Gulf of Mexico disturbance 93L a Lousiana flood threat; Katia a hurricane

By: Dr. Jeff Masters , 3:28 PM GMT on September 01, 2011

Share this Blog
26
+

Surface winds over the northern Gulf of Mexico are rising, pressures are falling, and heavy thunderstorms are building today thanks to a tropical disturbance (Invest 93L) that is the product of a tropical wave interacting with an upper-level low pressure system. At 8:35 am CDT, winds at the Mississippi Canyon 711 oil rig were south-southeast at 38 mph. This is just 1 mph below 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 30 mph. Long range radar out of Mobile, Alabama shows heavy rain showers building along the northern Gulf Coast, but these rain showers are not organized into spiral bands and show no signs of rotation. Strong upper-level winds out of the west-northwest are creating 30 knots of wind shear over 93L, keeping the storm's heavy thunderstorms disorganized. Strong onshore winds raising tides to 1 - 2 feet above normal are likely along the northern Gulf Coast through the weekend, and coastal flood statements have been issued for the region.


Figure 1. Predicted rainfall for the 5-day period ending at 8am EDT Sep 6, 2011. A large region of rains in excess of 15 inches is expected over Southeast Louisiana. Image credit: NOAA/HPC.


Figure 2. U.S. drought conditions on August 30. The rains from 93L have the potential to bring major drought relief to drought-stricken portions of the coast. Image Credit: U.S. Drought Monitor.

By late tonight, wind shear is expected to drop to the moderate range, below 20 knots, and 93L should begin to organize into a tropical depression. Wind shear is expected to remain moderate, 10 - 20 knots, into Monday. There is some cold, dry air aloft that will retard this process, and I think the earliest we would see a tropical depression is Friday afternoon. NHC is giving 93L a 70% chance of developing into a tropical depression by Saturday morning. All of the major models develop 93L near the Louisiana coast, and show a slow and erratic movement due to weak steering currents. Coastal Louisiana, Mississippi, Alabama, and the extreme western Panhandle of Florida will likely receive very heavy flooding rains beginning this afternoon and intensifying Friday and Saturday. The latest rainfall forecast from NOAA Hydrological Prediction Center (Figure 1) shows that a large area of 15+ inches of rain is expected over Southeast Louisiana. 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. Nevertheless, minor to moderate freshwater flooding is likely from 93L, and 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 (31.3°C), which will provide plenty of moisture for heavy rains, and plenty of energy to help 93L strengthen into a tropical storm. Most of the models predict 93L will have some motion to the west by Saturday, which would bring rains to the Texas coast near the Louisiana border. Steering currents will be weak in the Gulf this weekend and early next week, making it difficult to predict where the storm might go. If 93L stays over water through Tuesday, like the ECMWF model is predicting, the storm would be a threat to intensify into a hurricane. Most of the other models predict 93L will move ashore over Louisiana by Sunday, limiting the storm's development to just tropical storm strength. I think it at least 50% likely 93L will be a tropical storm with 40 - 60 mph winds along the coast of Louisiana by Sunday.

Hurricane Katia
Hurricane Katia intensified into the 2nd hurricane of the 2011 season last night, and continues its long trek across the Atlantic Ocean today. Katia is expected to arrive at a position several hundred miles north of the Northern Lesser Antilles Islands by Monday. The islands are not in the cone of uncertainty, and it appears unlikely that they will receive tropical storm-force winds from Katia. Satellite images show that Katia is a well-organized storm with plenty of heavy thunderstorms, but the storm has been struggling with dry air and moderate wind shear of 10 -20 knots, and is looking less organized than it did last night. These problems will likely diminish by Friday night, as the upper low bringing the wind shear moves away. It is still unclear how much of a threat Katia may post to the U.S. Dr. Bob Hart's Historical Tropical Cyclone Probability web page suggests shows that tropical storms in Katia's current position have an 16% chance of hitting North Carolina, a 21% chance of hitting Canada, a 12% chance of hitting Florida, and a 54% chance of never hitting land. I suspect that Katia will turn north before reaching the U.S. and potentially threaten Bermuda and Canada, based on what past storms in similar situations have done, and assuming the jet stream maintains its current pattern of bringing frequent troughs of low pressure off the coast of the U.S. It will be another day or two before the models will begin to have a handle on the long-term fate of Katia, though.


Figure 3. Morning satellite image of Katia.

94L
A well-organized low pressure system with a surface circulation and limited heavy thunderstorm activity has developed between Bermuda and the Canadian Maritimes. This disturbance, (94L), is headed out to sea, and is being given a 10% chance of developing into a tropical depression by NHC. 94L is under a very high 30 - 40 knots of wind shear, and will not be able to intensify very much. However, Tropical Storm Jose formed from a similar type of system, and we might get surprised by 94L.

I'll have more on Irene in tomorrow's post.

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: 3195 - 3145

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 | 64Blog Index

3195. Patrap
12:09 PM GMT on September 02, 2011
Member Since: July 3, 2005 Posts: 420 Comments: 127543
3194. Patrap
12:09 PM GMT on September 02, 2011



Member Since: July 3, 2005 Posts: 420 Comments: 127543
3193. CaribBoy
11:47 AM GMT on September 02, 2011
WEATHER IS BORING IN THE E CARIB LOOKS LIKE APRIL lol. MuST CHANGE KATIA GO AWAY YOU ONLY GIVE US UNUSEFUL WAVES AND SUBSIDENCE!
Member Since: October 6, 2007 Posts: 0 Comments: 5929
3192. 996tt
8:50 AM GMT on September 02, 2011
Quoting nodramaman1022:
Does anyone think that the gulf disturbance can influence the trajectory of Katia and pull her more West in the runs?


Nah, not under this current set up.
Member Since: September 5, 2008 Posts: 0 Comments: 308
3191. FrankZapper
6:31 AM GMT on September 02, 2011
TD 13 sure doesn't look very impressive this AM. Overhyped?
Member Since: May 26, 2011 Posts: 0 Comments: 1193
3190. HurricaneHunterJoe
5:27 AM GMT on September 02, 2011
Quoting MiamiHurricanes09:
Well, the raw T-numbers from ADT have certainly reacted to the recent convective cooling. A T1.5 increase in just 2 hours.

2011SEP02 001500 3.6 995.8 57.0 2.9 2.8 2.8 NO LIMIT ON FLG -62.56 -56.78 UNIFRM N/A N/A 16.38 49.87 FCST GOES13 34.6
2011SEP02 011500 3.6 995.8 57.0 2.9 3.4 3.5 0.5T/hour ON OFF -73.36 -64.95 IRRCDO N/A N/A 16.45 50.07 FCST GOES13 34.4
2011SEP02 014500 3.6 995.8 57.0 3.0 3.4 3.8 0.5T/hour ON OFF -74.36 -74.07 UNIFRM N/A N/A 16.49 50.17 FCST GOES13 34.4
2011SEP02 021500 3.6 995.7 57.0 3.1 3.4 4.3 0.5T/hour ON OFF -73.36 -76.35 UNIFRM N/A N/A 16.64 50.44 FCST GOES13 34.2
Could I please get a link for this site?
Member Since: September 18, 2010 Posts: 0 Comments: 5103
3189. jpsb
5:09 AM GMT on September 02, 2011
Quoting SavannahStorm:


Also, I think distributed computing has a huge potential to help out the computer models. if you've ever used SETI@Home or Folding@Home, you are familiar with it. Imagine millions of private computers crunching model data continuously, 24/7... Model resolution could be bumped exponentially and models could be updated more frequently as well. Imagine the GFS Ensemble creating a mean track out of 200,000 variable runs, not just 20.
I can't help but I have heard from reliable sources that quantum mechanics is a piece of cake compared to fluid dynamics.
Member Since: June 30, 2009 Posts: 0 Comments: 1174
3188. will40
5:07 AM GMT on September 02, 2011
Quoting nodramaman1022:
Does anyone think that the gulf disturbance can influence the trajectory of Katia and pull her more West in the runs?



could possibly but too early to tell how close each would be for that to happen
Member Since: September 19, 2005 Posts: 2 Comments: 4110
3187. NCHurricane2009
5:05 AM GMT on September 02, 2011
Quoting JLPR2:


To be on the safe side, I'll say pre-95L. :P


Well I know one thing...if there was a weather-betting Casino in Vegas (which I seriously doubt there is)...my money's on that become 95L....

And in said Casino...consequences of a bad forecast are probably worse than eating crow....
Member Since: September 15, 2009 Posts: 437 Comments: 3600
3186. ProgressivePulse
5:05 AM GMT on September 02, 2011
Rhut Rho Rastro. TD13 is going to be a player with Katia down the line.

HOWEVER...IN THE LONG RANGE...A STRONG MID-LEVEL
TROUGH IS FORECAST TO DEVELOP OVER THE GULF OF MEXICO AS THE
ATLANTIC SUBTROPICAL RIDGE BUILDS WESTWARD.
Member Since: August 19, 2005 Posts: 5 Comments: 5039
3185. AtHomeInTX
5:05 AM GMT on September 02, 2011
NEW BLOG!!! LOL
Member Since: August 24, 2010 Posts: 0 Comments: 676
3184. nofailsafe
5:05 AM GMT on September 02, 2011
Quoting MississippiWx:


Lol...That run of the CMC isn't complete yet...It goes from 12z Saturday to 0z Saturday.


How on earth do you move a whole tropical cyclone (84 to 96 hours) down the coast from New Orleans to Brownsville in 12 hours? I mean, I guess it makes sense, but it just feels like CMC is missing something there in the middle.
Member Since: June 18, 2010 Posts: 3 Comments: 941
3183. MiamiHurricanes09
5:04 AM GMT on September 02, 2011
Quoting MississippiWx:


Lol...That run of the CMC isn't complete yet...It goes from 12z Saturday to 0z Saturday.
Look at the black and white maps. Goes out to 12z Monday. Run's already completed out to 144 hours.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
3182. NCHurricane2009
5:03 AM GMT on September 02, 2011
Quoting MississippiBoy:
do ya'll ever get a sick feeling in your stomach?i'm starting to.


Well...I don't know about that...but I have some serious heartburn tonight that's keeping me up....

Looks like you need PEPTO and I need some ANTACID or something...LOL...
Member Since: September 15, 2009 Posts: 437 Comments: 3600
3181. nodramaman1022
5:03 AM GMT on September 02, 2011
Does anyone think that the gulf disturbance can influence the trajectory of Katia and pull her more West in the runs?
Member Since: August 30, 2011 Posts: 0 Comments: 24
3180. MississippiWx
5:03 AM GMT on September 02, 2011
Quoting MiamiHurricanes09:
Link.


Lol...That run of the CMC isn't complete yet...It goes from 12z Saturday to 0z Saturday.
Member Since: July 15, 2006 Posts: 17 Comments: 10159
3179. KoritheMan
5:01 AM GMT on September 02, 2011
Quoting MississippiBoy:
do ya'll ever get a sick feeling in your stomach?i'm starting to.


It's way too early for that.
Member Since: March 7, 2007 Posts: 553 Comments: 19890
3178. jpsb
5:01 AM GMT on September 02, 2011
Quoting Dennis8:


That was way after my time.....I was back in the Cecilia Sinclair days....
Cecilia Sinclair! That is who I am thinking of, she was great. I miss her. She did a great job on Rita, I was glued to her every word, lol. Just as I decided to leave and was driving north on 45, she said she thought Rita would come on north of Galveston bay. North of the bay? We are on the clean side? I hit the brakes and drove back to San Leon. There were only about 15 people left in San Leon it was fun, and the evac was a horror, glad I listened to Cecilia and was sparred the evac.
Member Since: June 30, 2009 Posts: 0 Comments: 1174
3177. AllStar17
5:01 AM GMT on September 02, 2011
Quoting nofailsafe:
These still impress me, they're practically broadcast quality. Most excellent indeed.


Thank you very much! There are actually pretty easy to make once the main "template" is done.
Member Since: June 29, 2009 Posts: 13 Comments: 5300
3176. TexasHurricane
5:01 AM GMT on September 02, 2011
Quoting MiamiHurricanes09:
Link.


wow...12z 251k
Member Since: July 2, 2009 Posts: 0 Comments: 2811
3175. nodramaman1022
5:01 AM GMT on September 02, 2011
Quoting nodramaman1022:


The system in the gulf may come in to play and may pull Katia more West than the models show


Any thoughts regarding my observation?
Member Since: August 30, 2011 Posts: 0 Comments: 24
3174. AtHomeInTX
5:01 AM GMT on September 02, 2011

Quoting will40:


ty Tex we sure dont want her here. But im still wishing for Tex to get some much needed rain
Thanks Will. :) We'll take all the good wishes we can get!
Member Since: August 24, 2010 Posts: 0 Comments: 676
3173. MississippiBoy
5:01 AM GMT on September 02, 2011
well it looks like mother nature's going to load the wagon on us,all these storms popping up.
Member Since: April 6, 2008 Posts: 1 Comments: 283
3172. nofailsafe
5:01 AM GMT on September 02, 2011
Quoting MiamiHurricanes09:


...must study. Dang tropics.


I understand that feeling. I could read some out of Al Cotton's Advanced Inorganic Chemistry, or... I could not.
Member Since: June 18, 2010 Posts: 3 Comments: 941
3171. ConnecticutWXGuy
4:59 AM GMT on September 02, 2011
Link

some hurricane irene aftermath from a location near me
Member Since: November 17, 2010 Posts: 11 Comments: 527
3170. JLPR2
4:59 AM GMT on September 02, 2011
Quoting nofailsafe:


I hate it when they clip like this in the evenings.


Member Since: September 4, 2007 Posts: 7 Comments: 8499
3169. AtHomeInTX
4:59 AM GMT on September 02, 2011

Quoting TexasHurricane:


lol... I am actually having a good laugh tonight. It feels a heck of a lot better than being frustrated. :)
Lol. Yes it does! I'm giving up frustration tomorrow. :D
Member Since: August 24, 2010 Posts: 0 Comments: 676
3168. nofailsafe
4:58 AM GMT on September 02, 2011
Quoting AllStar17:
11:00pm Advisories
*Click on graphics to magnify (Graphics can further be magnified in Link window by clicking on them)




These still impress me, they're practically broadcast quality. Most excellent indeed.
Member Since: June 18, 2010 Posts: 3 Comments: 941
3167. JLPR2
4:58 AM GMT on September 02, 2011
Quoting NCHurricane2009:


May I say...95L?


To be on the safe side, I'll say pre-95L. :P
Member Since: September 4, 2007 Posts: 7 Comments: 8499
3166. NCHurricane2009
4:58 AM GMT on September 02, 2011
Quoting nofailsafe:


I hate it when they clip like this in the evenings.


Ugh...I know! That was also annoying during IRENE too....

Well at least we don't have a solar storm now, that would completely knock out the satellites, right?
Member Since: September 15, 2009 Posts: 437 Comments: 3600
3165. MiamiHurricanes09
4:58 AM GMT on September 02, 2011
Quoting louisianaboy444:


Link?
Link.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
3164. MississippiBoy
4:58 AM GMT on September 02, 2011
Quoting Dennis8:


GUESS? 80-100 MPH
do ya'll ever get a sick feeling in your stomach?i'm starting to.
Member Since: April 6, 2008 Posts: 1 Comments: 283
3163. AllStar17
4:58 AM GMT on September 02, 2011
Have an excellent night, everyone! I'll check in on TD 13 and Katia (and maybe more?) in the morning. I'll be interested to see if and where 13L relocates its "center".
Member Since: June 29, 2009 Posts: 13 Comments: 5300
3162. will40
4:58 AM GMT on September 02, 2011
Quoting AtHomeInTX:

Hey Will. Hope she just completely misses the east coast.


ty Tex we sure dont want her here. But im still wishing for Tex to get some much needed rain
Member Since: September 19, 2005 Posts: 2 Comments: 4110
3161. louisianaboy444
4:57 AM GMT on September 02, 2011
Quoting MiamiHurricanes09:
00z CMC has 13L stalling over southern Louisiana as a strong tropical storm for over 2 days before slowly starting to skirt off towards the east.

...must study. Dang tropics.


Link?
Member Since: August 29, 2006 Posts: 22 Comments: 1342
3160. AllStar17
4:57 AM GMT on September 02, 2011
11:00pm Advisories
*Click on graphics to magnify (Graphics can further be magnified in Link window by clicking on them)


Member Since: June 29, 2009 Posts: 13 Comments: 5300
3159. NCHurricane2009
4:56 AM GMT on September 02, 2011
Quoting JLPR2:
Wow, I have been busy, didn't even notice the spin at 10N, 30W was analyzed as a low since at least 06z yesterday. xD


May I say...95L?
Member Since: September 15, 2009 Posts: 437 Comments: 3600
3158. nofailsafe
4:56 AM GMT on September 02, 2011


I hate it when they clip like this in the evenings.
Member Since: June 18, 2010 Posts: 3 Comments: 941
3157. JLPR2
4:55 AM GMT on September 02, 2011
Wow, I have been busy, didn't even notice the spin at 10N, 30W was analyzed as a low since at least 06z yesterday. xD
Member Since: September 4, 2007 Posts: 7 Comments: 8499
3156. MiamiHurricanes09
4:55 AM GMT on September 02, 2011
00z CMC has 13L stalling over southern Louisiana as a strong tropical storm for over 2 days before slowly starting to skirt off towards the east.

...must study. Dang tropics.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
3155. SavannahStorm
4:55 AM GMT on September 02, 2011
Quoting SavannahStorm:
All this look at models has me wondering- why hasn't there been a serious attempt at quantum modeling of tropical systems? If quantum mechanics can predict when a photon or neutrino will appear at a certain point, why can't it be applied to fluid systems, like the atmosphere?

I'm no trained physicist, and it's a bit over my head, but is anyone familiar enough with quantum physics or string theory to tell me if the tropics could be applicable?


Also, I think distributed computing has a huge potential to help out the computer models. if you've ever used SETI@Home or Folding@Home, you are familiar with it. Imagine millions of private computers crunching model data continuously, 24/7... Model resolution could be bumped exponentially and models could be updated more frequently as well. Imagine the GFS Ensemble creating a mean track out of 200,000 variable runs, not just 20.
Member Since: September 22, 2005 Posts: 18 Comments: 2312
3154. TexasHurricane
4:55 AM GMT on September 02, 2011
Quoting AtHomeInTX:

Awe. Lol. I guess we both need Tex's laugh therapy. :)


lol... I am actually having a good laugh tonight. It feels a heck of a lot better than being frustrated. :)
Member Since: July 2, 2009 Posts: 0 Comments: 2811
3153. louisianaboy444
4:54 AM GMT on September 02, 2011
Quoting Levi32:


Not that far away from the loop track I forecasted this morning.


I read the model wrong it actually takes it on a straight track into SW LA then back south then basically due east right along the coast then NE into SE La..that would really suck
Member Since: August 29, 2006 Posts: 22 Comments: 1342
3152. AtHomeInTX
4:54 AM GMT on September 02, 2011

Quoting will40:
GFS out 204 hrs left feeder bands just brushing the NC coast so it not change much from 18z run
Hey Will. Hope she just completely misses the east coast.
Member Since: August 24, 2010 Posts: 0 Comments: 676
3151. nodramaman1022
4:54 AM GMT on September 02, 2011
Quoting Levi32:
0z GFS looks like a near miss for Katia, too close for comfort, but right between the uprights of Cape Hatteras and Bermuda. This solution still makes sense to me, as it has ever since Katia got to 40W, but the U.S. should still keep watch just in case. The same goes for Bermuda.


The system in the gulf may come in to play and may pull Katia more West than the models show
Member Since: August 30, 2011 Posts: 0 Comments: 24
3150. Dennis8
4:53 AM GMT on September 02, 2011
Quoting MississippiBoy:
anybody got a guess on how strong td13 may get?


GUESS? 80-100 MPH
Member Since: August 15, 2008 Posts: 0 Comments: 446
3149. MississippiWx
4:53 AM GMT on September 02, 2011
Quoting Levi32:


Agreed.


Are you starting to believe it could have subtropical characteristics?
Member Since: July 15, 2006 Posts: 17 Comments: 10159
3148. nodramaman1022
4:53 AM GMT on September 02, 2011
Quoting Levi32:
0z GFS looks like a near miss for Katia, too close for comfort, but right between the uprights of Cape Hatteras and Bermuda. This solution still makes sense to me, as it has ever since Katia got to 40W, but the U.S. should still keep watch just in case. The same goes for Bermuda.
Member Since: August 30, 2011 Posts: 0 Comments: 24
3147. AtHomeInTX
4:53 AM GMT on September 02, 2011

Quoting TexasHurricane:


Well since I have kinda been keeping up with storms (since Rita) we tend to get them (if we do) around the middle to end of month (September). So we will get relief then. Yeah, I'll go with that. :)
Sounds good to me! :)
Member Since: August 24, 2010 Posts: 0 Comments: 676
3146. MississippiBoy
4:52 AM GMT on September 02, 2011
anybody got a guess on how strong td13 may get?
Member Since: April 6, 2008 Posts: 1 Comments: 283
3145. AtHomeInTX
4:52 AM GMT on September 02, 2011

Quoting beell:


I got an extra dog today. So I could kick it...
Awe. Lol. I guess we both need Tex's laugh therapy. :)
Member Since: August 24, 2010 Posts: 0 Comments: 676

Viewing: 3195 - 3145

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 | 64Blog 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.

Local Weather

Mostly Cloudy
73 °F
Mostly Cloudy