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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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: 12716
Quoting MississippiWx:
Going to have to disagree with the Doc about satellite not showing a well-defined center. It's easy to see on RAMSDIS visible loops, just on the edge of the convection on the north side.

Excellent! Our first catch of the day!
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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
Member Since: March 16, 2012 Posts: 127 Comments: 7972
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.
Member Since: July 6, 2010 Posts: 113 Comments: 32813
Quoting LargoFl:
..dunno about that


Major global models..
Member Since: August 19, 2006 Posts: 13 Comments: 16226
Great job Levi. I always enjoy your analysis.I hope you're right and that this storm will struggle throughout it's lifetime.
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Quoting MississippiWx:
Yeah, with every visible loop frame that passes, I have to scratch my head how anyone thinks 99L doesn't have a well-defined circulation.


Sure doesn't get any more classic than this. Characteristic "S" shape commonly found in developing cyclones.

Member Since: August 19, 2005 Posts: 5 Comments: 5458
Quoting ncstorm:


models are trending north..


yes,I note that and i think will shift a little more to the north when gain strength
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Nice job Levi!

Agree for the most part.

Here's the link to the new (and fairly impressive) Barbados radar.
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Quoting MississippiWx:
Yeah, with every visible loop frame that passes, I have to scratch my head how anyone thinks 99L doesn't have a well-defined circulation.


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.
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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.
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This is the 6z GFS Ensemble Spread..you got the GOM and you got the East Coast after the islands..which shall it be?

Member Since: August 19, 2006 Posts: 13 Comments: 16226
Quoting wxchaser97:
There are two typhoons ready to hit China
I'm surprised the out flow from Saola has not ripped Dermey apart.
Member Since: August 14, 2010 Posts: 10 Comments: 17808
Quoting TropicalAnalystwx13:

From this mess, I'm guessing?


Yep. that mess is actually called 99W

They have labelled it wrong
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IMO this WV loop indicates that dry air should not be a problem for 99L. The convection currently approaching the southern Lesser Antilles is acting to moisten the atmosphere in front of 99L, and also appears to be blocking unfavorable wind shear from reaching 99L.
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Quoting washingtonian115:
People in Tampa feel as though a hurricane can't touch them.Those people are so ignorant when it comes to hurricanes it's not even funny.


I don't think all people in Tampa think they are immune from a hit, but there are those that have been lulled into a false sense of security. But, we do have those shields that we turn on when a storm threatens . . . and for years they have been working out quite well.
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There are two typhoons ready to hit China
Member Since: March 16, 2012 Posts: 127 Comments: 7972
Quoting ncstorm:


models are trending north..
..dunno about that
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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.



Was wondering why it never strengthened it much and then showed it weakening.
Member Since: July 6, 2010 Posts: 113 Comments: 32813
The surface circulation is pretty obvious.
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Quoting aspectre:
1August12amGMT's 9.3n39.6w - 9.5n41.3w - 9.7n43.0w was re-evaluated&altered to
1August06amGMT's 9.3n39.8w - 9.4n41.4w - 9.6n42.8w - 9.7n44.0w which was re-evaluated&altered to
1August12pmGMT's 9.3n39.8w - 9.4n41.4w - 9.6n43.1w - 9.9n45.0w - 10.2n47.0w as the most recent positions
Derived from (NHC) ATCF data for 99L for 1August12pmGMT:
MinimumPressure had held at 1009millibars
MaximumSustainedWinds had held at 25knots(29mph)46km/h
Its vector changed from 279.2°West at 21.9mph(35.2km/h) to 278.8°West at 23mph(37km/h)

For those who like to visually track 99L's path...
SLU is SaintLucia :: BGI is Barbados :: CRU is Carriacou :: GND is Grenada :: TAB is Tobago

The Easternmost dot on the connected line-segments is where 99L became a LOw
The Easternmost dot on the longest line is 99L's most recent position

The longest line is a straightline projection through 99L's 2 most recent positions to a coastline.
On 1August12pmGMT, 99L was headed toward passing over FortJeudy,Grenada in ~1day17hours from now

Copy&paste axa, slu, bgi, cru, gnd, tab, 9.3n39.8w-9.4n41.4w, 9.4n41.4w-9.6n43.1w, 9.6n43.1w-9.9n45.0w, 9.9n45.0w-10.2n47.0w, 9.9n45.0w-12n61.707w into the GreatCircleMapper for more information
The previous mapping for comparison.


umm winds increased to 30kt
Member Since: June 13, 2009 Posts: 2 Comments: 12716
I'm a tad blue today myself,

.. but it's getting better all the time.
Member Since: July 3, 2005 Posts: 428 Comments: 129838
...hmmm watch the water vapor loop til the end
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Quoting TropicalAnalystwx13:

From this mess, I'm guessing?


It's connected to Damrey..
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Quoting LargoFl:


models are trending north..
Member Since: August 19, 2006 Posts: 13 Comments: 16226
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.



My path's is like TVCN's.
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Quoting MississippiWx:


If by north of 99L, you mean way up at 50N.


well that is because you are only looking at the blue lines but you need to keep an eye one the colour change in the background right now it is in that small blue area between that blue line area at 50W and the orange and yellow bit to its N E and S before that N side had little blue more yellow and oranges and even reds now red is gone orange has retreated N and yellow doing the same with blue expanding
Member Since: June 13, 2009 Posts: 2 Comments: 12716
Quoting washingtonian115:
People in Tampa feel as though a hurricane can't touch them.Those people are so ignorant when it comes to hurricanes it's not even funny.
...LOL not ignorant, its just a matter of fact that this time of year..UNLESS a hurricane strikes east coast florida and comes across state to us..when a storm goes into the gulf..it usually goes to texas or the mid gulf coast..most times...we here do get some of the outer effects, some wind and lots of rain yes..and I have said before...I-75 north if this changes LOL
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Quoting washingtonian115:
People in Tampa feel as though a hurricane can't touch them.Those people are so ignorant when it comes to hurricanes it's not even funny.


Well, that might be a tad bit of a generalization :)
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Remember Wunderkidcayman is forecasting a cat four in the N.W caribbean.
So if it happens he called it first.Lol.All though I highly doubt...
Member Since: August 14, 2010 Posts: 10 Comments: 17808
Quoting washingtonian115:
Remember the last one..they had to shorten it because Gustav was threatening the Gulf coast...
And they think they can run the country because?????? Sorry, getting off topic. I have looked at 99L and think it will stay south. Watch out ABC's you may get this one.
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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.


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Yeah, with every visible loop frame that passes, I have to scratch my head how anyone thinks 99L doesn't have a well-defined circulation.
Member Since: July 15, 2006 Posts: 17 Comments: 10284
Good morning.

Blog update:

Tropical Tidbit for Wednesday, August 1st, with Video
Member Since: Posts: Comments:
1August12amGMT's 9.3n39.6w - 9.5n41.3w - 9.7n43.0w was re-evaluated&altered to
1August06amGMT's 9.3n39.8w - 9.4n41.4w - 9.6n42.8w - 9.7n44.0w which was re-evaluated&altered to
1August12pmGMT's 9.3n39.8w - 9.4n41.4w - 9.6n43.1w - 9.9n45.0w - 10.2n47.0w as the most recent positions
Derived from (NHC) ATCF data for 99L for 1August12pmGMT:
MinimumPressure had held at 1009millibars
MaximumSustainedWinds had increased from 25knots(29mph)46km/h to 30knots(35mph)56km/h
Its vector changed from 279.2*West at 21.9mph(35.2km/h) to 278.8*West at 23mph(37km/h)

For those who like to visually track 99L's path...
SLU is SaintLucia :: BGI is Barbados :: CRU is Carriacou :: GND is Grenada :: TAB is Tobago

The Easternmost dot on the connected line-segments is where 99L became a LOw
The Easternmost dot on the longest line is 99L's most recent position

The longest line is a straightline projection through 99L's 2 most recent positions to a coastline.
On 1August12pmGMT, 99L was headed toward passing over FortJeudy,Grenada in ~1day17hours from now

Copy&paste axa, slu, bgi, cru, gnd, tab, 9.3n39.8w-9.4n41.4w, 9.4n41.4w-9.6n43.1w, 9.6n43.1w-9.9n45.0w, 9.9n45.0w-10.2n47.0w, 9.9n45.0w-12n61.707w into the GreatCircleMapper for more information
The previous mapping for comparison.
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Quoting AussieStorm:

It's another typhoon.

From this mess, I'm guessing?

Member Since: July 6, 2010 Posts: 113 Comments: 32813
Quoting TropicalAnalystwx13:

Lol. You're about to get yelled at.


Lol. Wouldn't be the first time and won't be the last. I'm just in a sarcastic mood this morning.
Member Since: July 15, 2006 Posts: 17 Comments: 10284
Quoting kwgirl:
Yeah, we kinda have that mindset here in the Keys. But any company, corporation, entity who schedules soemthing in Florida during Hurricane season without a second option, well, let's say they need their heads examined. It's almost like the brides who book outdoor weddings and then are saddened and sometimes furious that it is raining on their day! Mother Nature has a twisted sense of humor at times.
Remember the last one..they had to shorten it because Gustav was threatening the Gulf coast...
Member Since: August 14, 2010 Posts: 10 Comments: 17808
99L will prolly be a slow developer.
Dr. M's "Forecast for 99L" (above) pretty much sums it up.
Although we can watch every moment of its struggle here!
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Quoting Stormchaser2007:
Gonna be a wait and see kind of day.

It could go either way for now.

Really not liking the dry air/increased shear combo.

There is moisture for 99 to work with.
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Quoting TropicalAnalystwx13:

Then what is it...?

It's another typhoon.
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Quoting MississippiWx:


I bet your blog handle spits that one out automatically now. Kind of like an auto-response, but just a different invest/storm name every time. Lol.

Dropping shear is debatable...


Lol. You're about to get yelled at.
Member Since: July 6, 2010 Posts: 113 Comments: 32813
Quoting washingtonian115:
People in Tampa feel as though a hurricane can't touch them.Those people are so ignorant when it comes to hurricanes it's not even funny.
Yeah, we kinda have that mindset here in the Keys. But any company, corporation, entity who schedules something in Florida during Hurricane season without a second option, well, let's say they need their heads examined. It's almost like the brides who book outdoor weddings and then are saddened and sometimes furious that it is raining on their day! Mother Nature has a twisted sense of humor at times.
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Quoting TropicalAnalystwx13:

Then what is it...?
Another Typhoon!.
Member Since: August 14, 2010 Posts: 10 Comments: 17808
Blog update!
Tropical Disturbance 99L a threat to develop - 8/1/12
Member Since: July 8, 2005 Posts: 259 Comments: 24574
GFS 48hrs.... 99L enters stage right.


GFS 174hrs....
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Quoting wunderkidcayman:

it has one


and and to the N it is droping as well


If by north of 99L, you mean way up at 50N.

Member Since: July 15, 2006 Posts: 17 Comments: 10284
Quoting Chicklit:
...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. -- JM

Check out the shear to its north!


Yes, but is matter of hours for the wind shear start to fall, the Jet stream will weakening
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Gonna leave with this.

6z HWRF

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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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