#Invest area in the #Atlantic

As the sun rises over the eastern Atlantic this morning, media weather personalities are breathlessly generating gigabyles of content over an “invest area”. Here’s a quick overview. On the visual band image it’s hard to pick out the system …

click to embiggen. Notice the tilt of the terminator (the line between day and night) since we are so close to the summer solstice (June 21st), the maximum of the year at 23.5 degrees.

The global forecast models are all tracking some kind of organized low spinning up from this tropical wave in 4-5 days, and the US National Hurricane Center gives it a 50% chance of becoming a depression over the next five days. Here is the obligatory spaghetti map showing the major global track models … there is a remarkable consensus in the track given it’s not very organized yet:

Raw spaghetti. Do not consume until cooked.

The TLDR is a tropical depression will likely form this weekend or early next week as the system approaches Barbados, and there is the potential for a tropical storm to spin up from that as it makes its way across the southern Caribbean. There are no “magic words” in the NHC tropical weather outlook, so nothing specific to worry about at this point. Those in the Caribbean might want to double check your hurricane supplies and plans if your haven’t already, but again nothing to get excited about if you’ve done your pre-season prep.

Tropical update, storms across the US

Tropical Storm Blas has formed off of the west coast of Mexico. It is expected to stay offshore, becoming a hurricane later today before it encounters adverse conditions Friday and begins to decay. Other that some higher than normal waves shouldn’t be a problem. Elsewhere, two “invest” areas are being tracked by NHC, both near Central America. The GFS model shows the one off of Nicaragua (AL932022) moving across Belize/Yucatan perhaps reaching tropical storm strength. The outlook for one off of Costa Rica isn’t so clear, it will probably bring rains to the region but how organized it gets isn’t obvious yet. Here’s the map …

Tropical Outlook, 15 June 2022

Some strong thunderstorms wandered through coastal Georgia yesterday, caused some scattered damage. The NWS Local Storms Report database shows quite a few trees down and power outages across the region …

Red icons are thunderstorm damage

Wild contrasts in weather across the country. While there are record droughts in some areas (link to UNL Drought Monitor), in Montana and Wyoming Yellowstone National Park is closed (link to NPS) and the Yellowstone River is overflowing, causing significant damage. The North Entrance road that many visitors use to get into the park from the Montana side via Mammoth Hot Springs looks like this right now …

Central America Surrounded by Weather!

The system off of the west coast of Mexico has been upgraded to a tropical depression as of 5am this morning, making it the second storm of the East Pacific season (EP022022). It will likely strengthen into a tropical storm and perhaps minimal hurricane as it skirts the coast, but conditions are not favorable for any more than that, and most of the damaging impacts should stay offshore with the main impact being waves. Elsewhere, NHC has a 30% probability area behind EP02, and has increased the five day formation odds for the blob in the western Caribbean to 40%.

Central America Doomwatch, click to embiggen.

But there are no organized model tracks or “magic words” in the forecast as of yet. Most likely this will be a rain event in Central America, GFS shows a weak system drifting into the coast of Belize in this weekend, and spins up another system next week. This is typical behavior where an area is favorable for storm formation, and as systems move through it they have the potential to spin up. Some do, most don’t, so if you have prepared for hurricane season and have your plan and supplies organized (link to FEMA’s “ready” site), nothing to worry about.

Quick look at the tropics; nothing terribly concerning at the moment.

Most of the world is quiet from a tropical standpoint. There are a couple of areas on the US National Hurricane Center’s five day outlook. The one with the highest potential is just off the west coast of Mexico. Here’s a quick look at the areas tagged in the outlook …

NHC’s Five Day Outlook formation probabilities

The system off of Mexico might spin up into a depression over the next couple of days. The main model runs keep it just offshore, some upwards of a Cat 1 or 2 hurricane, but the ensemble runs have a bit of a “squashed spider” look to them. Once a circulation forms the forecasts should stabilize. The other two areas aren’t anything to worry about for a few days.

#Alex (AL012022) passing #Bermuda

Tropical Storm Alex (formerly Potential Tropical Cyclone One) is passing Bermuda today, causing some wind and rain but shouldn’t be anything bad unless something breaks that shouldn’t. Alex is already losing what tropical characteristic it had, and will be absorbed into the wider north Atlantic weather by mid-week. Here is the impact swath (winds over 40mph, the point at which you start to see big tree limbs break), probably a bit exaggerated due to the disorganized nature of the storm.

Tropical Storm Alex Damage Swath, click to enlarge.

#Alex finally forms

Potential Tropical Cyclone One finally became organized enough for the US National Hurricane Center to declare it a Tropical Storm Alex. Alex is well offshore now, with the last few showers departing The Bahamas, and looks to pass north of Bermuda tomorrow (Monday 6 June), still as a tropical storm but more than likely already transitioning to an extra-tropical system. Here is Alex as the sun rises over the Atlantic …

click to make larger.

PTC1/Alex was never really a traditional tropical storm, and in past years would not likely have been tracked. This presents a dilemma for those trying to figure out if hurricane climatology is changing. Better technology and changing criteria for tracking and warning means comparing 2022 with 2000, much less 1970, 1950, or 1920, is a major challenge. NOAA has been trying to do a reanalysis of the “satellite era” to try to identify tropical systems that were not in the data bases, and found 14 in the five years from 1966 to 1970. This is a major reason why you should be very careful when people say this or that weather system, or changing numbers, is due to climate change. In many cases we just don’t have the data to say. Now, that’s not an excuse to do nothing about human impacts on the environment (not to mention the many related resource and socioeconomic issues that are convoluted with this problem), but it does show it’s not simple or straightforward.

PTC1 on Saturday Morning (4 June)

Potential Tropical Cyclone One is still an unrealized potential, and shows no signs of organization before the associated mess of rain squalls moves past Florida. Here is what it looks like on InfraRed satellite (the sun isn’t up yet as I write this):

Click any image to embiggen.

There are actually several “centers” depending on how you define that, including the small convection-free swirl of clouds you can see in the center of the image. NHC thinks this mess will consolidate into a single center once it moves past Florida and The Bahamas, but they are off the hook for a real tropical storm. That doesn’t mean that some rain squalls with tropical storm force winds won’t pass by this morning, but more like the typical summer downpours and thunderstorms than a real tropical storm.

For being such a disorganized mess the track models and forecasts are remarkably consistent, taking it out parallel to the US Southeast coast towards Bermuda. There is still a chance that this will develop briefly in to Tropical Storm Alex before it gets there, but it will likely be short lived before conditions deteriorate and it becomes extratropical.

Raw spaghetti. Not for human consumption until cooked.

PTC1 still not a tropical storm

So far Potential Tropical Cyclone One can’t get it’s act together. It’s a very broad and disorganized system, and all of the rain and wind is displaced far to the east of the center, here from GOES East just before 5pm …

Click to embiggen

Here is the regional radar composite – Florida is getting a lot of rain already. It may well be that the rain will be ending before the storm itself actually passes over the state!

Multi Radar Multi Sensor composite at 5pm Friday,

The hurricane center is still thinking PTC1 will organize enough to become Tropical Storm Alex before landfall, which should just after noon tomorrow (Saturday). The biggest “threat” from PTC1, even if it does evolve in to Tropical Storm Alex, will be heavy rain. Here’s a link to NHC’s latest Key Messages regarding Potential Tropical Cyclone One (en Español: Mensajes Claves).

Elsewhere, just off the US east coast there is an area NHC is watching, but chances of development are small, and if something does spin up it seems at worst it would give Bermuda a windy day before moving out to sea.

Potential Tropical Cyclone One (AL012022) heads to #Florida

Potential Tropical Cyclone One is a large, disorganized system that is producing tropical storm force winds, but technically isn’t a tropical storm (more on that later). In terms of impacts, it should just be some wind and rain – here are NHC’s Key Messages regarding Potential Tropical Cyclone One. As a reminder, once a storm forms the “Key Messages” product is a nice summary of watches, warnings, and forecast. Here is my TAOS/TC impact estimate based on the 5am forecast. Bottom line is windy/rainy weekend for Cuba, south Florida and the northern islands of The Bahamas, minimal damage other than some trees down, scattered power outages, very scattered roof damage, that sort of thing. Economic impact should be transitory, under $100 million, and recovered quickly. Elsewhere the storm may cause rip currents along the Southeastern US coast next week.

Click to enlarge.

So what the heck is a “Potential Tropical Cyclone”? In the past these kinds of storms were not tracked and reported by the Hurricane Center until they met the formal criteria for being a tropical storm. That would mean a distinct (from other systems) warm core, closed circulation. The problem is that in some conditions a tropical storm can form from an otherwise disorganized disturbance before the system crosses land, and less than the normal time frame when watches are issued. This became more of an issue in 2010 when the lead time for a watch was increased from 36 to 48 hours, and a warning form 24 to 36 hours, and more storms were forming withing those time frames and people were not getting as much notice. So in order to give people warning and time to prepare, NHC starts advisories as a “Potential Tropical Cyclone” on systems that are forecast to become actual tropical systems. So like a lot of things in tropical meteorology, it’s a mix of actual meteorology, administrative issues, and emergency management needs.

Here is a handy reference to terms like PTC, tropical wave, tropical storm, etc., from the NWS Mobile, AL office. And here are the “new” (as of 2010) criteria for watches and warnings.

NHC Likely to start advisories, post watches for #Florida today for potential #tropicalstorm

Although still not well organized, and not in a great environment for development, the system off of Yucatan continues to move slowly northeast. Since it has a good potential to become at least a tropical depression or low end tropical storm, the hurricane center will likely start advisories and post watches later today as at least a “potential tropical cyclone.” At the moment the models aren’t terribly enthusiastic about the system, most keeping it at minimal tropical storm strength. Here is what the US GFS model shows for Saturday Morning at 8am, a disorganized minimal tropical storm …

850mb heights and winds (about 5000 feet above ground, a good indication of organization)

Some of the models don’t even form a coherent system (just a broad area of disturbed weather). In the map above you can see two distinct “centers” (the “L” symbols), indicating a very disorganized system. Here is what some of the models are showing as tracks, for a disorganized mess they are actually fairly consistent …

Computer Models as of 5am ET; click any image to embiggen. “Dispersion” is a measure of where a mix of models puts the storm each day. The tighter the ellipse, the better. The orientation shows the most likely direction of error.

Other than a lot of rain it’s not likely this storm will get organized enough to produce significantly damaging winds. Unless you’re just unlucky and a tree falls on your house, or something breaks that shouldn’t, this should be just a rain event for Cuba, Florida and The Bahamas. For the Southeastern US (Georgia and Florida), an approaching cold front that will bring rain Friday and early Saturday will have moved past, and the system (tropical storm or not) should stay far enough away to not cause any impacts other than perhaps waves and a risk of rip tides at the beach.