Dr. Jeff Masters' WunderBlog

Bill is gone; Invest 92 pops up

Posted by: Dr. Jeff Masters, 02:08 PM GMT on August 24, 2009

Hurricane Bill is no more. The hurricane swept past Canada's Nova Scotia province Sunday afternoon, then made landfall early this morning in southeastern Newfoundland as a borderline tropical storm/Category 1 hurricane. Bill's waves claimed two lives over the weekend, a 54-year old swimmer that drowned in Florida, and a 7-year old girl in Maine that got swept into the sea by a big wave. The first death of the 2009 Atlantic hurricane season occurred on August 16, when a swimmer drowned in the rough surf from Tropical Storm Claudette at Pananma City Beach, FL.

Nova Scotia misses a direct hit
The center of Bill scooted parallel to the coast of Nova Scotia Sunday afternoon, and never quite came onshore. Since the storm's forward speed was so rapid--about 35 mph--this resulted in a highly asymmetric wind distribution. Since the top winds of a hurricane include the forward motion of the storm, Bill's top winds of 85 mph observed in the offshore, right front quadrant of the storm meant that the winds on the weak side of the storm, over Nova Scotia, were 85 mph minus 35 mph, or just 50 mph. Winds along most of the coast stayed below 39 mph, the borderline for tropical storm-force winds. The strongest winds measured in Canada were at Sable Island, which lies 150 miles offshore of Nova Scotia. Winds on the island hit 61 mph, gusting to 77 mph, between 4 - 5 pm ADT Sunday afternoon. A few islands along the Nova Scotia coast, such as Beaver Island and Hart Island, reported sustained winds of 39 - 40 mph. The big story for Nova Scotia was the waves from Bill. Buoy 44258 at the mouth of Halifax Harbor recorded significant wave heights of 29.5 feet and maximum wave heights of 49 feet as Bill passed 50 miles offshore. The buoy recorded top sustained winds of 35 mph, gusting to 51 mph. The waves combined with a 1.5 - 3 foot storm surge flooded many coastal roads. Buoy 44150, about 160 miles offshore of of the southwest tip of Nova Scotia, was in the east eyewall of Bill between 10 - 11 am ADT, and reported sustained winds of 62 mph, gusting to 85 mph, with significant wave heights of 44 feet. The buoy recorded a maximum wave height of 87 feet, according to Environment Canada. The highest official rain report on Nova Scotia was 2.6" (65 mm) at Yarmouth. Rainfall cause some localized flooding and road damage. Bill's winds cut power to about 40,000 people at the height of the storm. At Peggys Cove, three men were hit by a giant wave but were not hurt. A gift shop and attached home in the village were swept off of their foundation.

Newfoundland gets hit, but damage is minor
The southeast corner of Newfoundland took a direct hit from Bill. The storm made landfall early this morning as a borderline tropical storm/Category 1 hurricane. Top winds on the island were measured at Cape Race, which recorded sustained winds of 58 mph, gusting to 76 mph, between 1:30 and 2:30 am NDT. A storm surge of 1.2 meters (4 feet) was estimated by Environment Canada for Placentia Bay where Bill made landfall. Damage was minor on Newfoundland, with no major flooding reported. Bill dumped up to three inches of rain on Newfoundland.

Figure 1. The eye of Hurricane Bill on August 19 at 2157 UTC, from a NOAA P-3 Hurricane Hunter aircraft flying at 10,000 feet. Photo credit: Jack Parrish of NOAA's Aircraft Operations Center.

Kelvin-Helmholtz instability waves in the eye of Bill
Flight Director Jack Parrish of NOAA's Aircraft Operations Center snapped a cool photo in the eye of Hurricane Bill on Friday, showing the existence of a Kelvin-Helmholtz instability wave (Figure 1). The photo was taken on August 19 at 2157 UTC, from a NOAA P-3 Hurricane Hunter aircraft flying at 10,000 feet. The photo is taken looking WNW towards the eyewall. The towering clouds of the eyewall extend up to 50,000 - 55,000 feet in the photo, and the ocean surface is not visible, due to stratocumulus clouds covering the bottom of the eye. The center of the photo shows that the top of one of these stratocumulus clouds has a feature that looks like a breaking wave in the ocean. Well, that is an example of a breaking wave in the atmosphere known as a Kelvin-Helmholtz instability wave. The atmosphere behaves as a fluid, and thus has wave-like motions. When there is a sudden change of wind speed along the top of a cloud (wind shear), the flow can become unstable and cause breaking waves to form. One can see Kelvin-Helmholtz in the sky several times per year, and several alert wunderphotographers have uploaded photos of these waves over the years. However, it is uncommon to see these waves in the stratocumulus clouds covering the eye of a hurricane.

Figure 2. Water vapor satellite image for 8:15 am EDT 8/24/09. A tropical wave is approaching the Northern Lesser Antilles Islands, but is running into high wind shear from an upper-level cold low to the west of it. Image credit: NOAA/SSD.

Tropical wave approaching Lesser Antilles becomes Invest 92
A tropical wave with a moderate amount of shower activity is moving west-northwest at 20 - 25 mph and is approaching the northern Lesser Antilles Islands. This wave was designated "Invest 92" (92L) by NHC this morning. The wave is under about 20 - 30 knots of wind shear due the strong upper-level winds from the west. These winds are being created by the counter-clockwise flow of air around an upper-level cold-cored low north of Puerto Rico (Figure 2). This low is expected to move west-southwest and slowly weaken over the next two days, allowing shear to drop to the moderate 10 - 20 knot range beginning Tuesday night, according to the SHIPS model. By Wednesday, the upper low is predicted to be weak enough and far enough away from 92L that it will have a chance to develop. Most of the models show some degree of development of 92L by Thursday, when it is expected to be a few hundred miles off the coast of South Carolina. This wave could turn northward and give a wet weekend to New England, though it is too early to be confident of this. NHC is giving 92L a low (less than 30% chance) of developing into a tropical depression by Wednesday morning. The upper-level low will create plenty of wind shear and dump cold, dry air into 92L over the next two days, so Wednesday is probably the earliest we can expect the system to begin organizing into a tropical depression.

Several models predict the development of a tropical wave coming off the coast of Africa late this week.

I'll have an update Tuesday.

Jeff Masters

Beach Wall wave 1 (BeachBecky)

Waves from Hurricane Bill crashing on the sea wall during high tide in Lynn, MA

Hurricane Bill Waves Day 2 # 9 (RIWXPhoto)

Kelvin-Helmholtz Instabilities (btangy)

Kelvin-Helmholtz Instabilities to the S of Boston. Wavy like pattern in clouds is caused by a difference in winds between the cloud layer and the layer just above (called wind shear). The manifestation of this at the top of the altostratus deck is quite a beautiful and rare sight!

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451. Floodman 06:52 PM GMT on August 24, 2009
Quoting 7544: 92l looking better this hour it just may do it before wends imo Still being pretyy heavily sheared though; at this rate it won't last until the shear starts to ease Member Since: August 2, 2006 Posts: 10 Comments: 9919

453. IKE 06:53 PM GMT on August 24, 2009
Quoting btwntx08: aoi in sw carb looking good too Looks like that AOI is moving slightly south of west and may head N 2 the east-Pac. Member Since: Juni 9, 2005 Posts: 23 Comments: 37044

454. TampaSpin 06:53 PM GMT on August 24, 2009
The ULL is actually helping to vent 92L. Member Since: September 2, 2007 Posts: 175 Comments: 19747

455. PortABeachBum 06:55 PM GMT on August 24, 2009
Quoting SQUAWK: He is just trying to get his numbers up so people will think he really has something going on at his blog. Then they see what is there and discover what he really is. Thanks, you're right. Having worked with computers for 52 years I have learned to recognize that kind of action! I would just ignore but that does little to help when others just quote him. Besides, he sometimes has things of interest to the whole blog and I wouldn't want to miss them! I'm a lurker, not much for making invalid contributions! Member Since: Oktober 4, 2007 Posts: 0 Comments: 198

457. TriniGirl26 06:56 PM GMT on August 24, 2009
Quoting caneluver: I am coming to get you Allstar.... LMAO !!! Member Since: August 18, 2009 Posts: 0 Comments: 201

458. TheCaneWhisperer 06:56 PM GMT on August 24, 2009
CSU and the NHC need to compare notes.

459. AllStar17 06:56 PM GMT on August 24, 2009
Shear now decreasing over 92L Member Since: Juni 29, 2009 Posts: 13 Comments: 5135

460. Grothar 06:57 PM GMT on August 24, 2009
http://xlr8.sfwmd.gov/portal/page?_pageid=2854,19644915,2854_19644936:2854_19645022:2854_19645029&_da d=portal&_schema=PORTAL This just came out. Hope I did it correctly. Member Since: Juli 17, 2009 Posts: 56 Comments: 19488

461. PortABeachBum 06:58 PM GMT on August 24, 2009
Quoting btwntx08: incorrect Your turn SQUAWK ! Member Since: Oktober 4, 2007 Posts: 0 Comments: 198

462. seminolesfan 06:58 PM GMT on August 24, 2009
Quoting TampaSpin: The ULL is actually helping to vent 92L. I'll agree to that for the N, but seems to be impinging on the western semi-circle. Member Since: Juni 14, 2006 Posts: 0 Comments: 1692

464. pearlandaggie 06:59 PM GMT on August 24, 2009
Quoting Grothar: We all feel it is impolite to write in languages other than English on this blog because it is mostly English speaking people. Thanks for that! Much appreciated! :) Member Since: September 14, 2007 Posts: 3 Comments: 3963

465. futuremet 06:59 PM GMT on August 24, 2009
Quoting TampaSpin: The ULL is actually helping to vent 92L. 1 Tim The diffluent flow aloft caused by the ULL is helping this system to maintain its convection. This is why convection has not decreased despite diurnal minimum. However, the ULL is also making it difficult for it effectively coalesce. Albeit a ULL does help convection, but an upper level anticyclone is best for tropical cyclone, because it provides good divergence with a lack of shear. But, this is exactly what is going to happen, when the degenerating trough over the eastern U.S. start to split in about 24hrs. As the detached trough propagates southward, it will help ventilate the area to the east--creating an upper anticyclone. This will provide ideal conditions for tropical cyclogenesis. Member Since: Juli 19, 2008 Posts: 43 Comments: 4049

466. futuremet 07:00 PM GMT on August 24, 2009
12Z ECMWF Member Since: Juli 19, 2008 Posts: 43 Comments: 4049

467. justalurker 07:00 PM GMT on August 24, 2009
Quoting btwntx08: yep isnt this the wave that gfs shows in 144 hr to be going towards california coast? Link Member Since: August 18, 2009 Posts: 0 Comments: 157

468. usa777 07:00 PM GMT on August 24, 2009
Anyone have any idea of which of the models performed best on "bill"??? Thanks in advance. Member Since: August 11, 2008 Posts: 0 Comments: 164

469. futuremet 07:01 PM GMT on August 24, 2009
Quoting usa777: Anyone have any idea of which of the models performed best on "bill"??? Thanks in advance. ECMWF!!! Member Since: Juli 19, 2008 Posts: 43 Comments: 4049

470. AllStar17 07:02 PM GMT on August 24, 2009
Quoting Grothar: http://xlr8.sfwmd.gov/portal/page?_pageid=2854,19644915,2854_19644936:2854_19645022:2854_19645029&a mp;_da d=portal&_schema=PORTAL This just came out. Hope I did it correctly. Please post it again, it did not work. Member Since: Juni 29, 2009 Posts: 13 Comments: 5135

472. SaoFeng 07:02 PM GMT on August 24, 2009
Hows the shear over the SW Caribbean disturbance? Member Since: September 1, 2008 Posts: 0 Comments: 70

473. TampaSpin 07:03 PM GMT on August 24, 2009
Quoting SaoFeng: Hows the shear over the SW Caribbean disturbance? Very low but, it does not matter its going inland and into the Pacific soon. Member Since: September 2, 2007 Posts: 175 Comments: 19747

474. AllStar17 07:03 PM GMT on August 24, 2009
Member Since: Juni 29, 2009 Posts: 13 Comments: 5135

478. ConchHondros 07:05 PM GMT on August 24, 2009
My daughter just text messaged me, asked what I was doing...told her...she replied OMG, WTFO..what is the BFD with that lamo site anyway? Flood, rare...translation?? Member Since: Oktober 1, 2007 Posts: 0 Comments: 551

479. futuremet 07:06 PM GMT on August 24, 2009
474 B..but...I wanna know....where is it gonna hit?!?!?!?!?!?!? Member Since: Juli 19, 2008 Posts: 43 Comments: 4049

480. IKE 07:07 PM GMT on August 24, 2009
Space shuttle takes off at 1:36 am EDST tomorrow morning. All systems are go for now. Member Since: Juni 9, 2005 Posts: 23 Comments: 37044

482. justalurker 07:09 PM GMT on August 24, 2009
Quoting Acemmett90: i afraied of what you will do when i tell you what it means lmao= laughing my a$$ off WTF= what the F%^& not sure on the other one BFD= BIG F$#%% DEAL Member Since: August 18, 2009 Posts: 0 Comments: 157

483. atmoaggie 07:10 PM GMT on August 24, 2009
. Member Since: August 16, 2007 Posts: 6 Comments: 12461

484. nrtiwlnvragn 07:10 PM GMT on August 24, 2009
Quoting usa777: Anyone have any idea of which of the models performed best on "bill"??? Thanks in advance. Here is one site that tracks performance, however I don't know what their criteria are or how they complile the stats. I have seen others that don't agree with their data. Also, since the info from the NHC on the ECMWF model is not released it is difficult to determine it's performance other than a gut feel. Member Since: September 23, 2005 Posts: 11 Comments: 8916

485. Grothar 07:12 PM GMT on August 24, 2009
Quoting AllStar17: Please post it again, it did not work. Hey Allstar, you have helped me many times before. I have never posted an image before. I am trying to show the South Florida Water Management Department image of tropical storm forecasts which shows 92L. It is really a very interesting site. Just can't do it. HELP!!! Member Since: Juli 17, 2009 Posts: 56 Comments: 19488

489. Floodman 07:12 PM GMT on August 24, 2009
Quoting ConchHondros: My daughter just text messaged me, asked what I was doing...told her...she replied OMG, WTFO..what is the BFD with that lamo site anyway? Flood, rare...translation?? And I quote: "Oh, my god, what the f@k...what is the big f@king deal with that lamo site anyway?" Member Since: August 2, 2006 Posts: 10 Comments: 9919

490. nrtiwlnvragn 07:12 PM GMT on August 24, 2009
AL 92 2009082418 BEST 0 170N 580W 20 1010 DB Member Since: September 23, 2005 Posts: 11 Comments: 8916

491. tropicfreak 07:13 PM GMT on August 24, 2009
Quoting futuremet: 474 B..but...I wanna know....where is it gonna hit?!?!?!?!?!?!? Ok I don't know exactly where it will hit, but I can tell you IF it hits the US it will be an east coast storm. The carolinas, GA and possibly FL bears watching with 92L. Member Since: September 2, 2006 Posts: 110 Comments: 6566

492. justalurker 07:13 PM GMT on August 24, 2009
Quoting ConchHondros: My daughter just text messaged me, asked what I was doing...told her...she replied OMG, WTFO..what is the BFD with that lamo site anyway? Flood, rare...translation?? complete sentence.. oh my god, what the F%^%, OVER, what is the big f%$% deal with that lame site Member Since: August 18, 2009 Posts: 0 Comments: 157

493. WeatherBubba 07:13 PM GMT on August 24, 2009
Quoting Acemmett90: i afraied of what you will do when i tell you what it means lmao= laughing my a$$ off WTF= what the F%^& not sure on the other one BFD= Big F***ing Deal, I'm afraid...

494. ConchHondros 07:14 PM GMT on August 24, 2009
Aaa...I see, well...I would smash her phone with a hammer, because I cant afford a ticket to New Zealand to whack her...but then again I cant afford to replace her iphone...I could take it away...but she would put everyone within a 20 mile radius through hell until she got it back...oh wtf..16 is the new 30...right? Member Since: Oktober 1, 2007 Posts: 0 Comments: 551

495. TheCaneWhisperer 07:14 PM GMT on August 24, 2009
Quoting Grothar: Hey Allstar, you have helped me many times before. I have never posted an image before. I am trying to show the South Florida Water Management Department image of tropical storm forecasts which shows 92L. It is really a very interesting site. Just can't do it. HELP!!! You need to send the photo through an image hosting site. The SFWMD does not allow direct image placement.

497. presslord 07:15 PM GMT on August 24, 2009
Link shuttle visability Member Since: August 13, 2007 Posts: 0 Comments: 10377

498. kmanislander 07:15 PM GMT on August 24, 2009
Quoting ConchHondros: My daughter just text messaged me, asked what I was doing...told her...she replied OMG, WTFO..what is the BFD with that lamo site anyway? Flood, rare...translation?? Translation ??. She thought she was texting someone other than her father. Member Since: August 19, 2006 Posts: 0 Comments: 14939

500. AllStar17 07:15 PM GMT on August 24, 2009
Quoting Grothar: Hey Allstar, you have helped me many times before. I have never posted an image before. I am trying to show the South Florida Water Management Department image of tropical storm forecasts which shows 92L. It is really a very interesting site. Just can't do it. HELP!!! All you do is click on "Image" above the post box. Then right click on the image you want to post and click view image in new window, copy the URL, and paste the URL into the "URL box" (the first one that appears) when you click on image. Then click OK twice (dont bother to worry about the width or length of your image), and it should appear in the posting box, then click post. Member Since: Juni 29, 2009 Posts: 13 Comments: 5135

501. TheCaneWhisperer 07:17 PM GMT on August 24, 2009
Quoting nrtiwlnvragn: AL 92 2009082418 BEST 0 170N 580W 20 1010 DB Brought it down to 17N I see. 18.2 seemed rather high.

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