TD 13 intensifying; Katia may pass uncomfortably close to U.S.
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
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"It looks more likely that Lee will ease into the SE bringing tremendous rain totals along the Gulf spreading inland with a major flood threat... and then stall. Katia will head straight for the SE. Lee could steer Katia near or along the east coast, depending on where it stalls mid/late next week. Stay tuned for evolving details." I still think OTS, but I cannot be certain.
WHAT STORM ARE YOU TALKING ABOUT - THERE IS MORE THAN ONE GOING ON RIGHT NOW!!!!!!!!!!!!!!
Lee...I thought it was apparent based on what was posted. Sorry...settle down there terminator.
The NHC has always stated, along with most reputable mets, that models are subject to change and NOTHING is etched in stone. Once it starts raining, it is then ok to say for certain it is going to rain. I knew a few days ago that there was a good possibility of Katia coming closer than what was initially projected, because the NHC had spoke about the ULL to the NW shearing Katia, hence allowing the LLC to move farther west in the low level flow. But, a trough is expected to move to along the east coast by Sunday, as steering winds even here in ECFL will become S/SW. I just dont forsee this storm making it any farther west than 75W, and 70W may be pushing it, too.
Talk about running into a brick wall. "Is that land ahead? Someone hit the brakes and put it in reverse quick!" :-)
Ok so I told you all that SEPTEMBER will be the month you all get a storm. I expected the high to back off and allow a storm into the Gulf of Mexico; therefore this might not be your storm but I feel confident it IS coming!
The fact that Lee has formed in the gulf is evident enough to me that the pattern is changing. If not this month then certainly in October I hope.
YAY! Someone is forecasting the same move that I am. I keep saying that Lee should have went west cause now he is going to have a little dance with Katia.
This year may be an exception, but typically we don't get storms this far west in October.
In case you haven't noticed though, despite that Florida historically has had so many impacts, we have been almost untouched by tropical systems since the breakout seasons of 2004 and 2005. Which is very interesting, because this might be the one of the largest period of Florida inactivity in proportion to how active the hurricane seasons have been during this period of inactivity for Florida.
I'm surprised nobody else is really noticing this, but I sure have. Heck, I'm not complaining, hurricanes will kill the economy in Florida that is barely surviving as it is. But I have noticed this.
The question is, why? Well I don't know exactly, I haven't done any research on it. But lets hope whatever is causing so many storms to miss Florida will continue.
What I do know is the dominant steering currents around Florida are similar to previous years, I predicted Florida to have a lower than normal chance of a hurricane making landfall in proportion to how active the season will be. However, it doesn't mean I I'll be right at all of course, I'm just basing it on my educated guess from looking at past events and seeing what patterns occurred when hurricanes missed as apposed to hit Florida, or lack-there-of, LOL.
But the ULL that was on the coast of Texas has been transitioned into the storm.
It will be hard to point to a distinct LLC due to how broad our center is.....
Hybrid still.
Yea now wouldn't it be nice if LEE did the same? The NOGAPS sure wishes to do that.
That is what I'm concerned about but in terms of track and possible strengthening to a Cat 1 (I agree that it shouldn't get any stronger though). Lee is not moving and its a sit and spin. There seems to be wobbles slightly to the East. Opal did the same thing. If I remember (it's been a long time and those on this forum that are better with history can be more specific) it kept wobbling East till it went over the Mouth of the Mississippi (the orientation of the land in are part of the World makes it a precarious situation in terms of storms like these) allowing it to strengthen over water more. Though, there are quite a few instances in terms of a much more amplified trough and the greater strength and organization of Opal, and the accelerated speed of its movement . But I guess it is a wait and see right now.
It's because most of us Floridian's don't want to curse ourselves. So shhhhh!
He who's name shall not be spoken (aka those little swirly things in the ocean).
Completely agree. I'm in Clear Lake with my family and a boat in Kemah... We don't want a hurricane but at least some spin-off from Lee. And although I want rain, I wouldn't want another Allison. To much water on a ground that's hard a cement would be bad too.
"Pat- roll that beautiful NOLA radar footage..."
It almost looks like the LLC has popped out of the convection and is sliding under that ULL...
Watch for the smaller coc in the NE corner of that big ULL...
Anyone else see that?
That may be why it looks like the convection is trying to wrap that ULL... Maybe they are merging?
I think the easier question is how much of Texas ISN'T in a drought.
ummmm...if you are serious...all of it...
sounded more like a riddle...thought it was national news sorry
Hopefully you are right, but October storms in Texas are fairly rare due to the pattern changes and increased troughiness that fall brings. The last one we've had was in 1989.
"WATER VAPOR IMAGERY AND UPPER-AIR OBSERVATIONS INDICATE A SMALL
UPPER-LEVEL LOW OVER SOUTHWESTERN LOUISIANA THAT HAS BEEN PRODUCING
MODERATE TO STRONG SOUTHWESTERLY WIND SHEAR ACROSS THE CYCLONE HAS
BEEN WEAKENING AND LIFTING OUT TO THE NORTHWEST. THIS HAS ALLOWED
THE WIND SHEAR TO DECREASE AND ALSO TURN TO THE SOUTH AND
SOUTHEAST. DISSIPATION OF THIS UPPER-LEVEL LOW AND ITS ATTENDANT
DRY AIR INFLUENCE IS FORECAST TO OCCUR IN THE NEXT 24
HOURS...ALLOWING THE SYSTEM TO STRENGTHEN. GIVEN
THE SLOW MOTION...LESSENING SHEAR...AND VERY WARM SSTS NEAR 30C THE
CYCLONE COULD BE NEAR HURRICANE STRENGTH BEFORE LANDFALL OCCURS IN
ABOUT 48 HOURS. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE
NHC INTENSITY CONSENSUS MODEL...ICON...WITH THE STATISTICAL MODELS
ABOVE AND THE DYNAMICAL MODELS BELOW THE OFFICIAL FORECAST".
If this system is out of land by monday I predict a weak hurricane in the area.
Hi Jed,
Good post. I've noticed. Just figured it was because we all bought generators, got accordian shutters and new roofs and new garage doors, etc and now we are all "ready" for another strong storm after we got clobbered in 2004/2005...
Seriously, it seems since then they all went south of us into Caribbean or GOM or they all curved to North/Northeast..
Just an environmental pattern....
but now I think about it, we do at least "prepare" for a storm because we get under a warning almost every year since I arrived in 1979 except for 2006/2007/2008/2009/2010 and so far 2011..
wonder what's up with that.. more cold fronts moving thru earlier each year???
Yes I was thinking about that. Right now I am "wishful thinking" for October. I figure someone might as well hope something happens because we know some areas of Texas last rainfall was in September 2010 and I sure don't want to repeat that again.
I am sure TEXAS would cry if they had to go from September 2011 onward for almost another year with rainfall. That would be brutal.
When Katrina was on the east coast of Florida, Bob Breck said that it would go up the east coast and not bother us "at all". However, he might be right his time.
This much.
We also had a big gap from 1966 Betsy to 1992 Andrew here in SE Fl and the complacency that created was horrible i remember people insting until the night before Andrew hit that it was going to turn away at the last minute!
It will be interesting watching this one morph.
Oh Come one...I was trying to have a good Labor day weekend party in FWB, Fl. I guess that put a stop to it:0
Did I mentioned I moved back to Florida in 2006 after leaving "for good" when I turned 18 in 1990? :-)
I just think that the ULL just HAD to show right at the moment a storm was about to get comfortably close to Texas. All the Texas Folks are like, "Hey look RAIN!?!?!" and then the ULL forms and shoves Lee off to the east.
I figure the ULL either has it out for Texas or it's task is to make sure NOLA gets more rain than they want to have at one time.
I mentioned that a couple hours ago, water vapor looked like Lee was trying to eat the ULL!
That ULL is also keeping Louisiana from being hit by a Cat 4 hurricane..lol
So Viking it seems to be getting worse and worse for us by the minute?...Well...crap...I guess there is no family Crab Island fun anymore for me:o
let me guess, after you saw 2004/2005 from outside the State You wanted to "experience" a storm and moved back.....
so YOU are our protective shield!!! LOL
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