TD 13 intensifying; Katia may pass uncomfortably close to U.S.

By: Dr. Jeff Masters , 3:28 PM GMT on September 02, 2011

Share this Blog
30
+

Tropical Depression Thirteen formed last night over the Northern Gulf of Mexico and is slowly intensifying, but isn't in a hurry to go anywhere. What TD 13 will do is dump torrential rains along the northern Gulf Coast over the next three or more days. So far, rain amounts along the coast have mostly been below one inch. At New Orleans Lakefront Airport, just 0.32" inches of rain had fallen from TD 13 as of 10 am CDT. Some coastal regions have received up to two inches, according to radar rainfall estimates. TD 13 is generating a large area of 30 - 35 mph winds over the Gulf of Mexico. At 7:20 am CDT, winds at the Mississippi Canyon 711 oil rig were southeast at 47 mph. This is above tropical storm force, but the wind instrument was 348 feet (106 m) above the ocean surface, and winds near the surface were probably considerably lower, near 35 mph. Latest surface wind observations from an Air Force hurricane hunter aircraft support leaving TD 13 as a tropical depression. Long range radar out of Mobile, Alabama shows heavy rain showers building along the northern Gulf Coast, but these rain showers are not well-organized into spiral bands. Strong upper-level winds out of the west-northwest are creating a moderate 10 - 20 knots of wind shear over TD 13, keeping the storm's heavy thunderstorms disorganized and pushed to the east side of the storm. However, latest satelllite loops show TD 13 is becoming increasingly organized, with a respectable spiral band forming on the southeast side, and an increase and areal coverage of heavy thunderstorm activity. This is very likely to be a tropical storm later today.


Figure 1. Radar-estimated rainfall from TD 13 from the New Orleans radar.


Figure 2. U.S. drought conditions on August 30. The rains from TD 13 have the potential to bring major drought relief to drought-stricken portions of the coast. Note how Eastern North Carolina is no longer in drought, thanks to the rains from Hurricane Irene. These rains also came close to putting out a persistent fire that had been burning in the Great Dismal Swamp near the Virginia/North Carolina border. Image Credit: U.S. Drought Monitor.

Forecast for TD 13
TD 13's large size, ill-formed circulation center, and the presence of dry air on its west side due to an upper-level trough of low pressure argue against rapid intensification of the storm for the next three days. Also tending to slow intensification will be the slow movement of the storm, which will allow cold water from the depths to rise to the surface, thanks to wind and wave action. Tropical cyclones strongly cool the water's surface when they pass over it, as seen in the time vs. depth chart of sea surface temperatures during Hurricane Irene's passage along the New Jersey coast (Figure 3.) However, the Gulf of Mexico has some very warm waters near TD 13 that extend to great depth (Figure 4), so the surface cooling imparted by TD 13 will be less than that seen for Hurricane Irene. As TD 13 moves closer to the coast, more and more of its circulation will be over land, which will also slow intensification. NHC's 11 am EDT wind probability forecast for TD 13 gave the storm a 23% chance of intensifying into a hurricane by Sunday. Assuming TD 13 does not attain hurricane strength, wind damage and storm surge damage will likely not be the main concern--fresh water flooding from heavy rains will be the most dangerous impact. Also of concern is the possibility of tornadoes. NOAA's Storm Prediction Center is currently not highlighting the Gulf Coast in their "slight risk" area for severe weather, due to the lack of enough solar heating to create instability. However, there will be plenty of wind shear in the lower part of the atmosphere that can potentially create spin in the coastal thunderstorms, and it is possible that as TD 13 intensifies, it may be able to generate several dozen tornadoes.

Coastal Louisiana, Mississippi, Alabama, and the extreme western Panhandle of Florida will likely receive very heavy flooding rains that will intensify Saturday and peak on Sunday. These rains should be able to put out the stubborn marsh fire east of New Orleans that has brought several days of air quality alerts to the city, but may cause moderate to severe flooding problems in other areas. The latest rainfall forecast from NOAA Hydrological Prediction Center shows that a large area of 15+ inches of rain is expected over Southeast Louisiana and coastal Mississippi. The region is under moderate drought, so flooding problems will be delayed compared to what we'd normally expect from heavy rains of over a foot. Flash flood watches are posted for New Orleans and surrounding areas, and rainfall amounts of 1 - 3 inches per hour are possible in some of the heavier rain squalls. Ocean temperatures are near record warmth, 88°F (31°C), which will provide plenty of moisture for heavy rains, and plenty of energy to help TD 13 strengthen into a strong tropical storm. Steering currents will be weak in the Gulf this weekend and early next week, which will likely make the motion of TD 13 erratic at times.


Figure 3. EPA, in conjunction with Rutgers University and the NJ Department of Environmental Protection, has an Autonomous Underwater Vehicle (AUV, aka the Glider) deployed off the coast of NJ (since early August) continuously monitoring ocean temperature, density, salinity, sound velocity and dissolved oxygen at different depths. The AUV's path and data are displayed at the following website: http://marine.rutgers.edu/cool/auvs/index.php?did =221&view=imagery. The plot of temperature versus time above shows that in the weeks prior to the arrival of Irene, the ocean was heavily stratified, with warm waters of 24 - 26°C (75 - 79°F, red colors) extending from the surface to a depth of 10 - 15 meters. A sharp thermocline existed at a depth of about 15 meters, and ocean temperatures were colder than 14°C (57°F, dark blue colors) below the thermocline. The strong winds and high wave action of Hurricane Irene on August 28 - 29 stirred up cold water from the depths to the surface, cooling the surface waters to 17 - 19°C (63 - 67°F). In the days since the hurricane, surface waters have begun to warm again. Thanks go to Kevin Kubik, Deputy Director of the Division of Environmental Science and Assessment for EPA Region 2, for making me aware of this data.


Figure 4. The total amount of heat energy in the ocean available to fuel a tropical cyclone, in kilojoules per square centimeter of surface area. Tropical cyclones that move over ocean areas with TCHP values in excess of 70 - 90 kJ/cm^2 commonly undergo rapid intensification. Waters that are warm to a great depth have the highest TCHP, and the Loop Current that brings warm water northwards from the Caribbean to the Gulf of Mexico usually has the highest TCHP values in the Atlantic. Currently, we have an eddy that broke off from the Loop Current earlier this summer, now located a few hundred miles south of the Louisiana coast, that also has high TCHP values. Image Credit: NOAA/AOML.

Hurricane Katia
Hurricane Katia is continuing its long trek across the Atlantic Ocean today, and will not pose a danger to any land areas over the next five days. Katia is still struggling with dry air and moderate wind shear of 10 - 20 knots. Latest satellite loops show surface-based arc-shaped clouds racing to the southwest away from Katia's core, a sign that dry air is penetrating into Katia's thunderstorms and creating strong downdrafts that are robbing the storm of heat and moisture. Katia is over warm ocean waters of 28.5°C, and these waters will increase in temperature to 29°C over the next five days. Katia will pass well north of the region of cooler waters stirred up by the passage of Hurricane Irene last week.

The models are split on when the upper-level trough of low pressure bringing the wind shear to Katia will move away, and the storm may spend two more days battling wind shear and dry air before the upper-level trough pulls away to the north and allows Katia to intensify more readily. It is still unclear how much of a threat Katia may pose to the U.S., but it is becoming increasingly clear that Katia will pass uncomfortably close to the U.S. East Coast. The trough of low pressure currently steering Katia to the northwest will lift out early next week, and a ridge of high pressure is expected to build in, forcing Katia more to the west. This decreases the danger to Bermuda, but increases the danger to the U.S. A second trough of low pressure is expected to begin affecting Katia by the middle of next week, and will potentially recurve the storm out to sea before it hits the U.S. However, the models differ widely on the strength and timing of this trough. Meteorologist Grant Elliot of Australia's Bureau of Meteorology in Perth pointed out to me yesterday that the long-range forecast for Katia has more than the usual amount of uncertainty, due to the inability of the computer models to agree on what will happen to Tropical Storm Talas in the Western Pacific. Talas is expected to hit Japan early on Saturday as a strong tropical storm, then race northwestwards into the Bering Sea off the coast of Alaska. Talas is then expected to transition into a powerful extratropical storm in the waters south of Alaska. This storm will create a ripple effect downstream in the jet stream, all the way to North America, by early next week. The timing and amplitude of the trough of low pressure off the U.S. East Coast expected to potentially recurve Katia out to sea next week is highly dependent upon the strength of Tropical Storm Talas during its transition to an extratropical storm. The computer models are not very good at handling these sorts of transitions, leading to more than the usual amount of uncertainty in the long-range outlook for Katia. It will probably be another 2 - 3 days before the models will begin to converge on a solution for the long-term fate of Katia. Dr. Bob Hart's Historical Tropical Cyclone Probability web page suggests shows that tropical storms in Katia's current position have a 17% chance of hitting North Carolina, a 21% chance of hitting Canada, a 13% chance of hitting New England, and a 55% chance of never hitting land. One almost certain impact of Katia on the U.S. will be large waves. Long period swells from Katia will begin affecting the Bahamas on Sunday night, then reach the Southeast U.S. by Monday morning. By Tuesday morning, the entire U.S. East Coast will see high surf from Katia, and these waves will increase in size and power as the storm grows closer. Given the slow movement of Katia as it approaches the coast, plus its expected Category 1 to 3 strength as it approaches, the storm will probably cause extensive beach erosion and dangerous rip tides for many days.

94L
A well-organized low pressure system with a surface circulation but limited heavy thunderstorm activity due to high wind shear is 450 miles south of Halifax, Canada. This disturbance, (94L), is headed northeast out to sea, and is being given a 60% chance of developing into a tropical depression by NHC. 94L is under a high 25 - 30 knots of wind shear, but this shear is expected to fall to the moderate range, 10 - 20 knots, by Saturday morning. However, sea surface temperature will fall from 27°C today to 25°C Saturday morning underneath 94L, and the storm will have a very short window of time to get organized enough to get a name. At this point, it's really a subjective judgement call on whether or not 94L is already a tropical storm.


Figure 5. A Portlight volunteer works to clear storm debris from Hurricane Irene in Hollywood, Maryland.

Portlight disaster relief effort in Maryland
Hurricane Irene heavily damaged the town of Hollywood, Maryland, when a tornado cut off electric power, water, and phone service. Portlight and Team Rubicon volunteers arrived before emergency personnel, after following up on a local tip. What they found was an isolated area whose plight was unknown to the larger community. Most residents were trapped at their homes by heavy debris. Portlight and Team Rubicon worked for two days to clear paths to each address, extract vehicles from debris, and cut down trees that constituted safety hazards. Portlight also instructed local residents how to operate and maintain chainsaws and safely clear debris. No other volunteer organizations or emergency personnel arrived at any time, and Portlight succeeded in meeting the specific needs of the underserved, unserved, and forgotten. Visit the Portlight blog to learn more; donations are always welcome.

I'll have a new post each morning over the coming holiday weekend; wunderground meteorologists Angela Fritz, Rob Carver, and Shaun Tanner will be handling the afternoon and evening posts. Have a great holiday weekend, everyone!

Jeff Masters

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 1787 - 1737

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 | 70 | 71 | 72 | 73 | 74 | 75 | 76 | 77Blog Index

Quoting Patrap:
Yeah,,no one from NOLA helped Texas after IKE at all.

LoL


Hmm. I had to come down there and clean up the mess at my mom's house. Between Allison, Alicia, and Ike, I pick Allison by far. Her house wasn't flooded. There wasn't much yard debris to clean up. We had a lot more pine trees during Alicia
Quoting Patrap:
Yeah,,no one from NOLA helped Texas after IKE at all.

LoL


Strangely, for some reason Katrinans never left Houston after IKE.
Member Since: Posts: Comments:
1785. Patrap
Quoting cat5hurricane:

You out of all folks ridiculing others for spelling?

Ah Pat, you never cease to amaze me...


Thanx,,wish I could say the same for you.


I misspell for dialect, not cuz I dont know how.

I'd go on but I have u on iggy.

Member Since: Posts: Comments:
Quoting capquest:
TO ALL WISHCASTERS

Wish the rain over to Texas...they need it bad
Here I'll try to wave my magical wand.Uno!Presto!WallaKazam!!!
Member Since: Posts: Comments:
huge rain squall heading to Mississippi Coast
Member Since: Posts: Comments:
1781. pcola57
Quoting TexasHoosier:
/

Leave out the "Storm" guy and I'll bet you would get a better answer.
JMO
Member Since: Posts: Comments:
Quoting Patrap:


6 years and they still cant spell Levee?

LOL

The Coast Guard inspects Levee's now.

Phunny,,the Army COE Builds them.

No one could even spell Levee before 05.


Now that is funny!
Member Since: Posts: Comments:
1779. breald
Quoting HoustonTxGal:


Was not bragging about it, mojo.. whatever his name is was bashing so I was stating facts re: the matter.


Sorry, I just assumed we are all Americans and should help each other out no matter what.
Member Since: Posts: Comments:
Quoting Patrap:


6 years and they still cant spell Levee?

LOL

The Coast Guard inspects Levee's now.

Phunny,,the Army COE Builds them.

No one could even spell Levee before 05.


A levy is something that can happen to your paycheck.
Member Since: Posts: Comments:
1777. Patrap
Member Since: Posts: Comments:
Thank You Levi, listen to your videos every Day
Member Since: September 1, 2011 Posts: 0 Comments: 24
1774. Levi32
Quoting PensacolaDoug:




Prolly so...But it does look like a hybrid regardless.


Yeah, I admit that it does. It has that "comma" look. However, the thing is warm-core, and its shape is due to dry air entrainment.
Member Since: Posts: Comments:
1773. Patrap
Quoting mossyhead:
Heard on the news that the levy system just got a "F" from the Coast Guard.


6 years and they still cant spell Levee?

LOL

The Coast Guard inspects Levee's now.

Phunny,,the Army COE Builds them.

No one could even spell Levee before 05.
Member Since: Posts: Comments:
Quoting Termite3344:


What is the link to the LSU site?


I didn't mean to quote Levi,, sorry, just learning
Member Since: September 1, 2011 Posts: 0 Comments: 24
1770. Levi32
Quoting Termite3344:


What is the link to the LSU site?


LSU Earth-Scan Laboratory
Member Since: Posts: Comments:
Does anyone have any good intel on 94L? I have seen several ask about it but have not been able to find much on it either.

Thanks
Member Since: Posts: Comments:
Quoting Levi32:


It's not a hybrid. It's a sheared, lopsided tropical cyclone, and that's all.




Prolly so...But it does look like a hybrid regardless.
Member Since: Posts: Comments:
Quoting HoustonTxGal:


Was not bragging about it, mojo.. whatever his name is was bashing so I was stating facts re: the matter.

I must have missed the original bashing - the blog moves so fast during tropical weather.
Nothing personal - I get very defensive about my home, and realize that there are probably safer, more functional places to live. But my roots and love go deep here. And so I defend it.
Member Since: Posts: Comments:
Quoting Levi32:


It's not a hybrid. It's a lopsided tropical cyclone, and that's all.


What is the link to the LSU site?
Member Since: September 1, 2011 Posts: 0 Comments: 24
1765. Patrap
Quoting Asta:
"



Indeed,..




Calamity Knows no Border's, only men's minds and Map's do
Member Since: Posts: Comments:
TO ALL WISHCASTERS

Wish the rain over to Texas...they need it bad
Member Since: Posts: Comments:
Quoting 5Rockets:
Well, by looking at AllStar17's pics from his blog, I can say a few things about the storms:

1. If it weren't for wind shear, Katia would have been on this long adventure across the Atlantic just to gain enough power to smash the SE region of the US (Yes, people. Katia will hit. Guarantee. Maybe not in the place I expect it to, but it will.

2. At this rate, Lee is gonna do some serious reversing on New Orleans' repair after Hurricane Katrina.

Feel free to tell me I'm wrong, but these are only very strong predictions.
Heard on the news that the levee system just got a "F" from the Coast Guard.
Member Since: Posts: Comments:
Quoting hahaguy:


She's very crafty.
Well she needs to go in between Bermuda and the U.S.She can have all the water supplies she wants out there in the ocean.
Member Since: Posts: Comments:
Quoting P451:
This ought to clear things up a little...


LMAO. Post of the decade right here.
Member Since: Posts: Comments:
1759. Asta
"
Quoting Patrap:


Patrap, Why even give that dribble air space..???

Member Since: Posts: Comments:
50/50 Katia hits land.

It was already much higher chances when Katia even started.
Member Since: Posts: Comments:
Quoting mojofearless:


Of course I am.
But it does get old - all the nasty comments from our bone-dry neighbors to the west. They have never ceased to cram their Katrina-era charity down our throats every chance they get, and quite frankly, I'd rather live on a rickety raft in an abandoned urban swamp here than live in a McMansion surrounded by big box boredom and smug pseudo-Christian superiority there.
But no - of course I wouldn't blame Houstonians.
Just meeting the stick and parry. Nothing more.

Louisiana and Texas share a permanent sister-state love for each other, and anybody who belittles or tries to tear that asunder is not a native of either state.
Member Since: August 4, 2007 Posts: 0 Comments: 3278
Quoting HoustonTxGal:


Guess that would be the "smug, self-righteous Houstonians" who took in all the NOLA evacuees after Katrina, most of which they are still stuck with.


Very true. Heard a lot of bad things about it. Two different cultures.
Member Since: Posts: Comments:
I would appreciate some quick comments and thoughts on what I have written below and on Dr. Master's excellent column on a worldwide weather system fused effect on a approaching hurricane, Katia.

Dr. Masters that was as good a column as you have ever written and I have been a mostly quiet reader of this blog since its start time many years ago.

You speak of the potential effects of a Tropical Storm probably 10,000 miles away or more on Katia. You could even bring in the potential effects of Lee as well given its movement east and how large a entity it is. I do a lot of work with sensor and data fusion here at Lockheed Martin on tactical fighter planes and the synergy of data correlation and fusion is similar in many respects to the effect of atmospheric weather events have on each other.

I don't remember when a incoming storm like Katia has had as many variables that could affect its intensity and path. Certainly, I don't remember ever seeing a tropical storm 10,000 miles away in another ocean predicted to have a significant impact on an approaching hurricane from the South Atlantic.

Perhaps some of the long-time bloggers like Patrap, Drak, Canewhisperer, or others (have not seen StormW this year - is he OK?) could pull something out of long-term memory that is relative to this almost worldwide event that may occur in the next week - just what is Katia going to do.

I'd love for the moisture to end up here in Fort Worth (we are burnt to a crisp) but if Katia gets into the GOM and keeps a 270 degree course to the West, all that TCHP in the Western Gulf could make for an amazingly bad atmospheric event....and there is a lot of very hot water neart the TX/LA/FL coastline right now.

Thank you for reading and commenting on this post.
Member Since: Posts: Comments:
Quoting breald:


Many places took them in, however, they are not bragging about it.


Was not bragging about it, mojo.. whatever his name is was bashing so I was stating facts re: the matter.
Member Since: Posts: Comments:
1751. pcola57
Quoting violet312s:



Sometimes even the slightest update, like a typo, gives the blog a new time stamp even though the comment threads don't change. Confuses me too.


Thanks violet..
Member Since: Posts: Comments:
1750. Levi32
Quoting P451:


Texas is just a crippler. The ULL that Lee has found it's way under is helping to inject all that dry air. Hybrid system to a degree.



It's not a hybrid. It's a sheared, lopsided tropical cyclone, and that's all.
Member Since: Posts: Comments:
Cue Aaron Neville's "Louisiana 1927"

or the Randy Newman original if you prefer !
Member Since: Posts: Comments:
Quoting MiamiHurricanes09:
Look at post 1674. It's dry air intrusion.


He was kidin dawg
Member Since: Posts: Comments:
1747. ncstorm
Quoting P451:


You would think this could have a profound effect on the QPF modeling...but it hasn't.





Image edited to fit the blog.

Original can be found HERE


thats epic right there..last thing the midatlantic to northwards need
Member Since: August 19, 2006 Posts: 13 Comments: 16041
1745. hahaguy
Quoting washingtonian115:
Katia wants the envieriment to do this on purpose so that sje can get closer to the U.S.Please no Bonnie and Fran or Jeanne and Frances tracks.


She's very crafty.
Member Since: Posts: Comments:
Quoting CC45:


Wow. I hope you're joking.


Of course I am.
But it does get old - all the nasty comments from our bone-dry neighbors to the west. They have never ceased to cram their Katrina-era charity down our throats every chance they get, and quite frankly, I'd rather live on a rickety raft in an abandoned urban swamp here than live in a McMansion surrounded by big box boredom and smug pseudo-Christian superiority there.
But no - of course I wouldn't blame Houstonians.
Just meeting the stick and parry. Nothing more.
Member Since: Posts: Comments:
Thanks Miami!
Member Since: September 1, 2008 Posts: 0 Comments: 672
Quoting TropicalAnalystwx13:


Or it is actually an eye...


Pinhole??
Member Since: Posts: Comments:
Quoting Patrap:


Any post can be made short,,or gone using the HIDE or Iggy feature..but thanks for the words.


Posting the full article in this case made sense. Few would read it otherwise. Tells a very true story for so many cities in the US badly located. People move to where the money and jobs are, regard less of risk from nature's fury.

Houston, New Orleans, Miami...
Member Since: Posts: Comments:
Quoting Orcasystems:


How about blaming the people who built a place below sea level.. then act bewildered when it floods?

I am from NOLA, and I think the problem comes when we abandoned traditional raised building techniques. The onslaught of ranch houses in areas that traditionally are floodplains is disasterous.
Member Since: Posts: Comments:
Taking all bets on how long it will be before someone asks whether Katia is going annular...
Member Since: Posts: Comments:

Viewing: 1787 - 1737

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 | 70 | 71 | 72 | 73 | 74 | 75 | 76 | 77Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.