Flooding risks grow between Philadelphia, New York City, and southern New England Tuesday

In brief: A potentially significant flash flooding event may unfold between the Hudson Valley and Philadelphia on Tuesday, with some uncertainty remaining on exactly who will see the most rain. Flood watches are posted.

Keeping the focus on the Northeast this evening, we are setting the stage for a potentially impactful day of flooding risk Tuesday from North Jersey, across New York City, and into southwest New England and southeast New York. The table was set today with some slow-moving torrential downpours in Rockland County, NY and Passaic and Bergen Counties in New Jersey.

Radar estimates of total rainfall through just before 7 PM ET on Monday. (WeatherFront)

Spring Valley, NY, just near the intersection of the Garden State Parkway and New York Thruway and Ridgewood in Bergen County, NJ seem to have seen the most rain with radar estimates around 3.5 inches.

We go through again this tomorrow but on a larger scale. The area was upgraded to a moderate risk of excessive rainfall (level 3/4) on Tuesday from northeast Jersey to just south of Albany.

(NOAA NWS)

Storms will move across the Poconos and Catskills in the late morning, spreading east through the afternoon. There’s some debate right now if storms will get going around early to mid afternoon or mid to late afternoon across the NYC Metro area. Some of the more recent high resolution model guidance seems to have slowed things down a bit in terms of the onset. But there is still some modeling that favors storms increasing pretty quickly tomorrow.

Either way, as the upper disturbance responsible for this mess closes off, the forward progress of rain will slow and more widespread rain will develop on the northern side of things. That’s why we could be talking about a radar image that looks similar to this tomorrow evening.

Forecast composite radar from HREF ensemble Tuesday evening. (WeatherFront)

In addition to this broad upper support for rain, there’s going to be an influx of moisture converging over New Jersey, New York, and New England.

Moisture converging over NJ, NY, and New England Tuesday evening. (Plymouth State University)

Whatever happens, there will likely be very heavy rain somewhere between Philly and Albany tomorrow afternoon and/or evening. There’s a pretty curiously high probability of risk of 5 inches or more of rainfall over 24 hours from the HREF model, which ensembles multiple high-resolution models.

Some parts of the Lower Hudson Valley are in the 70% or greater risk of 5 inches or more of rainfall through tomorrow night. (WeatherFront)

The Lower Hudson Valley seems to have the highest odds, but there are not so insignificant probabilities south of there toward Philadelphia or northern Delaware also. Extreme western Connecticut is also on the edge of these higher probabilities too.

While many parts of New Jersey have been dry, the area around New York City through southwest Connecticut has seen a lot of rain in the last 7 to 10 days and the onset of flash flooding may occur a bit faster than usual given these totals. Flood Watches are posted around this region, and folks should be prepared for a bit of a rough go of it tomorrow afternoon and evening.

Forecast NBM model rainfall through Thursday evening. (WeatherFront)

Be safe, and don’t drive through flooded roads!

Quiet tropics, but watching another flooding risk in the Northeast this week

In brief: The tropics look quiet over the course of the next week or two. Meanwhile, a stubborn, slow-moving storm is likely to bring heavy rain and some flash flooding back into the Northeast this week, perhaps into Upstate New York and southern New England.

Just a quick editor’s note for you to let you know that I am now officially a Nutmegger, or a resident of Connecticut in the Westport area. We discussed this at Space City Weather last spring as to why I was relocating from Houston, but in the interest of transparency, if there is an East Coast bias in some of the writing here, this is why. I will try not to do that, and obviously with hurricanes and tropical systems, those will remain the primary focus here.

Tropics on pause for a bit

The good news to start this Sunday is that the tropics are taking a breather after Bertha last week.

Rainfall over the last 7 days ending Sunday morning. (Pivotal Weather)

The next couple weeks look mostly quiet. There is some chance that this week’s nonsense off the East Coast could congeal into something briefly that heads out to sea, but overall we expect the Atlantic, Caribbean, and the Gulf to behave through the early days of August. We’re approaching the seasonal ramp in historic activity now, so the stakes get a little higher by about mid-August. For now, we’re good.

Northeast flooding risk

A disturbance is going to track on the downstream side of a major Plains ridge this week, across the Great Lakes and into the Northeast. As it does so, the upper level disturbance will basically close off over Western New York and work across Southern New England, eventually pulling out by the end of the week or weekend. Slow moving, closed off upper level low pressure systems are always a headache, and this one should be no different.

Abundant atmospheric moisture hangs around through the end of the week. (Pivotal Weather)

Areas from the Mid-Atlantic into New England and New York should see abundant atmospheric moisture, especially on Tuesday and into Wednesday which should translate to heavy rainfall potential with showers and storms pretty widespread. The slow moving nature of the front and upper level storm system, as well as the potential for a coastal low will likely prolong the rainfall chances perhaps into Thursday and Friday as well.

European model forecast rainfall through Friday evening. (Pivotal Weather)

As of right now, it looks like Tuesday may be the worst day in Upstate and Western/Central New York and the Mid-Atlantic. Tuesday night into Wednesday may be the worst in New England. When all is said and done by Friday, rain totals should be anywhere from 1 to 5 inches, with a few locally higher amounts possible. Spread out over a few days, this will cause some minor flooding, but if a lot of this hits Tuesday into Wednesday, we could be talking about locally more serious flash flooding concerns, depending on exactly where that heaviest rain falls. Much of the region is in a slight risk (level 2/4) for flooding on Tuesday and Wednesday.

Flooding potential is highest from eastern Pennsylvania into New England. (NOAA)

So, just something to be aware of. I imagine we will see a handful of flood watches get issued tomorrow in more flood-prone areas from recent rainfall. At this time, severe storms are not likely. More to come as I’m able!

Bertha hopscotching the western Gulf Coast, heading for its demise tomorrow

In brief: Bertha is skipping along the western Gulf Coast as it heads toward a Texas finish. Impacts will be modest with some welcome rains in South Texas and a few gusty downpours north of there.

To Bertha’s credit, it has managed to hold on and cling to life, albeit barely it seems. This is more like a glorified blob or what we might call an MCS (thunderstorm complex) than a tropical storm, but even maligned tropical systems deserve love too.

(WeatherFront)

Bertha’s center is displaced far from the bulk of its storms, which are currently in the southwestern most blob off the middle Texas coast. Shear continues to pester Bertha, keeping it totally off-kilter, as does drier air over land, hence this “halficane” type look. While some of the elevated oil platfoms offshore have seen gusts of 60 to 80 mph since midnight, the bulk of the action is not quite making it to the surface and current maximum wind gusts are 15 to 25 mph from Galveston through New Orleans.

The bulk of Bertha’s rain is falling over the open Gulf, with a cluster of rather nasty looking storms hugging the northern fringe of the rain shield.

Rain is primarily headed for the Middle and Lower Texas coasts. (WeatherFront)

The bulk of this rain is going to push into the Middle and Lower Texas coasts, with the majority of it likely evaporating once it gets well inland. Hill Country does not need to worry about this, and South Texas is the one part of the state that could really use some rain.

Forecast rain through Sunday. (WeatherFront)

The yellow on the map above shows about 1 inch rainfall totals extending from near Matagorda Bay through Corpus Christi to just south of Laredo and some higher totals once it interacts with the mountains in Mexico. For the Houston area, I wrote about impacts earlier at Space City Weather but they’ll be mostly minor.

But, for the Texas and southwest Louisiana coasts, we’ll likely see some gusty downpours over the area this afternoon as Bertha’s close approach interacts with daytime heating. The steadier rains will increase today south of Matagorda Bay and into the Corpus area. Wind gusts could top off in the 40s mph in spots on the immediate coast but more than likely lower than that, especially as you work inland from the beachfront.

And we can then tie a ribbon on Bertha.

Beyond Bertha we’ve got nothing really in the Atlantic to discuss. A few models are showing risk of a developing system off the Southeast that would quickly scoot out to sea next week. I wouldn’t worry a ton about that one. More tomorrow.

Bertha beginning to slowly decline with very modest impacts to Louisiana and Texas expected

In brief: Bertha is beginning to slowly weaken as it drifts toward Louisiana. Some rain (not a whole lot) is likely in South Texas as Bertha or its remnants approach tomorrow and tomorrow night. Bertha’s remnants are expected to keep moving west to the Pacific side of Mexico by the weekend.

I am short on time today unfortunately, so we’ll keep this brief.

(NOAA/NHC)

Bertha is struggling this morning. The thunderstorms are displaced far, far from the center.

(WeatherFront)

Northeasterly shear seems to be hitting Bertha pretty hard this morning, and winds have dropped from a maximum of 60 mph to 50 mph. Bertha’s future track is relatively unchanged today, with most ensemble members tracking Bertha either along the coast or a little bit offshore.

Google Deep Mind ensemble tracks. (Tomer Burg)

The majority kill off Bertha entirely before it gets to the Texas coast, while a handful keep it going as a depression into South Texas. Either way, Bertha is unlikely to strengthen any further, even if it tracks offshore more. Bertha is also expected to keep moving, with the remnants arriving on the Pacific side of Mexico by later in the weekend. In other words, we do not expect hell to be unleashed on Texas in terms of heavy rainfall, thankfully.

5-day rainfall totals. (Pivotal Weather)

Also, with Bertha’s thunderstorms displaced to the south, this means that as it comes into Texas, it’ll send those rains down to the Middle Texas Coast and hopefully the Corpus Christi area. Far south Texas has not seen a whole heck of a lot of rain this month, so this would be mostly welcome. Hill Country is not expected to be impacted by Bertha. Houston and eastern Texas into western Louisiana will see some indirectly related storms tonight. I wrote about that over at Space City Weather this morning.

But for the most part, as expected, Bertha’s impacts will be primarily nuisance and mostly minor over the next few days. We’ll update later should anything else change.