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 Drakoen:
We don't even have a well-defined surface circulation with this system to tell where this is going.

Agreed
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Quoting Drakoen:
We don't even have a well-defined surface circulation with this system to tell where this is going.
Very true, but according to the current location of the convection now to where is was 24 hours ago, I will think it is going around 25 MPH, and moving just slightly north of west, imo.

-CanesRule1.
Quoting kmanislander:


Different times I guess. Sounded like a case of soap and water with the toothbrush !.


When I was a kid, you would have been absolutely correct...
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Quoting scCane:
also the gfs ensembles has it going in all kind of different directions.


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Quoting DestinJeff:


3,2,1 ...


Duck and cover!
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also the gfs ensembles has it going in all kind of different directions.
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Thanks Positive NAO!!!!!!!
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Quoting canesrule1:
I see we have 92L, can someone please explain why the models have this curving.

Thanks,

-CanesRule1


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.
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Quoting breald:


So it looks like if this develops from the early models another trough will come and sweep it away.


That is the thinking of HPC at this time.
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Quoting Drakoen:
We don't even have a well-defined surface circulation with this system to tell where this is going.


Correct, this is why I don't put trust in these runs.
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585. JLPR
Quoting stormpetrol:

I really hate to say this , but I bet if the same area of disturbed weather in the SW Caribbean was as close to the US as it was to Nicaragua it would have a red circle at this time, sad, real sad.


I hate to say this but yep
I agree
Member Since: September 4, 2007 Posts: 36 Comments: 5223
We don't even have a well-defined surface circulation with this system to tell where this is going.
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Quoting canesrule1:
I see we have 92L, can someone please explain why the models have this curving.

Thanks,

-CanesRule1


well i think a trough is supposed to dig in again, but not sure why else
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Quoting AllStar17:


Too early to tell.


Yes, the ECMWF is west of the preliminary model runs. It will likely parallel the FL coast and might pose a threat to the Carolinas.
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I see we have 92L, can someone please explain why the models have this curving.

Thanks,

-CanesRule1
Quoting K8eCane:
according to those models

NOgulfer and probably fishy


Too early to tell.
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Quoting nrtiwlnvragn:
Extended Forecast Discussion

ALONG THE EAST COAST...THE FORECAST TRACK OF THE LOW IS CLOSE TO
THE SLOW 24/12Z ECMWF THROUGH FRIDAY NIGHT AFTER COORDINATION WITH
TPC AT 16Z...WHEN HPC SPLIT THE DIFFERENCE BETWEEN HPC CONTINUITY
AND NHCS SIGNIFICANTLY SLOWER PROPOSED TRACK TO COME UP WITH THE
CURRENT SOLUTION. THEREAFTER...THERE IS NOT A SHRED OF MODEL
GUIDANCE AS SLOW AS THE MEDIUM RANGE PROGS...WHICH NOW LIE ALONG
THE SLOW/EXTREME SOUTHWEST FRINGE OF THE 90 MEMBER 00Z MULTI-MODEL
ENSEMBLE SPREAD.


Graphics


Disagreement between HPC and NHC on track after friday?


So it looks like if this develops from the early models another trough will come and sweep it away.
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according to those models

NOgulfer and probably fishy
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Those Trofs just wont give way so far this season.
Member Since: May 14, 2006 Posts: 8 Comments: 13597
Quoting Drakoen:
The area in the southern Caribbean is too close to land to expect significant development of the system.


Yeah, seems it would still be an area to watch though, if were to move into the GOM right?
Member Since: July 2, 2009 Posts: 0 Comments: 2811
Quoting Elena85Vet:


Drak..For good chuckle check post 210.


I saw that. Wasn't in a "LOL!!!" mood though
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Quoting hurricane23:
Updated 18z models...Nice fishy.

Still early though.



yes agree
also nice NOgulfer too
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Quoting btwntx08:

and that is why the nhc DID NOT mention it

I really hate to say this , but I bet if the same area of disturbed weather in the SW Caribbean was as close to the US as it was to Nicaragua it would have a red circle at this time, sad, real sad.
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ZOMG!!!!! what does WTFO mean? LOL
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Quoting Drakoen:
I see we have 92L. Model forecasting this thing to stay off the coast of possible threaten the middle atlantic states.


Drak..For good chuckle check post 210.
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hre is the GFDL 12 Z run its a little out of wack so don't be surprized next run should be better

774

WHXX04 KWBC 241717

CHGQLM

ATTENTION...NATIONAL HURRICANE CENTER



NCEP COUPLED GFDL HURRICANE MODEL FORECAST MADE FOR



TROPICAL DEPRESSION INVEST 92L



INITIAL TIME 12Z 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 16.1 56.3 290./20.0



STORM DISSIPATED AT 0 HRS AT THE ABOVE PSN.


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The area in the southern Caribbean is too close to land to expect significant development of the system.
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Updated 18z models...Nice fishy.

Still early though.
Member Since: May 14, 2006 Posts: 8 Comments: 13597
562. IKE
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS, MD
300 PM EDT MON AUGUST 24 2009

6-10 DAY OUTLOOK FOR AUG 30 - SEP 03, 2009

THE MOST RECENT ENSEMBLE MEANS FROM THE GFS, ECMWF, AND CANADIAN MODELS ARE IN
GOOD AGREEMENT ON THE OVERALL 500-HPA FLOW PATTERN OVER THE FORECAST DOMAIN.
LONGWAVE TROUGHS ARE PREDICTED FOR THE EASTERN CONUS AND ALASKA AND A RIDGE IS
FORECAST FOR MUCH OF WESTERN NORTH AMERICA.


8-14 DAY OUTLOOK FOR SEP 01 - 07 2009

DURING WEEK TWO, THE GFS BASED ENSEMBLE MEANS FORECAST TROUGHS OVER WESTERN
ALASKA, OFF THE WEST COAST OF THE CONUS, AND OVER THE GREAT LAKES. SUBTROPICAL
RIDGING IS PROGGED FOR THE SOUTHWEST CONUS WITH A WEAKNESS IN THE SUBTROPICAL
RIDGE FORECAST FOR THE GULF COAST REGION.
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Look like it could be a LLC near 11.5N/77W even though this ascat didn't catch all of it.
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Extended Forecast Discussion

ALONG THE EAST COAST...THE FORECAST TRACK OF THE LOW IS CLOSE TO
THE SLOW 24/12Z ECMWF THROUGH FRIDAY NIGHT AFTER COORDINATION WITH
TPC AT 16Z...WHEN HPC SPLIT THE DIFFERENCE BETWEEN HPC CONTINUITY
AND NHCS SIGNIFICANTLY SLOWER PROPOSED TRACK TO COME UP WITH THE
CURRENT SOLUTION. THEREAFTER...THERE IS NOT A SHRED OF MODEL
GUIDANCE AS SLOW AS THE MEDIUM RANGE PROGS...WHICH NOW LIE ALONG
THE SLOW/EXTREME SOUTHWEST FRINGE OF THE 90 MEMBER 00Z MULTI-MODEL
ENSEMBLE SPREAD.


Graphics


Disagreement between HPC and NHC on track after friday?
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Quoting jrweatherman:
Shoot, school is out.


I'm still on Summer Vacation, today's my last day.
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Same old arguments about models. It is still TOO EARLY TO TELL where this system will go.
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Quoting HIEXPRESS:

You should be pretty safe there until tornado season, dude.


funny thing, we had a tornado last week, a couple confirmed and several funnels, way to start off my college career lol
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Quoting Seastep:


It can be done direct. Can't do it by copying the address bar. Just have to right-click the graphic and "copy image location." After pasting into the image box, remove the "s" in the end of https://. Apparently WU won't accept an https, but can be worked around. Hope this helps.

Like this:



Thanks!
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Quoting tornadodude:


haha love it, well im sitting in my dorm listening to the Purdue band play, they are practicing.

You should be pretty safe there until tornado season, dude.
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Quoting TheCaneWhisperer:


You need to send the photo through an image hosting site. The SFWMD does not allow direct image placement.


It can be done direct. Can't do it by copying the address bar. Just have to right-click the graphic and "copy image location." After pasting into the image box, remove the "s" in the end of https://. Apparently WU won't accept an https, but can be worked around. Hope this helps.

Like this:

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Quoting jrweatherman:
Shoot, school is out.


what's that supposed to mean?
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Quoting STORMT0P:
I'm out...see you all next year...st


You do that original StormTop from 2005.

EDIT: oh wait, the 'o' is different. =/
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Quoting FloridaTigers:
17 years ago today, Andrew came by.
17 years ago today I learned that cat-5-hurricanes form and strike whether there is an El-Nino or not.I also learned that a good size chunk of the Everglades and the southern tip of Florida won,t look the same as it did for a long-long time.
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About JeffMasters

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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