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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Quoting TheCaneWhisperer:


That was fast. Vamco had the deadly pentagon shaped eye this morning.


i didn't realize an eye that resembles a pentagon is indicative of a deadly storm!
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At what level in the clouds does an eyewall begin to form (High or Low)?
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196. DDR
Quoting P451:


This one?





...alright, I'm outta here, off to be semi-productive.


LOL,nice one
sunny today in paradise(Trinidad)
We had plenty rain over the weekend,50+mm of rainfall.
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Quoting Skyepony:
Vamco's eye looks like it may soon be compromised.



That was fast. Vamco had the deadly pentagon shaped eye this morning.
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190. what? now I'M responsible for general ignorance of geography? LOL

there ya go...i modified the post for clarity! LOL
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193. IKE
12Z GFS.....doesn't do much with 92L.
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what is 92L current location
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Quoting Floodman:


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...


Hey there, Floodman, I am not defending myself here, I just asked what Allstar's opinion was on the previously observed thinking in the track. I hope you did not infer otherwise. It is bad enough my wife refers to me as a troll. I would not want to be conceived as such here. By the way I enjoy your blogs. If you read my blogs; I ask more questions than I answer and I try to word them in a manner which is not speculative, since my English is not always that good.
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Quoting pearlandaggie:
why is everybody always pickin' on me???


Hellooo:

Pearland, Aggie...are any bells ringing?

LOL
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Quoting presslord:
...no...I'm telling you "the Carolinas" don't exist...


So just what exactly did you do with them?
;-)
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I love the photo!

Quoting pearlandaggie:
175. LOL...now you're just poking the bear!]


of course, we won't comment about how penguins and polar bears only see each other in zoos....oops, i just did LOL
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"why is everybody always pickin' on me??? " <== presslord
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Hey Press dont you live on a boat, technically?
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In other news...



We are only a little over 2 weeks from the 20th anniversary of Hurricane Hugo's formation.
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Quoting TheCaneWhisperer:
BAM (Beta and Advection Model)...
This model follows a trajectory from the Aviation run of the MRF model to provide a track forecast. This model incorporates a correction known as the "Beta Effect". This is used to account for the fact that the Coriolis force resulting from the rotation of the earth is greater toward the poles, so the winds on the northern side of the storm in the Northern Hemisphere tropical cyclone are turned more than those on its southern side. If no other winds were steering a tropical cyclone the "Beta Effect" would cause a westward-headed storm to drift toward the north in the Northern Hemisphere, and toward the south in the Southern Hemisphere. There are three (3) versions of the BAM...

1.. BAMS - the BAM Shallow, this version averages winds from 5,000 to 10,000 feet (850 - 700 mb)
2.. BAMM - the BAM Medium, this version averages winds from 10,000 to 24,500 feet (850 - 400 mb)
3.. BAMD - the BAM Deep, this version averages winds from 24,500 to up to 47,000 feet (850 - 200 mb)

For a weak hurricane without a well-developed eye wall extending deep into the atmosphere, or for a tropical storm, the shallow version of the model may work well, because storms of this nature tend to be steered by low-level winds. As the storm grows stronger and the eye wall gets deeper the deeper versions become more accurate, for these types of storms are steered more by the winds in the upper-level. If the forecast from the three versions is similar the forecaster can then assume that the storm may go as predicted, but, if the version vary by a great deal, then the forecaster has less confidence in the track predicted. The large differences can also point to wind shear in the atmosphere, which could affect the intensity forecast as well.

SOURCE


Discussion of the "Beta" effect got me thinking about the Cloudsat graphic posted by Dr. Masters in his blog 8/21 & wondering about the effect of the earth's rotation on air that is rising or decending (and how this changes due to velocity, density, moisture content, etc..), especially during rapid intensification or dissipation, and what these different vectors do to different parts of a TC & the motion (steering) of the TC as a whole. Is there a name for this effect? Is it part of the Beta effect? Is there an "Alpha" effect. Links?

Saw this and thought is an interesting discussion of the Coriolis effect in TCs, but still LOL about the electromagnetic part.

I have seen KH waves, especially during the passage of cold fronts here (some rolling into vortices - is that the same?), and could see that they were caused by speed shear, but didn't know what they were called - interesting. BBL
Member Since: October 13, 2005 Posts: 4 Comments: 2156
183. Skyepony (Mod)
Vamco's eye looks like it may soon be compromised.

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175. LOL...now you're just poking the bear!]


of course, we won't comment about how penguins and polar bears only see each other in zoos....oops, i just did LOL
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StormW...please tell these people to quit pickin' on me...
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178. Relix
Why the heck are there thunders here in PR.... seems like a nasty thunderstorm as well.
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Quoting StormW:
Good afternoon all!

Hot off the press.

TROPICAL WEATHER SYNOPSIS /92L/ AUG. 24, 2009 ISSUED 12:10 P.M. EDT


Hi Storm...
Member Since: August 14, 2008 Posts: 4 Comments: 4925


Which Carolina?
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the other basins seems to have a little more activity...MJO related?

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I will be buying up coastal property on the new "Gulf of the Carolinas"
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Then US 58 would be Beach road.
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Quoting P451:


This one?





...alright, I'm outta here, off to be semi-productive.

That is beyond brilliant...
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Quoting P451:


This one?





...alright, I'm outta here, off to be semi-productive.



LOL
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Quoting BenBIogger:


Do the Dakotas exist?
lol.North Atlantic-South Atlantic....... The Atlantic... North Pole-South Pole------THe POLes,don,t exist Ect.....:)
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Quoting P451:


You might be on to something here... hmmm.



Yeah my state has more beach! Instead of packing everyone on VA Beach and clogging I 64 we could use some beach property in S VA. Then it would be: Emporia, Emporia Beach, South Hill Beach, Danville Beach.
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Quoting pearlandaggie:


great view!
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Quoting leftovers:
system is in in the deep tropics lots of warm water ahead tropical


That is correct.
Member Since: June 29, 2009 Posts: 13 Comments: 5300
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SSD now has a floater on 92L
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if there's only North Carolina and South Carolina, how can there be an East Carolina University?

LOL...i'm SO confused! ;p
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Quoting AllStar17:
good job..........wait until you get the feel
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Quoting BenBIogger:


Do the Dakotas exist?


Morning...guess this will lead to another man.
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155. JRRP
Link
Member Since: August 16, 2007 Posts: 0 Comments: 5238
Wow!!!! Out house on the GA/SC line just shot up in value!!!!!!!!!!!!!!!!!!!!!!!!!!
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Imagine the storm surge N of Atlanta, lol.
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Quoting presslord:
...no...I'm telling you "the Carolinas" don't exist...


Do the Dakotas exist?
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...that map is VERY nice...
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Quoting pearlandaggie:
aren't the Carolinas right next to the Dakotas? LOL


...just stirrin' the pot :)
Quoting P451:


You might be on to something here... hmmm.



Wow, look at all the extra beachfront property for Virginia!

LOL
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Will this go west?LOL
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About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.