In brief: Our nor’easter is winding down over the Northeast, so we take a look at some challenges this storm posed and some stats. Next, our attention shifts to Arizona, New Mexico, and Texas where significant rain may produce serious flooding in some areas, particularly north of I-10 from Arizona through Texas and west of I-35 in Texas, back toward Hill Country and in the DFW Metroplex.
Nor’easter wrapping up
This nor’easter was interesting, both in terms of how it unfolded and how it was perceived ahead of time. Most nor’easters do have an element of disparity that’s usually measured in variable snow totals or which part of the coast sees the highest winds & waves. This one had quite a dramatic disparity both in terms of where the strongest winds occurred, the most power outages occurred, the worst tidal flooding occurred, and even where the heaviest rain fell.
For coastal New Jersey, this was a bad event, full stop. Some of the worst tidal flooding those areas have seen in some cases almost since Hurricane Sandy in 2012. In every community, there are places that “typically flood” during storms like this. Having grown up outside Ocean City, NJ, I recall this vividly. However, this flooded a lot of places that don’t usually flood.
I’ll speculate that this was worse than perhaps anticipated in Jersey partially because tides and coastal flooding had been occurring for a couple days prior to the nor’easter forming, as well as the full moon. That’s me thinking out loud.
For Long Island, it was a solid moderate to locally major flooding event. For New England, it was a locally moderate event but mostly minor.
The heaviest rain, as expected, did fall south of Boston and east of Providence. A strong credit to the models for zeroing in on that days in advance and sticking with it. Correctly.
What was more interesting to me were the threads of disparity in terms of qualifying how bad a storm this was going to be. We tried to emphasize the coastal flooding aspect of things here. Our Thursday post emphasized that the flooding could be substantial in the back bays of Jersey and Delaware. That seems to have been correct, and it was also being emphasized by local NWS offices ahead of time. We did say on Thursday that “While this shouldn’t be a historic tidal flooding event by any means, it’ll be notable for the region.” That may have been a little bit underdone (while not a top 3 event in most cases, this did crack the top 5 to 10 in some locations).
But in some cases, folks were describing this as a historic storm, as if everyone from Delaware through Massachusetts was going to experience equally bad effects. A mutual follower here in inland Connecticut even messaged me asking why their apartment complex was saying the storm was historic. One thing I learned living in Houston for 14 years was that nuance matters in big events. A lot. A really awful storm for someone could be an absolute nothingburger for most other people. Threading that needle is difficult to message, and I’m not sure the overall perception of the storm here accurately conveyed that nuance.
Also, the only thing particularly abnormal about this storm was the calendar. Nor’easters like this don’t usually happen in September. They have in the past, of course, and they will happen again. But it’s not usually typical this early in autumn. There’s been a lot of conjecture about this storm being tropical potentially (including from us, though we said there was a chance, but that it would probably fall short) and conjecture about climate change “supercharging” the storm. As someone who supports climate change science and invoking it at times where it’s very clearly evident, I just don’t know if this was the right event for that sort of discourse. Though I suppose sea level rise making moderate flooding verify as major flooding or something like that is a valid discussion point. Because that is happening. Whatever the case, that’s my “get off my lawn” commentary today.
Polo rainfall risk
Hurricane Polo is back to a category 3 storm this evening.
Polo will turn northeast tomorrow and move ashore in Baja and then into mainland Mexico by the time we get to Tuesday morning. From here, copious amounts of moisture will surge into the Desert Southwest and eventually the Southern Plains and Texas. The first big concern will occur tomorrow night and Tuesday in Arizona and New Mexico. Here, precipitable water levels, or the amount of available moisture in the atmosphere will skyrocket to about an inch above normal, which is very strong for this part of the country. Not everyone in these areas will see copious amounts of rain, but there will be portions of Arizona and New Mexico that will be at risk for severe flash flooding.
The Weather Prediction Center has hoisted a moderate risk for both Monday and Tuesday in the Desert Southwest, mainly north of I-10 in anticipation of numerous reports of potentially significant flash flooding. This is a very dynamic setup, so we could see some areas pick up as much as 3 to 6 inches of rainfall, while others do a half inch to an inch.
There is potential that we see Tuesday get upgraded to a “high risk” of excessive rainfall in New Mexico. The Southwest has actually seen quite a bit of rain this September, so the combination of saturated grounds and a top-end moisture event coming through is a recipe for serious flooding risk. I don’t want to overstate things, but this may be the most serious tropical system related impact in the Continental U.S. this year. Folks in the Southwest will want to monitor this event closely and be ready to act. If you can contact anyone who may be backpacking or vacationing, they should also know this is a potentially serious event.
Keep an eye on this in the Texas Panhandle as well. Speaking of…
Texas & the Plains
Beyond the Southwest, the situation gets even more complex in the Plains. The moisture from Polo and a slow or stalling cold front will probably focus repeating rounds of rain from Hill Country into North Texas. Those areas are already under a moderate risk (level 3/4) for flash flooding on Wednesday, and that will likely extend into Thursday as well.
Rain totals are likely to end up in the 4 to 8 inch range from south of San Antonio through Dallas and perhaps up toward Durant, OK through Friday. There is a chance that some areas see as much as 10 to 12 inches though, as we know Texas flood history is littered with these types of remnant Pacific hurricane events.
Folks in Houston that read our site will want to follow Space City Weather for the latest. Eric or myself will keep you posted, but for now the more serious flooding concerns are likely to stay north and west of the Houston region. Texas folks in Hill Country and the Metroplex should monitor the next couple days of forecasts very closely and be prepared for disruptions on Wednesday and Thursday.
Elsewhere
Fay continues in the Atlantic, while Gonzalo has mercifully dissipated. Another area northeast of Bermuda has about a 60 percent chance of developing over the next couple days before dissipating. Otherwise, it remains calm.
Other than that, Hurricane Nolo has moved away from the Hawaiian Islands now and will skirt west of them over the next couple days, bringing rough seas.
