Tropical Storm Ana (Or Sub-Tropical) Could Be Born This Week

invest 90l projected path

Unfortunately, I don’t have the time to write a detailed discussion today, but at the least, I want to share some different graphics with you. You can read my previous forecasts on the site on the tropical/sub-tropical system that will likely develop later this week. If you’re just simply needing to know what to expect, this article should suffice.

The first graphic is just a visible satellite image. If this were to be put into motion, you’d notice a very broad circulation just east of Florida near the Bahamas. This area of disturbed weather should continue to organize throughout the week, eventually developing into a sub-tropical or tropical low that could be named Ana.

visible satellite

Invest 90L is simply the low pressure area that is currently being investigated, which could be what eventually becomes Ana. The next graphic shows you the sea surface temperatures, and as you can see, there’s a narrow stream of very warm waters being pulled up by the Gulf stream just off the East Coast. This could be responsible for enhancing development; however waters are cooler on the immediate coast, which might weaken the storm once it approaches land especially if it becomes fully tropical.

gulf stream

The next graphic shows you where the various forecast models have this system going. As you can see, most of the guidance moves this near the Carolina coast, which I currently agree with.

invest 90l projected path

The next graphic shows you how strong each model has this system getting. If the lines move into the lightly shaded grey region, that indicates tropical storm force winds. Some models strengthen this system quite nicely while others don’t.

tropical storm ana

Anyway, the regions most impacted will be along the SC/NC coast and possibly felt as far south as the GA coast later this week/weekend. The main threat will be heavy rainfall and in some regions, possible tropical storm force winds with higher than normal storm surge. Keep in mind that if this storm becomes fully tropical, the strongest winds will be more concentrated around the core of the storm, and if it remains sub-tropical, the winds will be a bit more spread out from the center but weaker.

What You Need To Know About The Tropics

tropical storm

I must admit that this possible tropical/sub-tropical system definitely has my attention, and if everything comes together just right, we could have our first named storm of the Atlantic hurricane season later this week. This is definitely NOT something to panic about, but this is a system that has a decent shot at becoming something notable.

I broke down some of the meteorology the other day, and I am going to attempt to further explain the situation currently at hand. If you look at the satellite image below, you can see the broad area of disturbed weather over Cuba and the Bahamas, which is due to an upper-level trough digging over the region. This is creating favorable conditions for cloudiness/storminess over the area, and eventually, a surface low should begin to develop and pull northward. That will be the storm to watch.

satellite image

A trough is currently moving over the western United States, which will really begin to dig into the southwestern United States and Baja California this week. In response to this building trough out West, a ridge is going to build and strengthen farther east over the eastern half of the U.S. into Canada. The reason why this is important to note is that this ridge is going to trap that low pressure area off the Georgia/South Carolina/North Carolina coast and not allow it to quickly slide north/northeast.

tropical storm

I mentioned the other day that there is a tongue of very warm waters being pulled up along the East Coast by the Gulf stream, and since this storm is going to get trapped, it will likely sit over those warmer waters for several days. Given that the environment will be conducive for the further strengthening of this system, I wouldn’t be surprised if we have Tropical/Sub-tropical Storm Ana on our hands by mid to late week, meandering barely off the Carolina or Georgia coast.

sst anomalies

The main threat right now will be very heavy rainfall along the coastal regions from Florida to North Carolina later this week. While the forecast models diverge on how strong this system could get, I can’t rule out the possibility of tropical storm force winds along parts of the Carolina coast.

As the trough out west pushes eastward, this storm could eventually get pulled into the coast, bringing heavy rains and gusty winds farther inland later in the week into the weekend.

If you’re located anywhere from the eastern coast of Florida through South Carolina/North Carolina, keep a close watch on everything. Again, there’s no need to panic by any means; however, this current weather situation will likely require me to put out future updates on the site. The overall pattern DOES favor sub-tropical/tropical development off the Southeast U.S. coast this week, and I will do my best to put out additional updates.

Possible Tropical Troubles Along East Coast Next Week?

tropical storm ana

By now, the majority of you have probably heard about the possibility of a tropical/sub-tropical system developing off the East Coast next week. It’s not uncommon to have a pre-season tropical system to develop, and it doesn’t necessarily mean that pre-season activity is a sign that the upcoming season is going to be active. However, just because a tropical or sub-tropical system develops early doesn’t mean it can’t bring heavy rain, higher surf, and strong winds just like during the normal Atlantic hurricane season (June 1st – November 30th).

The Setup:

A frontal boundary pushed past Florida the other day, bringing the area heavy rainfall, and now this old boundary has stalled below the state across the western Atlantic. You’ve heard me talk a lot about the active sub-tropical jet stream over the past few months, which is a column of strong winds in the upper-levels of the atmosphere and has been responsible for transporting a lot of moisture into parts of the United States this spring. That’s why many of you have been inundated with heavy rain this season.

In fact, this active jet stream is currently stretching across the entire Atlantic and into Europe, bringing many areas around the world wetter conditions. This sub-tropical jet stream is going to carry over a piece of energy across the Gulf that will eventually be responsible for triggering the development of a surface low pressure system along that stalled front in the western Atlantic/along the southern East Coast. This is the system to watch!

sub-tropical jet stream

It’s difficult to determine if this system will be fully tropical or sub-tropical, but the overall impacts should be about the same regardless. A sub-tropical system has the characteristics of a tropical system (e.g. tropical storm, hurricane) and a mid-latitude cyclone (e.g. a low pressure system with an associated cold front, warm front, etc.). I’m not going to take the time to get into any more detail on the differences between the two.

Once this low pressure system develops, it could strengthen as it slowly moves northward along the southern East Coast. A trough is currently moving off the East Coast (which has been responsible for the nicer/cooler weather for many), and a ridge (blocking high pressure) is going to build over much of the United States in its place. Since this is going to happen, our storm is not going to be able to go anywhere and will be suppressed to the south. This means it will likely meander off or along the coast for several days until it gets pulled farther north.

tropical storm ana

The sea surface temperatures in the Gulf of Mexico and along the East Coast are above average, and there is a tongue of warmer waters along the East Coast being pulled up from the Gulf stream. This could give this system the needed fuel to strengthen into the first named storm of the Atlantic hurricane season. That’s very uncertain at this point though.

sea surface temps

What To Expect:

This storm needs to track fairly close to the coast to have a decent chance of strengthening. The areas that will most likely be impacted with heavy rainfall and gusty winds will be from the Florida east coast up through South Carolina/North Carolina. Again, this storm will probably just sit along or over these regions for several days next week, and eventually a trough should move far enough east (maybe next weekend) to pull the storm farther up the coast, bringing heavy rain farther north along the coast.

As always, have a plan in place just in case. Although it’s early in the year, rapid strengthening can occur, and it’s definitely not impossible. Right now, it’s much too early for me to try to forecast actual strength, but I wouldn’t be surprised if this ends up being a decent tropical/sub-tropical system, which would be named Ana. Remember that forecasting the strength and exact track of a tropical system is difficult in meteorology, which is why you should always be prepared.

I’ll continue to keep everyone updated in the coming days.