Ernesto is on the way

By: Dr. Jeff Masters , 1:42 PM GMT on August 25, 2006

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Tropical Depression Five is looking much more organized this morning, and will likely be named Ernesto with the NHC 11am EDT advisory. Satellite intensity estimates from NOAA using a the standard "Dvorak technique" are the same for Debby and TD 5 this morning. Since Debby has a name, Ernesto should getting his name, as well. The visible satellite images from this morning show a large and expanding area of intense thunderstorms, some solid spiral bands forming, and the beginnings of some decent upper-level outflow. A QuikSCAT satellite pass at 7:40am EDT showed winds of up to 50 mph near the center, and I imagine this will be the maximum sustained wind speeds for the 11am advisory.


Figure 1. Current satellite image of TD 5.

Wind shear
As usual, the major question is, "what is wind shear doing, and what is the wind shear forecast?" My top hurricane bookmark is the real-time wind shear analysis done by the University of Wisconsin's CIMSS group. This image, updated every 3 hours from data taken by the GOES-East satellite, shows yellow contour lines of what the shear is, in knots. Pink arrows show what direction the shear is coming from. The shear is the difference between the winds at high altitude (200 mb) and low altitude (850 mb). Hurricanes like wind shear close to zero, but can tolerate shear up to 20 knots and still slowly intensify. As we can see from the winds shear plot from this morning at 9Z (5am EDT) (Figure 2), Tropical Storm Five was under about 10 knots of shear, from the west. This is low enough to allow some intensification, and that is what we are seeing this morning. However, Tropical Storm Debby was under about 20 knots of shear, and has not been able to intensify this morning.


Figure 2. Wind shear estimate at 9Z (5am EDT) Fri Aug 25 2006. Image credit: University of Wisconsin's CIMSS group.

To the west of TD 5 we see a large area of very high shear of up to 50 knots, south of Jamaica. This area of high shear is associated with a strong upper level trough of low pressure that has been a common feature over the Caribbean this season. The trough is moving westward, away from TD 5, but TD 5 is racing fast enough westward that it may catch up to this high shear area and get torn apart on Sunday. The 8pm UKMET and 2am GFS models both have TD 5 dissipating by Sunday, and this is reasonable forecast. However, the trough is forecast to split apart on Monday and leave a region of low shear very favorable for intensification of TD 5 in the western Caribbean. If the storm does manage to survive into Monday, we could end up with a dangerous hurricane in the Gulf of Mexico by the middle of next week. The latest runs of the GFDL and Canadian models prefer this solution, bringing the storm across Cuba and into the eastern Gulf of Mexico as a hurricane. This is also a reasonable forecast. If you have travel plans to Jamaica, Cuba, or Cancun in the coming days, I would wait as long as possible to change them until we see if TD 5 will survive.

Debby
Tropical Storm Debby remains a minimal tropical storm today, with 20 knots of vertical wind shear putting a damper on her intensification. She could slowly intensify in response to some warmer waters along her path the next two days. By the time Debby turns north this weekend, she could attain hurricane status, but this is looking unlikely now. Early next week, Debby is expected to get caught up in the jet stream and die in the North Atlantic.

New African wave
Several of the computer models are predicting that the tropical wave coming off the coast of Africa today will develop into a tropical storm early next week.

Next update
The next Hurricane Hunter mission into TD 5 is at 2pm EDT this afternoon, and I'll have an update when the reports from their mission come in. Also, I'm getting a lot of questions about which models are best, where to find model output, etc, and I will try to post a quick summary of this info this afternoon.

Jeff Masters

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741. snotly
5:37 PM GMT on August 25, 2006
looks like Ernie is being sheared with the LL storm moving out from below. Is a new Low forming under the the convection south-east of the center
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739. Chicklit
5:37 PM GMT on August 25, 2006
Taz, what has happen is that TD5 has slowed considerable. Weather456
If you look at the shear map on the top of this page, wouldn't it make sense that TD5 would move between the two 50-shear areas?
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738. silverstripes
10:39 AM PDT on August 25, 2006
So does this potentially mean we have Ernie? They have locacted only one area of tropical storm force winds lets see if they find more areas.
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737. Tazmanian
10:38 AM PDT on August 25, 2006
URNT12 KNHC 251724
VORTEX DATA MESSAGE
A. 25/17:15:20Z
B. 14 deg 04 min N
066 deg 58 min W
C. NA mb NA m
D. 45 kt
E. 48 deg 039 nm
F. 118 deg 048 kt
G. 048 deg 040 nm
H. EXTRAP 1005 mb
I. 23 C/ 304 m
J. 24 C/ 304 m
K. 24 C/ NA
L. NA
M. NA
N. 1 345/ 1
O. 0.02 / 2 nm
P. AF303 0205A CYCLONE OB 04
MAX FL WIND 48 KT NE QUAD 17:01:30 Z
SLP EXTRAP FROM 1500 FT


we have a TS now and what is 45kt or 48kt in mph?
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736. StormJunkie
1:38 PM EDT on August 25, 2006
I agree pat...Big shout out and thanks to Max Mayfield.
Member Since: August 17, 2005 Posts: 26 Comments: 16874
735. southbeachdude
1:38 PM EDT on August 25, 2006
miami..the gfdl might not be out to lunch!
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733. Patrap
5:38 PM GMT on August 25, 2006
..out to the Middle school run..b bac later...
Member Since: July 3, 2005 Posts: 428 Comments: 129904
732. thelmores
5:38 PM GMT on August 25, 2006
so whats the verdict????

TS Ernesto at 2pm..... or 5pm??????
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731. Weather456
1:37 PM AST on August 25, 2006
URNT12 KNHC 251724
VORTEX DATA MESSAGE
A. 25/17:15:20Z
B. 14 deg 04 min N
066 deg 58 min W
C. NA mb NA m
D. 45 kt
E. 48 deg 039 nm
F. 118 deg 048 kt
G. 048 deg 040 nm
H. EXTRAP 1005 mb
I. 23 C/ 304 m
J. 24 C/ 304 m
K. 24 C/ NA
L. NA
M. NA
N. 1 345/ 1
O. 0.02 / 2 nm
P. AF303 0205A CYCLONE OB 04
MAX FL WIND 48 KT NE QUAD 17:01:30 Z
SLP EXTRAP FROM 1500 FT
Member Since: July 24, 2005 Posts: 407 Comments: 19076
729. silverstripes
10:36 AM PDT on August 25, 2006
45 Kt = almost 52 mph at the surface from the vortex.
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728. StormJunkie
1:36 PM EDT on August 25, 2006
No Gulf, I was watching the flight data on here and noticed the temp rise two degrees and the winds drop, whent hey came out of this area winds started to rise in opposite direction. They found a center IMHO.
Member Since: August 17, 2005 Posts: 26 Comments: 16874
727. Patrap
5:37 PM GMT on August 25, 2006
..Oh..Okay..Franck..iz Okay..we were out the water..but tired from being in it.WE were the lucky ones...
Member Since: July 3, 2005 Posts: 428 Comments: 129904
726. franck
5:36 PM GMT on August 25, 2006
Then you just put your Muse on the shelf and go technical.
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725. Tazmanian
10:36 AM PDT on August 25, 2006
weather456 what dos that mean now
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724. southbeachdude
1:36 PM EDT on August 25, 2006
is the new center more north? this would change potential path and potential affect of wind sheer a lot
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723. thelmores
5:36 PM GMT on August 25, 2006
vortex data above......

14 deg 04 min N
066 deg 58 min W
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722. Patrap
5:34 PM GMT on August 25, 2006
..Max served us all well..and with dedication & a no-nonsense.attitude. He will be missed..
Member Since: July 3, 2005 Posts: 428 Comments: 129904
720. truecajun
5:34 PM GMT on August 25, 2006
looks like it's getting busted up a bit??
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719. vortextrance
5:36 PM GMT on August 25, 2006
45 knots at the surface
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717. franck
5:35 PM GMT on August 25, 2006
The 5:30 entry was pure poetry.
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716. vortextrance
5:34 PM GMT on August 25, 2006
Posted By: thelmores at 5:34 PM GMT on August 25, 2006.
google earth from storm2k

this one shows the 11am advisory position, in relation to the plane....


I think its safe to say we have a new center.
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715. Tazmanian
10:34 AM PDT on August 25, 2006
ok all i think they are flying out now so what did they find 50mph winds?
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714. nash28
5:31 PM GMT on August 25, 2006
Hey StPeteBill. Good to see you.

To answer your question, I believe the west coast of our state is susceptable. For me to pinpoint a Charley hook at this stage of the game would be irresponsible of me, but I do think the FL peninsula has a high chance of being affected by Ernie. I do strongly believe in the Northern model solutions.
Member Since: July 11, 2005 Posts: 190 Comments: 16972
712. thelmores
5:34 PM GMT on August 25, 2006
URNT12 KNHC 251724
VORTEX DATA MESSAGE
A. 25/17:15:20Z
B. 14 deg 04 min N
066 deg 58 min W
C. NA mb NA m
D. 45 kt
E. 48 deg 039 nm
F. 118 deg 048 kt
G. 048 deg 040 nm
H. EXTRAP 1005 mb
I. 23 C/ 304 m
J. 24 C/ 304 m
K. 24 C/ NA
L. NA
M. NA
N. 1 345/ 1
O. 0.02 / 2 nm
P. AF303 0205A CYCLONE OB 04
MAX FL WIND 48 KT NE QUAD 17:01:30 Z
SLP EXTRAP FROM 1500 FT
Member Since: Posts: Comments:
711. franck
5:32 PM GMT on August 25, 2006
The best measure of the potential of these storms is what they do at night, and Ernesto showed some spunk last night. The shear will probably mangle him, and he may be all shot up time he hits the beach, but he's probably going to hold together.
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710. charris
5:34 PM GMT on August 25, 2006
Thanks, Dr. Masters, for the explination of the wind shear chart. I had no idea how to read them.
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708. Patrap
5:33 PM GMT on August 25, 2006
..why.franck?
Member Since: July 3, 2005 Posts: 428 Comments: 129904
707. thelmores
5:31 PM GMT on August 25, 2006
google earth from storm2k

this one shows the 11am advisory position, in relation to the plane....
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706. StormJunkie
1:26 PM EDT on August 25, 2006
From the looks of the latest recon info, it looks like they found a center that had 5mph winds and a temp difference of about +2 degrees.
Member Since: August 17, 2005 Posts: 26 Comments: 16874
705. miracleaa1990
5:33 PM GMT on August 25, 2006
looks to this old jarhead's tired eyes the NE quad is getin blown away
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704. Weather456
1:31 PM AST on August 25, 2006
Taz, what has happen is that TD5 has slowed considerable. The ULL is moving at the same speed west.

Its like a rabbit running away from a turtle/slug.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
702. Tazmanian
10:32 AM PDT on August 25, 2006
Posted By: WunderYakuza (Admin) at 10:06 AM PDT on August 25, 2006.
Sorry for the hiccup everyone. Blogs should be fine again. Carry on!
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701. silverstripes
10:29 AM PDT on August 25, 2006
StormW,

Thanks...I was just using numbers that I have seen thrown about. HAHA. So it is 90% at a flight level of 1000 feet. I have also head it changes with flight level. So that reading we had of 54 mph would calculate to about 48.6 mph at surface.
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700. miracleaa1990
5:32 PM GMT on August 25, 2006
oops!!! NE quadrant being sheared?
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699. franck
5:30 PM GMT on August 25, 2006
Patrap..I'm humbled man.
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698. Patrap
5:30 PM GMT on August 25, 2006
..yeah..the G-4 data is the kinda stuff ya need to iron out a good CMC & super ensemble run..I believe come Sun evening..they be swinging into order ..some..maybe..kinda..LOL
Member Since: July 3, 2005 Posts: 428 Comments: 129904
697. reeldrlaura
5:28 PM GMT on August 25, 2006
ric....LOL!
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696. guygee
5:23 PM GMT on August 25, 2006
StormW - Well at least we know you are not one of those who forecast from below their belt. LOL.
Member Since: September 16, 2005 Posts: 0 Comments: 3202
695. miracleaa1990
5:30 PM GMT on August 25, 2006
is the NW quadranr being sheared off?
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694. thelmores
5:30 PM GMT on August 25, 2006
SJ, i am finding the google earth images here.... dont know their true origin....

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692. ricderr
5:29 PM GMT on August 25, 2006
thanx... for that thelmores....i was trying to find somewhere that extrapolates altitude to surface...there ha to be a formula..but i can't find one
Member Since: June 27, 2006 Posts: 676 Comments: 22383
691. StPeteBill
5:09 PM GMT on August 25, 2006
Hey nash, how you doing? I ask this of your earier but you must have already left but do you think TD5 could pull a 04 Charlie?
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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