Stormtalk

Friday, 10 September 2010

Jesse Duncan, shirt model. Was my awesome and fearless chase driver May 10.

Jesse Duncan models back of shirt.

The Stormgasm.com T-shirt and DVD giveaway is over. As promised, I have selected a winner randomly using a random number generator. Below is a screen capture of the number generator.

Screen capture of the random number generator

Linda's comment

So congratulations to Linda, you are the winner! Thank you so much for you heartfelt comment and sharing your personal experience about the May 3, 1999 Oklahoma tornadoes.

You should be receiving an email requesting a mailing address for winning this contest. Once I have the address, I will mail you a limited edition Stormgasm.com t-shirt and a 2003 tornado highlights dvd. If for some reason you don’t receive that email, please email me (stormgasm@yahoo.com).

Thanks to those of you who participated in this contest, and thanks to everyone for visiting Stormtalk. We will have another contest again in the near future.

- Jim

Thursday, 9 September 2010

Tornado reports from the SPC for September 8, 2010

Several tornadoes were reported on Wednesday afternoon and evening across north Texas and southern Oklahoma. Homes were damaged and one person was reported injured. The remnants of Tropical Storm Hermine are to blame.

Dallas tornado video (from CNN)
http://www.cnn.com/2010/US/09/08/tropical.weather/index.html?hpt=T1&ref=nf

Dallas tornado video (home video)
http://www.youtube.com/watch?v=j2zgpldKD4w

Dallas tornado video (fast forward to 1 minute)
http://www.the33tv.com/news/kdaf-dallas-tornado-story,0,7954171.story

Shortly after Tropical Storm Hermine made landfall early Tuesday morning, the tropical circulation continued north-northwestward and dumped tons of rain all over south, central and southeast Texas on Tuesday. A tornado watch had been issued Tuesday morning and midday for areas in Texas. But there was just too much tropical moisture and no breaks in the rain and clouds for daytime heating. As a result, very limited instability developed and only a couple weak tornadoes were report in Texas on Tuesday.

But Wednesday was different. The remnants of Hermine had made their way to north Texas, so the connection to deep, tropical moisture wasn’t as strong. A dry slot developed from the west and worked it’s way to central and north Texas by the afternoon. This helped to clear the Dallas area from expansive clouds and rain during the afternoon. The result was instability (CAPE) that was adequate enough to support vigorous thunderstorm updrafts. The low and mid level vertical wind shear was very strong thanks to Hermine’s remnant circulation. All these conditions came together and caused supercells to develop from the Dallas area to southern Oklahoma. Some of these supercells produced tornadoes and caused damage.

Tornadoes are not as common in Texas and Oklahoma in September as they are in the spring months. On top of that, a tropical system was moving through and not everyone associates a tropical storm with tornadoes. So, many people in the Dallas area were a bit surprised when they saw live video of tornadoes in Dallas on their local evening news.

- Jim

Tuesday, 7 September 2010

Radar overlaying a tornado watch issued by the Storm Prediction Center on September 7

Tropical Storm Hermine made landfall across portions of northern Mexico and south Texas late Monday night. Hermine remained a tropical storm Tuesday morning as the eye moved north-northwest across the Rio Grande Valley and portions of southern Texas. Heavy rains have prompted food watches and warnings across parts of southern and southeast Texas.

Tropical Storm Hermine has also prompted a tornado watch over parts of south and southeast Texas. It is common for landfalling tropical systems to bring the threat of tornadoes, especially on the east side of the tropical storm. The tornadoes form from thunderstorms that develop and intensify within the outer feeder bands of the tropical storm. Wind shear necessary in the lower levels to produce tornadoes is already present from the landfalling tropical storm. The ingredient that is usually missing is adequate instability (CAPE) to support strong, long lived cells that can become organized enough to produce tornadoes. Most of the time though, there is just enough instability to support one or two weak tornadoes.

In the right kind of setup, landfalling tropical storms or hurricanes can bring significant tornado outbreaks. This happens when a pronounced dry slot moves into the east or northeast quadrant of the tropical system. This allows breaks in the clouds to form between the feeder bands, allowing substantial instability to develop. When this occurs, supercell thunderstorms develop. Since the low to mid level wind shear is so strong due to the tropical system itself, many long lived tornadoes occur in these types of setups. A great example occurred September 15 – 17, 2004 when Hurricane Ivan made landfall near Mobile Bay, Alabama. As Ivan tracked northeast and weakened across the Southeastern U.S. and Mid Atlantic states, his feeder bands spawned 127 tornadoes across Florida, Georgia, the Carolinas, Virgina, Maryland and Pennsylvania. Several of these tornadoes caused fatalities.

Today’s setup across south and southeast Texas doesn’t look quite that formidable. There is an abundance of moisture on the east and northeast quadrants of Hermine, with no sign of a dry slot. The feeder bands will have limited instability to work with. So, I don’t expect more than two or three tornadoes across Texas today. If a handful end up verifying, they are likely to be weak, short lived tornadoes.

- Jim

Thursday, 2 September 2010

 
Final reminder: Leave a comment in the post: Stormgasm.com T-shirt and DVD Giveaway to be entered in the contest to win a free Stormgasm T-shirt and tornado DVD. This contest ends September 10.

 
DVD Sample: June 24, 2003 Manchester, South Dakota Tornado Video Part 2

 
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Hurricane Earl

Hurricane Earl on the morning of September 2

Hurricane Earl is a dangerous category 4 hurricane, with winds estimated near 145 mph. While he is going to come close to the outer banks of North Carolina, it looks like the strongest winds on the western eyewall will remain just offshore. Hurricane force winds are still expected in Cape Hatteras, and Earl remains a dangerous storm for residents in that area. Earl will turn north-northeast early on Friday and pass southeast of Cape Cod. Earl is large enough and will pass close enough to bring tropical storm force winds to the Cape and extreme eastern MA, with low end hurricane force wind gusts around Cape Cod.

National Hurricane Center track forecast for Hurricane Earl 11a.m. Sept 2

The other tropical feature of interest is Tropical Depression Gaston, which was recently downgraded this morning, after being upgraded to a Tropical Storm yesterday. Gaston, like nearly every storm so far this year that has formed over the eastern Atlantic, is being battered by dry air and even some African dust. We’ll have to watch Gaston’s progress over the next few days to see if he even survives. If he does, he is far enough south and in a weak enough flow pattern to have a decent shot of entering the Caribbean. But all it takes is a weakness in the ridge to pull him north.

National Hurricane Center track forecast for Tropical Depression Gaston 11a.m. Sept 2

I looked back at 1998 (a La Nina year) and found Hurricane Georges. He formed in a similar place to Gaston over the eastern Atlantic, and ended up in the Gulf of Mexico! This is hardly a good scientific approach to forecasting the long term track of a storm, but it’s interesting to mention. There are plenty of options on the table, and this is just one.

Hurricane Georges Sept 15- Oct 1 1998, from Weather Underground

- Jim

Tuesday, 31 August 2010 – Afternoon Thoughts

Long Island and Cape Cod still look like they will see Earl pass them by to the southeast on Friday (though not by much for Cape Cod). But, the outer banks of North Carolina (Cape Hatteras) has an increasing risk for significant impacts from Earl late Thursday night, and possibly a direct hit.

The GFS/Euro models both pretty much have Earl hitting Cape Hatteras, or passing just barely to the east. Earl will weaken a little before he reaches the outer banks, as he will be moving into an area of increasing wind shear and dry air over the next couple days. But, he will still be a dangerous hurricane by Thursday night.

Residents that live in the outer banks of North Carolina should take Earl very seriously.

- Jim

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Tuesday, 31 August 2010 – Update

Hurricane Earl on the morning of August 31

Hurricane Earl remains a dangerous category 4 hurricane, with maximum sustained winds of 135 mph. But the good news is he finally made the turn to the northwest last night, and it looks like New England is going to dodge the bullet. Click here for the latest NHC track forecast.

Some computer models still have Earl brushing by the outer banks of North Carolina late Thursday night. So, that area is not out of the woods completely. But, the Great Lakes trough is now forecast to move just fast enough to the east on Thursday to turn Earl towards the north-northeast very early on Friday. Throughout Friday, Earl should accelerate rapidly to the northeast in response to that trough ejecting eastward. This should keep Hurricane Earl to the southeast of Long Island and most of Cape Cod. The only risks left I think are the northwestern eyewall brushing by Nantucket, with gusty winds and heavy rain extending into the southern tip of Cape Cod.

This is all good news for coastal New England. If this trend continues, it’ll be good news for the outer banks of North Carolina, too.

We still have Tropical Storm Fiona out in the central Atlantic, making way towards the northern Leeward Islands. Most computer models and the National Hurricane Center’s forecast take Fiona north of the islands and then out to sea. But, Fiona is weak and hasn’t turned northward yet. If we’ve learned anything from Hurricane Earl’s track, then we should be skeptical of the northwest turn forecast for Fiona later this week. Additionally, Fiona continues to battle dry air, and wind shear is expected to increase a bit over the next couple days. This will keep her from doing any significant strengthening over the next few days. This kind of situation would normally favor a more southerly track than computer models and the NHC forecast indicate.

National Hurricane Center forecast for Tropical Storm Fiona August 31

So we’ll see how things progress in the coming days. I think there are more questions than answers right now regarding Fiona’s future. But, until she actually passes north of the northern Leeward Islands late tomorrow, she should still be considered a potential threat to the southeastern U.S. coast. We’ll find out soon enough…

- Jim

 
 
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Monday, 30 August 2010

Visible satellite image on August 30 of Hurricane Earl

Forecast track on August 30 at 11 a.m. for Hurricane Earl

Hurricane Earl rapidly intensified overnight. He now has maximum sustained winds of 120 mph, which brings him to category 3 status. The current forecast from the National Hurricane Center shows him threatening the Mid Atlantic and Northeast coast later this week. But, it’s interesting to note that Earl has been tracking south of the both the official forecast and some of the model guidance for a few days now (shown below). Even if you look at the track forecast history on the NHC website for Earl, you will see how the forecast has shown a northwest turn for several days, yet the turn has still not occurred.

Earl's actual track in black with model forecasts in other colors. You can see the north bias in the model.

 
Taking a closer look at the official forecast, the models and Earl’s actual track over the last 24 hours (image below), you can see the continued north/right bias in the models and the official NHC forecast. So the big question is: How much longer will Earl remain south/left of the models and official forecast? If this trend continues for much longer, we will be talking about a direct along the Mid Atlantic or Northeast coast. But alas, it’s just not that simple.

Earls forecast track and actual track in black, with tropical models in other colors. You can see the north bias in the models continues.

The other big piece of the puzzles is the timing and speed of a trough forecast to move into the Great Lakes and Northeast late this week. Exactly how it interacts with Hurricane Earl will be crucial in determining how sharp he turns to the north/northeast Thursday into Friday as he approaches New England. Based on the trends of late, it’s going to be a close call for both the outer banks of North Carolina and eastern Long Island/Cape Cod. However, Earl will probably miss just to the east on both accounts, especially for Cape Cod, since that trough is going to play a big role that I don’t think is fully seen in the modeling yet. But it’s going to be a close call and it’s still too early to say either way with confidence.

- Jim

Sunday, 29 August 2010

Tropical Atlantic Activity from the National Hurricane Center

This has been an interesting hurricane season to watch over the past week. I’ve mentioned plenty of times the abundance of dry air covering much of the Atlantic for quite some time. This has kept tropical storms and hurricanes from showing any significant strengthening for several days into their development. But, as seen from Hurricane Danielle after several days of organizing and some ups and downs in her life cycle, she reached major hurricane status in spite of the dry air. The warm waters and pockets of weak wind shear allowed it to happen – eventually.

Now we have Hurricane Earl who is quickly approaching the northern Leeward Islands. Dry air has been a major issue with him (what a surprise), but his center is becoming much better organized, and upper level outlfow is improving by the hour. This is pretty similar to what Danielle went through before reaching major hurricane status. Earl is moving over some very warm waters, and has more warm water ahead of him. Wind shear is also expected to relax over the next coule days. So, it’s no coincidence that he too is forecast to become a major hurricane over the next day or so as he turns northwest in response to a weakness in the Atlantic ridge.

Forecast advisory for Hurricane Earl from the NHC August 29

Earl will be moving northward by mid week (Sept 1) over the western Atlantic, not far from the Mid Atlantic coast. He will be picking up forward speed and maintaining major hurricane status as he moves over the warm waters of the Gulf stream. Meanwhile, a trough will be approaching the upper Midwest. By Friday, this trough will be moving through the Great Lakes, and will begin to cause Earl to turn towards the northeast. The questions that need answers are how 1)how close to the coast of New England will Earl have reached, and 2) how quickly will that Great Lakes trough eject eastward? The answers to those questions will determine whether or not Hurricane Earl hits Cape Cod or brushes by just to the east. More than likely it’ll be a near miss. But you never know, and it’s too early to be sure right now.

There’s another tropical wave that is located over the central Atlantic. I will become a tropical depression or tropical storm within the next day or two. When it does, it will be named Fiona. But, it too is struggling with dry air (big surprise, huh?) and has been having major problems developing a closed low level circulation. Computer models bring the future Fiona to about where Earl is now (near or just north of the northern Leeward Islands) by Wednesday (Sept 1).

Then, things get really interesting. Does Fiona turn northwest in response to the weakness in the Atlantic ridge caused by the Great Lakes trough and Earl? Or, does she miss the connection and continue westward toward Cuba and South Florida? Most computer models have Fiona making the connection to the northwest and reaching near the Bahamas by Sept 5. By then, it’s a question of how quickly a new ridge develops over the eastern U.S. The slower the ridge develops the better the chance Fiona hits central Florida to North Carolina. The faster it develops the better the chance Fiona stays further south and hits South Florida or enters the Gulf of Mexico.

00z August 29 European Operational model forecasing a major hurricane on September 6 to hit Florida.

12z August 29 European Operational model takes Hurricane Fiona to the central Gulf on September 7.

There are a lot of options on the table here with the future Hurricane Fiona. But with the way the pattern is setting up, the warm water temperatures and the weakening wind shear, it looks increasing likely that we are going to have our first major hurricane landfall in the U.S. around Labor Day weekend, or shortly after, anywhere from Florida to the Carolinas. The Gulf coast isn’t out of the woods, either.

Stay tuned, things could get really, really interesting.

- Jim

Friday, 27 August 2010

Hurricane Danielle Friday morning, August 27. Maximum sustained winds 135 mph.

I don’t really have a whole lot to say except wow, what a beast! Hurricane Danielle really took off over the last 24 hours, becoming a category 4 hurricane with maximum sustained winds of 135 mph. There is still plenty of dry air surrounding the outer bands of Danielle, but it finally came to the point where it just doesn’t matter. Her inner core is extremely organized, and the intense outflow is keeping the dry air from impacting her well defined eye. What a beast.

Tropical Storm Earl continues to fight dry air to his west, and hasn’t strengthened since yesterday. Computer models curve him northwest and then north over the western Atlantic next week. But some bring him uncomfortably close to Cape Cod. That could be an interesting situation if models trend further west. But, a trough lifting out of the Great Lakes late next week will help to keep Earl from actually hitting the Cape.

The next system near Africa should develop into a tropical storm over the next few days. Some models bring it (next name is Fiona) close to the Mid Atlantic coast in 12 days or so as a tropical storm or hurricane. I know that’s a long way away, and a lot of things can change between now and then. But, it will be something to watch.

- Jim

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Thursday, 26 August 2010

Satellite image on August 26 of the Atlantic showing Hurricane Danielle, Tropical Storm Earl, and a strong tropical wave coming off Africa.

The Cape Verde season has finally begun. After a sluggish start to the Atlantic hurricane season, things are starting to pick up, with two named storms currently in the Atlantic, and more waves coming off of Africa. The two named storms are Hurricane Danielle and Tropical Storm Earl. If the wave near Africa develops, it would be named Tropical Storm Fiona.

Danielle has been fighting an uphill battle for days, absorbing the abundance of dry air that surrounds the Atlantic waters. This dry air has been one of the main reasons for the slow start to the season, along with wind shear that hasn’t relaxed as quickly as forecast. But overnight and throughout the course of this morning, Danielle’s upper level outflow has blossomed. It’s this outflow that appears to be keeping the dry air well away from the storm’s center, allowing for intensification to occur. An eye is now visible on satellite imagery. As long as this trend continues, Danielle will become the first major hurricane of the season, if she hasn’t already.

August 26 morning visible satellite image of Hurricane Danielle. Notice the eye at the center, and the banding structure. This is a visual sign of good outlfow.

We have now had a total of five named storms so far this hurricane season, two of which have become hurricanes. This catches the hurricane season up to what would normally occur during a regular season. But, assuming Hurricane Danielle strengthens a little more, she will become the first major (category 3) hurricane of the 2010 Atlantic hurricane season. We don’t typically see the first major hurricane until the first week in September. Let’s not forget that Tropical Storm Earl is forecast to become a hurricane by this weekend. So, if Danielle can reach category 3 status and Earl becomes a hurricane, we will finally be on par with an active season.

But, we still have a long way to go to meet expectations set by forecasters before the season started. This active trend needs to continue in the near term, and things will have to be kicked up another notch in the longer term, for any of the seasonal hurricane forecasts calling for 18 named storms to stand a chance at verifying. At least this is a step in the right direction.

- Jim

Tuesday, 24 August 2010

 
Hurricane Danielle Forecast Advisory from NHC

NHC Forecast for Hurricane Danielle August 24

On Sunday, August 22 at 5 p.m. EDT Tropical Depression Four become Tropical Storm Danielle. Then by Monday at 5 p.m. Danielle become a hurricane, with maximum sustained winds of 75 mph. Danielle then moved over very warm waters and rapid intensification occurred. By 5 a.m. EDT on Tuesday, August 24 maximum sustained winds had increased to 100 mph, making Danielle a strong category 2 hurricane. However, dry air surrounded the outer bands of the hurricane, and it was only a matter of time before significant weakening would occur. Then, at 11 a.m. EDT, maximum sustained winds dropped to 80 mph. All the deep convection was almost completely gone, and an exposed center of circulation could be seen beneath a dense overcast. Danielle had ingested a lot of dry air, causing her to weaken.

The graphic above is the latest forecast from the National Hurricane Center. They no longer expect Danielle to become a major hurricane, which isn’t really that surprising. Quoting their discussion, “The period of rapid intensification has ended with a thud”. I’m not trying to be critical here, but it sounds like they were caught off guard.

From the water vapor image below, you can see an abundance of dry air covering a large portion of the central Atlantic to the west of Hurricane Danielle. It was only a matter of time before this dry air would start to cause weakening. Wind shear also remains an issue, and it seems very unlikely Danielle will become a major hurricane after all.

Water Vapor image August 24, showing dry air west of Danielle

Danielle did undergo a period of rapid intensification, which was very pretty impressive. I believe this was possible mostly because of the very warm waters she moved over last night (see image below). But in addition, the wind shear relaxed just enough, and the upper level outflow was strong enough for a few hours to keep the dry air away from the center of circulation and allow the strengthening to occur.

Sea Surface Temperature Anomalies August 21. Notice the warm pocket that Danielle just moved over.

But this season started slow for a reason, and the driving forces behind that haven’t really changed. Dry air across parts of the Atlantic remain an issue, along with areas of moderate to strong wind shear. It’s really going to take some big changes across the board to catch this season up to the very active season it is suppose to be, at least from Colorado State and NOAA’s forecasts.

The peak of the season is coming in a couple weeks, so surely things will pick up. I will say that there are signs the MJO may enhance the tropics starting some time next week. But since that idea didn’t work out last time, I’m naturally a little skeptical about that idea working out this time. We’ll see…

- Jim

Monday, 23 August 2010

A waterspout was seen off the coast of Okinawa, Japan on August 19, 2010. Below are links to some spectacular photos of the waterspout.

http://ireport.cnn.com/docs/DOC-483483
From Yahoo! News
CNN I-report

The waterspout lasted about five minutes. On average, waterspouts off the coast of Japan last about 14 minutes. According to a database on tornadoes and waterspouts in Japan from 1961 to 1993, there are 4.5 waterspouts per year in Japan. I found it interesting that according to the database, waterspouts in Japan occur most frequently in October.

Waterspouts are different than tornadoes. Waterspouts form during fair and relatively calm weather during the warm season, usually during the day. They develop from the water surface upward, while typical tornadoes form from the cloud base downward. Waterspouts form in light wind conditions, so they usually move very little. If a waterspout moves onshore, it is then called a tornado. Waterspouts typically dissipate rapidly when they make landfall and rarely move very far inland.

I’ve never been lucky enough to see a waterspout, but hopefully that will change at some point in the future. They are truly a different breed altogether than tornadoes that I see out in the Great Plains. It’s difficult enough to forecast a tornado, but it’s even harder to forecast a waterspout. They are like the popcorn thunderstorms that form over the southern U.S. in the summertime. I need a really big hurricane or tornado outbreak to happen so that I can discuss that on here instead of waterspouts; sorry guys, the material’s a little weak for now.

- Jim

Saturday, 21 August 2010
 
Tropical Storm Danielle trying to form over the eastern Atlantic…

Satellite image August 21, red circle outlines the tropical disturbance that will soon become Danielle.

It’s been a while since the Atlantic tropics have shown any life. For the past several days, all global computer models have consistently indicated that a tropical wave would move off Africa into the far eastern Atlantic, and form into a tropical storm. Finally, this tropical wave has generated an are of low pressure at the surface. Showers and thunderstorms have been increasing, and have even begun to show signs of a circulation. This has lead the National Hurricane Center to give this system a high probability of becoming a tropical cyclone within the next 48 hours. Should this tropical disturbance become a tropical storm, it would be Tropical Storm Danielle, the fourth named storm of the 2010 Atlantic Hurricane Season.

Below is some of the model guidance, showing the track of this system. As you can see, models indicate the future Danielle will track west-northwest across the central Atlantic over the next few days. By around Wednesday, August 25, models show this system turning northwest to northward and out to sea. This is in response to a trough moving through the northeastern U.S. over the next several days. It will create a weakness in the eastern Atlantic ridge, which is currently driving this tropical system westward. When this weakness occurs, the future Danielle will be forced northward and out to sea. Other global models show a similar track, so it appears highly likely this tropical system will have no impact on the U.S., and only be a concern for ships.

GFS Ensemble tropical model track forecast members August 21

It’s quite telling that I’m talking about a tropical system that hasn’t formed yet, and one that isn’t going to impact the U.S. It tells me and everyone else reading this something about this season — it’s not performing to the high expectations set by both the Colorado State forecasters and NOAA. Some of the reasons why haven’t changed. There remains an abundance of dry air across the Atlantic, and wind shear remains an issue. For this disturbance over the eastern Atlantic, these factors are going to make it an uphill battle to achieve beyond weak hurricane status. Even so, this will give us our fourth named storm of the season, keeping things on par with a normal season. At this rate, the hurricane forecasts issued recently calling for 18 named storms this season are in big trouble. But, maybe things will pick up in an incredible way in early September as we approach the peak of the hurricane season. If it doesn’t, people will begin to lose respect for long range seasonal hurricane forecasts, putting the science of meteorology one step behind in the general public’s mind.

Speaking of people losing respect for meteorologists, check out Dr. Hansimian’s Hurricane Forecast (the monkey). He’s forecasting 6-8 hurricanes this season. At this point, his prediction is looking better than others!

 
- Jim