Disturbance 99L more organized; record melting in Austrian Alps

By: Dr. Jeff Masters , 2:02 PM GMT on August 01, 2012

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A tropical wave (Invest 99L) near 11°N 47°W, about 1000 miles east of the Lesser Antilles Islands, is showing increasing organization, and has the potential to develop into a tropical depression today or tomorrow as it moves westward at 15 - 20 mph. Visible satellite loops show that the disturbance now has two respectable low-level spiral bands, one to the north and one to the south, and a moderate amount of heavy thunderstorms near the center. The thunderstorm activity has not changed much in intensity this morning. A well-defined surface circulation is not evident on satellite images, but last night's 8:30 pm EDT pass from the ASCAT satellite showed a broad, elongated center with light winds had formed. Water vapor satellite loops show that 99L has a reasonably moist environment, and the latest Saharan air layer analysis shows that the dry air from the Sahara is not present in large quantities over the central tropical Atlantic. WInd shear over the disturbance has increased some since Tuesday, and is now at the moderate level, 10 - 15 knots. Ocean temperatures are 28°C, (82°F) which is about 0.5°C above average for this time of year.


Figure 1. Morning satellite image of Invest 99L.


Figure 2. Vertical instability over the tropical Atlantic in 2012 (blue line) compared to average (black line.) The instability is plotted in °C, as a difference in temperature from near the surface to the upper atmosphere. Thunderstorms grow much more readily when vertical instability is high. Instability has been lower than average, due to an unusual amount of dry, sinking air in the atmosphere, reducing the potential for tropical storm formation. Image credit: NOAA/NESDIS/CIRA.

Forecast for 99L
Wind shear is expected to remain light to moderate, 5 - 15 knots, through Friday, ocean temperatures will remain near 28°C, and mid-level moisture will be a moderate 60 - 70%, according to the 8 am EDT run of the SHIPS model. The disturbance has gained a bit of latitude and is now at 11°N, which will help it leverage the Earth's spin more to acquire its own spin. These conditions are probably sufficient for 99L to become Tropical Depression Five, with Thursday being the most likely day for this to happen. However, the reliable computer models are not very eager to develop 99L, and none show it becoming a hurricane over the next five days. This is probably because the atmosphere over the tropical Atlantic is unusually stable for this time of year (Figure 2), with large-scale areas of dry, sinking air present. Climatologically, we see very few Cape Verdes-type hurricanes forming near the Lesser Antilles Islands this early in August, and I expect 99L will struggle at times over the next few days. This is particularly likely if 99L goes north of 13°N, where a band a high wind shear of 20 - 40 knots associated with the subtropical jet stream lies. At 8 am Wednesday, NHC gave 99L a 60% chance of developing into a tropical depression by Friday morning. Residents and visitors to the Lesser Antilles Islands should anticipate heavy rains and strong winds from 99L beginning to affect the islands as early as Friday morning. The long-range fate of 99L next week is uncertain, but a track west to west-northwest through the Caribbean is the most popular solution from the models.


Figure 3. Typhoon Saola (bottom) and Typhoon Damrey (top) perform a pincer maneuver on Shanghai, China in this MODIS photo from NASA's Terra satellite taken at 02 UTC August 1, 2012. Image credit: NASA.

Two typhoons headed towards China
In the Western Pacific, typhoon season is in full swing with two typhoons headed towards China. The more dangerous of the two is Category 2 Typhoon Saola, which is predicted to skirt the northern coast of Taiwan and hit mainland China 300 miles south of Shanghai on Friday as a Category 3 typhoon. Typhoon Damrey, a Category 1 storm located just south of Japan, is expected to hit China about 150 miles north of Shanghai on Thursday at Category 1 strength.

Extreme heat in Oklahoma
The withering heat in America's heartland continued on Tuesday, with the prize for most ridiculous heat a 113° temperature recorded in Chandler, Oklahoma. A close second: Tulsa hit 112°, just 3° below the city's all-time high of 115° set on August 10, 1936. The low temperature in Tulsa was 88° Tuesday morning, tying the record for warmest low temperature in city history set just the previous day. Six locations in Oklahoma hit 112° or hotter Tuesday, and the forecast calls for highs near 112° again today over portions of Oklahoma.

Extreme dryness in the Central U.S.
A few final tallies for July precipitation are in, and several U.S. cities in the heart of the drought region set new records for driest July:

Joplin, MO: 0.00" (ties record set in 1946)
Springfield, MO: 0.32" (previous record 0.33" in 1953)
Sioux Falls, SD: 0.24" (previous record, 0.24" in 1947, normal is 3.09")

Record early snow melt in the Austrian Alps
One of the longest meteorological data records at high altitude comes from Sonnblick, Austria, on a mountaintop in the Alps with an elevation of 3106 meters (10,200 feet.) The observatory typically sees maximum snow depths of 3 - 4 meters (10 - 13 feet) during winter. According to weather records researcher Maximiliano Herrera, the snow had never completely melted at Sonnblick until the summer of 1992. Complete snow melt did not happen again until August 12, 2003, and has happened an average of once every two years since then--but always in September. Yesterday, on July 31, the snow completely melted at Sonnblick, the earliest melting since record keeping began in 1886. It's been an exceptionally hot summer in Austria, which experienced its 6th warmest June since record keeping began in 1767. Sonnblick Observatory recorded its all-time warmest temperature of 15.3°C (60°F) on June 30. Vienna hit 37.7°C (100°F) that day--the hottest temperature ever measured in June in Austria. Note that the two mountains in the Alps with long climate records, Saentis in Switzerland and Zugspitze in Germany, beat their records for earliest melting last year in 2011 (Saentis beat the previous record of 2003, and Zugspitze tied the record set in 2003.)


Figure 4. The Sonnblick Observatory in Austria on April 26, 2010. Image credit: Michael Staudinger.

Jeff Masters

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Member Since: Posts: Comments:
Quoting cg2916:


Looks like a Dean/Felix track.
Except weaker thankfully, but where it goes in the long term will be a challenge to figure out for now.
Member Since: March 16, 2012 Posts: 127 Comments: 7948
Center looks close to 12N now per visible sat..
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Quoting SFLWeatherman:
99L is now up to 35MPH!!

He also mentioned the stronger it is when it enters Caribbean perhaps the more likely it will be to survive the crossing. Anyway, interesting morning. adios for now.
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Quoting RayT:


I was thinking the same thing. lots of banding. I guess there is insufficient surface circulation. I figure it's just a matter of time. I bet by tonite it's a TD or a TS.
99L has the environment and time, it just needs to improve its circulation some and gain more convection and it's good.
Member Since: March 16, 2012 Posts: 127 Comments: 7948
Quoting ProgressivePulse:
Some of the models are portraying a N-ward turn around the Central Caribbean today as shown in the consensus model TVCN. Could be that the Atl. Ridge is eroded on the western edge by the low on the east coast and the Twave near Hispaniola.



Looks like a Dean/Felix track.
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Reminds me of Ike size



Member Since: July 14, 2008 Posts: 1 Comments: 9630
Ernesto why do you have to be a pest?.Can't you just be like your 2000 counter part?.A tropical storm that had max intensity of 40mph and lasted only two days... and died out in the Atlantic....
Member Since: August 14, 2010 Posts: 10 Comments: 17071
99L is now up to 35MPH!!
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New convection blowing up near the center, as StormChaser mentioned. Definitely a good sign for development and further strengthening.

Member Since: July 15, 2006 Posts: 17 Comments: 10282
Quoting TropicalAnalystwx13:

I was going to change it anyways when TD #5/Ernesto was declared, but I switched a bit early.


Blue.
Thanks, guess I just forgot, hopefully we don't see code blue this year.
Member Since: March 16, 2012 Posts: 127 Comments: 7948
Quoting AussieStorm:

I have been having the same problem. been meaning to ask also. A real pain in the butt.
I get a Problem loading page message and then I have to look around for another site with ASCAT data.
Member Since: March 16, 2012 Posts: 127 Comments: 7948
Quoting trHUrrIXC5MMX:
OH HOLY COW!

80 MPH HURRICANE
..thats one model run BUT..it could happen
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Ernesto looks dangerous
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Quoting TropicalAnalystwx13:

I was going to change it anyways when TD #5/Ernesto was declared, but I switched a bit early.


Blue.
Cool! I actually didn't expect that you would, or the icon could be changed. Nice effect.
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Levi made some good points in today's tidbit about 99L having a series of struggles as it cross the caribbean but if it stays together until west caribbean and then is enhanced by tutt to its east, then it's a new ball game. And the SST's over there are even higher over a larger area than they were in 2005.
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Sorry a bit off topic but LOL
Camper in Brockton, Mass. pool
http://www.necn.com/08/01/12/Camper-in-Brockton-M ass-pool/landing.html?blockID=749573&feedID=4753

Bur 99L looks to become Ernesto or TD-5 at 5:00 pm.
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169. RayT
Quoting wxchaser97:
99L is looking better but could use some more convection so the NHC could make a good call but it already looks like a TD.


I was thinking the same thing. lots of banding. I guess there is insufficient surface circulation. I figure it's just a matter of time. I bet by tonite it's a TD or a TS.
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Quoting wxchaser97:
What is wrong with the ASCAT site, Link, I can't get into it for the past few days. Sorry if this has been already asked/answered.

I have been having the same problem. been meaning to ask also. A real pain in the butt.
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OH HOLY COW!

80 MPH HURRICANE
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Some of the models are portraying a N-ward turn around the Central Caribbean today as shown in the consensus model TVCN. Could be that the Atl. Ridge is eroded on the western edge by the low on the east coast and the Twave near Hispaniola.

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Quoting Levi32:


But not in a southeasterly direction. The elongated low-level vorticity siginature to the southwest of 99L's center suggests that the circulation may not yet be closed. We won't really know until another ASCAT pass.



Hard to say because that part is actually under convection. The speed at which you can see the northern half spinning would make me assume that it is a closed entity. I see the vort attachment you're referring to on the maps and you could actually see it on visible loops. However, it looks to be losing its involvement to me.
Member Since: July 15, 2006 Posts: 17 Comments: 10282
Quoting Articuno:

I am serious it looks that way.


That's a looooong connection
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What is wrong with the ASCAT site, Link, I can't get into it for the past few days. Sorry if this has been already asked/answered.
Member Since: March 16, 2012 Posts: 127 Comments: 7948
161. PTXer
Quoting pottery:
Looking at the Steering for 99L.....
With the highs where they are, and the fact that the system is still a long way south, I would expect west for the next 48 hrs.

850 mb steering map shows the set up well.

Looks like you're going to get wet Pottery. I'm sure you'll keep an eye on it.
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Quoting Stormchaser2007:
NRT will be able to confirm, but I don't even think the 12z BAM suite made it in. That supercomputer issue really messed things up.

The 12z SHIPS seems to have been run off of the 6z BAMM, which had an exteremely unfavorable track.





Appears you are correct, the aid file does not have data for the BAMs at 12Z, and the 12Z SHIPS coordinates are the same as the 06Z BAMM

AL 99 2012080106 03 BAMM 12 104N 462W
AL 99 2012080106 03 BAMM 24 109N 484W
AL 99 2012080106 03 BAMM 36 115N 505W
AL 99 2012080106 03 BAMM 48 121N 528W
AL 99 2012080106 03 BAMM 60 131N 554W
AL 99 2012080106 03 BAMM 72 141N 581W
AL 99 2012080106 03 BAMM 84 154N 611W
AL 99 2012080106 03 BAMM 96 167N 639W
AL 99 2012080106 03 BAMM 108 179N 669W
AL 99 2012080106 03 BAMM 120 187N 698W
Member Since: Posts: Comments:
Quoting Waltanater:
LOL...it's red now! (you didn't have to change it..j/k) :)

I was going to change it anyways when TD #5/Ernesto was declared, but I switched a bit early.

Quoting wxchaser97:
Code red, that means that you are confident that 99L will be a TD/TS, but yet again so am I. What is the last color again, I know its for a major storm making US landfall?

Blue.
Member Since: July 6, 2010 Posts: 113 Comments: 32249
some models are very promising



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THIS HAZARDOUS WEATHER OUTLOOK IS FOR EAST CENTRAL FLORIDA.

.DAY ONE...TODAY AND TONIGHT.

.THUNDERSTORM IMPACT...
ATMOSPHERIC CONDITIONS WILL LEAD TO SCATTERED LIGHTNING STORMS
THIS AFTERNOON INTO EARLY EVENING. THE BEST CHANCE WILL OCCUR WITH
THE COLLISION OF THE EAST AND WEST COAST SEA BREEZE BOUNDARIES
OVER INTERIOR...ESPECIALLY ALONG THE I-4 CORRIDOR IN THE EARLY TO
MID AFTERNOON. STORM MOTION WILL BE TOWARD THE EAST TO NORTHEAST
AT AROUND 10 TO 15 MPH. A FEW STRONGER STORMS MAY CONTAIN GUSTY
DOWNBURST WINDS UP TO 50 MPH...DANGEROUS LIGHTNING STRIKES AND
LOCALLY HEAVY RAIN UP TO 2 INCHES.

.MARINE THUNDERSTORM GUST IMPACT...
LIGHTNING STORMS MAY PRODUCE STRONG DOWNBURST WINDS OF 35 TO 45
KNOTS OVER INLAND LAKES THIS AFTERNOON AND EARLY EVENING. ESPECIALLY
FROM NORTHERN OSCEOLA AND CENTRAL BREVARD COUNTIES NORTHWARD.
STORM MOTION WILL BE TOWARD THE NORTHEAST AT 10 TO 15 MPH WITH A
FEW STORMS PUSHING OFFSHORE...ESPECIALLY FROM PORT CANAVERAL
NORTHWARD.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.
ISOLATED TO SCATTERED LIGHTNING STORMS ARE EXPECTED EACH AFTERNOON
THIS WEEK. THE PRIMARY THREATS WILL BE GUSTY DOWNBURST WINDS AND
DANGEROUS LIGHTNING STRIKES. INCREASING MOISTURE FROM AN APPROACHING
TROPICAL WAVE AROUND SATURDAY IS EXPECTED TO INCREASE COVERAGE OF
STORMS ALONG WITH RIP CURRENTS DURING THE WEEKEND.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY.
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I generally hate the Texas Death Ridge but quite often it comes to our rescue this time of year.
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Tropical Overshooting Tops (Colored dots) are beginning to develop with 99L very near the LLC. This could provide the convection it needs to survive the day.

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Quoting TropicalAnalystwx13:
Switched a bit early.
Code red, that means that you are confident that 99L will be a TD/TS, but yet again so am I. What is the last color again, I know its for a major storm making US landfall?
Member Since: March 16, 2012 Posts: 127 Comments: 7948
Quoting TropicalAnalystwx13:

Was wondering why it never strengthened it much and then showed it weakening.
LOL...it's red now! (you didn't have to change it..j/k) :)
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Quoting wxchaser97:
I'm just saying that 99L has top-end TD winds.
Don't respond to him.He did that yesterday to me.
Member Since: August 14, 2010 Posts: 10 Comments: 17071
Quoting MississippiWx:


I have to disagree. While it may not be "obvious" that the winds are responding at the surface, the low level clouds can be seen moving in a southerly direction in the convection-less part of the circulation.


But not in a southeasterly direction. The elongated low-level vorticity siginature to the southwest of 99L's center suggests that the circulation may not yet be closed. We won't really know until another ASCAT pass.

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Quoting TropicalAnalystwx13:
Some of the wind shear we see on this map is probably from 99L's anticyclone.



To put it together in one post, my thoughts are that 99L makes it to mid-grade tropical status before it passes through the Windward Islands (near 13N), and then maintains intensity as it passes through the eastern and central Caribbean. It then gets into the west Caribbean and begins very fast intensification.

This could be a serious situation in a few days.
It is a good thing that we are in a downward phase and no significant upward motion is expected for a while, This could change if the MJO switches gears as it has done in the recent past .
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Quoting wunderkidcayman:

duh
I'm just saying that 99L has top-end TD winds.
Member Since: March 16, 2012 Posts: 127 Comments: 7948
Switched a bit early.
Member Since: July 6, 2010 Posts: 113 Comments: 32249
Quoting AussieStorm:

I hate to tell you but it's not.


Typhoon Saola

I am serious it looks that way.

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...ok this on saturday must be the tropical wave the nws melbourne is talking about..must be going up the east coast..im guessing this is the storm down by PR right now
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Quoting DookiePBC:
I'm gonna get a template set up for the inevitable questions that will pop up later on when they declare this system a TD or TS...

"I have a [insert social event such as wedding, reunion, etc] in [insert coastal hometown] coming up next Saturday. Should I cancel it?"

This should be an interesting one to track.
Lol.So true.We've all ready seen several.
Member Since: August 14, 2010 Posts: 10 Comments: 17071

Link to radar
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Quoting Levi32:


It looks fine except the western and southwestern side. The ITCZ is still a big part of its life, and it is not obvious yet whether there are northerly and northwesterly winds to make a completely closed circulation. It's not fully detached from the ITCZ yet.


I have to disagree. While it may not be "obvious" that the winds are responding at the surface, the low level clouds can be seen moving in a southerly direction in the convection-less part of the circulation.
Member Since: July 15, 2006 Posts: 17 Comments: 10282
Quoting washingtonian115:
I'm surprised the out flow from Saola has not ripped Dermey apart.
Damrey is still hanging on and both will be a heavy rain and wind event for China which is not good.
Member Since: March 16, 2012 Posts: 127 Comments: 7948
Quoting wxchaser97:


Bearing 340, Is that the heading of 99L?
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Houston-Galveston forecast discussion:

FOCUS IS TURNING MORE TO THE TROPICS AS A CAPE VERDE WAVE LOCATED AROUND 45W TRAVELS INTO THE LESSER ANTILLES BY DAY 3. TPC HAS GIVEN THIS WAVE A DECENT CHANCE TO ORGANIZE INTO A TC. GIVEN THAT OUR ONGOING RIDGE WILL MOST LIKELY STILL BE A DOMINANT FEATURE...THE THREAT TO OUR COAST IS MINIMAL. AS THE RIDGE WILL SLIGHTLY WEAKEN AND THE AFOREMENTIONED EASTERN US/GULF TROF (OR BOUNDARY) WILL COME INTO PLAY...THIS MAY PROVIDE A MORE N-NE STEERING MECHANISM. IF THIS WAVE DOES EVOLVE...ANOTHER PATH WOULD BE UNDER GULF RIDGING...STEERED NEAR DUE WEST TOWARDS THE YUCATAN PENINSULA/BAY THIS TIME NEXT WEEK. NWP DOES NOT DO MUCH WITH THIS WAVE...BARELY DISCERNIBLE BY EARLY IN THE WEEK. IT DOES BEAR NOTE THAT BOTH THE GFS AND ECMWF LEAN TOWARDS A MORE ACTIVE GULF (QPF- WISE). THE EURO IS THE AGGRESSOR ON DEVELOPING AN UPPER-LEVEL INVERTED TROF OVER THE TEXAS COAST BY DAY 7 OR 8. IT`S GETTING TO BE THAT TIME OF YEAR AGAIN...
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Quoting Articuno:

It's connected to Damrey..

I hate to tell you but it's not.


Typhoon Saola
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Quoting Levi32:


It looks fine except the western and southwestern side. The ITCZ is still a big part of its life, and it is not obvious yet whether there are northerly and northwesterly winds to make a completely closed circulation. It's not fully detached from the ITCZ yet.
thanks for the tidbit levi. long term wise, whats the chance it goes around the ridge and heads northwestward around the high towards texas/lousiana? you didnt mention that as a possibility and if it is stronger would it take a more northward track like the HWRF is showing? thanks
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Quoting wxchaser97:
AL, 99, 2012080112, , BEST, 0, 107N, 469W, 30, 1009, LO, 34, NEQ, 0, 0, 0, 0, 1012, 150, 50, 0, 0, L, 0, , 0, 0, INVEST, M,
30knots= ~35mph

duh
Member Since: June 13, 2009 Posts: 2 Comments: 12138

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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.