92L Poised to Develop in Gulf of Mexico; Erin Struggling in Far Eastern Atlantic

By: Dr. Jeff Masters , 2:09 PM GMT on August 16, 2013

Tropical wave 92L crossed over Mexico's Yucatan Peninsula overnight, and the center of the disturbance is now located in the Gulf of Mexico along the west coast of the Yucatan Peninsula. Satellite loops show that 92L has a well-developed surface circulation, but there are no heavy thunderstorms near the center. A moderate-sized region of heavy thunderstorms does lie to the northeast and east of the center, over Cancun, Cozumel, and southwards to Belize. An upper-level low pressure system over the Gulf of Mexico is pumping dry air into 92L, slowing development. Wind shear is a moderate 10 - 20 knots over the the wave, which should allow slow development today. The hurricane hunter flight scheduled for today has been cancelled.


Figure 1. MODIS satellite image of 92L taken at 1:30 pm EDT Friday August 16, 2013. Image credit: NASA.

Forecast for 92L
The 12Z Friday SHIPS model forecast predicts that 92L will remain in an area of low to moderate wind shear through Saturday, and ocean temperatures will be a favorable 29 - 30°C. The topography of the Southern Gulf of Mexico's Bay of Campeche can aid in getting a storm spinning more readily, as well. Given these favorable conditions for intensification, 92L should be able to become a tropical depression by Saturday, and a tropical storm by Sunday. A trough of low pressure over the northern Gulf of Mexico will dip down by Sunday over the Central Gulf of Mexico, increasing the wind shear to a high 20 - 30 knots just to the north of 92L. This trough may also be able to pull the storm northwestwards to a landfall in Texas on Monday or Tuesday, as the 00Z Friday runs of UKMET and NAVGEM model predict. If 92L does follow this more northwesterly path, intensification into a strong tropical storm would be difficult, due to the high wind shear. An alternate scenario is presented by our two top-performing models, the European and GFS. They predict that 92L will take a nearly due west track, resulting in a landfall south of Tampico, Mexico on Monday. The storm would have more of an opportunity to strengthen in this scenario, since wind shear would be lower. Either scenario is reasonable, and residents of the Mexican and Texas Gulf Coast should anticipate the possibility of a tropical storm hitting the coast as early as Sunday night. Regardless of 92L's track, a flow of moist tropical air along the storm's eastern flank will form an atmospheric river of moisture that will bring a wide swath of 4+ inches of rain to the Gulf Coast from Louisiana to the Florida Panhandle over the next few days. In their 8 am EDT Wednesday Tropical Weather Outlook, NHC gave 92L a 50% of developing by Sunday, and a 60% chance of developing by Wednesday. I put these odds higher, at 70% and 80%, respectively.


Figure 2. MODIS satellite image of Tropical Depression Erin taken at 10:30 am EDT Friday August 16, 2013. At the time, Erin had maximum sustained winds of 35 mph. Image credit: NASA.

Tropical Storm Erin
Tropical Storm Erin is over the far Eastern Atlantic off the coast of Africa, and continues west-northwest at 15 mph. Erin is small and weak and has lost nearly all of its heavy thunderstorms, as seen on satellite loops. This is probably due, in part, to the fact the storm is over waters of 25.5 - 26°C, which is a marginal temperature for tropical cyclones. Erin is also having trouble with dry air from the Saharan Air Layer (SAL), and the storm's west-northwest motion is beginning to cut Erin off from a moist source of air to its south--the semi-permanent band of tropical thunderstorms called the ITCZ (Inter-Tropical Convergence Zone.) The latest 00Z runs of the major global computer models, except for the GFS, call for Erin to dissipate by early next week. Given Erin's struggles today, I expect the storm will be dead by Sunday.

Jeff Masters


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

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1841. Gearsts
Quoting 1829. JLPR2:


Nice spin starting on the African coast, we should see an invest pop in the area in a day or so.
GFS thinks the area will be broad and take time to come together until it gets closer to the islands, also it shows a rather large system.
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1840. nigel20
Quoting GTstormChaserCaleb:
Dangerous pattern continues to show up on the long range GFS:


Hi Caleb! It seems as if we're at the start of a very active period in the Atlantic as well.
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Quoting 1829. JLPR2:


Nice spin starting on the African coast, we should see an invest pop in the area in a day or so.


Uyy... Do you think we will pass the 15 year record?

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Quoting 1822. Gearsts:
Not trusting the gfs yet
Fernand and Gabrielle.
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Looks like the jet stream wants to stick its toes in some gulf water for awhile...
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1836. sar2401
Quoting whitewabit:


For the true cost per recon flight you would have to take the cost of the 53rd squadron for the year and then divide it by the number of missions flown .. there are many hidden costs that would have to be figured in for the total ..

There are also many fixed costs that have to get paid every month regardless of if an aircraft ever leaves the ground. Among those fixed costs are salaries and benefits for squadron personnel, who get paid the same amount each month regardless of how often they fly. Eeven if there were zero storms, there a minimum number of flight hours per month the crews have to make to maintain proficiency. The typical ratio for a military base is 70% fixed costs and 30% variable. For hurricane hunters, this would primarily be fuel, lubricants, and expendables, like the dropsondes.
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Quoting 1824. GTstormChaserCaleb:
Well unless 92L becomes Fernand, it is likely Fernand will not only become the first hurricane of the season, but the first major hurricane.



I know not everyone will agree with me on this (Bonnie, I'm thinking of you :) ), but I think I'd rather it work out that way, personally. I don't want to see a year with mostly struggling tropical storms, like 2011.

I hated it. :)
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1834. Gearsts
That would be our hurricane the gfs is showing.
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Quoting 1814. LAbonbon:


LOL, I'm getting wicked deja vu. Didn't this go-round already happen with Sar and Naga (or Nea?)? If only I could recall the outcome...


may have been on vacay for that one ;)
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Convection still fighting in short bursts in the ULL. Nothing to speak of in the LLC. DMAX will be pivotal - if 92L can't fight through the ULL, I don't think I can see it restrengthening. The vorticity seems to be elongating and weakening as we speak; a good, long burst of convection tonight and through the morning seems all but mandatory to pull everything back together.

If it dies, then we should watch that ULL. Upper level rotation is weakening, but notable vorticity is still present at the 500 and 700 millibar levels. The 700mb piece of vorticity seems to be consolidating around the center of the ULL as well. Lower level rotation still seems to be firmly rooted in the LLC though.
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Quoting 1824. GTstormChaserCaleb:
Well unless 92L becomes Fernand, it is likely Fernand will not only become the first hurricane of the season, but the first major hurricane.

Ok, I know I'm in Asheville now, but I am still not comfortable with that forecast.
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1829. JLPR2
Quoting 1817. sunlinepr:


Nice spin starting on the African coast, we should see an invest pop in the area in a day or so.
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1828. Patrap
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Quoting 1802. Patrap:
Latest 92L Guidance


Wish I could watch that video...my internet connection is too slow...
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Quoting 1799. LAbonbon:
Here's the link to the NOAA page where the graphic came from.

Link

From this page: "More information on return periods can be found from NOAA Technical Memorandum NWS NHC 38 (pdf) on the NHC Risk Analysis Program (HURISK)." Here is the Technical Memorandum:

Link

Beware, it's pre-computer, typed, and scanned. It's not searchable.

I was a bit disappointed, as I wrongly assumed they straight-up compared different storms and years between. As you'll see, that's not the case (whole lot of modeling).

Here's another paper I found, that is more easily digested (and to me, more easily understandable). It's from State of the LA/LSU (Keim, Muller and Stone, 2006), and it references other papers and the return periods from them as well.

Link

As you'll see, the return periods from NOAA's graphic, and the ones referenced in the paper from LA/LSU are quite different.

My interest in this started with a question from another blogger - why does central Maine have a return period for major hurricanes of 290 years, and where does this come from? After digging into the documents, I have yet to have a good answer to that question. I know there is a documented major in Maine in 1635, and another this past century. But, it doesn't calculate to 290 years. But, as per the Tech. Memorandum, that's not how they do it anyway.

Let me know if you can shed any light on the original question, though. I'd appreciate it!


It would depend on the time period, the start and cutoff date, how close the COC is to the location, and the intensity of the storm. So, it is very easy to get different return periods if these differ across the publications. For instance, the return period for a major hurricane (>cat3) is ~210 yrs for that location in Maine. However, the return period for any hurricane is 50 years for the same location. For any, if they are using a radius, like the 50 nm in the NOAA figures, one would have to discern if that is all storms (land and non-landfalling storms) or only landfalling storms. The devil is in the details.

The paper you cite looks at 105 yr period, but the cut off is 2005. That explains some of the differences observed. Hope this helps.
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974low
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Well unless 92L becomes Fernand, it is likely Fernand will not only become the first hurricane of the season, but the first major hurricane.

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1823. docrod
Quoting 1818. GTstormChaserCaleb:
Dangerous pattern continues to show up on the long range GFS:



I feel like a dart board this year. We've had it too easy for a while.
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1822. Gearsts
Not trusting the gfs yet
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Quoting 1808. sar2401:

Yes, but there are no pilots, nor any other Air Force personnel on furlough. The CARCAH civilian furloughs will not affect any normal hurricane hunter flights. As the story stated, the few furloughs involved have mostly already been covered by taking the days off during slow periods, and we've certainly had enough of those. The DOD also has the authority to declare an emergency and cancel furlough days for the extent of the emergency. No hurricane hunter flights are going to be adversely affected, but it makes great publicity why the DOD needs more money next year. I'm quite certain the DOD could find ways to cut costs enough to cover the costs of a three person unit.


but its not a 3 person unit .. there are 5 people on each flight crew and there are 10 flight crews ! plus 10 flight crews that are reservist that fly part time .. for a total of 20 ..

From Hurricane Hunters Association

We have five different flying jobs at the Hurricane Hunters. ALL jobs are part of the Air Force Reserve. Half of the positions are part-time (traditional reservists), and half are full-time (Air Reserve Technicians). We have 40 pilots, 20 each of navigators, aerial reconnaissance weather officers, and weather loadmasters. In addition, we have numerous support personnel that work in various fields such as flight administration, life support, and various maintenance specialties; without these folks we would never get airborne!
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1820. Patrap
After midnight, we're gonna shake your tambourine.

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1819. flsky
Quoting 1806. SuperStorm093:
HURRICANE on new GFS headed to FLORIDA east coast

Image? Notation?
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Dangerous pattern continues to show up on the long range GFS:

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Quoting 1811. daddyjames:


Sar, I can only go with what is reported in the Washington Post (Associated Press) from quotes by those in charge of the program. maybe for non-essential defense purposes, this is not the case.


LOL, I'm getting wicked deja vu. Didn't this go-round already happen with Sar and Naga (or Nea?)? If only I could recall the outcome...
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1813. Patrap
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Nevermind will end as a fish.
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Quoting 1808. sar2401:

Yes, but there are no pilots, nor any other Air Force personnel on furlough. The CARCAH civilian furloughs will not affect any normal hurricane hunter flights. As the story stated, the few furloughs involved have mostly already been covered by taking the days off during slow periods, and we've certainly had enough of those. The DOD also has the authority to declare an emergency and cancel furlough days for the extent of the emergency. No hurricane hunter flights are going to be adversely affected, but it makes great publicity why the DOD needs more money next year. I'm quite certain the DOD could find ways to cut costs enough to cover the costs of a three person unit.


Sar, I can only go with what is reported in the Washington Post (Associated Press) from quotes by those in charge of the program. maybe for non-essential defense purposes, this is not the case.
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1809. Patrap
Quoting 1803. whitewabit:


For the true cost per recon flight you would have to take the cost of the 53rd squadron for the year and then divide it by the number of missions flown .. there are many hidden costs that would have to be figured in for the total ..


Indeed wabit, it ain't a 737 Hop from MSY to LAX
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1808. sar2401
Quoting daddyjames:


And since the majority of the recon flights are military, they are not exempt from the sequestration. A recent article describing that if there are three potential storms, there may not be enough to do recon

Link

Yes, but there are no pilots, nor any other Air Force personnel on furlough. The CARCAH civilian furloughs will not affect any normal hurricane hunter flights. As the story stated, the few furloughs involved have mostly already been covered by taking the days off during slow periods, and we've certainly had enough of those. The DOD also has the authority to declare an emergency and cancel furlough days for the extent of the emergency. No hurricane hunter flights are going to be adversely affected, but it makes great publicity why the DOD needs more money next year. I'm quite certain the DOD could find ways to cut costs enough to cover the costs of a three person unit.
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How far South will that trough / front border (blue) will go over Texas.... If it reaches the Mexican border, it will impact 92L and take it to the NE....


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HURRICANE on new GFS headed to FLORIDA east coast
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Quoting 1662. HimacaneBrees:
5 yards from previous spot, replay 2nd down.


Saints football and a big bowl of shrimp?
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Quoting 1792. Kumo:


That is a small fraction of what some of our elected officials have been spending on their vacations. :(

I'd like to see the hunters fly anyway, 35k isn't much and besides the mission flights are good for their training.


For the true cost per recon flight you would have to take the cost of the 53rd squadron for the year and then divide it by the number of missions flown .. there are many hidden costs that would have to be figured in for the total ..
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1802. Patrap
Latest 92L Guidance
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1801. docrod
Quoting 1796. KEEPEROFTHEGATE:
that time of year from now till sept 15


Not looking forward to it. I've already knocked back my 40-50ft trees to 15ft, two more trees to go. I'm in the FL Keys (since 91). First major major "trim" here - take care
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Quoting 1781. sar2401:

Not true, no pilots are on furlough. They are Air Force Reserve, not NOAA. NOAA furloughs were also canceled in May,


Not according to the Washington Post. Reserves are also subject to the sequestration as they are part of the DoD.

Link
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Here's the link to the NOAA page where the graphic came from.

Link

From this page: "More information on return periods can be found from NOAA Technical Memorandum NWS NHC 38 (pdf) on the NHC Risk Analysis Program (HURISK)." Here is the Technical Memorandum:

Link

Beware, it's pre-computer, typed, and scanned. It's not searchable.

I was a bit disappointed, as I wrongly assumed they straight-up compared different storms and years between. As you'll see, that's not the case (whole lot of modeling).

Here's another paper I found, that is more easily digested (and to me, more easily understandable). It's from State of the LA/LSU (Keim, Muller and Stone, 2006), and it references other papers and the return periods from them as well.

Link

As you'll see, the return periods from NOAA's graphic, and the ones referenced in the paper from LA/LSU are quite different.

My interest in this started with a question from another blogger - why does central Maine have a return period for major hurricanes of 290 years, and where does this come from? After digging into the documents, I have yet to have a good answer to that question. I know there is a documented major in Maine in 1635, and another this past century. But, it doesn't calculate to 290 years. But, as per the Tech. Memorandum, that's not how they do it anyway.

Let me know if you can shed any light on the original question, though. I'd appreciate it!
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Quoting 1761. scott39:
Does this hunk of junk in the GOM have to work the ULL down to the surface for developement.


As Levi said, the naked swirl -- the official fix for 92L -- still has some chance of development before it reaches the western Gulf Coast in a few days, but I think that recent ASCAT pass confirms that nothing is going on with the northern vorticity we were watching. It would take more persistent convection than it's had to bring down a surface reflection in that area.
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1797. HadesGodWyvern (Mod)

surface map says DSIPT on that area near 40 west





well now.. that was quick even though it was along the inter-tropical convergence zone
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1796. KEEPEROFTHEGATE (Mod)
Quoting 1788. docrod:


True KOG ... but it's an impressive train goin' on right now!
that time of year from now till sept 15
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Quoting 1792. Kumo:


That is a small fraction of what some of our elected officials have been spending on their vacations. :(

I'd like to see the hunters fly anyway, 35k isn't much and besides the mission flights are good for their training.


I would like to see them fly, but doesn't seem the case this year ..
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1794. docrod
Quoting 1787. Patrap:
Google "Minuteman Missiles and Inspection" in news and get back to me in 5.


You pulled Rickles - mustabinaproblem?

ok
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1793. nigel20
Quoting sar2401:

Not true, no pilots are on furlough. They are Air Force Reserve, not NOAA. NOAA furloughs were also canceled in May,

Hi sar How's the weather in Alabama? It was a pretty dry and warm day in Jamaica Today.

Kingston Jamaica weather station
( updated Fri, 16 Aug 2013 10:59 pm EST )

28°C
High: 32°C | Low: 27°C
Partly Cloudy

Sunrise: 5:48 am
Sunset: 6:30 pm
Visibility: km
Feels like: 28°C
Humidity: 79%
Wind: 12.87 km/h
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1792. Kumo
Quoting 1759. whitewabit:


Just fuel for a 6 hour flight would be over 20K and then normal maintenance and the pay for 10 flight crews to cover the three aircraft.. 5 members in each flight crew .. so guessing at somewhere around 30-35K including the dropsonde they use each mission ..


That is a small fraction of what some of our elected officials have been spending on their vacations. :(

I'd like to see the hunters fly anyway, 35k isn't much and besides the mission flights are good for their training.
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1791. KEEPEROFTHEGATE (Mod)
surface map says DSIPT on that area near 40 west



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Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather