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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Gonna leave with this.

6z HWRF

Member Since: June 9, 2007 Posts: 4 Comments: 15921
Quoting AussieStorm:
WPAC in 48hrs


That's not Typhoon Saola either.

Then what is it...?
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84. 7544
mornin i dont think anyone knows where 99l will go till it becomes a storm its all a guessing game right now just have to wait and watch this one imo
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Quoting hurricanejunky:
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.

See? Doc M referred to 99L as a Cape Verde type storm too, so there!


That's what I mentioned this am; a little early for a CV system but here it is. The Dr. makes a very good scientific case for limited short-term potential based on current conditions/climatology for this time of the year but I think it has a chance at hurricane status if it retains a nice surrounding moisture feild to fight off any dry air and fires up more convection near the center of the low over the next 72 hours.
Member Since: August 8, 2006 Posts: 0 Comments: 9264
Quoting kwgirl:
I would love to see this turn into a storm in the gulf headed for Tampa. I want to see those conventioneers scream like scared little girls and run! Not that I am wishing anything on Tampa. Just the hint of the storm would probably cause a lot of people to change their drawers LOL.
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.
Member Since: August 14, 2010 Posts: 10 Comments: 17156
Quoting washingtonian115:
All 99L needs to do is close off it's circulation and we could have T.D 5.

it has one

Quoting Chicklit:


yes, as it goes west.

and to the N it is droping as well
Member Since: June 13, 2009 Posts: 2 Comments: 12180
Quoting kwgirl:
I would love to see this turn into a storm in the gulf headed for Tampa. I want to see those conventioneers scream like scared little girls and run! Not that I am wishing anything on Tampa. Just the hint of the storm would probably cause a lot of people to change their drawers LOL.
..LOL that would be funny huh...our last hurricane here was in 1934..Tampa is pretty safe so far
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Quoting wunderkidcayman:

shear is droping around 99L!!!!


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...

Member Since: July 15, 2006 Posts: 17 Comments: 10284
Quoting MississippiWx:


Oh, and have a look for yourself.

Link



yes it seems to be consolidating a bit but not quite up to a well defined LLC.
It has plenty of time anyway

Seems to have just started rolling up...
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Quoting wunderkidcayman:

shear is dropping around 99L!!!!


yes, as it goes west.
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WPAC in 48hrs


That's not Typhoon Saola either.
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99L Dvorak


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Did a blog update myself on the Atlantic tropics early this morning...including in-depth look at CMC vs GFS solutions on 99L...
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Quoting Jrrtrollkien:
"The local Distributor keeps me in FRESCA, so yeah, Im cool."

You realize of course, they are in cahoots with the denture distributors?


Fresca is sugar free.

Edit: though some bloggers may know otherwise.

"In Latin America, Coca-Cola markets an entirely different soft drink under the Fresca brand name. This drink is grapefruit-flavored, but contains sugar. Colombia is the only country in which this drink is distributed with the name Quatro using Fresca's same colors, logos and stickers."
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All 99L needs to do is close off it's circulation and we could have T.D 5.
Member Since: August 14, 2010 Posts: 10 Comments: 17156
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!

shear is droping around 99L!!!!
Member Since: June 13, 2009 Posts: 2 Comments: 12180
Quoting LargoFl:
..yes so far but too early to tell...we here in tampa bay will be recieving 600 thousand people here this month for the republican convention, some advance people are already here, and so far no one is cancelling..and the gulf coast of florida should be ok even if it does goes into the gulf..this time of year we just have to be careful and listen to the updates..just in case
I would love to see this turn into a storm in the gulf headed for Tampa. I want to see those conventioneers scream like scared little girls and run! Not that I am wishing anything on Tampa. Just the hint of the storm would probably cause a lot of people to change their drawers LOL.
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Experimental higher resolution GFS from yesterday afternoon.



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Quoting wunderkidcayman:


nope I just looked at the rgb floater loop at first I thought yeah but when I zoomed in I saw that was just the Northern rainband the center of circulation is S under the convection near 10.7N 47.0W its is very vell defined that which you saw was just the Northern rainband simple


Lol. Nothing would support it being south of there. It is partially exposed, my friend.
Member Since: July 15, 2006 Posts: 17 Comments: 10284
Quoting Pocamocca:
Anyone notice the developing feature south of Hispaniola?? Speed up the loop.

Link
some people disagree with me but I for one am watching that one as well
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8am SHIPS intensity down but HWRF to CAT-1/2!

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Beneath a lover's moon I'm waiting
I am the pilot of the storm - adrift in pleasure I may drown
I built this ship - it is my making
And furthermore my self control I can't rely on anymore




99L Long Floater - RGB Color Imagery Loop

click for Loop dee Loop

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Quoting hydrus:
If shear does not keep this system in check so to speak, our part of the world will have a dangerous storm to deal with.
It's all a wait watch and see situation hydrus.I'm nervous as well.And I don't even live anywhere where the storm might make an impact.
Member Since: August 14, 2010 Posts: 10 Comments: 17156
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.

Member Since: June 9, 2007 Posts: 4 Comments: 15921
...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!
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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.



nope I just looked at the rgb floater loop at first I thought yeah but when I zoomed in I saw that was just the Northern rainband the center of circulation is S under the convection near 10.7N 47.0W its is very vell defined that which you saw was just the Northern rainband simple
Member Since: June 13, 2009 Posts: 2 Comments: 12180
Quoting SFLWeatherman:
Not to bad!:)

If shear does not keep this system in check so to speak, our part of the world will have a dangerous storm to deal with.
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Quoting MississippiWx:


Just like you always have to ram disagreement down ours. :-)

Forreal.
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06Z GFDL is not even initializing the 99L LOL

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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.
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Vis Loop
Member Since: July 15, 2006 Posts: 17 Comments: 10284
Quoting hurricanejunky:
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.

See? Doc M referred to 99L as a Cape Verde type storm too, so there!


I thought if the origin of the wave is Cape Verde then you can't take the CV out of the storm even if it doesn't develop until after 50W.
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Quoting MississippiWx:


Just like you always have to ram disagreement down ours. :-)


well i mostly agree with dr. masters for now so thats a start :)
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Quoting washingtonian115:
:(.
..saved ya huh LOL
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Quoting GeorgiaStormz:


I agree with dr masters, its there but very very weak and not so consolidated.

Mississipi weather always rams 'dis RAMSDIS down our throat :) jk


Oh, and have a look for yourself.

Link
Member Since: July 15, 2006 Posts: 17 Comments: 10284
One of these things is not like the other...

Member Since: June 9, 2007 Posts: 4 Comments: 15921
Quoting washingtonian115:
It will be interesting to see the NHC's track for sure when they start issuing advisories.
and they probably wont until it becomes a depression huh..they are waiting to see IF it does keep developing
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Quoting LargoFl:
:(.
Member Since: August 14, 2010 Posts: 10 Comments: 17156
Quoting GeorgiaStormz:


I agree with dr masters, its there but very very weak and not so consolidated.

Mississipi weather always rams 'dis RAMSDIS down our throat


Just like you always have to ram disagreement down ours. :-)
Member Since: July 15, 2006 Posts: 17 Comments: 10284
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.



I agree with dr masters, its there but very very weak and not so consolidated.

Mississipi weather always rams 'dis RAMSDIS down our throats :) jk
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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.
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01/1145 UTC 9.3N 45.1W T1.5/1.5 99L -- Atlantic
01/0901 UTC 30.8N 129.7E T4.0/4.0 DAMREY -- West Pacific
01/0832 UTC 23.8N 123.0E T4.5/5.0 SAOLA -- West Pacific
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It will be interesting to see the NHC's track for sure when they start issuing advisories.
Member Since: August 14, 2010 Posts: 10 Comments: 17156
Not to bad!:)

Member Since: May 23, 2012 Posts: 0 Comments: 4716

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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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