Ophelia remains weak; TD 17 forms; dangerous Nesat headed for the Philippines

By: Dr. Jeff Masters , 4:54 PM GMT on September 24, 2011

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There's not much change to Tropical Storm Ophelia today, which continues to battle dry air and high wind shear. Satellite imagery shows that Ophelia has little heavy thunderstorm activity near its low level circulation center, which is mostly exposed to view. Most of the storm's heavy thunderstorms are to the east of the center, with just a few puffs of thunderstorms occasionally popping up near the center. An analysis from the University of Wisconsin CIMMS group shows a high 20 - 25 knots of wind shear due to strong upper-level southwesterly winds. Water vapor satellite images show Ophelia is at the eastern edge of large area of very dry air.


Figure 1. Afternoon satellite image of Ophelia showing the low-level center exposed to view, with all the storm's heavy thunderstorms in a band several hundred miles to the east and south. This is not a healthy-looking tropical storm.

Forecast for Ophelia
The latest SHIPS model forecast predicts that Ophelia will experience high wind shear of 20 - 40 knots over the next five days, and will move into a region with slightly drier air. This combination of shear and dry air may be enough to dissipate Ophelia, as predicted by several of the models. However, Ophelia has maintained itself better than the models have predicted, so the storm will probably survive until at least Sunday. Even it Ophelia does dissipate, it will have the chance to regenerate by Tuesday or Wednesday, when it may encounter a region of lower wind shear. At this time, it appears that Ophelia will only be a threat to Bermuda.

TD 17 forms
Tropical Depression 17 formed in the far eastern Atlantic off the coast of Africa last night, and is likely to intensify into Tropical Storm Philippe later today. TD 17 has some impressive low-level spiral bands and upper-level outflow, and is very close to tropical storm strength. The predicted west-northwest to northwest track of TD 17 will put it in a position where historically, very few storms have ever gone on to hit land.


Figure 2. MODIS satellite image of Hurricane Hilary at 4:05 pm EDT September 23, 2011. At the time, Hilary was a Category 4 storm with 145 mph winds. Image credit: NASA.

Powerful Hurricane Hilary remains at Category 4 strength
In the Eastern Pacific, Hurricane Hilary remains an impressive Category 4 hurricane with 140 mph winds. Hilary is headed west, away from Mexico, and the storm is small enough that its outer bands are not causing flooding problems for Mexico. A trough of low pressure expected to move over the Western U.S. by the middle of the week may be strong enough to turn Hilary to the north, eventually bringing Hilary to Mexico's Baja Peninsula. The timing of this event is highly uncertain, though. Hilary is small enough that it is unlikely to bring significant drought relief to Arizona, New Mexico, and Texas if the storm's remnants move north into those states. Hilary is the fourth Category 4 hurricane in the Eastern Pacific this year, and the second strongest, behind Hurricane Dora, which had 155 mph winds.

Invest 91L set to soak North Carolina
A moderate amount of heavy thunderstorm activity has developed over the Northwestern Bahamas in association with the tail end of an old stalled front. This disturbance, Invest 91L, is under a low 5 - 10 knots of wind shear, but water vapor loops show a considerable amount of dry air to the east and west of the disturbance that will likely interfere with development. In their 8 am Tropical Weather Outlook, NHC gave 91L a 20% chance of developing into a tropical depression by Monday. The disturbance has only a short window to develop, as it is headed northwards and is expected to make landfall in North Carolina by Sunday afternoon. The 8 am EDT SHIPS model forecast predicts 91L will hit 35 knots of wind shear by Sunday morning, when the storm will be approaching the coast of North Carolina. Heavy rains from 91L may cause localized flooding in Morehead City, NC and surrounding regions. A moist flow of tropical air over the region has already brought rainfall amounts of 1 - 3 inches to much of Eastern North Carolina today.

Dangerous Tropical Storm Nesat headed for the Philippines
What may be the season's most dangerous storm in the Western Pacific, Tropical Storm Nesat, has formed about 700 miles east of the Philippine Islands. Nesat is under a moderate 10 knots of wind shear, is embedded in a very moist environment, has very warm sea surface temperatures of 30°C under it, and a very favorable upper-level outflow pattern above it. Nesat has plenty of time to intensify into a major typhoon before its expected landfall on Luzon Island in the Philippines on Tuesday morning.

I'll have an update before 2 pm Sunday afternoon.

Jeff Masters

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Quoting WeatherNerdPR:

Any recent ASCAT passes?


From 8AM this morning I believe:



Still old.
Member Since: July 6, 2010 Posts: 113 Comments: 32692
Quoting interstatelover7165:
Holy smokes! A COC! A CLOSED COC!

It ain't legit. It shows a closed LLC on EVERYTHING.
Member Since: July 7, 2010 Posts: 0 Comments: 5725
Quoting TropicalAnalystwx13:


No, those images can only be used for tropical cyclones.

Any recent ASCAT passes?
Member Since: July 7, 2010 Posts: 0 Comments: 5725
Quoting WeatherNerdPR:
This can't be right...
Holy smokes! A COC! A CLOSED COC!
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Quoting will40:


but one thing to watch is a bigg decent or accent in recon height. That will sometimes throw all the data off


and those wind speeds are suspect it looks like
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Quoting CosmicEvents:
Imagine what would happen if everyone who encountered a roundabout decided to go WEST!


Hey Cosmic Trust all is well, you always give me a good laugh!
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Closer to Conus and PR???



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N Antilles need TS WATCHES
Member Since: October 6, 2007 Posts: 0 Comments: 6453
Quoting interstatelover7165:
where do you get that? if so can i have a Link?

Here ya go.
Member Since: July 7, 2010 Posts: 0 Comments: 5725
Don't leave !
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Quoting WeatherNerdPR:
This can't be right...


No, those images can only be used for tropical cyclones.
Member Since: July 6, 2010 Posts: 113 Comments: 32692
Quoting WeatherNerdPR:
91L Close-up:
where do you get that? if so can i have a Link?
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This can't be right...
Member Since: July 7, 2010 Posts: 0 Comments: 5725
Quoting stormwatcherCI:
Well, that would put her further SW than previous co-ordinates.


20:10:30Z 16.417N 59.633W 575.0 mb
(~ 16.98 inHg) 4,754 meters
(~ 15,597 feet) 1007.4 mb
(~ 29.75 inHg) - From 242° at 3 knots
(From the WSW at ~ 3.4 mph) 1.0°C
(~ 33.8°F) -11.5°C
(~ 11.3°F) 3 knots
(~ 3.4 mph) 0 knots*
(~ 0 mph*) 1 mm/hr*
(~ 0.04 in/hr*) 0.0 knots* (~ 0.0 mph*)
0.0%*


but one thing to watch is a bigg decent or accent in recon height. That will sometimes throw all the data off
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91L Close-up:
Member Since: July 7, 2010 Posts: 0 Comments: 5725
Quoting TropicalAnalystwx13:


ATCF agrees with you:

EP, 09, 2011092418, , BEST, 0, 167N, 1063W, 115, 951, HU, 64, NEQ, 30, 25, 20, 25, 1009, 150, 10, 0, 0, E, 0, , 0, 0, HILARY, D,
wooh :) wind shear isnt that bad about 10 to 15 knots. dry air is moderate. she will be slow to weaken because her inner structure has been EXTREMLY organized. if she does make it to Baja a ts or cat 1 isnt out of the question
Member Since: August 23, 2011 Posts: 0 Comments: 1726
Quoting will40:


yes imo it would be very near the center
Well, that would put her further SW than previous co-ordinates.


20:10:30Z 16.417N 59.633W 575.0 mb
(~ 16.98 inHg) 4,754 meters
(~ 15,597 feet) 1007.4 mb
(~ 29.75 inHg) - From 242° at 3 knots
(From the WSW at ~ 3.4 mph) 1.0°C
(~ 33.8°F) -11.5°C
(~ 11.3°F) 3 knots
(~ 3.4 mph) 0 knots*
(~ 0 mph*) 1 mm/hr*
(~ 0.04 in/hr*) 0.0 knots* (~ 0.0 mph*)
0.0%*
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Quoting stormwatcherCI:
Can someone please help me with something. On HH data when you see a line with 0 mph winds and lower pressure would that be the presumed coc ?


yes imo it would be very near the center
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Quoting TropicalAnalystwx13:


ATCF agrees with you:

EP, 09, 2011092418, , BEST, 0, 167N, 1063W, 115, 951, HU, 64, NEQ, 30, 25, 20, 25, 1009, 150, 10, 0, 0, E, 0, , 0, 0, HILARY, D,

The advisory might say something like
"HILARY STEADILY WEAKENING...MOVING AWAY FROM MEXICO..."

...am I this bored, to be making up advisory headers? XD
Member Since: July 7, 2010 Posts: 0 Comments: 5725
Quoting stormpetrol:
Ophelia looks to be headed into the Northern Antilles if I'm seeing correctly!


I would enjoy that!!!!!!!!!!!!!! lol
Member Since: October 6, 2007 Posts: 0 Comments: 6453
Can someone please help me with something. On HH data when you see a line with 0 mph winds and lower pressure would that be the presumed coc ?
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Quoting Skyepony:


I think so.. What was a tight naked circulation, is much looser. Much more of this & she'll come undone.


i think GFS has been dropping her in last two runs
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289. Skyepony (Mod)
Quoting luigi18:
Ophelia is moving more west than north in the last frames?


I think so.. What was a tight naked circulation, is much looser. Much more of this & she'll come undone.
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288. JLPR2
Quoting WeatherNerdPR:
Teeny-Tiny Philippe.


Tiny storms are always cute. XD
Member Since: September 4, 2007 Posts: 7 Comments: 8747
Quoting JLPR2:
What seems to have happened with Ophelia is that the tight swirl we were following opened up and a broader LLC formed slightly SW of where the main LLC was.

Ophelia is a broad mess.


I agree, looks like a broad center between 17/18N 57/58W
Member Since: October 6, 2007 Posts: 0 Comments: 6453
286. JLPR2
Quoting stormwatcherCI:
You come on here maybe for a few minutes and you tell him to take a chill pill. Spend a little more time and just maybe you will see why he says what he says.


Wow, was about to post something exactly like this. O.o

High-five!
Member Since: September 4, 2007 Posts: 7 Comments: 8747
Quoting wunderweatherman123:
i think she is 135mph at this time and will maintain major hurricane status until monday night


ATCF agrees with you:

EP, 09, 2011092418, , BEST, 0, 167N, 1063W, 115, 951, HU, 64, NEQ, 30, 25, 20, 25, 1009, 150, 10, 0, 0, E, 0, , 0, 0, HILARY, D,
Member Since: July 6, 2010 Posts: 113 Comments: 32692
Quoting WeatherNerdPR:
Teeny-Tiny Philippe.
Why do you even mention Phillipe when you know he is just another nothing fish storm ? Sarcasm flag :ON
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Quoting stormwatcherCI:
You come on here maybe for a few minutes and you tell him to take a chill pill. Spend a little more time and just maybe you will see why he says what he says.


i agree he is one of the smartest kids on here
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Looking at sped up visible satellite loops, it definitely shows that 91L has a low pressure area underneath this convection:

Member Since: July 6, 2010 Posts: 113 Comments: 32692
Quoting CosmicEvents:
Imagine what would happen if everyone who encountered a roundabout decided to go WEST!

Oh jiminy cricket Cosmic! It would be like a Aqua brownie with the REAL "magical" frosting on top. :-)

How have you been? I haven't seen you around lately. I hope the hurricane preparation and relief efforts are treating you well.
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Quoting TropicalAnalystwx13:
Dry air and wind shear are beginning to really affect the bands and outer part of Hilary, other its eye and eyewall are holding strong.

i think she is 135mph at this time and will maintain major hurricane status until monday night
Member Since: August 23, 2011 Posts: 0 Comments: 1726
Teeny-Tiny Philippe.
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Quoting BackwoodsTN:
take a chill pill tropical wx13. Life is too short to start calling others names and acting so childish. Wake up and learn about the NHC and what they can be about and what they try to do instead of ruling it in your favor and what you see them as.
You come on here maybe for a few minutes and you tell him to take a chill pill. Spend a little more time and just maybe you will see why he says what he says.
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Ophelia looks to be headed into the Northern Antilles if I'm seeing correctly!
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Quoting stormwatcherCI:
:) Wasn't referring to you.


i know see post 266 lol
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Quoting will40:


you and I are not good lol?
BTW, we are always good.
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Quoting will40:


you and I are not good lol?
:) Wasn't referring to you.
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Quoting SPLbeater:
an chance 91L will move NNE or NE? really dont want a wet rainy windy week at the beach here


nope it blocked to the east
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an chance 91L will move NNE or NE? really dont want a wet rainy windy week at the beach here
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just messin with ya girl :-)
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Quoting stormwatcherCI:
Probably got just as fed up with the BS as the rest of the valued bloggers. Not too many good ones left on here.


you and I are not good lol?
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Quoting stormpetrol:
Looks like Ophelia might have more centers than Grand Cayman has roundabouts!
I agree, saw the one to the SW coming on through the day, now ???????
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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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