Tropical Tidbits from the Tundra

Quiet Atlantic, Invest 90E forms in the East Pacific

By: Levi32, 6:11 PM GMT on May 30, 2009

Tropical Tidbits from the Tundra is up and running. If anybody has any feedback, suggestions, or corrections to be made, please let me know.

The Atlantic remains quiet today, and the models are not forecasting any disturbances to form in the near future. The GFS has been trying to form areas of low pressure along some tropical waves that will be passing through the tropical Atlantic during the next few days, but the ITCZ is still situated pretty far south due to abnormally high pressures over the Central Atlantic. These lows will be stuck at about 5N which makes it hard to spin up because the Coriolis Force there is weak so close to the equator. This is also forcing almost every tropical wave into South America, so for now they are of no concern, but that will change by the end of June and early July. The rest of the Atlantic is protected by the sub-tropical jetstream, which is also further south than normal, and is creating too much hostile wind shear for anything to develop yet.

If you want action then you'll have to try to find it in the Eastern Pacific, where an area of convection associated with a tropical wave has been dubbed Invest 90E, the first invest of the East Pacific hurricane season. Thunderstorm activity has continued to increase, mainly behind the wave axis which is situated at about 99W extending from 3N to 14N.

A broad mid-level circulation and an upper-level high are both situated right over the wave axis, but the new area of low pressure being put on the 12z surface map this morning is further east at about 97W. There are several different mid-to-low-level swirls within this broad area of convection. The only fairly well-defined surface circulation shown by QuikSCAT is displaced well to the east of the wave near 94W, 11N, and is very weak at that.

Despite the disorganized nature of 90E, it is in a very favorable environment for development with wind shear below 10 knots, great upper diffluence thanks to the upper high over the system, and SSTs of 28-30C. Models forecast the system to move towards the WNW for the next several days, and the GFS tries to form a tropical cyclone out of it. I still think there is decent potential for this system to develop further, and it shall continue to be monitored.

We shall see what happens!

NASA High-Resolution Visible Loop of 90E

Invest 90E:

East Pacific/West Atlantic visible satellite: (click image for loop)

Invest 90E Model Tracks:

TD 01L moves on; watching Eastern Pacific

By: Levi32, 5:00 PM GMT on May 29, 2009

Tropical Tidbits from the Tundra is up and running. If anybody has any feedback, suggestions, or corrections to be made, please let me know.

Tropical depression 01L has had its day and is now moving on into the north Atlantic as it turns extratropical. The NHC never did name it.

Our bored eyes now turn away from the hostile Atlantic and into the more favorable Eastern Pacific for development. A tropical wave embedded within the ITCZ at 95W below 10N is enhancing a broad area of showers and thunderstorms that have been growing since yesterday. There is a little bit of mid-level turning going on, and the area is in a nice spot for development. Wind shear over the area is 10 knots or less, and an upper high is sitting right over the wave. SSTs are running between 28-30C in the area, and extend WNW in the wave's path. The GFS is forecasting a low to develop in this area by tomorrow and move WNW for the next 4 days.

I believe the potential for development in this area during the next 2 days is high, and it will continue to be monitored.

We shall see what happens!

East Pacific/West Atlantic visible satellite: (click image for loop)

TD #1 forms

By: Levi32, 3:57 PM GMT on May 28, 2009

Tropical Tidbits from the Tundra is up and running. If anybody has any suggestions or corrections to be made please let me know.

We have the first tropical depression of the 2009 Atlantic hurricane season. It formed from Invest 91L last night as the warm waters of the gulf stream allowed a small ball of convection to form over the center of the circulation, prompting the NHC to upgrade the system to a TD with 35mph winds.

TD 1 is being steered towards the NE at about 17mph by the southwesterly flow in advance of a mid-latitude trough, following the gulf stream. As long as it does, TD 1 has a shot at strengthening, but it won't be much if it does. The waters in the gulf stream are 25-26C, so strengthening to a minimal tropical storm is not out of the question. The NHC is following this reasoning, forecasting TD 1 to become TS Ana during the next 12 hours. After 24-36 hours TD 1 should begin to weaken as SSTs become cooler and the system starts to become extratropical and absorbed into a larger system.

Fortunately this is one of those fun out-to-sea systems that is not a threat to anyone, and again demonstrates that it doesn't have to be hurricane season to have tropical systems just about anywhere in the western Atlantic. However, this does not necessarily mean we will have a more active season than normal. Early storms do not usually have any bearing on how the rest of the season will turn out. They can give clues, but just because they're there doesn't mean we'll have a ton of storms from now on. For now we can sit back and enjoy this fish storm while it's here =)

We shall see what happens!

NHC Public Advisory for TD 1

NHC Forecast Discussion for TD 1

NHC official track forecast for TD 1:

TD 1 visible satellite: (click image for loop)

TD 1 model track forecasts:

91L wets NC outer banks

By: Levi32, 3:55 PM GMT on May 27, 2009

Tropical Tidbits from the Tundra is up and running. If anybody has any suggestions or corrections to be made please let me know.

Update 2pm eastern: Recon flight canceled

Invest 91L has become slightly more organized overnight. The circulation is now much tighter and well-defined, and small patches of light convection are trying to flare up near the center. 91L's best chance at becoming a depression will come as it passes over the core of the gulf stream just east of the outer banks of North Carolina, but SSTs there are only barely 26C and 91L has very little upper-air support. The only things it has going for itself is low windshear and ample moisture. If the 91L manages to get enough convection going over the gulf stream, they might think about upgrading it to a TD, but I doubt 91L will be able to pull it off. The NHC gives 91L a less than 30% chance of development.

Regardless of whether this gets upgraded or not, just as with 90L in Florida, the effects will be the same. Moderate rain and gusty winds will be the worst it gets for the outer banks today and tomorrow. 91L will continue north until it gets picked up by a large low pressure system moving through the area and will accelerate NE out to sea. The system will continue to be monitored for further development.

We shall see what happens!

Morehead, NC Radar:

Invest 91L visible satellite: (click image for loop)

Invest 91L model track forecasts:

Invest 91L forms, not a threat

By: Levi32, 7:08 PM GMT on May 26, 2009

The broad elongated area of low pressure southeast of the Carolinas was labeled Invest 91L this morning. The low has now closed off, but remains elongated towards the west with at least one other low-level vortex spinning vigorously and moving off towards the WSW. There is a broad area of scattered light convection over the COC, but it is nowhere deep enough or consolidated enough to form a tropical depression.

Invest 91L's chances for further development are very slim. The SSTs that 91L is transversing are only barely at or below TC threshold (hovering around 26C in the core of the gulf stream and 24-25C elsewhere). Also the upper-level environment isn't particularly conducive for significant development, with outflow confined to the NE quadrant and little upper-level divergence over the system. Wind shear is at about 15 knots and will increase as 91L phases with a mid-latitude shortwave trough moving into the eastern US.

Invest 91L is being steered to the north by a weak area of high pressure to its east. As 91L rounds the periphery of this high it will turn towards the NNE and eventually NE as it gets absorbed by an extra-tropical low. 91L will pass close to the NC outer banks but will stay out to sea, and bring nothing but a little rain and gusty winds to North Carolina.

Elsewhere in the tropics, the 2nd tropical wave of the year is moving through the central Caribbean, but everything below 20N is protected by the sub-tropical jet still blowing hard and giving no chances for TC development. It is still May folks.

The GFS is forecasting one or two more lows to form off the southeast US coast during the next 5 days, but these should be cold-core in nature and will quickly move NE and out to sea.

We shall see what happens!

NOTE: 4 days ago, I was introduced to Google Sites. I've never done anything at all with websites, but I found it quite fun, so I decided to use Google Sites to create a website to consolidate my blog, all my main links, and all current information on the worldwide tropics into one place. Therefore I am proud to launch Tropical Tidbits from the Tundra. Please feel free to check it out, and I hope that anyone who does will enjoy it and find it useful.

Obviously the Atlantic Ocean has most of the attention and information, but I did my best to include links and info for all tropical ocean basins around the world, so that anybody threatened by a tropical cyclone can find relevent information for their area. Again I've never done anything like this before, so I'm sure there are some quirks and mistakes, and I am open to any suggestions anybody may like to give. I will add new links or features whenever my mind thinks of them lol. Anyway......enough advertising =D

^Click for Loop^

NASA High-Resolution Visible Loop of 91L

Invest 91L Model Tracks:

91L forming in the Bahamas?

By: Levi32, 4:09 PM GMT on May 25, 2009

A trough of low pressure just east of the Bahamas has a good chance at becoming Invest 91L during the next two days. Take a look at this nice visible loop:

NASA High-Resolution Visible Loop of the Bahamas

You can see the circulation starting to develop from the mid-levels down. It should make it to the surface by tonight. The sub-tropical jet is punching in dry air from the west, which can be seen in the visible loop as an absence of low-level cloud streets which are present to the east of the system, but not to the west.

Wind shear is currently 25-30 knots over the system, but this will change as it moves north into gradually less shear as time goes on. Upper diffluence is currently helping to sustain the thunderstorms east and north of the developing low center.

This low is being steered to the north by a weak upper-level high-pressure system to its east. This motion will continue over the next 3 days, and as the system rounds the periphery of the high it will gradually curve towards the NNE, passing close to North Carolina, but it remains to be seen how close. This system will most likely remain out to sea and be of no threat to the Carolinas except possibly some rain depending on how close it skirts the coast.The GFS does take this warm core over the gulf stream, which is just warm enough to support a tropical system with SSTs right around 26C.

The NHC needs to wake up. They won't admit what happened to them with 90L, and here is another chance for that to happen again, as the gulf stream is warm enough to support a warm-core system. These are signs of what the rest of the season is going to be. Developments like this close to the coast are going to be a theme throughout this season. Everyone should be aware of the potential threats. Just because the season is forecast to be average doesn't mean we can't have a large percentage of landfalls on the SE coast, or the Caribbean. The warning signs are there right now, with 2 systems developing before the season even starts.

We shall see what happens! And HAPPY MEMORIAL DAY to all our veterans!!!

^Click for Loop^

NASA High-Resolution Visible Loop of the Bahamas

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Tropical Tidbits from the Tundra

About Levi32

Masters student in tropical meteorology at FSU. Raised in Alaskan blizzards, but drawn toward tropical cyclones by their superior PGF.

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