Bill is gone; Invest 92 pops up

By: Dr. Jeff Masters , 2:08 PM GMT on August 24, 2009

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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
Beach Wall wave 1
Hurricane Bill Waves Day 2 # 9 (RIWXPhoto)
Hurricane Bill Waves Day 2 # 9
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!
Kelvin-Helmholtz Instabilities

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Will this go west?LOL
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Quoting scottsvb:
This system will not "Probably" be fully tropical... more of a subtropical system...too much cold air in it maybe..


Respectfully, I do not think so. Once the ULL weakens and gets out of the way, this should begin to organize faster. Also, it should have a warm core because when the ULL weakens, it will be able to pump out the cold air the ULL has infiltrated into the system.
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aren't the Carolinas right next to the Dakotas? LOL


...just stirrin' the pot :)
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144. JRRP


Floater
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Quoting presslord:


...and...besides...there is no such place as "the Carolinas"...


Point well taken, press, and I apologize...it's a bad habit of those of us in the rest of the country to make statements that take in both states, north and south and call them the "Carolinas"...kind of like people calling New Orleans "Nyu Orleenz"...
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Its all good here flood, high in the 80' nice 5 mph wind, not going to complain in august. Would like to see that wave develop some so we can all go drink a beer with Press!! in the north or south carolina area!
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This system will not "Probably" be fully tropical... more of a subtropical system...too much cold air in it maybe..
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Quoting NEwxguy:
Morning to all,weather has certainly become interesting here on the east coast recently.


Morning NE-

So the summer that never was in Northeast...and now the Tropics keep wanting to come to you!
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...no...I'm telling you "the Carolinas" don't exist...
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137. JRRP
Quoting Relix:


That seems to northerly to affect us in PR or even DR it seems. Of course it depends where, and IF, the COC forms.

i thought it as well

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Quoting rareaire:
Morning flood


Howdy, rare...how are you doing?
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Quoting Floodman:


First, there is no Danny as yet, secondly, 92L hasn't even made it to the surface. Any track that has it making landfall in the Carolinas is premature at best. Stop worrying so much and listen to the forecasts moving forward. We can;t even predict a landfall area within 500 miles with any accuracy until we're 72 hours out


...and...besides...there is no such place as "the Carolinas"...
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For Sable Island, they probably did not fare well if you look at Docs last blog entry regarding buoy positioned at 42N/64W.

"Buoy 44150 was in the east eyewall of Bill at 9:30 am EDT, and reported sustained winds of 62 mph, gusting to 85 mph, with waves of 40 feet."

Sable Island is at 43.95N/59.92W.
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132. Relix
Quoting JRRP:


That seems to northerly to affect us in PR or even DR it seems. Of course it depends where, and IF, the COC forms.
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Morning flood
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130. JRRP
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Quoting Floodman:


That's not an extrapolated path, that's a dead bang certainty...hop's things, brother?


Yeah...its dead on
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Quoting ConchHondros:
Flood...xtrap has TS Conch at the bar in Zios at 72hrs wreaking havoc on the Birra Moretti


That's not an extrapolated path, that's a dead bang certainty...how's things, brother?
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Just give Virgil Ward the xtrp model, he'll go away. :P
Member Since: August 18, 2008 Posts: 0 Comments: 628
Good morning all! Just checking in this morning before I leave for classes at noon. In looking at the latest available QuikSCAT data and analyzing satellite imagery, Invest 92 appears like it will take some time to develop into a tropical cyclone, if it ever does. Right now, I'm seeing very little low-level circulation, if any, and it will take some time for the disturbance to gain a defined low-level circulation center. Given that this disturbance lacks much organization and being that this is in such an early stage in development, I'm not buying any computer models right now and want to wait until we have a defined center and system for the computer models to base their forecasts off of. At this time, I think the NHC's outlook appears right on the money with their wording.
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Quoting Hurricane009:
I meant to say when Tropical Storm or Hurricane Danny hits


First, there is no Danny as yet, secondly, 92L hasn't even made it to the surface. Any track that has it making landfall in the Carolinas is premature at best. Stop worrying so much and listen to the forecasts moving forward. We can;t even predict a landfall area within 500 miles with any accuracy until we're 72 hours out
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Flood...xtrap has TS Conch at the bar in Zios at 72hrs wreaking havoc on the Birra Moretti
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Quoting NEwxguy:


Morning Flood,don't particularly like that CMC track.


Fortunately they're really only decent with formation and terrible on intensity and track
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Quoting Floodman:
The CMC with 92L making landfall in the area of Mass-Maine at 144 hours...thankfully the CMC is not the most accurate of the modeling suites for intensity and track:



You may need to rethink your view on the CMC. It was upgraded in June of this year:

In June 2009, the CMC GEM converted to a hybrid vertical coordinate system that is terrain-following in the boundary layer (sigma) and becomes purely isobaric (pressure) near the tropopause, a structure similar to that used by the other global models noted in Table 2. Also in June 2009, the upper boundary of the model was raised from 10 mb (32 km) to 0.1 mb (64 km). This change permits the incorporation of more satellite observations into the initial model analysis. This latest incarnation of the GEM is referred to as the GEM .Meso-Strato. version or simply .GEM-Strato..

Technical Summary of the National Hurricane Center Track and Intensity Models

It may perform as it has previously, but it may be better. Time will tell.
Member Since: September 23, 2005 Posts: 14 Comments: 11215
Quoting Grothar:


It does appear to be getting larger. However, I believe Dr. Masters's thinking is that the strong trough along the eastern seaboard, as depicted in his map above, is going to be a player in moving the system on a more northerly track. As we all know these features change by the minute. Are you of the opinion that 92L will stay on a more westerly track due to its current weak status?


As well as the fact this may be subtropical in nature. Troughs usually aren't this far down this time of year and it is very odd to be talking subtropical but, depending on how long the trough sits around it could be a STS if it were to develop.
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Quoting Hurricane009:
Does anybody know what the intensity will be when it hits or brushes North Carolina, because that is where i live.


What will hit?
Member Since: March 19, 2009 Posts: 0 Comments: 1421
Long time lurker here from Vancouver, Canada. These storms fascinate me. I have learned a lot from following the blog. Thanks for all of the information and great graphics.
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Quoting Hurricane009:
Does anybody know what the intensity will be when it hits or brushes North Carolina, because that is where i live.


We don't know where it will go yet, probably an aim for the carolinas, if not GA. Too early to tell what the intensity of the storm will be.
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Quoting Hurricane009:
Does anybody know what the intensity will be when it hits or brushes North Carolina, because that is where i live.


Again, way too early. If I was to make a prediction, it would just be speculation, and not an accurate forecast.
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Quoting Hurricane009:
Does anybody know what the intensity will be when it hits or brushes North Carolina, because that is where i live.


Nobody said, or nobody should have said, that it is gonna do either of those. WAIT.
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Hurricane Bill major swell event for the Florida east coast-9-12 feet on Saturday-just sat on my balcony & watched. But Sunday, 4-7 and glassy, can you say zippers? Very fast waves, lots of power, way more manageable with fast rides. Needed to be on your game with this swell, long lines closing out meant choosing your waves carefully with this size. Bring on 92L.....
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Quoting RiverLuvr:
I am going fishing at Portsmouth Island NC this weekend, would love your opinions to cancel or not???


Don't cancel it yet, there's a lot of uncertainty with 92L and where will it go when it starts developing. We should know where it will go by Tues and if not Wed. Keep a close eye on it though.
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Quoting AllStar17:


It is premature to try and speculate on where this system will eventually end up.


While grothar is correct in assuming that a weaker system would be less effected by higher level steering you are absolutely correct in stating that is is far too early to make any serious assumptions...not that this fact will stop folks in here from commenting about track, intensity future changes in terms of absolutes...lol

It's one of the more amusing reasons or coming in here...
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Quoting RiverLuvr:
I am going fishing at Portsmouth Island NC this weekend, would love your opinions to cancel or not???


To say the least... the stalled out frontal boundary should bring storminess that you would typically see with a frontal area... but so far as 92L is concern... is too early to tell. We should have a good idea by Tuesday night into Wednesday if 92L does develop.
Member Since: August 14, 2008 Posts: 4 Comments: 4977
Quoting Floodman:


Good morning!


Morning Flood,don't particularly like that CMC track.
Member Since: September 6, 2007 Posts: 881 Comments: 15840


and why do the insurance companies give him so much credibility???
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Quoting RiverLuvr:
I am going fishing at Portsmouth Island NC this weekend, would love your opinions to cancel or not???


Again, too early to say. When a definite center forms, we should have more of an idea. If we predicted something now, it would be just pure speculation, which is not good, because forecast can and do change by the hour.
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Remember the rule folks.... if a system isnt developed into a TD or TS... only go out 72 hrs on a movement... anything more than 3 days greatly decrease the accuracy! weaker systems and undeveloped systems will go more inline with the LLF!
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Quoting NEwxguy:
Morning to all,weather has certainly become interesting here on the east coast recently.


Good morning!
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Quoting Grothar:


It does appear to be getting larger. However, I believe Dr. Masters's thinking is that the strong trough along the eastern seaboard, as depicted in his map above, is going to be a player in moving the system on a more northerly track. As we all know these features change by the minute. Are you of the opinion that 92L will stay on a more westerly track due to its current weak status?


It is premature to try and speculate on where this system will eventually end up.
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The CMC with 92L making landfall in the area of Mass-Maine at 144 hours...thankfully the CMC is not the most accurate of the modeling suites for intensity and track:

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I feel this low will be further south than anticpated due to the influence of the cold-core low... so I expect it to organize more around 22N and 70W instead of up around 26N and 70W then move WNW into the bahamas... not sure yet how much troughiness there will be to pick up 92L yet...this isnt straight up like Bill...even though most models have this going up the east coast... its too early... the pattern isnt set yet cause this storm isnt developed yet like Bill was!.. We will know more on Tues and probably forsure on Weds by the time this develops. BTW there is a chance this might not ever be fully tropical.
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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.