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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Quoting 327. TXCWC:


Map I was just looking at showed the invest low still over very low OHC but getting close to higher OHC. Click on OHC tap once on linked map pg from Wisconsin University.

Link


The sst's are plenty warm there, it just shows reduced OHC because of the shallow depth of the water along the coast. 92L could not take advantage off deeper warm water anyway because of it's lack of development. My point is, water temp is not an issue for 92L. OHC plays a much larger role in developed storms (think CAT 2+) that can upwell cooler water because of the violent dynamics near the oceans surface and with developed systems which move very slow.
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Quoting 326. opal92nwf:
And that little mess east of the islands seems like it could do something:
Indeed..It looks even more robust today.
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As the warmer and deeper waters of the GoM eddys go, 92L is currently in a rather cooler spot so-to-speak comparatively; however, if model tracks play out, it could be traversing over a considerably warm eddy just away to its wnw, and could help with intensity.

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Quoting 315. Walshy:
Nike Weatherman Pack Release Date is Official



Link

I'm probably going to get a pair of those. Nike shoes fit my feet really good and it's weather themed, I can't ask for much more.
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...
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Quoting 315. Walshy:
Nike Weatherman Pack Release Date is Official



Link


I plan to already get some, I came across this last night.
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Quoting 199. 1900hurricane:

Did someone say Dog? :P



Yeah the Antilles had a ruff time with that storm. groan :)
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Quoting 271. wunderweatherman123:
erin is doing its job. clearing the leftover SAL
Yep..Clearing the path for the next 20 or so waves that will emerge over the next 2 and a half months. This next wave has good rotation and size,should be interesting.
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Quoting 322. hurricane23:


ECMWF and GFS MJO ensembles both look very favorable for Atlantic Tropical cyclone development in late Aug/early Sep. Plenty of rising air.


MJO still floating around not sure what to do yet, but the CFS as well as the ECMWF and GFS are saying it'll be quite potent in our basin right as we hit the last weeks of August. The season hasn't really "ignited" yet because of that, but it's going to in short order with numerous hurricanes possible. The only negative factor is the fact that vertical instability is a little below average across the tropical Atlantic, but as the MJO phase moves in that'll change.
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OMG Look Out!!!!
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SYNOPSIS FOR THE GULF OF MEXICO
1050 AM EDT FRI AUG 16 2013

.SYNOPSIS...LOW PRESSURE LOCATED NEAR 21N91W IS FORECAST TO MOVE
TO NEAR 21N93W EARLY SAT MORNING...NEAR 21N93W EARLY SUN MORNING...
THEN NEAR 22N95W BY EARLY MON MORNING. THE LOW WILL HAVE THE
POSSIBILITY OF BECOMING A TROPICAL CYCLONE DURING THE FORECAST
PERIOD IF IT MOVES TOWARD THE WEST OR WEST-NORTHWEST. A RIDGE WILL
DOMINATE MAINLY THE EASTERN GULF.
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Quoting 316. GTstormChaserCaleb:
Subtropical/Hybrid/Barotropical 92L: ULL/Surface Low, pretty neat system to have in the GOM during August, usually get these around the beginning or end of the season and winter time. Appreciate it while it still around.



GT. What am I seeing on the N tip of the Yuke?...the wrap around?
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327. TXCWC
Quoting 314. TideWaterWeather:


non-existent OHC? You are not reading the TCHP correctly at all...


Map I was just looking at showed the invest low still over very low OHC but getting close to higher OHC. Click on OHC tab once on linked map pg from Wisconsin University.

Link
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And that little mess east of the islands seems like it could do something:
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This mornings run had some winds on the southeast side up to tropical storm strength.

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Very large wave emerging off of Africa on the 12Z GFS.



Lots of moisture with this one as well.
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Quoting 316. GTstormChaserCaleb:
Subtropical/Hybrid/Barotropical 92L: ULL/Surface Low, pretty neat system to have in the GOM during August, usually get these around the beginning or end of the season and winter time. Appreciate it while it still around.

I'm hoping we see more of these during the winter that ride up the east coast during a cold priod.I will be very happy :)
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Quoting CybrTeddy:
Erin acted as a "sacrificial" wave for future storms. There's no model support for the wave emerging off the coast of Africa, but I'd imagine eventually within the week one will emerge that will have a threat to become a significant hurricane.


ECMWF and GFS MJO ensembles both look very favorable for Atlantic Tropical cyclone development in late Aug/early Sep. Plenty of rising air.
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Good morning!

Looks like the wave behind Erin is farther South:

Something to watch?
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Quoting 315. Walshy:
Nike Weatherman Pack Release Date is Official



Link


And the weather enthusiasts on the Blog go Ka-Ra-Zy... :)
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nevermind
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Quoting 309. LargoFl:


What a timely graphic! I'm learning something from TXCWC's questions :)
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Quoting 291. TXCWC:


Thanks - thank you Dakster as well. So would it be safe to say that the effect each has on a storm is determined by speed of storm? For example a slower storm effected more by a lower OHC and therefore OHC becoming more important than SST in that circumstance?
That's a beast of a question right there, because the speed a storm moves at has many different effects in many different situations.

For instance a slower storm may have more time over water to strengthen but if it's moving to slowly, its going to end up eating up all of the fuel below it.  That's why most stalled storms, or storms that sit in the same general place for extended periods of time will stall out in strength as well, and often weaken.

If a stronger storm stalls in place, it will weaken much faster than a weaker storm, simply because its wind is mixing up the water below it at a much faster pace, and it also needs much more energy to fuel itself.

The overall size of the storm is a major factor as well, very large storms need MUCH more energy to strengthen, while compact storms can spin up from a tropical storm to a major hurricane in a matter of a day even with meh conditions.

Faster storms generally run into the issue of creating their own shear, and water temperatures dont have as much of an affect on them as they do slow storms.  Particularly if the storm is heading up the east coast. 

Storms that move up the east coast are famous for moving VERY VERY quickly...upwards of 40mph.  This intense forward motion really starts to make the system shear and destroy itself, even if other conditions - including water temps - are ideal.

I dont know if I answered that well but hey lol
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Subtropical/Hybrid/Barotropical 92L: ULL/Surface Low, pretty neat system to have in the GOM during August, usually get these around the beginning or end of the season and winter time. Appreciate it while it still around.

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Nike Weatherman Pack Release Date is Official



Link
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Quoting 303. TXCWC:
Was asking about SST and OHC since current Gulf Low is over warm SST but almost non-existent OHC...was not sure if no OHC area it is currently over was having an effect on development right now or not.


non-existent OHC? You are not reading the TCHP correctly at all...
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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
1148 AM EDT Fri Aug 16 2013

.NEAR TERM [Today and Tonight]...
A very interesting surface chart this morning with temperatures
only in the mid 60s across Middle Georgia behind a well defined
stationary frontal boundary stretching from Coastal Alabama up
through Middle Georgia and into Coastal South Carolina. It is a
little odd to see a cool wedge set up this strong in mid August.
In any event, this boundary separates a relatively cool and stable
airmass from a deep tropical moist one across North Florida and
Southern Georgia. As more moisture continues to advect north today
along the eastern edge of a tropical disturbance in the Southern
Gulf, expect additional showers and storms to develop this
afternoon. This will be aided by the approach of a strong upper
level (non-tropical) disturbance moving into the Lower Mississippi
River Valley. While the bulk of the rain is anticipated for
Saturday, rainfall this afternoon and tonight could still be
locally impressive, with rainfall amounts piling up quickly in
some of the heaviest storms. Rainfall rates yesterday afternoon
were approaching 2 to 3 inches per hour, and given our current
environment, there is no reason why that would be any different
today. Storm motion will still be out of the SW at 10 to 15 knots,
so unless echo-training sets up, only anticipate localized
flooding from rainfall today.

Given our northern counties being right along the interface of the
cool wedge to the north, kept temperatures there only in the mid
to upper 70s with the extensive low level cloud cover.

&&

.SHORT TERM [Saturday Through Sunday]...
Overall, the forecast has not changed much from the previous
thinking. Several factors are coming together to produce this
heavy rain/flood threat, including an anomalously strong 250 mb
jet, an anomalous back-door cold front, and above normal tropical
moisture with precipitable water values of 2.2-2.4 inches by
Saturday.

The available hi-res guidance has responded by showing some very
high QPF values, and although the areal extent of the extreme QPF
may be somewhat overdone, the magnitudes may offer a glimpse at
what a few of the localized totals may end up looking like when
all is said and done. Given the rather efficient rainfall
producing storms we saw in southwest Georgia on Thursday (already
over 4 inches in some localized spots) and the possibility of
training convection today and Saturday, the current thinking is
that localized rainfall amounts of around a foot are possible
through Sunday morning. While most areas will instead see 3 to 5
inches, if a few areas do manage to see a foot of rain, then
obviously some significant flooding could occur in those areas.

The flash flood watch was expanded to cover the entire forecast
area. Although there are some indications that the highest
probability of flooding through the period resides across the
Florida panhandle, southeast Alabama, and southwest Georgia, we
cannot rule out the possibility of some of the localized very
heavy rain making it to the southeast big bend as some of the hi-
res guidance shows. Therefore, the watch was expanded to cover the
whole area.

&&

.LONG TERM [Sunday Night through Thursday]...
The wet weather pattern will remain in place into early next week
with a deep feed of tropical moisture energized by a nearly
stationary upper trough centered over the Lower Mississippi
Valley. By Tuesday, the upper trough is forecast to weaken with
the subtropical ridge building back into the southeastern states.
This should return the region to more climatological diurnal
convection with normal mid August temperatures.

&&
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312. L1990


sure hope this doesnt happen to my work place hehe
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Erin acted as a "sacrificial" wave for future storms. There's no model support for the wave emerging off the coast of Africa, but I'd imagine eventually within the week one will emerge that will have a threat to become a significant hurricane.
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Partial Ascat of the wave at 45 W showing a decent circulation with lots of West winds. It might even be closed but no Eastern half data. If the convection refires today this could be circled by the NHC later on. They will probably not do so while the convection is on the wane but you never know.

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Quoting 151. RitaEvac:
If you are in TX and if it did this....you do realize it will be sunny and dry and the drought will keep on keeping on



Yup. Exactly like TS Lee in 2011. Awful situation for TX. Id rather see 92 die than cause that dry air influx/wind scenario here and the resulting wildfires that I guarantee will follow.
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I discover that of the 4 name retired in the central pacific 3 out of 4 are with an I letter Iwa,Ioke and Iniki.Paka is the only one not starting with and I and be retired.That may mean that Iune have a great chance of being retired when use,Or it may pull and Isaac and be the only veteran I storm not being retired.
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Quoting 251. Dakster:


I bet you would have been saying the same thing in 1992... I don't consider that year a bust...

Just saying.


Which year had the biggest bust? Oh wait, nevermind.
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Here are the current readings from the one buoy in the middle of the Bay of Campeche which is the one to keep an eye on through the weekend for some readings of what is happening on the ground.

This position is still well to the West of the COC, and in the clear still, so air pressures are currently rising but note the wind direction from the North; the circulation is intact and trying to warp around some of the displaced convection. Might take a while to accomplish and will depend on how the sheer impacts the system but it is trying:

Station 42055
NDBC
Location: 22.203N 94W
Date: Fri, 16 Aug 2013 15:50:00 UTC
Winds: N (10°) at 13.6 kt gusting to 15.5 kt
Significant Wave Height: 2.6 ft
Dominant Wave Period: 6 sec
Mean Wave Direction: ENE (68°)
Atmospheric Pressure: 29.91 in and rising
Air Temperature: 84.9 F
Dew Point: 75.6 F
Water Temperature: 86.0 F


And look at those 86 degree sst's; that should help it a little bit if it can get it's act together.
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. L1990 4:10 PM GMT on August 16, 2013 +0
SWLA is in the room apparently lol


Yeah Shae' you do have the honor of our presents.
lol
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303. TXCWC
Was asking about SST and OHC since current Gulf Low is over warm SST but almost non-existent OHC...was not sure if no OHC area it is currently over was having an effect on development right now or not.
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Quoting 220. Patrap:


Don't like this one. The local mets are saying if it comes this way, before it hit s the coast it will back down on strength.
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Quoting 297. L1990:


unless it causes billions of dollars in lost revenue from an evacuation for a false alarm major hitting land
What part of "out to sea" you did not get?
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GFS at 87 hours - very wet gulf coast but no organized systems in the GOM
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Quoting 291. TXCWC:


Thanks - thank you Dakster as well. So would it be safe to say that the effect each has on a storm is determined by speed of storm? For example a slower storm effected more by a lower OHC and therefore OHC becoming more important than SST in that circumstance?


In addition to forward speed, SST'S and OHC(TCHP),the strength of the storm also plays a role(upwelling potential).
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297. L1990
Quoting 294. washingtonian115:
The weather enthusiast in me likes seeing these storms turn into beautiful majors out to sea.Nothing wrong with tracking/watching a major from a distance.


unless it causes billions of dollars in lost revenue from an evacuation for a false alarm major hitting land
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295. L1990
SWLA is in the room apparently lol
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Quoting 219. clwstmchasr:


You act like these storms are old girlfriends/boyfriends that have wronged you. They are just weather systems and will do what conditions will allow them do.
The weather enthusiast in me likes seeing these storms turn into beautiful majors out to sea.Nothing wrong with tracking/watching a major from a distance.
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With the deep layer trough down in the SE and the high SSTs in the GOM, the possibility of a Gulf Subtropical Storm is one of the cards in play, IMHO.

I have some peer-reviewed data to back up this up:
As the transition season approaches,
the baroclinic zone begins to extend farther south and
the warm SST remain, further increasing the chance of
ST genesis.
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Quoting 279. TXCWC:
Having trouble finding information on the subject of SSTs (sea surface temp) and OHC (ocean heat content). What is the diffrence between the two and which if any has more of an effect on storm development and strength?


Ocean heat content is defined as the integrated temperature change times the density of seawater, times specific heat capacity from the surface down to the deep ocean. It is calculated here base on observations from the upper 700 metres of ocean water.

In other words, how deep is the ocean. If there is enough heat deep down many feet, it can greatly aid in the strength of a system as was evidenced with Utor.
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291. TXCWC
Quoting 283. RyanSperrey:

SST = temperature at or near the surface

OHC = basically how much of the water is at what temperature. 

So SST indicates the potential fuel for storms, and OHC indicates the amount of fuel the storm has to work with...At least thats my understanding


Thanks - thank you Dakster as well. So would it be safe to say that the effect each has on a storm is determined by speed of storm? For example a slower storm effected more by a lower OHC and therefore OHC becoming more important than SST in that circumstance?
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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