Flooding

November 14, 2023 Outlook: South Florida flooding risks increase on Wednesday, while a separate Caribbean system makes a brief attempt to develop

One-sentence summary

Two separate systems are on the board, with one (non-tropical system) bringing heavy rain to Florida tomorrow and then heading off to the north, while another disturbance in the Caribbean has a chance to form before racing past Jamaica, Cuba, and Hispaniola later this week or weekend.

Florida flooding: Metro South Florida at risk for considerable flash flooding on Wednesday

Just a quick update this evening on what’s happening in the world of weather, and we’ll start in Florida. Areas just north of Miami have seen some heavy rainfall today, with two bullseyes of 4 inches or more, the first near Davie and the other around Pompano Beach, where over 5 inches has fallen.

Click to enlarge for impressive rain totals today north of Miami and west of Fort Lauderdale. (NOAA/RadarScope)

As showers diminish tonight, a quiet period will unfold before another, more widespread round of rain and storms tomorrow. This one will be capable of significant rain totals in excess of 4 to 6 inches to as much as 8 inches or even more tomorrow for parts of coastal, urban South Florida. Because of this, the NWS Weather Prediction Center has Miami-Dade, Broward, and portions of Palm Beach County under a moderate risk (level 3 of 4) for excessive rainfall and flooding risk on Wednesday.

A moderate risk (level 3 of 4) is posted for southeast Florida on Wednesday, as repeated rounds of heavy rainfall are possible, leading to more significant urban flooding. (NOAA)

Intriguingly (and somewhat confusingly), all of this may congeal into an area of low pressure off Florida’s east coast that has a low (albeit not zero) chance of developing into a tropical system as it races north and east. This is *not* the same system we’re watching in the Caribbean, but this one may produce a nor’easter type impact in eastern New England or Atlantic Canada by the weekend, including a chance of heavy snow on the back side of the storm for portions of Quebec, New Brunswick, or northern Maine.

Heavy snow is possible in portions of northern Maine and eastern Canada on the backside of this developing storm near Florida, as it comes north this weekend. (NOAA)

Tropical Update: Caribbean development remains possible later this week

Meanwhile, we continue to see at least the chance that a late season tropical system will form later this week in the Caribbean. The good news is that both the GFS and European model have tended to reduce the odds of anything significant developing.

Disorganized thunderstorms in the southwest Caribbean may develop into an organized system before it races north and northeast out to sea by the weekend. (Weathernerds.org)

So what was already a low chance of a significant storm is now quite low. Certainly heavy rain is possible, if not likely across the Caribbean, but getting this thing to depression status or even TS Vince, will take some effort. Can it get there? Sure, but I’m not sure it’s the most likely outcome. Regardless, interests in the central and western Caribbean should continue to monitor this thing until it passes.

September 29, 2023 Outlook: Atlantic ballet and non-tropical flooding risk in NYC metro

In case you missed it yesterday, we had our first real non-tropical post in which we discussed the ongoing salt water intrusion issues in Louisiana related to low-flow of the Mississippi River. While today’s post functions as an outlook, we will also discuss the developing flooding situation for New York City.

One-sentence summary

Philippe and Rina will dance, with Philippe eventually taking over as the dominant system, lifting into the Atlantic, while today we also check in on flooding in New York City.

Tropical Outlook: Philippe & Rina dance, while the rest of the basin settles down

Philippe & Rina

These two. Tropical Storms Philippe and Rina are now unable to be dissociated from one another, as we are seeing the Fujiwhara effect play out in real time. The two storms will interact and probably repel one another, with Rina likely taking a backseat to Philippe.

Philippe and Rina will track near each other with Philippe most likely to become the dominant system in the Atlantic before turning north. (Tomer Burg)

Basically, Philippe will stall, Rina will sling shot over the north side of Philippe, turn north and dissipate, and then Philippe will begin moving out to sea again. There has been a good deal of model uncertainty, particularly with respect to Philippe’s future intensity. And that is normal for a Fujiwhara interaction. When two storms engage like this and are this close together, inherent uncertainty increases, and that leads to a bit of forecast uncertainty. It’s becoming more likely however that Philippe becomes a stronger storm that pulls north, and I wouldn’t be to see the National Hurricane Center bump up their forecast intensity as it moves north into the open Atlantic.

Philippe and Rina will dance around each other over the next 4 or 5 days before Rina likely dissipates and Philippe becomes a larger storm over the open Atlantic. (Weathernerds.org)

As we’ve noted through the week however, even in the unlikely event that one of these systems ends up in the islands, it will be on the lower end of intensity and unlikely to create too much trouble. But confidence seems to be building in a no-impacts scenario. Both of these systems should be on their way out by later next week.

What else is out there?

Throughout the week we’ve also told you a bit about potential upper low or weak tropical development off the Southeast coast next week. Support for that has faded as a pretty decisive autumn cold front sweeps across the Southern and Eastern U.S. later next week. Finally! The hope would be that this leads to quieter tropics for a time. The season is by no means over (though for the northwest Gulf and Cabo Verde region it probably is), not with record warm water temperatures out there, but the pace should finally slow a bit. We’ll have more on this next week.

Metro New York City flooding underway

A few flash flood warnings have already been posted for the New York City area this morning as heavy rains stream into the area. Most of the City outside of the Bronx has seen some flooding with 1 to 3 inches of rain so far and the potential for a good deal more to come.

Heavy rain will continue to push into New York City and Long Island today, setting up a fairly substantial flash flooding event in that area. Travel to NYC area airports will likely be impacted through afternoon (RadarScope)

This should continue the flash flooding threat across northeastern New Jersey, New York City, Long Island, and southwest Connecticut. It’s likely that the heaviest rain will fall somewhere between Islip on Long Island and Newark, NJ. The worst conditions will be this morning into early afternoon with gradual improvement this evening.

The Weather Prediction Center arm of the NWS has set a moderate risk (level 3 of 4) for excessive rainfall and flooding in the Tri-State area around NYC. (Pivotal Weather)

Some places could see in excess of 3 or 4 inches more rainfall which will likely lead to considerable street and some local creek or river flooding. Be safe in the New York City area today, and if you’re traveling that direction, be prepared for some delays and hassle.