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 extreme236:


Well with more MJO action here soon we could see more convection develop with it.

Not sure that is going to happen.
Big time whiff by GFS on that for the last 5 days. Fine by me!

Member Since: Posts: Comments:
ATTENTION...NATIONAL HURRICANE CENTER

NCEP COUPLED HWRF HURRICANE MODEL FORECAST MADE FOR

TROPICAL DEPRESSION INVEST 92L

INITIAL TIME 18Z AUG 24

FORECAST POSITIONS (FROM STATS.SHORT FILE...)

HOUR LATITUDE LONGITUDE MIN PRESS (hPa) MAX SFC WIND (KTS)

HOUR: 0.0 LONG: -58.10 LAT: 17.00 MIN PRESS (hPa): 1016.00 MAX SURF WIND (KNOTS): 22.00
STORM DISSIPATED AT 0.0 HOURS AT ABOVE POSITION.
FORECAST WAS RUN COUPLED FOR THE ENTIRE PERIOD...

DISCLAIMER ... THIS INFORMATION IS PROVIDED AS GUIDANCE. IT
REQUIRES INTERPRETATION BY HURRICANE SPECIALISTS AND SHOULD
NOT BE CONSIDERED AS A FINAL PRODUCT. PLEASE SEE THE TPC/NHC
OFFICIAL FORECAST.


Member Since: September 23, 2005 Posts: 14 Comments: 10873
I will be the first one to admit that i know very little about how a storm forms. Im going to give my 2 cents anyway. It looks like right now on the Sat picture that 92L isnt far from being a TD or TS. It looks like the shear is relaxing and its starting to show more organization. Just sayin
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Quoting presslord:


clearly...it's gonna pass through the Youknowwhat Box...
LMAO, Hebert!!! lol
943. amd
Quoting stormsurge39:
Does it look like 92L is organizing more around the center of circulation?


looks like it is trying to organize near the location of highest 850 mb vorticity associated with 92L.

Link

however, shear is still high around 92L, around 20-30 kts, but shear is lower than this morning, where it was closer to 40kts.

I personally think 92L could organize real close to Hispaniola because it looks like the ULL is weakening, but not moving with any southern heading as forecasted this morning.
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Quoting Hurricane009:
The SHIPS Model develops this system to a tropical storm and the GFDL model developes it into a tropical storm


NO WAY in my opinion.....93L has a time to become a storm before moving onshore...its moving 24mph
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Quoting Mikla:
92L w/ models and 18Z Surface Analysis...


clearly...it's gonna pass through the Youknowwhat Box...
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Quoting Drakoen:
92L is producing an area of concentrated showers and thunderstorms.
Yes but it is very disorganized:


And very sheared because of the ULL:



92L=Bill track no need to worry 93L=We finally get developement in the carribean but its going west no need to woryy. the end you two tone talkers u
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938. Mikla
92L w/ models and 18Z Surface Analysis...
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Quoting P451:


If it were to be like this...would you feel the same way? Just asking.



I am kind of a stickler for the idea of if it meets the criteria to be designated that proximity to land, and what land that might be, should not weigh in on any decision to go ahead and do so.


Good point......
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Quoting extreme236:


Yeah, hence the "future" part lol
lol!
92L is producing an area of concentrated showers and thunderstorms.
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Quoting nrtiwlnvragn:


Currently lol
lol
Quoting P451:


If it were to be like this...would you feel the same way? Just asking.



I am kind of a stickler for the idea of if it meets the criteria to be designated that proximity to land, and what land that might be, should not weigh in on any decision to go ahead and do so.

I couldn't have said it better myself!!
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Quoting canesrule1:
true, but it will take its time, imo.


Yeah, hence the "future" part lol
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Quoting extreme236:


Well with more MJO action here soon we could see more convection develop with it.
true, but it will take its time, imo.
Quoting canesrule1:
there is a small problem, NO CONVECTION, lol:



-CanesRule1


Currently lol
Member Since: September 23, 2005 Posts: 14 Comments: 10873
Quoting stormsurge39:
If 92L developes faster than forcasted, how much will it change the forecasted path?
Well for now, Florida is no where near out of the woods that is for sure, but I do have to say and this is just my opinion, I do believe that no matter how strong or weak this gets I do not think it will effect the path, it is all a matter of timing with the jet stream and the forward speed of 92L.

-CanesRule1
Quoting canesrule1:
there is a small problem, NO CONVECTION, lol:



-CanesRule1


Well with more MJO action here soon we could see more convection develop with it.
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Quoting nrtiwlnvragn:
Future 94L?


there is a small problem, NO CONVECTION, lol:



-CanesRule1
ATTENTION...NATIONAL HURRICANE CENTER

NCEP COUPLED GFDL HURRICANE MODEL FORECAST MADE FOR

TROPICAL DEPRESSION INVEST 92L

INITIAL TIME 18Z AUG 24

DISCLAIMER ... THIS INFORMATION IS PROVIDED AS GUIDANCE. IT
REQUIRES INTERPRETATION BY HURRICANE SPECIALISTS AND SHOULD
NOT BE CONSIDERED AS A FINAL PRODUCT. PLEASE SEE THE TPC/NHC
OFFICIAL FORECAST.


FORECAST STORM POSITION

HOUR LATITUDE LONGITUDE HEADING/SPEED(KT)

0 16.5 58.2 290./20.0

STORM DISSIPATED AT 0 HRS AT THE ABOVE PSN.

Member Since: September 23, 2005 Posts: 14 Comments: 10873
923. 7544
Quoting stormsurge39:
Relix on the Sat Animation, 92L LOOKS like its trying to get its act together around 60W and 17n


could be right


its also getting large in size and trying to fill in at this hour doent loook like its moving at 20 to 25 mph seems slower
Member Since: May 6, 2007 Posts: 0 Comments: 6689
Quoting indianrivguy:
I like your new avatar Tim, evening to you too sir.


Thanks my good friend. That my youngest Daughter and me at a RAYS game just before her leaving off for College.....Wow its amazing how much one can miss your kids.
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If 92L developes faster than forcasted, how much will it change the forecasted path?
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Quoting Weather456:
Blessed rain has finally come...steady shower here all day.
i wish here was the same case, 90s all day with not 1 shower.
Future 94L?


Member Since: September 23, 2005 Posts: 14 Comments: 10873
Quoting aquak9:


How many Carolinas are there?


'fraid I'll have to plee a fifth on that one ; ) bud...
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Quoting presslord:


I have booze, Saltines, sardines, a Browning 12 guage automatic...and a water proof box of shells...bring it on...


How about some Canadian BAcon....LMAO
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Blessed rain has finally come...steady shower here all day.
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Quoting aquak9:


How many Carolinas are there?
LMAO, two.
Relix on the Sat Animation, 92L LOOKS like its trying to get its act together around 60W and 17n
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Quoting Relix:
About 92L... we don't even know where the center is! It could relocate at 17N for all we know and that would change the entire forecast!
there is no low level circulation, thus no center, so it is impossible for it to "relocate" as u meant, sorry if im being mean, bit blunt.

-CanesRule1
Quoting DaytonaBeachWatcher:

not just charleston, the whole CAROLINAS


How many Carolinas are there?
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Quoting TampaSpin:


Time to dig a hole and hunker down PRESS....LOL


I have booze, Saltines, sardines, a Browning 12 guage automatic...and a water proof box of shells...bring it on...
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Quoting stormsurge39:
Does it look like 92L is organizing more around the center of circulation?
first of all there is not center, but i know what u mean as in convection is getting stronger around the middle of the ball.
Think of the expenses Presslord can save on Diaster relief efforts.....All he has to do is walk out his backdoor.......LMAO.......just kidding Presslord....
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904. Relix
About 92L... we don't even know where the center is! It could relocate at 17N for all we know and that would change the entire forecast!
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I like your new avatar Tim, evening to you too sir.
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I guess NHC declared 93L because it looks pretty. It does not have a chance to become anything before going onshore....

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Don't think 93L will become of anything over the atlantic, imo, might become a hurricane over the EPAC according to SHIPS intensity model initialized at 2 PM.

-CanesRule1.
Quoting stormsurge39:
Does it look like 92L is organizing more around the center of circulation?


it seems you are correct
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Does it look like 92L is organizing more around the center of circulation?
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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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