it also keeps the heaviest precipitation and the strongest winds offshore. In the aftermath of Hurricane Sandy, this is indeed good news. How good? Overall sustained winds should peak at 30-40 mph, rather than 50-60 mph as originally anticipated and rainfall totals about an inch from the Carolinas to Maine — right on the coast.  Most areas will get less than half an inch, although many areas will see rain mixed with snow.  Peak rain indicated eastern DE and southeastern NJ — about one inch.

The Euro (ECMWF) numerical model has shifted the low pressure center about 50 miles east and farther offshore. This allows the snow band that had previously been in central PA and NY to also move eastward by about 50 miles. How much of the indicated snow will be a rain/snow/sleet mix remains a question. Image: StormGeo

Unfortunately, there’s plenty of bad news to report and it started this morning with many areas of the New York Tri-State region dipping into the 30s for overnight temperatures. Remember, many of the country’s heartiest residents are still without power and heat and, in many cases, housing. The cold is only the beginning. As the nor’easter approaches, the wind should start to pick up tonight, the rain moves in tomorrow midday, then the snow by tomorrow night (yes, snow). All the while, the winds continue to build.

Snow had not been part of the forecast — at least not part of the forecast for coastal New Jersey, New York City and Long Island, but it is now. As the low tracks 50 or so miles farther east, the snow belt that had been more inland is now also 50 miles farther east. Yet with temperatures as they are, a heavy, wet snow — likely mixed with rain and perhaps sleet — is expected, rather than purely a snowfall event. This makes for messy, messy conditions while clouding the accumulations aspect of the forecast.

Lastly, let’s not forget the tides — and there are two factors to consider. First, the approaching nor’easter and the onshore winds will drive significant tides higher than normal. On our graphic below, the indicated tides are above normal. Consider the easterly winds driving Atlantic waters westward across Long Island Sound, funneling into the East River, coastal Connecticut and western Long Island. Places like New York’s LaGuardia airport on the north shore of western Long Island, already submerged by Hurricane Sandy, will have to batten down the hatches again.  As one of the most dramatic examples, tides in Bridgeport, CT are expected to be 4.5 feet above normal and when high tide occurs at 1 PM tomorrow and total tidal surge is expected to reach 11.5 feet.

Estimated tides above normal. Image: StormGeo

And there’s one more tidal consideration: coastal barriers. Mother Nature has provided coastal barriers to approaching ocean storms since Day One, but with each passing storm coastlines change and coastal barriers are marginalized or disappear altogether. With time, we learn to account for the new parameters and adjust as needed. However, Hurricane Sandy was only last week. Not only have coastal barriers been severely damaged (or totally destroyed), but we’ve not had time to adjust and prepare. It’s a new paradigm that could result in additional losses to property and life, if not accounted for.

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