Dr. Jeff Masters' WunderBlog

Bill is gone; Invest 92 pops up

Posted by: Dr. Jeff Masters, 02:08 PM GMT on August 24, 2009

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

Hurricane Bill Waves Day 2 # 9 (RIWXPhoto)

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!

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1551. ftpiercecane 12:37 PM GMT on August 25, 2009
Quoting BeanTech: Good morning everyone... Extra coffee needed this morning as some nasty T-storms woke me up in Jupiter around 3:00. So much lightning it looked like daylight outside. It was going down in Port Saint Lucie also. Member Since: Oktober 9, 2008 Posts: 0 Comments: 204

1552. IKE 12:40 PM GMT on August 25, 2009
Quoting KEEPEROFTHEGATE: so far looks like another run up east coast As long as this pattern of troughs in the east holds, the GOM is off-limits. Long-term from New Orleans...... LONG TERM... GFS...NAM AND ECMWF ALL SHOW SOME SORT OF TROPICAL ORIGIN CYCLONE MOVING UP THE EASTERN SEABOARD AND SLINGING ANOTHER OUT OF SEASON COLD FRONT INTO THE GULF STATES FOR THE LATTER PART OF THIS WEEKEND INTO EARLY NEXT WEEK. THIS SCENARIO SEEMS PLAUSIBLE GIVEN THE UPPER LONG WAVE PATTERN. THIS SHOULD SPELL ANOTHER BOUT OF COOLER AND DRIER DAYS TOWARDS THE END OF THE FORECAST PERIOD. Member Since: Juni 9, 2005 Posts: 23 Comments: 37044

1553. largeeyes 12:41 PM GMT on August 25, 2009
Went red, do we even have anything close to an LLC yet? Member Since: August 22, 2006 Posts: 0 Comments: 1379

1554. Brallan 12:42 PM GMT on August 25, 2009
WOW, a red circle. That was surprising.

1555. KEEPEROFTHEGATE (Mod) 12:43 PM GMT on August 25, 2009
INV/92L/XX MARK 19.8N/61.0W Member Since: Juli 15, 2006 Posts: 143 Comments: 40368

1556. Tazmanian 12:44 PM GMT on August 25, 2009
25/1145 UTC 21.7N 63.3W T1.5/1.5 92L -- Atlantic 25/1145 UTC 10.9N 84.2W OVERLAND 93L -- Atlantic Member Since: Maj 21, 2006 Posts: 5088 Comments: 111311

1557. KEEPEROFTHEGATE (Mod) 12:45 PM GMT on August 25, 2009
Quoting Brallan: WOW, a red circle. That was surprising. red and a T.C.F.A. to boot Member Since: Juli 15, 2006 Posts: 143 Comments: 40368

1558. laflastormtracker 12:45 PM GMT on August 25, 2009

1559. Cavin Rawlins 12:45 PM GMT on August 25, 2009
Tropical Update Member Since: Juli 24, 2005 Posts: 407 Comments: 19076

1560. IKE 12:45 PM GMT on August 25, 2009
Quoting Tazmanian: 25/1145 UTC 21.7N 63.3W T1.5/1.5 92L -- Atlantic 25/1145 UTC 10.9N 84.2W OVERLAND 93L -- Atlantic Bingo....21.7N. Throw that BAM model suite in the gar-bage. Member Since: Juni 9, 2005 Posts: 23 Comments: 37044

1561. amd 12:46 PM GMT on August 25, 2009
92L is still not organized at all. Highest low level vorticity just NNE of the PR coast, and right at 20 N. Link In fact most of the convection with 92L seems to be associated with the 500 mb vorticity. Member Since: August 29, 2005 Posts: 0 Comments: 1024

1562. bingcrosby 12:46 PM GMT on August 25, 2009
Another squeeze play between the high pressure and the trough should take 92L away from the GOM and Florida. 92L looks a lot better today. Member Since: August 14, 2008 Posts: 0 Comments: 137

1563. KEEPEROFTHEGATE (Mod) 12:48 PM GMT on August 25, 2009
INV/92L/XX MARK 21.7N/63.3W Member Since: Juli 15, 2006 Posts: 143 Comments: 40368

1564. nrtiwlnvragn 12:49 PM GMT on August 25, 2009
Quoting IKE: Bingo....21.7N. Throw that BAM model suite in the gar-bage. Its not the model, that is where NHC initializes the system. Member Since: September 23, 2005 Posts: 11 Comments: 8916

1565. Tazmanian 12:50 PM GMT on August 25, 2009
92L is a lot better today FL needs to watch this 92L all so looking forword too what the HH finds out there today Member Since: Maj 21, 2006 Posts: 5088 Comments: 111311

1567. nrtiwlnvragn 12:51 PM GMT on August 25, 2009
AL 92 2009082512 BEST 0 216N 630W 25 1011 DB Member Since: September 23, 2005 Posts: 11 Comments: 8916

1568. bingcrosby 12:52 PM GMT on August 25, 2009
And on the other side of the world: Typhoon Vamco. Member Since: August 14, 2008 Posts: 0 Comments: 137

1569. KEEPEROFTHEGATE (Mod) 12:54 PM GMT on August 25, 2009
WEATHER RECONNAISSANCE FLIGHTS CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL. SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD) VALID 25/1100Z TO 26/1100Z AUGUST 2009 TCPOD NUMBER.....09-088 I. ATLANTIC REQUIREMENTS 1. SUSPECT AREA (NORTH OF PUERTO RICO) FLIGHT ONE - TEAL 70 A. 25/2100Z B. AFXXX 01AAA INVEST C. 25/1900Z D. 22.0N 67.0W E. 25/2000Z TO 26/0001Z F. SFC TO 10,000 FT FLIGHT TWO - TEAL 71 A. 26/0600Z B. AFXXX 0205A CYCLONE C. 26/0400Z D. 23.0N 71.0W E. 26/0530Z TO 26/1000Z F. SFC TO 10,000 FT 2. OUTLOOK FOR SUCCEEDING DAY: BEGIN 6-HRLY FIXES AT 26/1800Z IF SYSTEM DEVELOPS. II. PACIFIC REQUIREMENTS 1. NEGATIVE RECONNAISSANCE REQUIREMENTS. 2. SUCCEEDING DAY OUTLOOK.....NEGATIVE. JWP Member Since: Juli 15, 2006 Posts: 143 Comments: 40368

1570. earthlydragonfly 12:54 PM GMT on August 25, 2009
That African wave coming off the coast right now is quite impressive. Member Since: Juli 1, 2005 Posts: 10 Comments: 1649

1571. MahFL 12:54 PM GMT on August 25, 2009
Code red !!!!!! lol. Member Since: Juni 9, 2004 Posts: 0 Comments: 2417

1572. PensacolaDoug 12:55 PM GMT on August 25, 2009
As long as this pattern of troughs in the east holds, the GOM is off-limits. And thats a beau-ti-ful thang..... Member Since: Juli 25, 2006 Posts: 0 Comments: 4827

1573. Orcasystems 12:57 PM GMT on August 25, 2009
Blog Update Reflector site for those at work, which includes Weather456, daily update. AOI AOI AOI AOI Member Since: Oktober 1, 2007 Posts: 77 Comments: 26077

1574. IKE 12:58 PM GMT on August 25, 2009
Quoting PensacolaDoug: As long as this pattern of troughs in the east holds, the GOM is off-limits. And thats a beau-ti-ful thang..... Yes it is. Member Since: Juni 9, 2005 Posts: 23 Comments: 37044

1575. Chicklit 12:59 PM GMT on August 25, 2009
Loop Member Since: Juli 11, 2006 Posts: 14 Comments: 10239

1576. KEEPEROFTHEGATE (Mod) 01:01 PM GMT on August 25, 2009
my only concearn is the forecasted rex block that is to set up south of greenland by the weekend it will keep the poss storm from going that way so a due n or nw may be only choice for it to go Member Since: Juli 15, 2006 Posts: 143 Comments: 40368

1577. nrtiwlnvragn 01:02 PM GMT on August 25, 2009
AL 92 200908251145 10 DVTS CI 2170N 6330W SAB MS VI 3 1515 ///// AL 92 200908251145 10 DVTS CI 2180N 6270W TAFB JS VI 5 1010 ///// Member Since: September 23, 2005 Posts: 11 Comments: 8916

1579. largeeyes 01:07 PM GMT on August 25, 2009
Anyone got a quikscat on 92L? Member Since: August 22, 2006 Posts: 0 Comments: 1379

1580. PensacolaDoug 01:07 PM GMT on August 25, 2009
This is for anyone who may not realize how unusual it is to have this strong a trough in August: RECORD EVENT REPORT NATIONAL WEATHER SERVICE MOBILE AL 545 PM CDT MON AUG 24 2009 ...RECORD LOW TEMPERATURE TIED AT MOBILE... ...RECORD LOW TEMPERATURE SET AT PENSACOLA... A RECORD LOW TEMPERATURE OF 60 DEGREES WAS SET AT MOBILE TODAY. THIS TIES THE OLD RECORD OF 60 SET IN 1891. A RECORD LOW TEMPERATURE OF 63 DEGREES WAS SET AT PENSACOLA TODAY. THIS BREAKS THE OLD RECORD OF 64 SET IN 1891. Member Since: Juli 25, 2006 Posts: 0 Comments: 4827

1581. KEEPEROFTHEGATE (Mod) 01:07 PM GMT on August 25, 2009
298 WHXX01 KWBC 251302 CHGHUR TROPICAL CYCLONE GUIDANCE MESSAGE NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1302 UTC TUE AUG 25 2009 DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS. PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE AND SUBTROPICAL CYCLONE INFORMATION. ATLANTIC OBJECTIVE AIDS FOR DISTURBANCE INVEST (AL922009) 20090825 1200 UTC ...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS... 090825 1200 090826 0000 090826 1200 090827 0000 LAT LON LAT LON LAT LON LAT LON BAMS 21.6N 63.0W 24.0N 66.5W 26.3N 69.5W 28.2N 71.6W BAMD 21.6N 63.0W 23.8N 65.1W 25.7N 67.1W 27.4N 68.9W BAMM 21.6N 63.0W 23.5N 65.7W 25.2N 68.0W 26.8N 69.9W LBAR 21.6N 63.0W 23.9N 65.3W 25.9N 67.2W 27.4N 68.3W SHIP 25KTS 32KTS 40KTS 49KTS DSHP 25KTS 32KTS 40KTS 49KTS ...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS... 090827 1200 090828 1200 090829 1200 090830 1200 LAT LON LAT LON LAT LON LAT LON BAMS 29.8N 72.8W 31.7N 72.7W 33.0N 70.6W 35.9N 66.5W BAMD 29.0N 69.9W 32.1N 69.6W 35.7N 67.2W 41.6N 63.1W BAMM 28.2N 71.1W 30.5N 71.3W 33.0N 69.7W 37.1N 66.3W LBAR 28.8N 68.8W 31.3N 67.7W 33.6N 66.9W 36.2N 66.6W SHIP 56KTS 71KTS 77KTS 76KTS DSHP 56KTS 71KTS 77KTS 76KTS ...INITIAL CONDITIONS... LATCUR = 21.6N LONCUR = 63.0W DIRCUR = 305DEG SPDCUR = 20KT LATM12 = 18.4N LONM12 = 59.9W DIRM12 = 313DEG SPDM12 = 22KT LATM24 = 16.5N LONM24 = 56.0W WNDCUR = 25KT RMAXWD = 50NM WNDM12 = 20KT CENPRS = 1010MB OUTPRS = 1012MB OUTRAD = 120NM SDEPTH = M RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM $$ NNNN Member Since: Juli 15, 2006 Posts: 143 Comments: 40368

1582. KEEPEROFTHEGATE (Mod) 01:08 PM GMT on August 25, 2009
they fix up the run for ya ike Member Since: Juli 15, 2006 Posts: 143 Comments: 40368

1583. FloridaTigers 01:14 PM GMT on August 25, 2009
Wait, Europe NAMES their highs and lows? What a silly practice. Member Since: Maj 17, 2009 Posts: 0 Comments: 559

1584. KEEPEROFTHEGATE (Mod) 01:14 PM GMT on August 25, 2009
Quoting largeeyes: Anyone got a quikscat on 92L? navy got a partial but not complete Member Since: Juli 15, 2006 Posts: 143 Comments: 40368

1585. Orcasystems 01:18 PM GMT on August 25, 2009
These models are all in agreement that something will come from 92L. The CMC is the one showing a substantial system smacking the Carols. Member Since: Oktober 1, 2007 Posts: 77 Comments: 26077

1586. Tazmanian 01:19 PM GMT on August 25, 2009
looks like 92L is moveing NW Member Since: Maj 21, 2006 Posts: 5088 Comments: 111311

1587. GatorWX 01:21 PM GMT on August 25, 2009
Looks like a surface low trying to form off the Carolina coast. Easily visible on radar. Member Since: Januar 1, 2008 Posts: 0 Comments: 631

1588. mikatnight 01:21 PM GMT on August 25, 2009
Good Morning. Blog's a little slow this a.m. so thought I'd ask a question. I noticed the other day someone said something about a user map for the main bloggers here...is it possible to get a copy, or is that something one has to compile individually? Member Since: Oktober 18, 2005 Posts: 0 Comments: 1935

1589. laflastormtracker 01:22 PM GMT on August 25, 2009
Quoting Orcasystems: These models are all in agreement that something will come from 92L. The CMC is the one showing a substantial system smacking the Carols. That CMC run is awful. Is it the only outlier model that brings this system into NC or SC?

1590. largeeyes 01:22 PM GMT on August 25, 2009
Thanks, Keeper. Not even anything close to a COC. Member Since: August 22, 2006 Posts: 0 Comments: 1379

1591. Orcasystems 01:24 PM GMT on August 25, 2009
Quoting laflastormtracker: That CMC run is awful. Is it the only outlier model that brings this system into NC or SC? Its the only one on that link that hits it, the others show it staying off shore. Member Since: Oktober 1, 2007 Posts: 77 Comments: 26077

1592. IKE 01:23 PM GMT on August 25, 2009
Quoting KEEPEROFTHEGATE: they fix up the run for ya ike I see that...lol...thanks. Member Since: Juni 9, 2005 Posts: 23 Comments: 37044

1593. nrtiwlnvragn 01:24 PM GMT on August 25, 2009
Member Since: September 23, 2005 Posts: 11 Comments: 8916

1594. KEEPEROFTHEGATE (Mod) 01:24 PM GMT on August 25, 2009
Quoting largeeyes: Thanks, Keeper. Not even anything close to a COC. its incomplete we have to wait for a better snapshot later today hopefully Member Since: Juli 15, 2006 Posts: 143 Comments: 40368

1595. Orcasystems 01:26 PM GMT on August 25, 2009
Member Since: Oktober 1, 2007 Posts: 77 Comments: 26077

1596. mikatnight 01:28 PM GMT on August 25, 2009
Quoting nrtiwlnvragn: Noticed the CMC says "not available"...NOGP and a couple others missing too from that... Member Since: Oktober 18, 2005 Posts: 0 Comments: 1935

1597. laflastormtracker 01:30 PM GMT on August 25, 2009
Know why the models may be trending east this morning?

1598. Engine2 01:31 PM GMT on August 25, 2009
Quoting laflastormtracker: Know why the models may be trending east this morning? We also have to remember that since this thing doesn't have a LLC the models don't have a fixed point to initialize on Member Since: Februar 27, 2006 Posts: 0 Comments: 482

1599. GatorWX 01:32 PM GMT on August 25, 2009
Quoting earthlydragonfly: That African wave coming off the coast right now is quite impressive. I agree and has looked impressive during its trek across the continent Member Since: Januar 1, 2008 Posts: 0 Comments: 631

1600. IKE 01:32 PM GMT on August 25, 2009
What I think of when I see the latest tracks for 92L....riptides again along the east coast. Member Since: Juni 9, 2005 Posts: 23 Comments: 37044

1601. GatorWX 01:33 PM GMT on August 25, 2009
93L looks impressive, but I'm afraid it's time is numbered Member Since: Januar 1, 2008 Posts: 0 Comments: 631

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