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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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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I am going fishing at Portsmouth Island NC this weekend, would love your opinions to cancel or not???
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96. 7544
92l is sure trying to consolidate shear aand ull in its way but making a good bid this hour those waters are boiling out there any thing can happen
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I don't like that track W456 =P!
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Quoting AllStar17:
In the last few frames, JMO, but it looks like I am seeing more rotation in the clouds and 92L looks to be getting larger.


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?
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Morning... 456 & NE...
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Morning to all,weather has certainly become interesting here on the east coast recently.
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Good Morning

Tropical Update
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting NRAamy:
mornin' Jerry....everyone playing nice so far?

:)


Howdy, Amy...so far so good...LOL
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Quoting KEHCharleston:
A picture is worth a thousand words - thanks.

Any word on how the horses of Sable Island fared?

I was wondering the same thing.
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Allstar I think (JMHO) that the ULL is effecting 92L too much right now for it to do anything other than remain disorganized(in the near term).
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Quoting AllStar17:
Talk about model uncertainty....LOL!!!

Some little models had way too much fun this weekend!
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84. JRRP

me recuerda a Noel y Olga en el 2007
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Talk about model uncertainty....LOL!!!
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Quoting Elena85Vet:
#67 for POD (Post of the Day).


I second the motion
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In the last few frames, JMO, but it looks like I am seeing more rotation in the clouds and 92L looks to be getting larger.
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#67 for POD (Post of the Day).
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Mornin' all!
Looks like the invest may be trying to form an LLC looking at how the convection is building...
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mornin' Jerry....everyone playing nice so far?

:)
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Quoting caneluver:


And where would you get that from?


It was a question, not a statement. Hense the ?
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Quoting P451:




ROTF
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Preliminary Extended Forecast Discussion

POSSIBLE TROPICAL SYSTEM MOVING UP THE EAST COAST...
THE PROGRESS OF AN AREA OF DISTURBED WEATHER NEAR 18N/54W
CONTINUES TO BE MONITORED AND THE BIGGEST FORECAST PROBLEM OF THE
DAY...WHICH IS FORECAST BY NEARLY ALL OF THE GUIDANCE /SAVE THE
06Z GFS AND FOR THE MOST PART THE 00Z AND 06Z GEFS MEMBERS/ TO
STRENGTHEN AS IT MOVES EAST OF THE BAHAMAS BEFORE LIFTING
NORTHWARD AND JUST OFFSHORE THE EAST COAST/ATLANTIC CANADA FROM
THIS WEEKEND ONWARD AHEAD OF THE NORTHEAST TROUGHING. THE 00Z
CANADIAN...AS USUAL...WAS THE MOST BULLISH WITH ITS STRENGTH. THE
ECMWF/CANADIAN MODELS HAVE GENERALLY TRENDED TOWARDS A
STRONGER/QUICKER SOLUTION OVER THEIR PAST COUPLE DAYS OF
RUNS...WITH THEIR SOLUTIONS CONVERGING WITH THE SYSTEMS POSSIBLE
TRACK OVER THAT TIME FRAME. THIS COMBINED WITH THE 00Z
MULTI-MODEL ENSEMBLE CLUSTERING DECREASES THE UNCERTAINTY
ASSOCIATED WITH THIS EVENT. ALONG THE EAST COAST...THE EXPECTED
TRACK OF THE LOW IS CLOSEST TO THE 00Z ECMWF SOLUTION WHICH IS
ONLY SLIGHTLY QUICKER THAN THE POINTS COORDINATED WITH TPC AT 16Z
ON SUNDAY AND ALSO FITS IN BEST WITH THE 00Z ECMWF/CANADIAN
ENSEMBLE LOW CLUSTERING.


Graphics
Member Since: September 23, 2005 Posts: 14 Comments: 10875
Quoting Skyepony:


I think you described that last part better then I. Models showing a weak cut off low from the trough kicking out 92L. CMC~ It looks like kinda a weak low to pull that off compared to the strength of 92L at that point. Not a real simple set up.


Yeah... is going to be a little dynamic with this one.
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Quoting P451:


lolololol.
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Quoting P451:


Good one! lol
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We can sit here all day predicting,but its way too early.Its just so hard trying to predict what the steering patterns are going to do by the end of next week.
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So...is September supposed to be a quiet month this year? *crosses fingers*
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Quoting OSUWXGUY:
Good Morning All!

I'm not really all that concerned with 92L and here's why...

Even after the ULL to its west retreats and weakens, 92L will be sheared by westerlies on the northeastern side of a strong ridge forecast to build over the western Caribbean.

Also, a weakness is consistently shown by all the models to form in the mid-latitude ridge east of the Outer Banks.

I could see a depression or tropical storm forming from 92L, but ultimately not a real threat.

I'm more concerned with Eastern Atlantic stuff at the moment...


I understand your opinion, but I still think it is a bit to early to say that.
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Quoting DestinJeff:


its there. just disguised as a statement not using Xtrp in it. ref: "here in Galveston"
My Bad...lol..
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Strong winds with the system east of the windwards.
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Quoting slavp:
Don't forget about the XTRAP showing GOM Hit...lol


OMG, the X-TRAP?!?! The end, my friends, is near! LOL

Howdy folks
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62. Skyepony (Mod)
Quoting WxLogic:
12Z NAM trending W as it keeps 92L disorganized longer. Based on my observations the cut off slow that comes from the trough split in the N GOM starts to weaken and there's a appears to be an induced High developing to the N/NW of 92L as it gets closer to the Bahamas and sits there waiting for a steering pattern to take shape.

There's also some indication of a trough in the CONUS mid section taking shape and starting to get the pieces of the cut off low in the N GOM... which could be strong enough to kick 92L out.



I think you described that last part better then I. Models showing a weak cut off low from the trough kicking out 92L. CMC~ It looks like kinda a weak low to pull that off compared to the strength of 92L at that point. Not a real simple set up.
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Quoting AllStar17:


Everyone should just remember this is the FIRST run of the models on this system, which are prone to large forecast errors.


Absolutely.......The models should shift WEST as the HIGH builds back to the WEST
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Good Morning All!

I'm not really all that concerned with 92L and here's why...

Even after the ULL to its west retreats and weakens, 92L will be sheared by westerlies on the northeastern side of a strong ridge forecast to build over the western Caribbean.

Also, a weakness is consistently shown by all the models to form in the mid-latitude ridge east of the Outer Banks.

I could see a depression or tropical storm forming from 92L, but ultimately not a real threat.

I'm more concerned with Eastern Atlantic stuff at the moment...
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Quoting DestinJeff:
GFS at +180 (because that is WAY accurate) TC headed for NE corner of the dreaded Bobby Hebert Box:



CMC at +132 ... Bastardidamus' prediction comes true:



bastardidamus-predicts that bill will circle around the bermuda high,and reform with the remnants of ana,claudette and jeanne making landfall in tazmania as a cat-3 and a half, warnings have now been extended to the ross ice shelf.
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Quoting TheDawnAwakening:


That is not a model. It shows the low's current movement.
I know that. I was being Sarcastic...lol
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Morning Glory clouds over Australia.

Link
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Quoting slavp:
Don't forget about the XTRAP showing GOM Hit...lol


That is not a model. It shows the low's current movement.
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53. Skyepony (Mod)
That recon photo is incredible..
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Quoting P451:


The point is, everyone, EVERYONE, needs to watch it.
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12Z NAM trending W as it keeps 92L disorganized longer. Based on my observations the cut off slow that comes from the trough split in the N GOM starts to weaken and there's a appears to be an induced High developing to the N/NW of 92L as it gets closer to the Bahamas and sits there waiting for a steering pattern to take shape.

There's also some indication of a trough in the CONUS mid section taking shape and starting to get the pieces of the cut off low in the N GOM... which could be strong enough to kick 92L out.

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Quoting DestinJeff:


"I expect those models to shift west at the next update"

"Is there a chance it could do a loop and come back west towards CONUS"

"That one model taking it to the Houston area concerns me here in Galveston!"

"SFL should stay aware since it looks like it might pass thru the Hebert Box" (usually posted as Herbert Box)
Don't forget about the XTRAP showing GOM Hit...lol
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49. Skyepony (Mod)
The CMC has been very insistent & pretty consistent about 92L for days. Up til day before yesterday it had a landfall on FL, then accounted for a trough turning it over the Bahamas & on up into Eastern North Carolina.
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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.