Earl a Category 4 storm again

By: Dr. Jeff Masters , 9:23 PM GMT on September 01, 2010

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Hurricane Earl has regained Category 4 strength this afternoon, and continues on a steady northwest path towards the North Carolina coast. Recent satellite imagery shows that Earl has become more symmetrical, with improved upper-level outflow and no signs of dry air wrapping into the core. The improved appearance is probably due to lower wind shear. Latest wind shear tendency imagery from the University of Wisconsin CIMSS group shows that shear on the southwest side of Earl has fallen by about 10 knots over the past 24 hours.


Figure 1. Afternoon satellite image of Earl.

Forecast for Earl
The latest set of model runs from 8am EDT (12Z) this morning shows little change to Earl's track. Thus, my write-up of the possible impacts to North Carolina, New England, and Canada in this morning's post remain unchanged. The latest SHIPS model forecast shows wind shear will remain moderate, about 15 knots, through Friday afternoon. This should allow Earl to maintain major hurricane status as it passes North Carolina early Friday morning. By Friday night, as Earl gets caught in the jet stream and accelerates to the northeast, wind shear will rise to 20 - 30 knots and ocean temperatures will plunge to 20°C, resulting in considerable weakening. Earl will still probably be a Category 1 or 2 hurricane early Saturday morning, when it will make its closest approach to New England. Earl is more likely to be a strong tropical storm or weak Category 1 hurricane early Saturday afternoon, when it is expected to make landfall in Nova Scotia, Canada.

Earl is a large hurricane, which gives it a higher potential for storm surge damage than a smaller hurricane with the same top winds. One measure of a storm's power, useful for gauging storm surge threat, is to measure the speed of the winds and multiply by the area over which those winds blow. This total is called the Integrated Kinetic Energy (IKE). Based on the storm's IKE, one can come up with a scale from 0 - 6 rating the storm's destructive power from its storm surge. A separate rating can be given to the destructive potential of the storm's winds. The IKE value of 112 Terrajoules for Earl, at 3:30pm EDT today, gives its storm surge a destructive power of 5.0 on a scale of 0 - 6. Earl's winds have a lower destructive power, 3.4 on a scale of 0 - 6. Let's hope the right front quadrant of Earl, where the main storm surge would occur, stays offshore! For comparison, the small Category 5 Hurricane Camille of 1969 had an IKE of 80 Terrajoules, and the very large Category 2 Hurricane Ike of 2008 had an IKE of 116 Terrajoules--similar to Category 3 Earl's.

Fiona
Tropical Storm Fiona is struggling due to high wind shear, courtesy of strong upper-level northerly winds from Hurricane Earl's outflow. The latest Hurricane Hunter center fix at 1:29pm EDT found Fiona had weakened some, with a central pressure of 999 mb. This is a rise of 1 mb from this morning. The wind shear analysis from the University of Wisconsin CIMSS group shows that shear has increased to a moderately high 15 - 20 knots this afternoon. Satellite loops show the classic signature of a tropical storm experiencing high wind shear--an exposed center of circulation, and all the heavy thunderstorms pushed to one side (the south side in this case). Martinique radar shows that the outer bands from Fiona are bringing heavy rain squalls to the same islands of the northern Lesser Antilles that were affected by Earl. Our wundermap for the northern Lesser Antilles shows no stations recorded winds over 20 mph this afternoon, though there was no reporting station on Barbuda, the island closest to Fiona.

Forecast for Fiona
Moderate wind shear and dry air should keep Fiona from attaining hurricane status over the next two days, as big brother Earl continues to bring high wind shear. The shear may be strong enough to destroy Fiona, as predicted by the NHC. However, by this weekend, Earl may pull far enough away for shear to drop and Fiona to survive. The 4 - 5 day track forecast is highly uncertain, as there is a large spread in the model solutions. It is possible Fiona may pose a threat to Bermuda on Saturday or Sunday, and the storm could wander for a week or more in the waters between Bermuda and the U.S. East Coast.


Figure 2. Afternoon satellite image of Fiona.

Tropical Storm Gaston forms
Tropical Storm Gaston developed enough heavy thunderstorms near its center this afternoon to get a name, and appears destined to become Hurricane Gaston by early next week. Water vapor satellite images show a large area of dry air to the north and west of Gaston, and this dry air will be the dominant inhibiting factor for development. The latest SHIPS model forecast predicts shear will remain moderate, 10 - 15 knots, for the next four days, and perhaps fall to the low range 4 - 5 days from now. Gaston is over warm 28°C waters, and should be able to steadily intensify into a hurricane by Saturday or Sunday, as predicted by the many of the intensity models. Gaston may threaten the northern Lesser Antilles Islands as early as Tuesday.

Next post
I'll have an update in the morning, and Dr. Rob Carver will have a late night update tonight.

Jeff Masters

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How many mph would a flight level wind of 130kt recorded at 633.6mb calculate to at the surface?
Member Since: September 2, 2009 Posts: 130 Comments: 21098
GOES-13 animated Atlantic IR
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Quoting wildman1117:
Yep i agree cat 5 within a couple hrs


Quite bullish, although I agree, especially if the recent pressure drop is official and as his current appearance looks on satellite imagery, I expect the winds to pick up soon enough as the more circular and completed the eyewall is, the easier the winds are to reach the surface. So I expect the winds will react soon enough.
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Quoting CybrTeddy:
Earl's flirting with Category 5 status right now per Recon.


Hopefully he won't ask her out!!!!
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Quoting MiamiHurricanes09:
Pretty darn impressive upper level outflow channels (particularly the poleward outflow channel) associated with Earl.



Agreed 100%

To think those 50+ knot flow over a large area is mass being pumped out of a relatively small area. Hello pressure drop we're seeing.
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Don't you know that has to be a wild ride through Hurricane Earl....wheeeee
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Quoting Ryuujin:


Look again. It's turning back NW


Yep, NW.
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Quoting bird72:
In the transition from Earl about PR. We had some winds that caused the loss of electrical power for one day, where I live. I have an electric power plant, but at night use a power inverter to run my fans. I need someone to recommend me some sort of 12v battery that lasts more than a car battery, since use of my car and lasted only six hours? And that is not very expensive.


with car on?
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That is just a very sudden and frightening drop in pressure. Combined with the sharply improved appearance and symmetry, it indicates that Earl has gotten its act together while still passing over favorable waters, in an atmosphere of diminishing shear. I would be surprised, frankly, if its pressure doesn't drop further.

Will it get all the way to Category 5? That will depend on the NHC. They've been relying on extrapolated winds for most of their intensity estimates - the actual observed winds have generally been 5-15kts below the advisory levels, which have been adjusted upwards based on satellite estimates. If they follow the same methodology, then yes, I fully expect Earl to turn into a Category Five storm overnight. If, however, they decide to proceed more cautiously so as not to induce panic, they can rely on observed winds. I doubt those will rise as high.
Member Since: August 18, 2009 Posts: 0 Comments: 460
Quoting HurricaneGeek:
wow we've got a new 10%-er in the EATL. this is literally never stopping.

Earl is looking good, which means he's looking bad for the people in his path. I wish everyone there the best of luck and be safe and smart!!



At the rate this year is going, that 10%er is going to be a TD by morning. jajaja,
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846. xcool


Member Since: September 26, 2009 Posts: 2 Comments: 15648
Earl's flirting with Category 5 status right now per Recon.
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wow we've got a new 10%-er in the EATL. this is literally never stopping.

Earl is looking good, which means he's looking bad for the people in his path. I wish everyone there the best of luck and be safe and smart!!

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Yeah,,its all a show.

A cat 4 borderline 5 is as Big as you'll see that far North.


But its passing by the State of Bob and company so the downplay and looking east are in da wings already.

Very er,..enlightening

LOL

Pffft.


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Man. Everytime I look at Earl I just think of how lucky Florida is right now.
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The vortex data message has the pressure at 932mb. A 9mb drop since the 8pm EDT advisory. Also note the 130kt flight level winds in the NE quadrant.

000
URNT12 KWBC 020001
VORTEX DATA MESSAGE AL012010
A. 1/2350Z
B. 26 DEG 59 MIN N
73 DEG 26 MIN W
C. NA
D. 98 KT
E. 088 DEG 16 NM
F. 183 DEG 130 KT
G. 087 DEG 19 NM
H. 932 MB
I. 9 C/3510 M
J. 16 C/3994 M
K. 8 C/NA
L. OPEN S
M. C30
N. 12345/7
O. 1/1 NM
P. NOAA3 WX07A EARL9 OB 13
MAX FL WIND 130KT NE QUAD 2346Z

Member Since: September 2, 2009 Posts: 130 Comments: 21098
Quoting wildman1117:
Yep i agree cat 5 within a couple hrs
Maybe...but it is hard for a hurricane to maintain that status. Can only hope for the best for OBX
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Thumb rules (pressure to wind)

Cat 4
114 to 134 knots
131 to 155 mph
210 to 249 kph
944- 920 mb

Cat 5
135+ knots
155+ mph
249+ kph
< 920 mb
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Quoting hurricane556:
927.5 mb extrap
I just saw that... Is that for real... 927MB...
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Dear Mr. Cantore,

Please send me some cool googles like yours. Thanx. Bye.

<3 Tink
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167mph winds at the 925mb level

Member Since: June 9, 2007 Posts: 4 Comments: 15864
834. amd
Product: NOAA Vortex Message (URNT12 KWBC)
Transmitted: 2nd day of the month at 00:01Z
Aircraft: Lockheed WP-3D Orion (Reg. Num. N43RF)
Mission: Non-Tasked Mission, possibly not tropical (flight in the North Atlantic basin)
Mission Identifier: Earl9
Mission: Non-Tasked Mission
Observation Number: 13
A. Time of Center Fix: 1st day of the month at 23:50Z
B. Center Fix Coordinates: 26°59'N 73°26'W (26.9833N 73.4333W) (View map)
B. Center Fix Location: 277 miles (445 km) to the ENE (61°) from Nassau, Bahamas.
C. Minimum Height at Standard Level: Not Available
D. Estimated (by SFMR or visually) Maximum Surface Wind: 98kts (~ 112.8mph)
E. Location of the Estimated Maximum Surface Wind: 16 nautical miles (18 statute miles) to the E (88°) of center fix
F. Maximum Flight Level Wind Inbound: From 183° at 130kts (From the S at ~ 149.6mph)
G. Location of Maximum Flight Level Wind Inbound: 19 nautical miles (22 statute miles) to the E (87°) of center fix
H. Minimum Sea Level Pressure: 932mb (27.52 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 9°C (48°F) at a pressure alt. of 3,510m (11,516ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 16°C (61°F) at a pressure alt. of 3,994m (13,104ft)

K. Dewpoint Temp (collected at same location as temp inside eye): 8°C (46°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Open in the south
M. Eye Shape & Diameter: Circular with a diameter of 30 nautical miles (35 statute miles)
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Level: 700mb
O. Navigation Fix Accuracy: 1 nautical mile
O. Meteorological Accuracy: 1 nautical mile
Remarks Section:
Maximum Flight Level Wind: 130kts (~ 149.6mph) in the northeast quadrant at 23:46Z
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Earl is trying so hard to be come a cat 5 it wants to be come a cat 5
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In the transition from Earl about PR. We had some winds that caused the loss of electrical power for one day, where I live. I have an electric power plant, but at night use a power inverter to run my fans. I need someone to recommend me some sort of 12v battery that lasts more than a car battery, since use of my car and lasted only six hours? And that is not very expensive.
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Quoting StormW:


Yep. Intermission time. The real show should start next week.


If this is the intermission, I'm not liking what the "real game" is going to show! However, I am afraid that he is correct.
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Wait with what Miami is say we have a Cat5!
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Quoting tinkahbell:

Sorry Stormchaser...I got excited.


LOL

Dont worry about it.
Member Since: June 9, 2007 Posts: 4 Comments: 15864
827. 900MB
Quoting pilotguy1:


Could and might should be eliminated from all media lexicon. Just the facts please!


TWC also keeps howing cone that is about 100 miles East of cone of uncertainty on Long Island. Arrgghh!
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Quoting StormW:


Yep. Intermission time. The real show should start next week.
Storm quick question: is it worse for New England that this is heading north earlier taking the trough longer to influence it? Or was the original NW track worse? Thanks
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You see a storm like that and you hope for the EWRC to catch it again or for it to pull away from the coast. That is darn scary.
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Quoting originalLT:
It does appear to be moving again to the NW, or just slightly North of true NW, but we're splitting hairs here.

It's stair-stepping. Which is what I said about 2 hours ago, which is an indicator of a strengthening storm (which Earl is...) and now he's speeding up. It's really getting cruch-time for either the NC coast, or interests along the entire eastern seaboard. Earl is really starting to wear out his welcome.
Member Since: August 20, 2010 Posts: 0 Comments: 373
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According to my rough estimates, a 928mb pressure could support 145mph winds.....

If this is the case, then Earl could "possible" flirt with Cat5 Status before the night is over!!!!

Looks as good on imagery now as it ever has!
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819. amd
winds are much higher with the dropsonde than the SFMR


Deep Layer Mean Wind (average wind over the depth of the sounding):
- Wind Direction: 155° (from the SSE)
- Wind Speed: 130 knots (150 mph)
- Depth of Sounding: From 631mb to 951mb

Surface eyewall Info:

951mb 115° (from the ESE) 113 knots (130 mph)

Highest winds above the surface:

905mb 140° (from the SE) 154 knots (177 mph)
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Looks like Earl ate his Wheaties again ............................................and Fiona,s too.
Member Since: September 27, 2007 Posts: 1 Comments: 20896
Quoting Stormchaser2007:

Googles?

Sorry Stormchaser...I got excited.
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EARL RGB to Night IR Loop
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Yep i agree cat 5 within a couple hrs
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'Miss Piggy' dropped a dropsonde into the eyewall. The surface wind speed and pressure is unavailable, but quite staggeringly, the winds at 925mb were at 167mph.

000
UZNT13 KWBC 020002
XXAA 52007 99270 70730 08073 99/// ///// ///// 00/// ///// /////
92/// 24601 13145 85/// 21801 15637 70/// 14000 17635 88999 77999
31313 09608 82345
61616 NOAA3 WX07A EARL9 OB 11
62626 REL 2700N07302W 234524 SPG 2718N07310W 235051 DLM WND 15630
951631 EYEWALL 090=

XXBB 52008 99270 70730 08073 00/// ///// 11951 26402 22689 13201
33678 13402 44672 12603 55641 120// 66631 09800
21212 00/// ///// 11951 11613 22949 12105 33948 12111 44946 12616
55945 12624 66944 12142 77942 12143 88939 12117 99937 12111 11934
12622 22932 13122 33929 13143 44927 13140 55924 13148 66919 13144
77915 12650 88909 13641 99905 14154 11902 14143 22899 13643 33896
13635 44891 14145 55887 14144 66883 14638 77876 14141 88871 14631
99867 14144 11864 15131 22861 15144 33639 18631 44634 17619 55631
18129
31313 09608 82345
61616 NOAA3 WX07A EARL9 OB 11
62626 REL 2700N07302W 234524 SPG 2718N07310W 235051 DLM WND 15630
951631 EYEWALL 090=

Member Since: September 2, 2009 Posts: 130 Comments: 21098
It does appear to be moving again to the NW, or just slightly North of true NW, but we're splitting hairs here.
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a drop of ~13 millibars in 6 hours (if official). Winds will most likely catch up with the pressure drop soon.
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Quoting Anotherboringday:
This is looking strikingly similar to 1995 when we got hit by Hurricane Fran... (I currently live in central NC)....Amazingly Earl and Fran look like identical on satellite.. for one thing...the other...the number storms in a row (one after another) coming off Africa...going to be an interesting rest of the season as to how it plays out...


Fran was in 1996 and Earl is 10 times better organized than Fran ever was. Fran moved inland from Wilm to Raleigh, Earl will no even come close to doing such. Fran was barely a cat 3 with winds of 115 mph! at landfall on Wrightsville Beach NC
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Quoting sarahjola:
don't take it so personal. i said gaston looks better than fiona. i also said fiona should be down graded. the question was why didn't they call gaston a depression first? i always get amazed at how people can have their opinion and refuse to let others have their own opinion without getting angry about it. its just opinion. i actually think the nhc does a great job.
I saw gaston as a TD this morning, it was Fiona they skipped.
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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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