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The unnamed "TD Six"/"TS Erika," or Where Is The NHC? August 31, 2009 at 1:17 am

First, a couple of disclaimers:

1. this is purely fun intellectual speculation. I highly respect the tireless work the amazing folks down at the National Hurricane Center do all year long.

2. The NHC has had this to say about the topic of this post discussion:

SHOWERS AND THUNDERSTORMS ASSOCIATED WITH A BROAD AREA OF LOW PRESSURE LOCATED ABOUT 850 MILES EAST OF THE WINDWARD ISLANDS HAVE DECREASED DURING THE LAST FEW HOURS. HOWEVER…ENVIRONMENTAL CONDITIONS STILL APPEAR FAVORABLE FOR DEVELOPMENT…AND THIS SYSTEM HAS THE POTENTIAL TO BECOME A TROPICAL DEPRESSION DURING THE NEXT DAY OR SO AS IT MOVES WEST-NORTHWESTWARD AT AROUND 15 MPH. THERE IS A HIGH CHANCE…GREATER THAN 50 PERCENT…OF TROPICAL CYCLONE FORMATION IN THIS AREA DURING THE NEXT 48 HOURS. INTERESTS IN THE LESSER ANTILLES SHOULD MONITOR THE PROGRESS OF THIS SYSTEM.

So it’s certainly on the Center’s “radar,” so to speak.

However, my informal analysis of the system, dubbed Invest 94L, tells a different story: one of a tropical depression about to become a tropical storm (Erika, soon?).

Let’s back up for a second and look at the definition of a “tropical cyclone” according to the NHC’s “Glossary of NHC Terms” a tropical cyclone is defined as follows: “A warm-core non-frontal synoptic-scale cyclone, originating over tropical or subtropical waters, with organized deep convection and a closed surface wind circulation about a well-defined center.

If we ignore the rather technical terminology in the first half of the sentence and just focus on the second half we can emerge with our two important pieces of information: organized thunderstorms and a closed surface circulation.

Here’s an infrared satellite image of “Invest 94L” about an hour ago:
sat

We can see what the NHC means about minimal thunderstorm activity, but it is looking more organized than a few hours ago (here’s a loop, but it’s live so if it’s much past 1am Monday August 31 you won’t get much out of it) and since the official Center definition of tropical cyclone doesn’t declare how much “deep convection” (read: strong thunderstorms) have to be present we’ll just say that this qualifies.

Now for “closed circulation,” which is usually much harder to find and less likely to be present in “tropical disturbances” (read: areas of thunderstorms in the tropics) we can turn to NASA’s QuikSCAT satellite for data about ocean surface winds to begin our investigation of this issue: the satellite passes over any one spot about every 11 hours and so the data is sometimes dated (it also takes a few hours to post online) but there’s some data covering Invest 94L from 21:13 UTC yesterday (roughly 7.5 hours ago). (Again, that map will be updated with new data sometime on Monday so it might not be what I was looking at. Sorry.)

The QuikSCAT data tells us an interesting story: not only does Invest 94L have a closed circulation, winds at 5:13pm EDT were generally weak, but there was one measurement of 30 knot winds, just 4 knots below the definition for tropical storm force winds (a buoy located near that measurement reported winds of 23 knots and a gust of 29 knots at 2am last night). And as I noted earlier, this system was looking much less organized several hours ago, when that measurement was taken. By now the storm not only has “organized deep convection” but also has a “closed surface wind circulation” with winds of very near tropical storm force. I feel certain that what’s out in the Atlantic, only 48-72 hours away from affecting the easternmost islands of the Caribbean according to some forecasting models (click on “Storm 94″ and again, the data is live, results may vary, blah, blah, blah), is already Tropical Depression Six and should be defined as such. I understand that the thunderstorms are not all packed close around the center of the storm, but the system’s organization over the past few hours has really improved to where it looks just like any other tropical depression: somewhat disorganized, but with the potential (under a favorable atmospheric environment, which the NHC says it has) to turn into a better organized storm, and probably Tropical Storm Erika.

I hope the NHC will do one of the following at the 5am advisory time:
1. start advisories on Tropical Depression Six, or
2. send an Air Force or NOAA Hurricane Hunter airplane to take a closer look at the system;

I should head to bed, fall semester classes start tomorrow….

Cheers,
-jimmy

Tropical Weekend: Ana, Bill…and Claudette?? August 16, 2009 at 3:31 am

Well, it’s been a big day in the Atlantic, and it doesn’t look like it will end any time soon.

You may have read my history of Tropical Depression Two (now Tropical Storm Ana) yesterday morning, and you may have further seen my tweet about the formation of Tropical Storm Bill (only 6 hours after being declared a Tropical Depression) on Saturday evening.

Coming on the heels of a completely quiet June, July and first half of August, this is all pretty intense. But it’s not over yet. Not only are both Ana and Bill heading toward land (Ana has prompted a Tropical Storm Watch for parts of the Leeward Islands and Bill is currently forecast to pass near the same area as a hurricane next week), but now there’s a new system brewing much closer to home: the Gulf of Mexico, just off the coast of Tampa, FL.

Dubbed Invest 91L*, here’s the latest from the Hurricane Center on this new system:

SATELLITE AND RADAR DATA INDICATE THAT A SMALL AREA OF LOW PRESSURE IN THE EASTERN GULF OF MEXICO…CENTERED ABOUT 80 MILES SOUTHWEST OF TAMPA…IS BECOMING BETTER ORGANIZED AND MAY BE DEVELOPING A CLOSED SURFACE CIRCULATION. ENVIRONMENTAL CONDITIONS ARE FAVORABLE FOR ADDITIONAL DEVELOPMENT AND THERE IS A HIGH CHANCE…GREATER THAN 50 PERCENT…OF THIS SYSTEM BECOMING A TROPICAL CYCLONE SOMETIME TODAY.

[*systems that aren't quite organized enough to be called Tropical Depressions but that bare watching are called invests and numbered from 90-99 (when they hit 99 they just go back to 90).]


(live IR satellite image of invest 91L)

Invest 91L is already looking like it’s spinning on radar imagery out of Tampa (and on infrared satellite, for that matter) and the radar presentation is overall fairly impressive (see image below). As the NHC noted above, the one thing holding this system back from being declared T.D. 4 (or even T.S. Claudette?) is the surface circulation. Not closed, not a storm. Closed, and the NHC declares it. It’s that simple.


(Click to visit UCAR for latest images.)

If the system does get a closed circulation (which I’m 90% sure it will by 5am EDT, when the NHC issues advisories and would likely start advisories on this system if deemed necessary) it doesn’t have a lot of time to mature before it makes landfall. The NHC has it moving to the NNW at 15mph, and most models bring it inland near the Florida/Alabama state line within the day.

Given the presentation of the system on radar and satellite my money is on T.S. Claudette by the end of Sunday, but we’ll see.

Gotta say, this weekend isn’t boring in the Atlantic!

Stay tuned and stay safe.

Cheers,
-j

A few random thoughts/observations November 6, 2008 at 10:43 pm

There’s a hurricane in the Caribbean. I kid you not:

Hurricane Paloma is predicted to impact the Cayman Islands, where there are hurricane warnings currently in effect, on Friday night and to cross central Cuba on Saturday night on its way toward the Bahamas on Monday.

Didn’t expect that this week, although I had noticed the area of disturbed weather near central America for the last several days so maybe I should’ve realized it could turn into something more. Hmm.

—————————

Maybe I’m reading way too much into things, but can someone please explain to me why the stock market was climbing for over a week through Election Day (gaining over 15%) but in the last 2 days it’s lost nearly 10%? Even though Obama’s election was supposedly going to save us all from all of life’s ills, especially the ones the government has control over? I know Obama’s not in office yet, but given that the stock market is based on investor PERCEPTIONS and not any one policy and the fact that the market was RISING until Tuesday…I don’t know. I just think it’s kinda odd and telling.

——————–

As a result of gaining half a dozen (or so) seats in the Senate, Democrat Majority Leader Harry Reid has started the process of kicking turncoat Joe Lieberman out of the dem caucus, seeing as Lieberman turned independent in 2006 when he lost a primary battle with a real democrat, vocally supported John McCain during this election season and spoke at the Republican National Convention this summer.

I am incredibly happy to see Lieberman finally being removed from the dem caucus, and more importantly being stripped of his chairmanship of the Homeland Security Committee. I know we needed him on our side the last 2 years to have a majority in the senate, but it was always annoying having a more and more vocally republican member of the democratic caucus.

——————

I heard a rumor somewhere that Robert F. Kennedy Jr. might be tapped to head the EPA under Obama’s administration. I think that would be the best thing to happen since Al Gore realized that the world was warming.

—————-

That’s all for now, folks.

Cheers.

-j

93l not T.D. yet, but could become one soon September 21, 2008 at 5:00 pm

At 4:15pm EDT the NHC issued another Special Tropical Disturbance Statement regarding invest 93l:

SATELLITE IMAGERY…SURFACE OBSERVATIONS…RECONNAISSANCE AIRCRAFT DATA…AND NOAA DOPPLER WEATHER RADAR DATA FROM SAN JUAN PUERTO RICO INDICATE THE BROAD LOW PRESSURE AREA PREVIOUSLY OVER THE NORTHEASTERN CARIBBEAN SEA IS NOW CENTERED OVER CENTRAL AND WESTERN PUERTO RICO. THE AIRCRAFT REPORTED 30 TO 35 MPH SURFACE WINDS IN SQUALLS TO THE SOUTH AND EAST OF THE CENTER. HOWEVER…THE DATA SHOW THE SYSTEM DOES NOT YET HAVE A WELL-DEFINED SURFACE CIRCULATION.

THE LOW IS EXPECTED TO MOVE GENERALLY NORTHWARD DURING THE NEXT DAY OR TWO…AND COULD BECOME A TROPICAL DEPRESSION AT ANY TIME. REGARDLESS OF DEVELOPMENT…LOCALLY HEAVY RAINFALL WILL CONTINUE OVER PUERTO RICO AND THE U. S. AND BRITISH VIRGIN ISLANDS THROUGH MONDAY. THESE RAINS COULD CAUSE LIFE-THREATENING FLASH FLOODS AND MUDSLIDES. INTERESTS IN PUERTO RICO…THE U.S. AND BRITISH VIRGIN ISLANDS…AND EASTERN HISPANIOLA SHOULD MONITOR THE PROGRESS OF THIS SYSTEM AND ANY PRODUCTS ISSUED BY THEIR RESPECTIVE WEATHER FORECAST OFFICES.

This statement seems a little less “bullish” than the ones earlier today, but it still tells us that 93L is only one step away from becoming a Tropical Depression: all that needs to happen is for a closed surface circulation to form.

The 18z (2pm EDT) computer prediction model data has come in, and most of the models seem to be coming into consensus behind a track generally toward the north, with perhaps a turn toward the north-northwest or northwest in several days:

I’m not sure how this plays into my theory of this system merging with the predicted Nor’easter, but I think that given how close the two systems are forecasted to be late this week that it’s still possible or likely that they’ll merge. We’ll see.

As for intensity, the consensus of the 18z models forecasts the system to be Tropical Storm Kyle by tomorrow afternoon and to reach hurricane force by Thursday afternoon or evening. There’s quite a bit of spread in the predictions even a couple of days out, but they all bring the system to tropical storm force by Monday night. This, of course, is dependent on the surface circulation closing off really soon, but I think that’s likely to happen within the next 12-24 hours.

Until later, stay safe and sound everyone.

Cheerio!

-j

93l better organized, could become T.D. "at any time" at 2:42 pm

At 10:30am EDT the National Hurricane Center had this to say about invest 93l:

SATELLITE IMAGERY…SURFACE OBSERVATIONS…AND NOAA DOPPLER WEATHER RADAR DATA FROM SAN JUAN PUERTO RICO INDICATE THE LOW PRESSURE AREA LOCATED ABOUT 70 MILES SOUTH OF PUERTO RICO HAS CONTINUED TO BECOME BETTER ORGANIZED THIS MORNING. THIS SYSTEM COULD BECOME A TROPICAL DEPRESSION AT ANY TIME AS IT MOVES SLOWLY NORTH-NORTHWESTWARD OR NORTHWARD AT ABOUT 5 MPH. AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT IS CURRENTLY ENROUTE TO INVESTIGATE THE SYSTEM.

By 2pm, this is what they had to say:

THE LOW PRESSURE SYSTEM LOCATED OVER THE NORTHEASTERN CARIBBEAN SEA ABOUT 50 MILES SOUTH OF PUERTO RICO HAS CONTINUED TO BECOME BETTER ORGANIZED TODAY…AND A TROPICAL DEPRESSION COULD FORM AT ANY TIME AS THE SYSTEM MOVES SLOWLY NORTH OR NORTH-NORTHWESTWARD. AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT IS CURRENTLY ENROUTE TO INVESTIGATE THE SYSTEM TO PROVIDE MORE INFORMATION ON BOTH ITS STRUCTURE AND STRENGTH. A WIND GUST IN EXCESS OF 40 MPH WAS REPORTED AT ST. THOMAS IN THE U.S. VIRGIN ISLANDS EARLIER TODAY. HEAVY RAINFALL AND STRONG GUSTY WINDS WILL AFFECT PUERTO RICO…THE VIRGIN ISLANDS…AND THE NORTHERN LEEWARD ISLANDS THROUGH MONDAY. INTERESTS IN THESE AREAS SHOULD CLOSELY MONITOR PRODUCTS FROM THEIR LOCAL WEATHER FORECAST OFFICE FOR ADDITIONAL INFORMATION ON THIS SYSTEM. IN ADDITION…A SPECIAL ADVISORY PACKAGE WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER THIS AFTERNOON…IF NECESSARY…WHICH COULD REQUIRE THE ISSUANCE OF WARNINGS AND WATCHES.

It sounds to me like the NHC is ready to start issuing advisories on this system, but they’re just waiting for the data from the hurricane hunters before doing so. Given the reported wind gust of Tropical Storm strength at St. Thomas, which is more than 100 miles from the center, I wouldn’t be surprised if the Hurricane Hunters find this system to already be Tropical Storm Kyle. Of course it’s all dependent on the storm having a closed surface circulation, if there’s no closed surface circulation the wind speed doesn’t matter because it’s not considered a tropical cyclone.

We’ll know soon enough, though, so I guess it’s just time to wait. In the meantime, the storm seems to have a nice (mid-level?) spin in San Juan radar, as well as visible satellite imagery.

As for where the system is heading, there seem to be two schools of thought among the computer prediction models (click on “storm 93″ for plots of this system)(also see this plot for a slightly different set of models): first is that the storm will slowly move west-northwest or northwest along the northern coast of Hispaniola before taking a north-northeastward turn, second is that the storm will move more quickly off toward the north or north-northwest. As for me, I’m going to split the difference and say the storm will head off on a heading just north of northwest and will travel just to the northeast of the Bahamas before being absorbed into the Nor’easter that’s predicted to form off the coast of Florida in several days.

Alright. That’s all I’ve got for now. Stay safe everyone.

-j

State of the Tropics 9/19/08: Invest 93L September 19, 2008 at 8:24 pm

Not to be content after sending seven tropical storms or hurricanes in a row into the United State coastline (count ‘em: T.S. Cristobal battered the coasts of Florida, Georgia, South Carolina and North Carolina in mid-July; Hurricane Dolly hit southern Texas just a few days later; T.S. Edouard made landfall near the Texas/Louisiana border in early August; T.S. Fay I blogged about quite a bit as it made it’s way through the Caribbean and hit Florida several times in mid-August; Hurricane Gustav I again blogged about as it slammed Cuba and hit Louisiana in late August and early September; Hurricane Hanna you might remember as the storm that simply could not decide where to go in late August and early September; and finally Hurricane Ike which we all know had a little fun with Galveston, Texas a week ago today) the tropics are again bubbling and threatening toil and trouble. Or something.

Anyway, Invest 93L has formed in the southeastern Caribbean and the NHC has this to say about it at 8pm EDT:

A WESTWARD-MOVING TROPICAL WAVE…ACCOMPANIED BY A BROAD SURFACE LOW PRESSURE SYSTEM OVER THE SOUTHEASTERN CARIBBEAN SEA…IS PRODUCING WIDESPREAD CLOUDINESS AND SHOWERS OVER THE LESSER ANTILLES…AND ADJACENT CARIBBEAN AND ATLANTIC WATERS. THIS SYSTEM HAS CHANGED LITTLE IN ORGANIZATION DURING THE PAST SEVERAL HOURS. WHILE UPPER-LEVEL WINDS ARE CURRENTLY UNFAVORABLE…THEY ARE EXPECTED TO BECOME MORE CONDUCIVE FOR SOME DEVELOPMENT TO OCCUR OVER THE NEXT COUPLE OF DAYS.

So I guess the bottom line is, it’s not a big worry at the moment, but it could become a bigger worry in the next couple of days, and it certainly bares watching over the next few days as it’s predicted by the computer forecasting models to be near Haiti, Jamaica and Cuba in a few days. Its general direction of movement also suggests that if it forms into something that something could be entering the Gulf of Mexico in a little over a week.

So. I guess we weren’t going to get off that easy with the tropical weather just ending, huh? Hurricane season runs for nearly another 2.5 months, after all.

Stay safe, dear readers.

Cheerio!

-j

Clouds, wind, rain, hurricane Ike and a cold front September 14, 2008 at 9:34 pm

Today has been eventful weatherwise here in Northern Indiana. Last night the remains of Hurricane Ike merged with a cold front while in the Ozark area and began picking up speed moving toward the northeast. By this afternoon the combined extra-tropical low (although my parents tell me that the air felt pretty warm, humid and tropical for a while this afternoon, so I’m guessing Ike still had a bit of tropical-ness left in the low pressure area) and cold front were upon us and brought us nearly half an inch of rain, gusty winds and some interesting temperatures. The whole thing passed over very quickly as Ike’s remnant low was apparently moving at upwards of 40 miles per hour. We had about an hour of rain, and than a little bit later (roughly 30 minutes) a couple hours of gusty winds started. The top wind gust wasn’t that impressive at 31mph, but it’s nothing to frown at either seeing as Ike’s been ashore and away from its native tropical waters for over 36 hours now.

Now we’re under clouds and 15 degree cooler air as a high pressure system covering most of the northern Plains moves in to bring us a bit clearer and certainly cooler weather tomorrow (high of 67 degrees! Oh yeah).

Coupled with the surprise 89 degrees we had yesterday while in the warm sector of this weather system, it’s certainly been an interesting 36 hours in terms of weather here in Indiana.

Meanwhile, down in hurricane Ike ground zero Galveston CNN reports that the largest search-and-rescue operation in Texas history is underway as emergency workers seek to account for the roughly 20,000 people who stayed in the city as Hurricane Ike made landfall there.

I should probably go freak out some more over homework and an exam I have tomorrow morning.

Cheerio!

-j

Ike quick note September 12, 2008 at 7:00 pm

Over the last couple of hours it seems that a new inner eyewall has formed in Hurricane Ike that’s about 60% the size of the old eyewall. I wonder if this will translate into any higher winds….

Gotta go now.

-j

P.S. the NHC reports at 7pm EDT that winds are up a bit to 110mph (from 105mph at 5pm EDT). If winds increase a little more, to 115mph, Ike will be a category 3 hurricane. I’m not sure the people of Galveston will really be able to notice the difference, though.

Ike evening 9/9: becoming more organized September 9, 2008 at 11:24 pm

I wrote the following two sentences from 7:30pm to just after 9pm during breaks in my evening CS class, some of the data is outdated now that the 11pm advisory is out, but I think it’s a cool “stream of conscience”/”live blogging” sort of thing, and I think some of the analysis is sound.

In their 5pm forecast discussion on Hurricane Ike, the NHC noted that the inner core of the storm had survived the transit over the island of Cuba very well and that re-strengthening over the Gulf could happen very soon. That indeed is happening as Ike’s small eye that had disappeared from radar earlier today when Ike was only halfway through its passage over the western end of Cuba reappeared by 7pm this evening, barely 2 hours after it had emerged back over water after traveling over fairly mountainous terrain in western Cuba.

The NHC reports in their 8pm Intermediate Advisory that Hurricane Ike’s winds are still 75 mph, but with the organization of the inner core seeming to improve fairly quickly, I wouldn’t be surprised if the intensity of the storm jumps up soon, fueled by the warm waters of the Gulf of Mexico and helped by very low atmospheric shear. The only thing that looks to me like it might slow down re-strengthening is that fact that, as of 9pm, the inner core of the storm looks like it’s detached from the otter rain bands on radar. I don’t think this will be much of an issue, however, since on infrared satellite imagery the upper clouds already seem to be “reattaching” (for lack of a better word) and I’m guessing that the rain bands will follow suit soon.

As of 11pm, the clouds look much better and the radar presentation is improving, with several outer rain-bands attached to the eyewall now. The NHC reports that winds have increased a little to 80mph, and they expect more strengthening.

The official NHC forecast brings the storm ashore in central Texas on Friday night as a major hurricane.

As for my personal prediction, the models still seem to have a bit of a spread at that point, so I’m going to narrow my forecast landfall location to the state of Texas sometime on Friday evening or night. As for intensity, I’m not comfortable making a forecast yet, but if I had to, I’d say the storm will be at least a category 2 storm, and likely not a category 5…so, for short: Texas, Friday evening or night, category 2, 3 or 4.

Stay safe everyone. And remember: please use the National Hurricane Center forecasts and warnings in lieu of my analysis when making life-or-death decisions. My analysis is for “entertainment” purposes only. *grin*

Cheers!

-j

Ike noon 9/8: moving out over the far northern Caribbean September 8, 2008 at 12:01 pm

As I suggested might happen earlier this morning, Hurricane Ike’s refusal to turn toward the west-northwest (as predicted by both the model consensus and the NHC) and instead continue west has resulted in the storm’s center emerging back over water in the far northern Caribbean as seen on Cuban radar (it’s kind of hard to tell exactly where the center is, but even if the center hasn’t quite made it to water yet, it will very soon, within the hour I’m sure). This new track means that the center of the storm, even after it makes the turn toward the west-northwest sometime today, will most likely stay just offshore until it crosses the western tip of Cuba on Tuesday, a track that will slow down the weakening that the storm has undergone over Cuba during the past 12 hours, and might even provide a chance for re-strengthening over the next 24 hours, depending on how far from the coast the center travels. Given that water temperatures along the coast of Cuba there are pretty warm and atmospheric shear is low and is forecasted to stay that way for the next couple of days it seems to me that the only thing governing strengthen for now is how close or far the center of the storm is from land. Put simply: the farther the center moves from the coast of Cuba, the less weakening and the more chance of strengthening over the next 24 hours.

Obviously, the strengthen over the next 24 hours, before Hurricane Ike’s center crosses the western end of Cuba, has a direct effect on how strong the storm gets once it’s in the open Gulf of Mexico, so the tiny track movements are something to water carefully over the next 24 hours. Luckily I love mesoscale forecasting, so I’ll be very much in my element, so to speak, for the next day or so.

For those of you wondering about final landfall in the US, the NHC keeps telling us in their Hurricane Ike Forecast Discussions that “IT IS STILL MUCH TOO SOON TO KNOW WHAT PORTIONS OF THE GULF COAST COULD BE IMPACTED BY IKE.” Which I agree with you, to a degree. I agree in spirit: final landfall isn’t going to happen until the weekend, and it’s still many days away, and a lot can happen in that time so don’t freak out Houston just because the current track forecast brings the storm toward you. On the other hand, I don’t agree with the implication that any part of the Gulf coast is still at risk of being hit by Ike. I don’t think it’s very likely that Florida’s Gulf Coast will be impacted by this storm, for example.

Along those lines, I’m going to make a very general landfall prediction now: I predict landfall somewhere in the states of Texas or Louisiana. It’s important to remember though, that 4- and 5-day track forecasts have an average error of over 300 miles, so the data that I’m basing this forecast on could be 300 miles off and pretty much the entire western and center Gulf Coast should be watching this storm closely.

Did I say anything in those last two paragraphs? Hmm.

Anyway. Here’s the latest 3-day track forecast from the NHC. Basically the center of the storm is going to track along just off the southern coast of Cuba for the next 24 hours, then the center will cross the western end of Cuba and will emerge into the southeastern Gulf of Mexico on Tuesday evening on a west-northwest heading, by Thursday morning the storm will be in the Central Gulf, exact heading unknown and final destination unknown.

OK, that’s all I’ve got for now. Stay safe everyone, and please use official forecasts and warning and watchings in lieu of my college student sleep-deprived ramblings. :)

Cheerio!

-j