Dr. Jeff Masters' WunderBlog

Bill is gone; Invest 92 pops up

Posted by: Dr. Jeff Masters, 2:08 PM GMT en Agosto 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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601. stormsurge39 8:10 PM GMT en Agosto 24, 2009
Why does Nogaps have it going so far west?

603. canesrule1 8:11 PM GMT en Agosto 24, 2009
Quoting yonzabam: 1) Because that's what hurricanes do in that part of the world. They want to go north, then recurve. In order for this not to happen, the Bermuda High must be big and strong. 2) The abnormally strong trough that recurved Bill is still there. I think it might have something to do with the jet stream. Your are incorrect in number one for the simple reason that 92L is not a hurricane. And number 2 is incorrect because it is a different jet stream that is supposed to dip and it is a matter of time to know if this will affect me in Florida or if it will actually recurve. -CanesRule1.

604. Engine2 8:11 PM GMT en Agosto 24, 2009
Since the invest doesn't have a low level center of circulation to initiate on, the models are going to be all over the place. Just sit back watch and be vigilant thats all Member Since: Febrero 27, 2006 Posts: 0 Comments: 482

605. SavannahStorm 8:11 PM GMT en Agosto 24, 2009
Hope this isn't the case... Member Since: Septiembre 22, 2005 Posts: 18 Comments: 2135

606. Floodman 8:12 PM GMT en Agosto 24, 2009
Quoting justalurker: what the f, over, OMG! "Tower, this is PanAm flight 17; WTFO?" Member Since: Agosto 2, 2006 Posts: 10 Comments: 9919

607. Drakoen 8:12 PM GMT en Agosto 24, 2009
An upper level trough is advecting towards the eastern seaboard and will likely create some degree of weakness. Member Since: Octubre 28, 2006 Posts: 57 Comments: 29010

608. tornadodude 8:13 PM GMT en Agosto 24, 2009
well im off to work, later guys Member Since: Junio 28, 2006 Posts: 22 Comments: 7816

609. reedzone 8:13 PM GMT en Agosto 24, 2009
Too early to say 92L will recurve, still days away from impacting land IF ANY. I said this with Bill when it was still east of the Leeward Islands but people said it was clearly going to go out to sea which in very little case, it did, but impacted Cape Cod, Bermuda, and Canada... Not a "fish" like storm in my opinion. I saw the models on 92L, still no defined circulation so all of the coastline from Florida to Maine needs to monitor 92L. It appears all models form something once it nears the Bahamas. All I'm gonna do like I did with Bill, is advise everyone in it's "possible" path to watch it and not worry until we know for a certainty it's coming there way. Member Since: Julio 1, 2008 Posts: 13 Comments: 7247

610. Elena85Vet 8:14 PM GMT en Agosto 24, 2009
Quoting HIEXPRESS: Yeah, I thought about that. What season? Remember that trough that rolled through the Plains and Midwest was more like a May/June trough. Member Since: Agosto 18, 2008 Posts: 0 Comments: 619

612. Engine2 8:15 PM GMT en Agosto 24, 2009
Quoting reedzone: Too early to say 92L will recurve, still days away from impacting land IF ANY. I said this with Bill when it was still east of the Leeward Islands but people said it was clearly going to go out to sea which in very little case, it did, but impacted Cape Cod, Bermuda, and Canada... Not a "fish" like storm in my opinion. I saw the models on 92L, still no defined circulation so all of the coastline from Florida to Maine needs to monitor 92L. It appears all models form something once it nears the Bahamas. All I'm gonna do like I did with Bill, is advise everyone in it's "possible" path to watch it and not worry until we know for a certainty it's coming there way. exactly Member Since: Febrero 27, 2006 Posts: 0 Comments: 482

613. pearlandaggie 8:16 PM GMT en Agosto 24, 2009
606. Roger, Roger. What's your vector, Victor? LOL Member Since: Septiembre 14, 2007 Posts: 3 Comments: 3963

614. canesrule1 8:17 PM GMT en Agosto 24, 2009
Quoting SavannahStorm: Hope this isn't the case... Well luckily, 92L is not a CAT 1, and according to satellite imagery 92L's convection is moving slightly north of west, not quite WNW in my opinion, more like WWNW.

616. Drakoen 8:19 PM GMT en Agosto 24, 2009
Member Since: Octubre 28, 2006 Posts: 57 Comments: 29010

617. PSL2007 8:17 PM GMT en Agosto 24, 2009
Quoting canesrule1: Well luckily, 92L is not a CAT 1, and according to satellite imagery 92L's convection is moving slightly north of west, not quite WNW in my opinion, more like WWNW. Whaaaaaaaaaaaaaaaaaaaat??

619. rwdobson 8:18 PM GMT en Agosto 24, 2009
Quoting caneluver: Why does there always seem to be a trough coming towards the E Coast when a Hurricane nears? This year, there has been a trough coming towards the E coast all summer... Member Since: Junio 12, 2002 Posts: 0 Comments: 1574

620. KarenRei 8:19 PM GMT en Agosto 24, 2009
Hey all, just checking in. What's up with that swirl just west of the CVs? Looks like there's lots of air in rotation. Member Since: Septiembre 7, 2007 Posts: 1 Comments: 934

621. fire635 8:19 PM GMT en Agosto 24, 2009
Quoting caneluver: Why does there always seem to be a trough coming towards the E Coast when a Hurricane nears? Why ask why? Im just thankful that there usually is Member Since: Junio 24, 2006 Posts: 0 Comments: 478

622. yonzabam 8:19 PM GMT en Agosto 24, 2009
Quoting canesrule1: Your are incorrect in number one for the simple reason that 92L is not a hurricane. And number 2 is incorrect because it is a different jet stream that is supposed to dip and it is a matter of time to know if this will affect me in Florida or if it will actually recurve. -CanesRule1. Quoting canesrule1: Your are incorrect in number one for the simple reason that 92L is not a hurricane. And number 2 is incorrect because it is a different jet stream that is supposed to dip and it is a matter of time to know if this will affect me in Florida or if it will actually recurve. -CanesRule1. Well, that's the last time I answer any of your questions. yonzabam Member Since: Julio 20, 2008 Posts: 0 Comments: 1731

623. StormChaser81 8:20 PM GMT en Agosto 24, 2009
Quoting canesrule1: Your are incorrect in number one for the simple reason that 92L is not a hurricane. And number 2 is incorrect because it is a different jet stream that is supposed to dip and it is a matter of time to know if this will affect me in Florida or if it will actually recurve. -CanesRule1. Yup need to have some mass associated with for the coriolus effect to take it north. Member Since: Agosto 11, 2008 Posts: 0 Comments: 2315

624. justalurker 8:20 PM GMT en Agosto 24, 2009
Quoting Floodman: OMG! "Tower, this is PanAm flight 17; WTFO?" LOL.roger, roger, over, over..airplane movie. Member Since: Agosto 18, 2009 Posts: 0 Comments: 157

625. HIEXPRESS 8:21 PM GMT en Agosto 24, 2009
Quoting Engine2: Since the invest doesn't have a low level center of circulation to initiate on, the models are going to be all over the place. Just sit back watch and be vigilant thats all That's what we do, right deuce? Melb. FL Radar - this should clear out by launch time - let's not take any (major)lightning strikes! Member Since: Octubre 13, 2005 Posts: 4 Comments: 2153

626. NRAamy 8:22 PM GMT en Agosto 24, 2009
Dude Florida is Safe... not per our Bidet Blogger, JFV... Member Since: Enero 24, 2007 Posts: 315 Comments: 31937

627. NEwxguy 8:22 PM GMT en Agosto 24, 2009
this has been the summer of the troughs,except for last week,the east coast has been near a trough or had a trough sitting right over it. Member Since: Septiembre 6, 2007 Posts: 816 Comments: 13132

631. clwstmchasr 8:26 PM GMT en Agosto 24, 2009
rwdobson 4:18 PM EDT on August 24, 2009 Quoting caneluver: Why does there always seem to be a trough coming towards the E Coast when a Hurricane nears? This year, there has been a trough coming towards the E coast all summer... Agreed. The trough has been in place the entire summer and there are no indications of a major weather pattern change. Basically what that means is that FL is pretty safe from anything in the Atlantic. Where FL is in danger is if a storm forms in the SE Caribbean (Charley) or the NW Caribbean or GOM. Member Since: Julio 29, 2006 Posts: 0 Comments: 2758

632. Floodman 8:24 PM GMT en Agosto 24, 2009
Quoting StormChaser81: Yup need to have some mass associated with for the coriolus effect to take it north. And height; weaker storms are effected less. There's latitude too; storms south of 10N tend to be less effected or not at all... Member Since: Agosto 2, 2006 Posts: 10 Comments: 9919

633. reedzone 8:25 PM GMT en Agosto 24, 2009
As with Bill, timing is crucial with 92L. If the trough came late or if 92L speeds up, we would be looking the EURO track. If the trough comes in fast or if 92L is slow, the trough will likely sweep it out to sea affecting no one, maybe Bermuda. This is still way too early to make tracks right now. Lets give 92L a few more days, possibly till the weekend before we make bold and confident statements. Member Since: Julio 1, 2008 Posts: 13 Comments: 7247

635. justalurker 8:26 PM GMT en Agosto 24, 2009
hey guys, dont you think WS had enough humiliation for one day..give a guy a break. He may seem a little off the wall sometimes, but no one deserves this... Member Since: Agosto 18, 2009 Posts: 0 Comments: 157

636. Floodman 8:26 PM GMT en Agosto 24, 2009
Quoting KarenRei: Hey all, just checking in. What's up with that swirl just west of the CVs? Looks like there's lots of air in rotation. Some of the models are calling for some development in that area soon; that msut be the energy they're calling for... Member Since: Agosto 2, 2006 Posts: 10 Comments: 9919

639. Relix 8:27 PM GMT en Agosto 24, 2009
I just want to know if it posses a threat to PR =( Member Since: Agosto 3, 2006 Posts: 0 Comments: 2358

641. caneswatch 8:27 PM GMT en Agosto 24, 2009
Quoting reedzone: As with Bill, timing is crucial with 92L. If the trough came late or if 92L speeds up, we would be looking the EURO track. If the trough comes in fast or if 92L is slow, the trough will likely sweep it out to sea affecting no one, maybe Bermuda. This is still way too early to make tracks right now. Lets give 92L a few more days, possibly till the weekend before we make bold and confident statements. Where is the Euro track taking it? Member Since: Octubre 8, 2008 Posts: 14 Comments: 4473

642. NRAamy 8:28 PM GMT en Agosto 24, 2009
lurker....JFV/WS loves it....who else gets this much attention, bud? Member Since: Enero 24, 2007 Posts: 315 Comments: 31937

643. futuremet 8:29 PM GMT en Agosto 24, 2009
Pugnacious much? Member Since: Julio 19, 2008 Posts: 43 Comments: 4049

644. Alockwr21 8:29 PM GMT en Agosto 24, 2009
Quoting rwdobson: This year, there has been a trough coming towards the E coast all summer... I hope these troughs don't continue into the winter months.. Member Since: Septiembre 12, 2007 Posts: 0 Comments: 724

645. PSL2007 8:30 PM GMT en Agosto 24, 2009
Quoting caneswatch: Where is the Euro track taking it? to JV.

646. justalurker 8:30 PM GMT en Agosto 24, 2009
Quoting NRAamy: lurker....JFV/WS loves it....who else gets this much attention, bud? dude this has been posted 3 times today..its gets old after a while. Member Since: Agosto 18, 2009 Posts: 0 Comments: 157

648. reedzone 8:30 PM GMT en Agosto 24, 2009
Quoting caneswatch: Where is the Euro track taking it? Wouldn't you like to know? lol Lets just say it effects someone in the CONUS. Trying to keep it cool here. Member Since: Julio 1, 2008 Posts: 13 Comments: 7247

649. JLPR 8:30 PM GMT en Agosto 24, 2009
Quoting Relix: I just want to know if it posses a threat to PR =( I don't think so 92L will be already to our north once the ULL gets away and then is when 92L will really start getting going Member Since: Septiembre 4, 2007 Posts: 36 Comments: 5223

650. PSL2007 8:31 PM GMT en Agosto 24, 2009
Quoting StormChaser81: We dont deserve his bable, and crazy ideas. Creativity comes from seeming 'nonsense'.

651. KarenRei 8:31 PM GMT en Agosto 24, 2009
Quoting Floodman: Some of the models are calling for some development in that area soon; that msut be the energy they're calling for... Well, if it does develop, it's going to be a large one (diameter), judging from how large of an area is feeding into it. Shear looks low in the area. Needs a lot more convection, though. If convection flares up, I'd expect it to take off. Member Since: Septiembre 7, 2007 Posts: 1 Comments: 934

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