Gulf of Mexico disturbance 93L a Lousiana flood threat; Katia a hurricane
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
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 — Blog Index
You mad.
Down from Spring as we have been below normal in Rainfall.
Something just nagging at me about the potential...
Something like this:
Loop
You mad bro?
LOOP!
I totally agree. This is NOT your usual, run-of-the-mill drought...even for Texas. This one + the hottest summer EVER (by a long shot) is almost beyond description for those who haven't endured it. Texas and the contiguous drought areas around it need a drought buster. The most likely candidate (aka SAVIOR) is a tropical cyclone. I've lived through several hurricanes and tropical storms in my 50+ years, and I can honestly say that this drought is as devastating as ANY of them including Beulah and Allen, both major storms. In fact, it may be worse because it's a slow death that rates very little attention and no relief. Whereas, with a tropical cyclone re-building can start after it's over. (And yes, there have, sadly, been plenty of deaths from this drought and heat wave also.)
And Jose was a warm core storm. So all that stament was simply wrong. :)
I do believe the correct term is "U MAD?".
He mad bro LOL
Humberto i think. 18 hours
Paula in 2010 tied it until it was said in the post season she went from td to H in 24 hours.
lol...
I know. The guy who posted that lives one town north of me. He just seemed a bit stressed. Lol. Aggravation with our local mets. I understand completely! :)
No Im 20 ft elevation near Audubon bend by Magazine and Jefferson.
r at a Glance
Weather Station
Uptown, New Orleans
Elevation
20 ft
as well as I taz.. regardless of the models and NHC forecast track.. this is far from being a certain hit on anywhere in LA. I wouldn't be surprised if TD13 followed the far left side of the track.
That's the pic it originated from.
I don't think I've ever seen that ad, actually. Sure you don't have some sort of malware?
I think the GFDL has a bug in the code, and keeps showing a western bias...but we will see.
Send me some. They had predicted high 90's and it got to 101. Started out looking hopeful. Some nice cumulus at 11 am. By noon looked like most of the moisture had mixed out. By 5 pm the cloud base was up where the cloud tops were at noon.
Still, there were a few weenie clouds ... weenie cumulus.
Glad to know that.
"Go West Young Man (insert TD), GO West" Texas PLeeeeze
Eastridge Drive The Roy's, SlidellElevation
53 ft
It's not impossible because there remains the possibility that the upper level high extends a little further NE-ward and provides at least 2 outflow channels and only 5-10 kts of shear. Then we would have to consider a minimal hurricane being possible if she has at least 36-48 hours. But the big factor for me is its broad circulation and very weak core. We see this all the time with tropical cyclones, those that have very well defined banding features and a well organized core are much more likely to rapidly strengthen. Those that don't - even in near ideal conditions - tend to strengthen more gradually.
Well, I feel threatened. ;)
The last thing Texas needs right now is 93L/TD #12/Lee, or whatever you want to call it. 93L promises to be a HUGE rain-maker, and torrential rains up to 20" is not good for Texas. It would cause significant flooding, and would probably be as damaging as Tropical Storm Allison (2001).
What Texas needs is several days of LIGHT rain, nothing heavy.
Sorry, but that is completely the opposite of what we need.
Any kind of rain, we dont CARE, AT ALL. let it be an allison, let it flood, we need 18 inches of rain out of the 20 anyway. Dont be calling out to TX and telling us what we dont and should need, RAIN is RAIN, and we need ALOT OF IT NOW.
Don't Mess With Texas, boy...
Lol you're right...my brain is soooo fried.
Ive lived here 9 years, but have never been present for a tropical entity. Thanks.
Good to hear. If the HPC forecast pans out, you all will need every bit of space to hold the water that is projected.
Viewing: 2001 - 2051
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 — Blog Index