Lesser Antilles Disturbance 97L a Threat to Develop

By: Dr. Jeff Masters , 2:46 PM GMT on September 01, 2013

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A tropical wave over the Lesser Antilles Islands (Invest 97L) is moving westward at 15 mph, and is bringing heavy rains and gusty winds to the islands. Top sustained winds in the islands as of 10 am AST Sunday were 26 mph at Monserrat. Heavy thunderstorm activity has sharply increased since Saturday, as seen on satellite loops. A large circulation is evident, with some westerly winds blowing to the south of the disturbance. However, the thunderstorms are poorly organized, and there is no sign of a well-organized surface circulation. Martinique radar shows some rotation to the echoes, though well-organized spiral bands are not evident, and do not appear to be forming. Wind shear has dropped to a moderate 10 - 20 knots over the system. An area of dry air from the Saharan Air Layer (SAL) surrounds 97L and is interfering with development.


Figure 1. Latest satellite image of Invest 97L.

Forecast for 97L
Wind shear is expected to be in the low to moderate range for the next five days, and ocean temperatures will be warm, 28 - 29°C. The disturbance is steadily moistening the atmosphere and is moving into a moister environment, so dry air will be less of an impediment to development as the week progresses. The main factor keeping the disturbance from developing over the next two days would appear to be the fact that 97L is quite large, and is stretched out from east to west over a wide expanse. Large, elongated systems like 97L usually take several days to consolidate and spin up. Another factor that will likely retard development is the presence of strong surface trade winds over the Eastern Caribbean ahead of 97L, south of the Dominican Republic. These strong trade winds are a common feature of the Eastern Caribbean, and make the region something of a hurricane graveyard. As the surface wind flow to the west of 97L accelerates into this wind max, air will be sucked from aloft downward towards the surface, creating sinking air, interfering with the formation of thunderstorm updrafts. The best chance for development of 97L would appear to be on Wednesday or Thursday, when the disturbance reaches the Central Caribbean. The wave will likely spread heavy rains to Puerto Rico, the Virgin Islands, and the Dominican Republic by Tuesday, and to Haiti by Wednesday. These rains will be capable of causing life-threatening flash flooding and mudslides in mountainous regions in Puerto Rico and Hispaniola. Of our three reliable models for predicting genesis, the UKMET, GFS, and European models, only the UKMET model develops the disturbance, predicting it will become a tropical depression south of Haiti on Wednesday, and near Jamaica on Thursday. In their 8 am EDT Sunday Tropical Weather Outlook, NHC boosted the 5-day odds of formation of 97L to 30%, and the 2-day odds to 20%.


Video 1. You can see why landslides triggered by heavy rains from a tropical cyclone are among the most dangerous hazards of these storms, thanks to a dashboard cam that caught this extraordinary rock slide in Northeast Taiwan on August 31, 2013, after heavy rains from a cold front drenched the island with up to 200 mm (7.87") of rain in 24 hours. The rains fell upon soils already saturated by Thursday's torrential rains from Tropical Storm Kong-Rey, which dumped up to 482 mm (19") of rain on Taiwan, killing three people. The driver of the car caught in the rock slide survived with minor injuries. Thanks go to wunderground member Robert Speta for bringing this video to my attention. A separate video showing the damage to the car and the course of the rock slide is here.

Jeff Masters

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Quoting interpreter:

Looking good but NO threat to the US.

I'm not a good enough fortune teller to make that kind of judgement. Give it five days and we'll see.
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Oh dear. It appears that most of us are thinking a major hurricane for the gulf coast. I certainly hope that doesn't happen!
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Product: NOAA High Density (HDOB) Message (URNT15 KWBC)
Transmitted: 1st day of the month at 18:08Z
Date: September 1, 2013

Aircraft: Gulfstream IV-SP (G-IV) (Reg. Num. N49RF)

Mission: Training Mission (flight in the North Atlantic basin)

Observation Number: 15

18:08:30Z 27.717N 82.483W 848.1 mb
(~ 25.04 inHg) 1,576 meters
(~ 5,171 feet) 1016.1 mb
(~ 30.01 inHg) - From 218° at 3 knots
(From the SW at ~ 3.4 mph) 18.9°C
(~ 66.0°F) -2.5°C
(~ 27.5°F) 4 knots
(~ 4.6 mph) - - - -
Time Coordinates Aircraft
Static Air Pressure Aircraft
Geopotential Height Extrapolated
Surface Pressure D-value Flight Level Wind (30 sec. Avg.) Air Temp. Dew Point Peak (10 sec. Avg.)
Flight Level Wind SFMR
Peak (10s Avg.) Sfc. Wind SFMR
Rain Rate Estimated Surface Wind (30 sec. Avg.)
Using Estimated Reduction Factor Peak Wind at Flight Level to
Est. Surface Reduction Factor

HDOB Observations

Independent Calculations from Tropical Atlantic

At 17:59:00Z (first observation), the observation was 50 miles (80 km) to the N (5°) from Fort Myers, FL, USA.
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Quoting 593. SLU:
01/1745 UTC 14.0N 60.6W TOO WEAK 97L -- Atlantic

This is because they used to wrong "center". The surface observations from Barbados totally disagree with SAB.


It also disagrees with the NHC's placement of the low which is a whole degree off from SAB.
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Quoting 588. CybrTeddy:


A well developed tropical cyclone would undoubtedly become a powerful hurricane in those conditions, which is what the LGEM and SHIPS are showing. The question will be if it becomes a tropical storm by the time it reaches that location.
I agree, if it's able to consolidate a well-defined closed surface circulation, it will have no problems intensifying as it traverses the Caribbean.

Obviously, it still has plenty of organizing to do, but in those conditions, it shouldn't be too much of an issue.
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Quoting 597. KEEPEROFTHEGATE:
could be taz first cane of the season cat 5 with a pinhole eye



yep



watch out from the gulf coast too FL
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Quoting 595. unknowncomic:

Deep convection alert for northern and central leeward islands.
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Quoting 589. Tazmanian:




this is really not good look at shear ouch

SHEAR (KT) 5 11 8 5 7 9 9 9 8 8 4 9 8


this could be a lot stronger then what ships are showing with that kind of shear
could be taz first cane of the season cat 5 with a pinhole eye
Member Since: July 15, 2006 Posts: 171 Comments: 53811
Quoting 590. seer2012:

Geez, step out for 5 hours and the world changes!!
LOL yeah it sure does..
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Member Since: August 2, 2011 Posts: 0 Comments: 1918
Quoting Tribucanes:
Only missing a closed surface circulation and we're there. Will the dry air in the mid levels and the size of 97L hamper that? With 97L looking as good as it is and the NHC only giving it a 50% chance over five days; makes me wonder if the NHC thinks this may be as good looking as 97L gets.

There's a more interesting possibility ahead. A low will move from the Yucatan into the BOC just ahead or possible the same time that 97L arrives in the area, assuming it holds together. That could make things in the Gulf a bit dicey.
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593. SLU
01/1745 UTC 14.0N 60.6W TOO WEAK 97L -- Atlantic

This is because they used to wrong "center". The surface observations from Barbados totally disagree with SAB.
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Geopotential height chart for the 500-milibar level, showing Elena (the closed isohypse over the Gulf of Mexico) on August 30. The trough that turned Elena toward the east can be seen embedded within the flow over the United States, and the ridge responsible for eventually pushing the storm back is denoted to the east of Florida.

The origins of Hurricane Elena can be traced to an easterly tropical wave that was first identified off the western coast of Africa on August 23, 1985. The system sped westward across the Atlantic at up to 35 mph (56 km/h). Its rapid motion, combined with the presence of an unusually hostile Saharan Air Layer, prevented tropical cyclogenesis for several days. Driven by a strong subtropical ridge to its north, the wave quickly approached North America as it began to show signs of organization.

At 00:00 UTC on August 28, the disturbance developed into a tropical depression while over the Windward Passage. The newly designated depression began to track west-northwestward over Cuba, which is known to disrupt tropical cyclone development. Despite that, its central barometric pressure continued to deepen, and reconnaissance aircraft found winds exceeding 50 mph (80 km/h) near the center. In response, the National Hurricane Center upgraded the depression to Tropical Storm Elena over northern Cuba later on August 28.

After passing north of Havana, Cuba, Elena emerged into the Gulf of Mexico. At 12:00 UTC on August 29, Elena intensified into a Category 1 hurricane. Analysis of steering currents through the morning of August 30 suggested that Elena would continue on its northwestward track, striking the area between New Orleans, Louisiana, and Biloxi, Mississippi within 30 hours.

Unexpectedly, a mid-to-upper-level trough of low pressure diving in from the northwest created a weakness in the easterly currents, allowing Elena to recurve and slow drastically in forward speed. Roughly 24 hours after attaining hurricane intensity, the storm abruptly turned east in response to the trough. Having defied initial forecasts, Hurricane Elena drifted on its new course toward the coast of northwest Florida. Forecasters now called for the trough to direct the hurricane across the Florida Peninsula and into the western Atlantic.

However, the relatively weak trough moved rapidly, and instead of fully engaging Elena, its axis passed over the storm's center. Further, post-storm analysis of water vapor imagery suggested that the hurricane split the trough into two distinct segments.



Geopotential height chart for the 500-milibar level, showing Elena (the closed isohypse over the Gulf of Mexico) on August 30. The trough that turned Elena toward the east can be seen embedded within the flow over the United States, and the ridge responsible for eventually pushing the storm back is denoted to the east of Florida.

Extrapolation from the storm's eastward progress yielded a projected landfall location near Levy County. However, after the passage of the upper-level system early on August 31, steering currents became extremely weak, and Elena became nearly stationary in the extreme northeastern Gulf of Mexico. At its closest, the center of the storm was around 50 mi (80 km) from Cedar Key, Florida, with maximum sustained winds estimated at 105 mph (170 km/h).

While it was nearly stalled, Elena's intensity remained consistent; the cyclone was able to continue strengthening as soon as movement resumed. Early on September 1, Elena reached Category 3 major hurricane status. An area of high pressure soon began to build over the eastern United States, causing Elena to slowly retrograde westward.

For much of September 1, the center of the hurricane was within range of the WSR-57 radar station in Apalachicola, Florida, allowing extensive study of the complex features within the eye and surrounding eyewall. During that period of observation, the previously unobstructed eye became covered by clouds.

The hurricane accelerated on a trajectory toward the central U.S. Gulf Coast, sliding south of the Florida Panhandle. During the afternoon of September 1, the hurricane attained its peak intensity, with winds of 125 mph (205 km/h) as confirmed by reconnaissance aircraft. On the morning of September 2, Elena approached coastal Mississippi from the east-southeast, still at major hurricane status. It came ashore close to Biloxi, which was coincidentally within the hurricane's first forecast destination range before its extended detour.

Once inland, the hurricane immediately deteriorated, weakening to a tropical storm just hours after landfall, and its center rapidly filled. The system curved northwestward over Mississippi and Louisiana, and despite its weakening, it continued to ignite thunderstorm activity which spawned heavy rains. Elena persisted for several days before it degenerated a remnant area of low pressure on September 4. Its associated cloud structure became distorted on September 5, and dissipated over Kentucky that same night.
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Quoting 568. MiamiHurricanes09:
AL, 97, 2013090118, , BEST, 0, 146N, 597W, 30, 1008, LO


Due to the current convective structure and the overall large circulation, it wouldn't surprise me to see the center hang back a bit or even develop further to the east a bit.
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Quoting 557. LargoFl:

Geez, step out for 5 hours and the world changes!!
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Quoting 579. MiamiHurricanes09:
LGEM taking 97L to 109kts; SHIPS to 87kts.


V (KT) LGE mod 30 33 36 40 44 52 63 75 87 98 106 109 109

V (KT) LAND 30 34 38 42 46 54 63 70 76 81 85 86 87

Takes it south of Cuba, 29C SSTs throughout the forecast period.




this is really not good look at shear ouch

SHEAR (KT) 5 11 8 5 7 9 9 9 8 8 4 9 8


this could be a lot stronger then what ships are showing with that kind of shear
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Quoting 579. MiamiHurricanes09:
LGEM taking 97L to 109kts; SHIPS to 87kts.


V (KT) LGE mod 30 33 36 40 44 52 63 75 87 98 106 109 109

V (KT) LAND 30 34 38 42 46 54 63 70 76 81 85 86 87

Takes it south of Cuba, 29C SSTs throughout the forecast period.


A well developed tropical cyclone would undoubtedly become a powerful hurricane in those conditions, which is what the LGEM and SHIPS are showing. The question will be if it becomes a tropical storm by the time it reaches that location.
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Quoting 544. Patrap:
The 40% is warranted easily. Giving the overall synoptic pic.


Hints of a annular spreading canopy.



Looking good but NO threat to the US.
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Quoting 574. CybrTeddy:


Good sign when they change from DB to LO.

They had changed that from long ago

Quoting 575. LargoFl:
anything is possible right now.........

Yikes
Member Since: June 13, 2009 Posts: 2 Comments: 11986
Quoting 578. CybrTeddy:


DB = Disturbance.
LO = Low pressure area.

OK thanks! Just wanted to make sure.
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Quoting 579. MiamiHurricanes09:
LGEM taking 97L to 109kts; SHIPS to 87kts.


V (KT) LGE mod 30 33 36 40 44 52 63 75 87 98 106 109 109

V (KT) LAND 30 34 38 42 46 54 63 70 76 81 85 86 87

Takes it south of Cuba, >10kt upper-level winds, and >29˚C SSTs throughout the forecast period.




thanks not good
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TXNT28 KNES 011804
TCSNTL

A. TROPICAL DISTURBANCE (97L)

B. 01/1745Z

C. 14.0N

D. 60.6W

E. FIVE/GOES-E

F. TOO WEAK

G. IR/EIR/VIS

H. REMARKS...THIS SYSTEM IS TOO WEAK TO CLASSIFY DUE TO LACK OF DISCREET
BANDING AND LOW LEVEL CENTER.

I. ADDL POSITIONS

NIL


...SCHWARTZ


Link
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Quoting 576. 62901IL:

What does LO mean?


add a W to it
Member Since: September 19, 2005 Posts: 2 Comments: 4227
Product: NOAA High Density (HDOB) Message (URNT15 KWBC)
Transmitted: 1st day of the month at 17:58Z
Date: September 1, 2013

Aircraft: Gulfstream IV-SP (G-IV) (Reg. Num. N49RF)

Mission: Training Mission (flight in the North Atlantic basin)

Observation Number: 14

17:58:30Z 27.333N 81.733W 450.9 mb
(~ 13.32 inHg) 6,685 meters
(~ 21,932 feet) - 358 meters
(~ 1,175 feet) From 164° at 9 knots
(From the SSE at ~ 10.3 mph) -11.4°C
(~ 11.5°F) -15.5°C
(~ 4.1°F) 10 knots
(~ 11.5 mph) - - - -
Time Coordinates Aircraft
Static Air Pressure Aircraft
Geopotential Height Extrapolated
Surface Pressure D-value Flight Level Wind (30 sec. Avg.) Air Temp. Dew Point Peak (10 sec. Avg.)
Flight Level Wind SFMR
Peak (10s Avg.) Sfc. Wind SFMR
Rain Rate Estimated Surface Wind (30 sec. Avg.)
Using Estimated Reduction Factor Peak Wind at Flight Level to
Est. Surface Reduction Factor

HDOB Observations

Independent Calculations from Tropical Atlantic

At 17:49:00Z (first observation), the observation was 29 miles (46 km) to the WNW (283°) from West Palm Beach, FL, USA.
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Quoting 555. hydrus:
Hello Taco. Actually, there are similarities to Elena, and that is why he posted.. He knows what he,s doing.


I agree 1000% Pat has been through as many as I have over the years and we do relate to just about all of them :o)


Taco :o)
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LGEM taking 97L to 109kts; SHIPS to 87kts.

V (KT) LGE mod 30 33 36 40 44 52 63 75 87 98 106 109 109

V (KT) LAND 30 34 38 42 46 54 63 70 76 81 85 86 87

Takes it south of Cuba, <10kt upper-level winds, and 29C SSTs throughout the forecast period.
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Quoting 576. 62901IL:

What does LO mean?


DB = Disturbance.
LO = Low pressure area.
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Quoting 574. CybrTeddy:


Good sign when they change from DB to LO.



they all ready did chages it from DB too LO


AL, 97, 2013090118, , BEST, 0, 146N, 597W, 30, 1008, LO
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Quoting 574. CybrTeddy:


Good sign when they change from DB to LO.

What does LO mean?
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anything is possible right now.........
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Quoting 568. MiamiHurricanes09:
AL, 97, 2013090118, , BEST, 0, 146N, 597W, 30, 1008, LO


Good sign when they change from DB to LO.
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Quoting 562. Tazmanian:



am not really sure on that the more it moves W I think that will changes overe time with the modes I think will see them shift more W has 97L moves W


depends on how strong it gets Taz
Member Since: September 19, 2005 Posts: 2 Comments: 4227
Over 13,000 homes were damaged in Mississippi, and 200 were completely destroyed. Cities close to the Alabama border—including Pascagoula—experienced widespread damage to residences, schools, and businesses, and the community of Gautier was effectively isolated from the outside world. Several apparent but unconfirmed tornadoes appear to have exacerbated the damage in the Gulfport area.

Wind damage extended into portions of eastern Louisiana. Overall, nine people died as a result of the hurricane: two in Texas due to drownings in rip currents, three in Florida, two in Louisiana, one in Arkansas, and one in a maritime accident in the Gulf of Mexico. Damage totaled about $1.3 billion, and power outages from the storm affected 550,000 people.

In Elena's wake, President Ronald Reagan declared parts of Alabama, Mississippi, and Florida federal disaster areas, making storm victims eligible for financial aid and temporary housing. The name Elena was later retired from the cyclical list of Atlantic hurricane names because of the storm's effects.
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Quoting 554. JRRP:
more North




Anywere form Texas to FL should watch it.
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570. JRRP
06 GMT 09/1/13 14.0N 58.3W 25 1009 Invest
12 GMT 09/1/13 14.6N 60.5W 30 1008 Invest
18 GMT 09/1/13 14.6N 59.7W 30 1008 Invest
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Quoting 560. Patrap:
A shuttle was on Orbit during Elena and gave some great images..and Live TV as well.



STS-51-I I believe, Joe Engle (Apollo guy, original Apollo 17 LEM pilot), Richard Covey, James van Hoften, John Lounge, and Bill Fisher on Discovery.
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AL, 97, 2013090118, , BEST, 0, 146N, 597W, 30, 1008, LO
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Quoting 553. Patrap:


Don't I know.

I moved 12 woodworking machines upstairs with the forklift Labor Day weekend in Long Beach.

Then took them down,then it turned back, and well, u know.

Tampa was lucky, Gulfport, not so.




Oh yea Pat I do remember and the tornados we had here, well I would say "Very Troublesome" to say the least....

Taco :o)
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566. SLU
Quoting 556. Gearsts:
where do you put it?


14.5n 58w
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Quoting TropicalAnalystwx13:

Recon is scheduled for Tuesday.

Were you out walking your dog again? ;)

No, but, as I said, no recon was scheduled, meaning today, not Tuesday. I'm quite certain that the NHC would be flying 97L today if they thought it had any chance to develop in the next 24 hours...or don't you agree?
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Quoting 560. Patrap:
A shuttle was on Orbit during Elena and gave some great images..and Live TV as well.

I waved, but they didnt wave back...i cried
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Member Since: August 2, 2011 Posts: 0 Comments: 1918
Quoting 554. JRRP:
more North



am not really sure on that the more it moves W I think that will changes overe time with the modes I think will see them shift more W has 97L moves W
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There is moisture for 97L to eat along with its popcorn.

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Shuttle Discovery was on Orbit during Elena and gave some great images..and Live TV as well.



Hurricane Elena in the Gulf of Mexico from Space Shuttle Discovery on September 1, 1985
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Click for Animation.

g
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Quoting 552. Hurricanes101:


Lets not get ahead of ourselves
lol
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Quoting 549. SLU:
Here comes empirical evidence that the center has relocated further east.

Barbados

2:00 PM 80.6 °F 87.1 °F 77.0 °F 89% 29.83 in 6.2 mi NW 10.4 mph - N/A Mostly Cloudy
where do you put it?
Member Since: August 2, 2010 Posts: 0 Comments: 1741
Quoting 543. taco2me61:


With all due respect Pat, I don't think we need to use Elena.... She was a True Puzzle until she finally made landfall....

Taco :o)
Hello Taco. Actually, there are similarities to Elena, and that is why he posted.. He knows what he,s doing.
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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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